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gnu/gcc.git/ab7c7b46c35ed1be68d4c020a2f20ee96f68b64b/./libphobos/libdruntime/core/thread.d
blob: fb5f942e551ada32cb70b81a10f85134e04d9da4 [file]
/**
* The thread module provides support for thread creation and management.
*
* Copyright: Copyright Sean Kelly 2005 - 2012.
* License: Distributed under the
* $(LINK2 http://www.boost.org/LICENSE_1_0.txt, Boost Software License 1.0).
* (See accompanying file LICENSE)
* Authors: Sean Kelly, Walter Bright, Alex Rønne Petersen, Martin Nowak
* Source: $(DRUNTIMESRC core/_thread.d)
*/
/* NOTE: This file has been patched from the original DMD distribution to
* work with the GDC compiler.
*/
module core.thread;
public import core.time; // for Duration
import core.exception : onOutOfMemoryError;
version (OSX)
version = Darwin;
else version (iOS)
version = Darwin;
else version (TVOS)
version = Darwin;
else version (WatchOS)
version = Darwin;
private
{
// interface to rt.tlsgc
import core.internal.traits : externDFunc;
alias rt_tlsgc_init = externDFunc!("rt.tlsgc.init", void* function() nothrow @nogc);
alias rt_tlsgc_destroy = externDFunc!("rt.tlsgc.destroy", void function(void*) nothrow @nogc);
alias ScanDg = void delegate(void* pstart, void* pend) nothrow;
alias rt_tlsgc_scan =
externDFunc!("rt.tlsgc.scan", void function(void*, scope ScanDg) nothrow);
alias rt_tlsgc_processGCMarks =
externDFunc!("rt.tlsgc.processGCMarks", void function(void*, scope IsMarkedDg) nothrow);
}
version (Solaris)
{
import core.sys.solaris.sys.priocntl;
import core.sys.solaris.sys.types;
}
version (GNU)
{
import gcc.builtins;
version (GNU_StackGrowsDown)
version = StackGrowsDown;
}
else
{
// this should be true for most architectures
version = StackGrowsDown;
}
/**
* Returns the process ID of the calling process, which is guaranteed to be
* unique on the system. This call is always successful.
*
* Example:
* ---
* writefln("Current process id: %s", getpid());
* ---
*/
version (Posix)
{
alias getpid = core.sys.posix.unistd.getpid;
}
else version (Windows)
{
alias getpid = core.sys.windows.windows.GetCurrentProcessId;
}
///////////////////////////////////////////////////////////////////////////////
// Thread and Fiber Exceptions
///////////////////////////////////////////////////////////////////////////////
/**
* Base class for thread exceptions.
*/
class ThreadException : Exception
{
@safe pure nothrow this(string msg, string file = __FILE__, size_t line = __LINE__, Throwable next = null)
{
super(msg, file, line, next);
}
@safe pure nothrow this(string msg, Throwable next, string file = __FILE__, size_t line = __LINE__)
{
super(msg, file, line, next);
}
}
/**
* Base class for thread errors to be used for function inside GC when allocations are unavailable.
*/
class ThreadError : Error
{
@safe pure nothrow this(string msg, string file = __FILE__, size_t line = __LINE__, Throwable next = null)
{
super(msg, file, line, next);
}
@safe pure nothrow this(string msg, Throwable next, string file = __FILE__, size_t line = __LINE__)
{
super(msg, file, line, next);
}
}
private
{
import core.atomic, core.memory, core.sync.mutex;
// Handling unaligned mutexes are not supported on all platforms, so we must
// ensure that the address of all shared data are appropriately aligned.
import core.internal.traits : classInstanceAlignment;
enum mutexAlign = classInstanceAlignment!Mutex;
enum mutexClassInstanceSize = __traits(classInstanceSize, Mutex);
//
// exposed by compiler runtime
//
extern (C) void rt_moduleTlsCtor();
extern (C) void rt_moduleTlsDtor();
/**
* Hook for whatever EH implementation is used to save/restore some data
* per stack.
*
* Params:
* newContext = The return value of the prior call to this function
* where the stack was last swapped out, or null when a fiber stack
* is switched in for the first time.
*/
extern(C) void* _d_eh_swapContext(void* newContext) nothrow @nogc;
version (DigitalMars)
{
version (Windows)
alias swapContext = _d_eh_swapContext;
else
{
extern(C) void* _d_eh_swapContextDwarf(void* newContext) nothrow @nogc;
void* swapContext(void* newContext) nothrow @nogc
{
/* Detect at runtime which scheme is being used.
* Eventually, determine it statically.
*/
static int which = 0;
final switch (which)
{
case 0:
{
assert(newContext == null);
auto p = _d_eh_swapContext(newContext);
auto pdwarf = _d_eh_swapContextDwarf(newContext);
if (p)
{
which = 1;
return p;
}
else if (pdwarf)
{
which = 2;
return pdwarf;
}
return null;
}
case 1:
return _d_eh_swapContext(newContext);
case 2:
return _d_eh_swapContextDwarf(newContext);
}
}
}
}
else
alias swapContext = _d_eh_swapContext;
}
///////////////////////////////////////////////////////////////////////////////
// Thread Entry Point and Signal Handlers
///////////////////////////////////////////////////////////////////////////////
version (Windows)
{
private
{
import core.stdc.stdint : uintptr_t; // for _beginthreadex decl below
import core.stdc.stdlib; // for malloc, atexit
import core.sys.windows.windows;
import core.sys.windows.threadaux; // for OpenThreadHandle
extern (Windows) alias btex_fptr = uint function(void*);
extern (C) uintptr_t _beginthreadex(void*, uint, btex_fptr, void*, uint, uint*) nothrow;
//
// Entry point for Windows threads
//
extern (Windows) uint thread_entryPoint( void* arg ) nothrow
{
Thread obj = cast(Thread) arg;
assert( obj );
assert( obj.m_curr is &obj.m_main );
obj.m_main.bstack = getStackBottom();
obj.m_main.tstack = obj.m_main.bstack;
obj.m_tlsgcdata = rt_tlsgc_init();
Thread.setThis(obj);
Thread.add(obj);
scope (exit)
{
Thread.remove(obj);
}
Thread.add(&obj.m_main);
// NOTE: No GC allocations may occur until the stack pointers have
// been set and Thread.getThis returns a valid reference to
// this thread object (this latter condition is not strictly
// necessary on Windows but it should be followed for the
// sake of consistency).
// TODO: Consider putting an auto exception object here (using
// alloca) forOutOfMemoryError plus something to track
// whether an exception is in-flight?
void append( Throwable t )
{
if ( obj.m_unhandled is null )
obj.m_unhandled = t;
else
{
Throwable last = obj.m_unhandled;
while ( last.next !is null )
last = last.next;
last.next = t;
}
}
version (D_InlineAsm_X86)
{
asm nothrow @nogc { fninit; }
}
try
{
rt_moduleTlsCtor();
try
{
obj.run();
}
catch ( Throwable t )
{
append( t );
}
rt_moduleTlsDtor();
}
catch ( Throwable t )
{
append( t );
}
return 0;
}
HANDLE GetCurrentThreadHandle() nothrow @nogc
{
const uint DUPLICATE_SAME_ACCESS = 0x00000002;
HANDLE curr = GetCurrentThread(),
proc = GetCurrentProcess(),
hndl;
DuplicateHandle( proc, curr, proc, &hndl, 0, TRUE, DUPLICATE_SAME_ACCESS );
return hndl;
}
}
}
else version (Posix)
{
private
{
import core.stdc.errno;
import core.sys.posix.semaphore;
import core.sys.posix.stdlib; // for malloc, valloc, free, atexit
import core.sys.posix.pthread;
import core.sys.posix.signal;
import core.sys.posix.time;
version (Darwin)
{
import core.sys.darwin.mach.thread_act;
import core.sys.darwin.pthread : pthread_mach_thread_np;
}
//
// Entry point for POSIX threads
//
extern (C) void* thread_entryPoint( void* arg ) nothrow
{
version (Shared)
{
import rt.sections;
Thread obj = cast(Thread)(cast(void**)arg)[0];
auto loadedLibraries = (cast(void**)arg)[1];
.free(arg);
}
else
{
Thread obj = cast(Thread)arg;
}
assert( obj );
// loadedLibraries need to be inherited from parent thread
// before initilizing GC for TLS (rt_tlsgc_init)
version (Shared) inheritLoadedLibraries(loadedLibraries);
assert( obj.m_curr is &obj.m_main );
obj.m_main.bstack = getStackBottom();
obj.m_main.tstack = obj.m_main.bstack;
obj.m_tlsgcdata = rt_tlsgc_init();
atomicStore!(MemoryOrder.raw)(obj.m_isRunning, true);
Thread.setThis(obj); // allocates lazy TLS (see Issue 11981)
Thread.add(obj); // can only receive signals from here on
scope (exit)
{
Thread.remove(obj);
atomicStore!(MemoryOrder.raw)(obj.m_isRunning, false);
}
Thread.add(&obj.m_main);
static extern (C) void thread_cleanupHandler( void* arg ) nothrow @nogc
{
Thread obj = cast(Thread) arg;
assert( obj );
// NOTE: If the thread terminated abnormally, just set it as
// not running and let thread_suspendAll remove it from
// the thread list. This is safer and is consistent
// with the Windows thread code.
atomicStore!(MemoryOrder.raw)(obj.m_isRunning,false);
}
// NOTE: Using void to skip the initialization here relies on
// knowledge of how pthread_cleanup is implemented. It may
// not be appropriate for all platforms. However, it does
// avoid the need to link the pthread module. If any
// implementation actually requires default initialization
// then pthread_cleanup should be restructured to maintain
// the current lack of a link dependency.
static if ( __traits( compiles, pthread_cleanup ) )
{
pthread_cleanup cleanup = void;
cleanup.push( &thread_cleanupHandler, cast(void*) obj );
}
else static if ( __traits( compiles, pthread_cleanup_push ) )
{
pthread_cleanup_push( &thread_cleanupHandler, cast(void*) obj );
}
else
{
static assert( false, "Platform not supported." );
}
// NOTE: No GC allocations may occur until the stack pointers have
// been set and Thread.getThis returns a valid reference to
// this thread object (this latter condition is not strictly
// necessary on Windows but it should be followed for the
// sake of consistency).
// TODO: Consider putting an auto exception object here (using
// alloca) forOutOfMemoryError plus something to track
// whether an exception is in-flight?
void append( Throwable t )
{
if ( obj.m_unhandled is null )
obj.m_unhandled = t;
else
{
Throwable last = obj.m_unhandled;
while ( last.next !is null )
last = last.next;
last.next = t;
}
}
try
{
rt_moduleTlsCtor();
try
{
obj.run();
}
catch ( Throwable t )
{
append( t );
}
rt_moduleTlsDtor();
version (Shared) cleanupLoadedLibraries();
}
catch ( Throwable t )
{
append( t );
}
// NOTE: Normal cleanup is handled by scope(exit).
static if ( __traits( compiles, pthread_cleanup ) )
{
cleanup.pop( 0 );
}
else static if ( __traits( compiles, pthread_cleanup_push ) )
{
pthread_cleanup_pop( 0 );
}
return null;
}
//
// Used to track the number of suspended threads
//
__gshared sem_t suspendCount;
extern (C) void thread_suspendHandler( int sig ) nothrow
in
{
assert( sig == suspendSignalNumber );
}
body
{
void op(void* sp) nothrow
{
// NOTE: Since registers are being pushed and popped from the
// stack, any other stack data used by this function should
// be gone before the stack cleanup code is called below.
Thread obj = Thread.getThis();
assert(obj !is null);
if ( !obj.m_lock )
{
obj.m_curr.tstack = getStackTop();
}
sigset_t sigres = void;
int status;
status = sigfillset( &sigres );
assert( status == 0 );
status = sigdelset( &sigres, resumeSignalNumber );
assert( status == 0 );
version (FreeBSD) obj.m_suspendagain = false;
status = sem_post( &suspendCount );
assert( status == 0 );
sigsuspend( &sigres );
if ( !obj.m_lock )
{
obj.m_curr.tstack = obj.m_curr.bstack;
}
}
// avoid deadlocks on FreeBSD, see Issue 13416
version (FreeBSD)
{
auto obj = Thread.getThis();
if (THR_IN_CRITICAL(obj.m_addr))
{
obj.m_suspendagain = true;
if (sem_post(&suspendCount)) assert(0);
return;
}
}
callWithStackShell(&op);
}
extern (C) void thread_resumeHandler( int sig ) nothrow
in
{
assert( sig == resumeSignalNumber );
}
body
{
}
// HACK libthr internal (thr_private.h) macro, used to
// avoid deadlocks in signal handler, see Issue 13416
version (FreeBSD) bool THR_IN_CRITICAL(pthread_t p) nothrow @nogc
{
import core.sys.posix.config : c_long;
import core.sys.posix.sys.types : lwpid_t;
// If the begin of pthread would be changed in libthr (unlikely)
// we'll run into undefined behavior, compare with thr_private.h.
static struct pthread
{
c_long tid;
static struct umutex { lwpid_t owner; uint flags; uint[2] ceilings; uint[4] spare; }
umutex lock;
uint cycle;
int locklevel;
int critical_count;
// ...
}
auto priv = cast(pthread*)p;
return priv.locklevel > 0 || priv.critical_count > 0;
}
}
}
else
{
// NOTE: This is the only place threading versions are checked. If a new
// version is added, the module code will need to be searched for
// places where version-specific code may be required. This can be
// easily accomlished by searching for 'Windows' or 'Posix'.
static assert( false, "Unknown threading implementation." );
}
///////////////////////////////////////////////////////////////////////////////
// Thread
///////////////////////////////////////////////////////////////////////////////
/**
* This class encapsulates all threading functionality for the D
* programming language. As thread manipulation is a required facility
* for garbage collection, all user threads should derive from this
* class, and instances of this class should never be explicitly deleted.
* A new thread may be created using either derivation or composition, as
* in the following example.
*/
class Thread
{
///////////////////////////////////////////////////////////////////////////
// Initialization
///////////////////////////////////////////////////////////////////////////
/**
* Initializes a thread object which is associated with a static
* D function.
*
* Params:
* fn = The thread function.
* sz = The stack size for this thread.
*
* In:
* fn must not be null.
*/
this( void function() fn, size_t sz = 0 ) @safe pure nothrow @nogc
in
{
assert( fn );
}
body
{
this(sz);
() @trusted { m_fn = fn; }();
m_call = Call.FN;
m_curr = &m_main;
}
/**
* Initializes a thread object which is associated with a dynamic
* D function.
*
* Params:
* dg = The thread function.
* sz = The stack size for this thread.
*
* In:
* dg must not be null.
*/
this( void delegate() dg, size_t sz = 0 ) @safe pure nothrow @nogc
in
{
assert( dg );
}
body
{
this(sz);
() @trusted { m_dg = dg; }();
m_call = Call.DG;
m_curr = &m_main;
}
/**
* Cleans up any remaining resources used by this object.
*/
~this() nothrow @nogc
{
if ( m_addr == m_addr.init )
{
return;
}
version (Windows)
{
m_addr = m_addr.init;
CloseHandle( m_hndl );
m_hndl = m_hndl.init;
}
else version (Posix)
{
pthread_detach( m_addr );
m_addr = m_addr.init;
}
version (Darwin)
{
m_tmach = m_tmach.init;
}
rt_tlsgc_destroy( m_tlsgcdata );
m_tlsgcdata = null;
}
///////////////////////////////////////////////////////////////////////////
// General Actions
///////////////////////////////////////////////////////////////////////////
/**
* Starts the thread and invokes the function or delegate passed upon
* construction.
*
* In:
* This routine may only be called once per thread instance.
*
* Throws:
* ThreadException if the thread fails to start.
*/
final Thread start() nothrow
in
{
assert( !next && !prev );
}
body
{
auto wasThreaded = multiThreadedFlag;
multiThreadedFlag = true;
scope( failure )
{
if ( !wasThreaded )
multiThreadedFlag = false;
}
version (Windows) {} else
version (Posix)
{
pthread_attr_t attr;
if ( pthread_attr_init( &attr ) )
onThreadError( "Error initializing thread attributes" );
if ( m_sz && pthread_attr_setstacksize( &attr, m_sz ) )
onThreadError( "Error initializing thread stack size" );
}
version (Windows)
{
// NOTE: If a thread is just executing DllMain()
// while another thread is started here, it holds an OS internal
// lock that serializes DllMain with CreateThread. As the code
// might request a synchronization on slock (e.g. in thread_findByAddr()),
// we cannot hold that lock while creating the thread without
// creating a deadlock
//
// Solution: Create the thread in suspended state and then
// add and resume it with slock acquired
assert(m_sz <= uint.max, "m_sz must be less than or equal to uint.max");
m_hndl = cast(HANDLE) _beginthreadex( null, cast(uint) m_sz, &thread_entryPoint, cast(void*) this, CREATE_SUSPENDED, &m_addr );
if ( cast(size_t) m_hndl == 0 )
onThreadError( "Error creating thread" );
}
slock.lock_nothrow();
scope(exit) slock.unlock_nothrow();
{
++nAboutToStart;
pAboutToStart = cast(Thread*)realloc(pAboutToStart, Thread.sizeof * nAboutToStart);
pAboutToStart[nAboutToStart - 1] = this;
version (Windows)
{
if ( ResumeThread( m_hndl ) == -1 )
onThreadError( "Error resuming thread" );
}
else version (Posix)
{
// NOTE: This is also set to true by thread_entryPoint, but set it
// here as well so the calling thread will see the isRunning
// state immediately.
atomicStore!(MemoryOrder.raw)(m_isRunning, true);
scope( failure ) atomicStore!(MemoryOrder.raw)(m_isRunning, false);
version (Shared)
{
import rt.sections;
auto libs = pinLoadedLibraries();
auto ps = cast(void**).malloc(2 * size_t.sizeof);
if (ps is null) onOutOfMemoryError();
ps[0] = cast(void*)this;
ps[1] = cast(void*)libs;
if ( pthread_create( &m_addr, &attr, &thread_entryPoint, ps ) != 0 )
{
unpinLoadedLibraries(libs);
.free(ps);
onThreadError( "Error creating thread" );
}
}
else
{
if ( pthread_create( &m_addr, &attr, &thread_entryPoint, cast(void*) this ) != 0 )
onThreadError( "Error creating thread" );
}
}
version (Darwin)
{
m_tmach = pthread_mach_thread_np( m_addr );
if ( m_tmach == m_tmach.init )
onThreadError( "Error creating thread" );
}
return this;
}
}
/**
* Waits for this thread to complete. If the thread terminated as the
* result of an unhandled exception, this exception will be rethrown.
*
* Params:
* rethrow = Rethrow any unhandled exception which may have caused this
* thread to terminate.
*
* Throws:
* ThreadException if the operation fails.
* Any exception not handled by the joined thread.
*
* Returns:
* Any exception not handled by this thread if rethrow = false, null
* otherwise.
*/
final Throwable join( bool rethrow = true )
{
version (Windows)
{
if ( WaitForSingleObject( m_hndl, INFINITE ) != WAIT_OBJECT_0 )
throw new ThreadException( "Unable to join thread" );
// NOTE: m_addr must be cleared before m_hndl is closed to avoid
// a race condition with isRunning. The operation is done
// with atomicStore to prevent compiler reordering.
atomicStore!(MemoryOrder.raw)(*cast(shared)&m_addr, m_addr.init);
CloseHandle( m_hndl );
m_hndl = m_hndl.init;
}
else version (Posix)
{
if ( pthread_join( m_addr, null ) != 0 )
throw new ThreadException( "Unable to join thread" );
// NOTE: pthread_join acts as a substitute for pthread_detach,
// which is normally called by the dtor. Setting m_addr
// to zero ensures that pthread_detach will not be called
// on object destruction.
m_addr = m_addr.init;
}
if ( m_unhandled )
{
if ( rethrow )
throw m_unhandled;
return m_unhandled;
}
return null;
}
///////////////////////////////////////////////////////////////////////////
// General Properties
///////////////////////////////////////////////////////////////////////////
/**
* Gets the OS identifier for this thread.
*
* Returns:
* If the thread hasn't been started yet, returns $(LREF ThreadID)$(D.init).
* Otherwise, returns the result of $(D GetCurrentThreadId) on Windows,
* and $(D pthread_self) on POSIX.
*
* The value is unique for the current process.
*/
final @property ThreadID id() @safe @nogc
{
synchronized( this )
{
return m_addr;
}
}
/**
* Gets the user-readable label for this thread.
*
* Returns:
* The name of this thread.
*/
final @property string name() @safe @nogc
{
synchronized( this )
{
return m_name;
}
}
/**
* Sets the user-readable label for this thread.
*
* Params:
* val = The new name of this thread.
*/
final @property void name( string val ) @safe @nogc
{
synchronized( this )
{
m_name = val;
}
}
/**
* Gets the daemon status for this thread. While the runtime will wait for
* all normal threads to complete before tearing down the process, daemon
* threads are effectively ignored and thus will not prevent the process
* from terminating. In effect, daemon threads will be terminated
* automatically by the OS when the process exits.
*
* Returns:
* true if this is a daemon thread.
*/
final @property bool isDaemon() @safe @nogc
{
synchronized( this )
{
return m_isDaemon;
}
}
/**
* Sets the daemon status for this thread. While the runtime will wait for
* all normal threads to complete before tearing down the process, daemon
* threads are effectively ignored and thus will not prevent the process
* from terminating. In effect, daemon threads will be terminated
* automatically by the OS when the process exits.
*
* Params:
* val = The new daemon status for this thread.
*/
final @property void isDaemon( bool val ) @safe @nogc
{
synchronized( this )
{
m_isDaemon = val;
}
}
/**
* Tests whether this thread is running.
*
* Returns:
* true if the thread is running, false if not.
*/
final @property bool isRunning() nothrow @nogc
{
if ( m_addr == m_addr.init )
{
return false;
}
version (Windows)
{
uint ecode = 0;
GetExitCodeThread( m_hndl, &ecode );
return ecode == STILL_ACTIVE;
}
else version (Posix)
{
return atomicLoad(m_isRunning);
}
}
///////////////////////////////////////////////////////////////////////////
// Thread Priority Actions
///////////////////////////////////////////////////////////////////////////
version (Windows)
{
@property static int PRIORITY_MIN() @nogc nothrow pure @safe
{
return THREAD_PRIORITY_IDLE;
}
@property static const(int) PRIORITY_MAX() @nogc nothrow pure @safe
{
return THREAD_PRIORITY_TIME_CRITICAL;
}
@property static int PRIORITY_DEFAULT() @nogc nothrow pure @safe
{
return THREAD_PRIORITY_NORMAL;
}
}
else
{
private struct Priority
{
int PRIORITY_MIN = int.min;
int PRIORITY_DEFAULT = int.min;
int PRIORITY_MAX = int.min;
}
/*
Lazily loads one of the members stored in a hidden global variable of
type `Priority`. Upon the first access of either member, the entire
`Priority` structure is initialized. Multiple initializations from
different threads calling this function are tolerated.
`which` must be one of `PRIORITY_MIN`, `PRIORITY_DEFAULT`,
`PRIORITY_MAX`.
*/
private static int loadGlobal(string which)()
{
static shared Priority cache;
auto local = atomicLoad(mixin("cache." ~ which));
if (local != local.min) return local;
// There will be benign races
cache = loadPriorities;
return atomicLoad(mixin("cache." ~ which));
}
/*
Loads all priorities and returns them as a `Priority` structure. This
function is thread-neutral.
*/
private static Priority loadPriorities() @nogc nothrow @trusted
{
Priority result;
version (Solaris)
{
pcparms_t pcParms;
pcinfo_t pcInfo;
pcParms.pc_cid = PC_CLNULL;
if (priocntl(idtype_t.P_PID, P_MYID, PC_GETPARMS, &pcParms) == -1)
assert( 0, "Unable to get scheduling class" );
pcInfo.pc_cid = pcParms.pc_cid;
// PC_GETCLINFO ignores the first two args, use dummy values
if (priocntl(idtype_t.P_PID, 0, PC_GETCLINFO, &pcInfo) == -1)
assert( 0, "Unable to get scheduling class info" );
pri_t* clparms = cast(pri_t*)&pcParms.pc_clparms;
pri_t* clinfo = cast(pri_t*)&pcInfo.pc_clinfo;
result.PRIORITY_MAX = clparms[0];
if (pcInfo.pc_clname == "RT")
{
m_isRTClass = true;
// For RT class, just assume it can't be changed
result.PRIORITY_MIN = clparms[0];
result.PRIORITY_DEFAULT = clparms[0];
}
else
{
m_isRTClass = false;
// For all other scheduling classes, there are
// two key values -- uprilim and maxupri.
// maxupri is the maximum possible priority defined
// for the scheduling class, and valid priorities
// range are in [-maxupri, maxupri].
//
// However, uprilim is an upper limit that the
// current thread can set for the current scheduling
// class, which can be less than maxupri. As such,
// use this value for priorityMax since this is
// the effective maximum.
// maxupri
result.PRIORITY_MIN = -clinfo[0];
// by definition
result.PRIORITY_DEFAULT = 0;
}
}
else version (Posix)
{
int policy;
sched_param param;
pthread_getschedparam( pthread_self(), &policy, &param ) == 0
|| assert(0, "Internal error in pthread_getschedparam");
result.PRIORITY_MIN = sched_get_priority_min( policy );
result.PRIORITY_MIN != -1
|| assert(0, "Internal error in sched_get_priority_min");
result.PRIORITY_DEFAULT = param.sched_priority;
result.PRIORITY_MAX = sched_get_priority_max( policy );
result.PRIORITY_MAX != -1 ||
assert(0, "Internal error in sched_get_priority_max");
}
else
{
static assert(0, "Your code here.");
}
return result;
}
/**
* The minimum scheduling priority that may be set for a thread. On
* systems where multiple scheduling policies are defined, this value
* represents the minimum valid priority for the scheduling policy of
* the process.
*/
@property static int PRIORITY_MIN() @nogc nothrow pure @trusted
{
return (cast(int function() @nogc nothrow pure @safe)
&loadGlobal!"PRIORITY_MIN")();
}
/**
* The maximum scheduling priority that may be set for a thread. On
* systems where multiple scheduling policies are defined, this value
* represents the maximum valid priority for the scheduling policy of
* the process.
*/
@property static const(int) PRIORITY_MAX() @nogc nothrow pure @trusted
{
return (cast(int function() @nogc nothrow pure @safe)
&loadGlobal!"PRIORITY_MAX")();
}
/**
* The default scheduling priority that is set for a thread. On
* systems where multiple scheduling policies are defined, this value
* represents the default priority for the scheduling policy of
* the process.
*/
@property static int PRIORITY_DEFAULT() @nogc nothrow pure @trusted
{
return (cast(int function() @nogc nothrow pure @safe)
&loadGlobal!"PRIORITY_DEFAULT")();
}
}
version (NetBSD)
{
//NetBSD does not support priority for default policy
// and it is not possible change policy without root access
int fakePriority = int.max;
}
/**
* Gets the scheduling priority for the associated thread.
*
* Note: Getting the priority of a thread that already terminated
* might return the default priority.
*
* Returns:
* The scheduling priority of this thread.
*/
final @property int priority()
{
version (Windows)
{
return GetThreadPriority( m_hndl );
}
else version (NetBSD)
{
return fakePriority==int.max? PRIORITY_DEFAULT : fakePriority;
}
else version (Posix)
{
int policy;
sched_param param;
if (auto err = pthread_getschedparam(m_addr, &policy, &param))
{
// ignore error if thread is not running => Bugzilla 8960
if (!atomicLoad(m_isRunning)) return PRIORITY_DEFAULT;
throw new ThreadException("Unable to get thread priority");
}
return param.sched_priority;
}
}
/**
* Sets the scheduling priority for the associated thread.
*
* Note: Setting the priority of a thread that already terminated
* might have no effect.
*
* Params:
* val = The new scheduling priority of this thread.
*/
final @property void priority( int val )
in
{
assert(val >= PRIORITY_MIN);
assert(val <= PRIORITY_MAX);
}
body
{
version (Windows)
{
if ( !SetThreadPriority( m_hndl, val ) )
throw new ThreadException( "Unable to set thread priority" );
}
else version (Solaris)
{
// the pthread_setschedprio(3c) and pthread_setschedparam functions
// are broken for the default (TS / time sharing) scheduling class.
// instead, we use priocntl(2) which gives us the desired behavior.
// We hardcode the min and max priorities to the current value
// so this is a no-op for RT threads.
if (m_isRTClass)
return;
pcparms_t pcparm;
pcparm.pc_cid = PC_CLNULL;
if (priocntl(idtype_t.P_LWPID, P_MYID, PC_GETPARMS, &pcparm) == -1)
throw new ThreadException( "Unable to get scheduling class" );
pri_t* clparms = cast(pri_t*)&pcparm.pc_clparms;
// clparms is filled in by the PC_GETPARMS call, only necessary
// to adjust the element that contains the thread priority
clparms[1] = cast(pri_t) val;
if (priocntl(idtype_t.P_LWPID, P_MYID, PC_SETPARMS, &pcparm) == -1)
throw new ThreadException( "Unable to set scheduling class" );
}
else version (NetBSD)
{
fakePriority = val;
}
else version (Posix)
{
static if (__traits(compiles, pthread_setschedprio))
{
if (auto err = pthread_setschedprio(m_addr, val))
{
// ignore error if thread is not running => Bugzilla 8960
if (!atomicLoad(m_isRunning)) return;
throw new ThreadException("Unable to set thread priority");
}
}
else
{
// NOTE: pthread_setschedprio is not implemented on Darwin, FreeBSD, OpenBSD,
// or DragonFlyBSD, so use the more complicated get/set sequence below.
int policy;
sched_param param;
if (auto err = pthread_getschedparam(m_addr, &policy, &param))
{
// ignore error if thread is not running => Bugzilla 8960
if (!atomicLoad(m_isRunning)) return;
throw new ThreadException("Unable to set thread priority");
}
param.sched_priority = val;
if (auto err = pthread_setschedparam(m_addr, policy, &param))
{
// ignore error if thread is not running => Bugzilla 8960
if (!atomicLoad(m_isRunning)) return;
throw new ThreadException("Unable to set thread priority");
}
}
}
}
unittest
{
auto thr = Thread.getThis();
immutable prio = thr.priority;
scope (exit) thr.priority = prio;
assert(prio == PRIORITY_DEFAULT);
assert(prio >= PRIORITY_MIN && prio <= PRIORITY_MAX);
thr.priority = PRIORITY_MIN;
assert(thr.priority == PRIORITY_MIN);
thr.priority = PRIORITY_MAX;
assert(thr.priority == PRIORITY_MAX);
}
unittest // Bugzilla 8960
{
import core.sync.semaphore;
auto thr = new Thread({});
thr.start();
Thread.sleep(1.msecs); // wait a little so the thread likely has finished
thr.priority = PRIORITY_MAX; // setting priority doesn't cause error
auto prio = thr.priority; // getting priority doesn't cause error
assert(prio >= PRIORITY_MIN && prio <= PRIORITY_MAX);
}
///////////////////////////////////////////////////////////////////////////
// Actions on Calling Thread
///////////////////////////////////////////////////////////////////////////
/**
* Suspends the calling thread for at least the supplied period. This may
* result in multiple OS calls if period is greater than the maximum sleep
* duration supported by the operating system.
*
* Params:
* val = The minimum duration the calling thread should be suspended.
*
* In:
* period must be non-negative.
*
* Example:
* ------------------------------------------------------------------------
*
* Thread.sleep( dur!("msecs")( 50 ) ); // sleep for 50 milliseconds
* Thread.sleep( dur!("seconds")( 5 ) ); // sleep for 5 seconds
*
* ------------------------------------------------------------------------
*/
static void sleep( Duration val ) @nogc nothrow
in
{
assert( !val.isNegative );
}
body
{
version (Windows)
{
auto maxSleepMillis = dur!("msecs")( uint.max - 1 );
// avoid a non-zero time to be round down to 0
if ( val > dur!"msecs"( 0 ) && val < dur!"msecs"( 1 ) )
val = dur!"msecs"( 1 );
// NOTE: In instances where all other threads in the process have a
// lower priority than the current thread, the current thread
// will not yield with a sleep time of zero. However, unlike
// yield(), the user is not asking for a yield to occur but
// only for execution to suspend for the requested interval.
// Therefore, expected performance may not be met if a yield
// is forced upon the user.
while ( val > maxSleepMillis )
{
Sleep( cast(uint)
maxSleepMillis.total!"msecs" );
val -= maxSleepMillis;
}
Sleep( cast(uint) val.total!"msecs" );
}
else version (Posix)
{
timespec tin = void;
timespec tout = void;
val.split!("seconds", "nsecs")(tin.tv_sec, tin.tv_nsec);
if ( val.total!"seconds" > tin.tv_sec.max )
tin.tv_sec = tin.tv_sec.max;
while ( true )
{
if ( !nanosleep( &tin, &tout ) )
return;
if ( errno != EINTR )
assert(0, "Unable to sleep for the specified duration");
tin = tout;
}
}
}
/**
* Forces a context switch to occur away from the calling thread.
*/
static void yield() @nogc nothrow
{
version (Windows)
SwitchToThread();
else version (Posix)
sched_yield();
}
///////////////////////////////////////////////////////////////////////////
// Thread Accessors
///////////////////////////////////////////////////////////////////////////
/**
* Provides a reference to the calling thread.
*
* Returns:
* The thread object representing the calling thread. The result of
* deleting this object is undefined. If the current thread is not
* attached to the runtime, a null reference is returned.
*/
static Thread getThis() @safe nothrow @nogc
{
// NOTE: This function may not be called until thread_init has
// completed. See thread_suspendAll for more information
// on why this might occur.
return sm_this;
}
/**
* Provides a list of all threads currently being tracked by the system.
* Note that threads in the returned array might no longer run (see
* $(D Thread.)$(LREF isRunning)).
*
* Returns:
* An array containing references to all threads currently being
* tracked by the system. The result of deleting any contained
* objects is undefined.
*/
static Thread[] getAll()
{
static void resize(ref Thread[] buf, size_t nlen)
{
buf.length = nlen;
}
return getAllImpl!resize();
}
/**
* Operates on all threads currently being tracked by the system. The
* result of deleting any Thread object is undefined.
* Note that threads passed to the callback might no longer run (see
* $(D Thread.)$(LREF isRunning)).
*
* Params:
* dg = The supplied code as a delegate.
*
* Returns:
* Zero if all elemented are visited, nonzero if not.
*/
static int opApply(scope int delegate(ref Thread) dg)
{
import core.stdc.stdlib : free, realloc;
static void resize(ref Thread[] buf, size_t nlen)
{
buf = (cast(Thread*)realloc(buf.ptr, nlen * Thread.sizeof))[0 .. nlen];
}
auto buf = getAllImpl!resize;
scope(exit) if (buf.ptr) free(buf.ptr);
foreach (t; buf)
{
if (auto res = dg(t))
return res;
}
return 0;
}
unittest
{
auto t1 = new Thread({
foreach (_; 0 .. 20)
Thread.getAll;
}).start;
auto t2 = new Thread({
foreach (_; 0 .. 20)
GC.collect;
}).start;
t1.join();
t2.join();
}
private static Thread[] getAllImpl(alias resize)()
{
import core.atomic;
Thread[] buf;
while (true)
{
immutable len = atomicLoad!(MemoryOrder.raw)(*cast(shared)&sm_tlen);
resize(buf, len);
assert(buf.length == len);
synchronized (slock)
{
if (len == sm_tlen)
{
size_t pos;
for (Thread t = sm_tbeg; t; t = t.next)
buf[pos++] = t;
return buf;
}
}
}
}
///////////////////////////////////////////////////////////////////////////
// Stuff That Should Go Away
///////////////////////////////////////////////////////////////////////////
private:
//
// Initializes a thread object which has no associated executable function.
// This is used for the main thread initialized in thread_init().
//
this(size_t sz = 0) @safe pure nothrow @nogc
{
if (sz)
{
version (Posix)
{
// stack size must be a multiple of PAGESIZE
sz += PAGESIZE - 1;
sz -= sz % PAGESIZE;
// and at least PTHREAD_STACK_MIN
if (PTHREAD_STACK_MIN > sz)
sz = PTHREAD_STACK_MIN;
}
m_sz = sz;
}
m_call = Call.NO;
m_curr = &m_main;
}
//
// Thread entry point. Invokes the function or delegate passed on
// construction (if any).
//
final void run()
{
switch ( m_call )
{
case Call.FN:
m_fn();
break;
case Call.DG:
m_dg();
break;
default:
break;
}
}
private:
//
// The type of routine passed on thread construction.
//
enum Call
{
NO,
FN,
DG
}
//
// Standard types
//
version (Windows)
{
alias TLSKey = uint;
}
else version (Posix)
{
alias TLSKey = pthread_key_t;
}
//
// Local storage
//
static Thread sm_this;
//
// Main process thread
//
__gshared Thread sm_main;
version (FreeBSD)
{
// set when suspend failed and should be retried, see Issue 13416
shared bool m_suspendagain;
}
//
// Standard thread data
//
version (Windows)
{
HANDLE m_hndl;
}
else version (Darwin)
{
mach_port_t m_tmach;
}
ThreadID m_addr;
Call m_call;
string m_name;
union
{
void function() m_fn;
void delegate() m_dg;
}
size_t m_sz;
version (Posix)
{
shared bool m_isRunning;
}
bool m_isDaemon;
bool m_isInCriticalRegion;
Throwable m_unhandled;
version (Solaris)
{
__gshared bool m_isRTClass;
}
private:
///////////////////////////////////////////////////////////////////////////
// Storage of Active Thread
///////////////////////////////////////////////////////////////////////////
//
// Sets a thread-local reference to the current thread object.
//
static void setThis( Thread t ) nothrow @nogc
{
sm_this = t;
}
private:
///////////////////////////////////////////////////////////////////////////
// Thread Context and GC Scanning Support
///////////////////////////////////////////////////////////////////////////
final void pushContext( Context* c ) nothrow @nogc
in
{
assert( !c.within );
}
body
{
m_curr.ehContext = swapContext(c.ehContext);
c.within = m_curr;
m_curr = c;
}
final void popContext() nothrow @nogc
in
{
assert( m_curr && m_curr.within );
}
body
{
Context* c = m_curr;
m_curr = c.within;
c.ehContext = swapContext(m_curr.ehContext);
c.within = null;
}
final Context* topContext() nothrow @nogc
in
{
assert( m_curr );
}
body
{
return m_curr;
}
static struct Context
{
void* bstack,
tstack;
/// Slot for the EH implementation to keep some state for each stack
/// (will be necessary for exception chaining, etc.). Opaque as far as
/// we are concerned here.
void* ehContext;
Context* within;
Context* next,
prev;
}
Context m_main;
Context* m_curr;
bool m_lock;
void* m_tlsgcdata;
version (Windows)
{
version (X86)
{
uint[8] m_reg; // edi,esi,ebp,esp,ebx,edx,ecx,eax
}
else version (X86_64)
{
ulong[16] m_reg; // rdi,rsi,rbp,rsp,rbx,rdx,rcx,rax
// r8,r9,r10,r11,r12,r13,r14,r15
}
else
{
static assert(false, "Architecture not supported." );
}
}
else version (Darwin)
{
version (X86)
{
uint[8] m_reg; // edi,esi,ebp,esp,ebx,edx,ecx,eax
}
else version (X86_64)
{
ulong[16] m_reg; // rdi,rsi,rbp,rsp,rbx,rdx,rcx,rax
// r8,r9,r10,r11,r12,r13,r14,r15
}
else
{
static assert(false, "Architecture not supported." );
}
}
private:
///////////////////////////////////////////////////////////////////////////
// GC Scanning Support
///////////////////////////////////////////////////////////////////////////
// NOTE: The GC scanning process works like so:
//
// 1. Suspend all threads.
// 2. Scan the stacks of all suspended threads for roots.
// 3. Resume all threads.
//
// Step 1 and 3 require a list of all threads in the system, while
// step 2 requires a list of all thread stacks (each represented by
// a Context struct). Traditionally, there was one stack per thread
// and the Context structs were not necessary. However, Fibers have
// changed things so that each thread has its own 'main' stack plus
// an arbitrary number of nested stacks (normally referenced via
// m_curr). Also, there may be 'free-floating' stacks in the system,
// which are Fibers that are not currently executing on any specific
// thread but are still being processed and still contain valid
// roots.
//
// To support all of this, the Context struct has been created to
// represent a stack range, and a global list of Context structs has
// been added to enable scanning of these stack ranges. The lifetime
// (and presence in the Context list) of a thread's 'main' stack will
// be equivalent to the thread's lifetime. So the Ccontext will be
// added to the list on thread entry, and removed from the list on
// thread exit (which is essentially the same as the presence of a
// Thread object in its own global list). The lifetime of a Fiber's
// context, however, will be tied to the lifetime of the Fiber object
// itself, and Fibers are expected to add/remove their Context struct
// on construction/deletion.
//
// All use of the global thread lists/array should synchronize on this lock.
//
// Careful as the GC acquires this lock after the GC lock to suspend all
// threads any GC usage with slock held can result in a deadlock through
// lock order inversion.
@property static Mutex slock() nothrow @nogc
{
return cast(Mutex)_slock.ptr;
}
@property static Mutex criticalRegionLock() nothrow @nogc
{
return cast(Mutex)_criticalRegionLock.ptr;
}
__gshared align(mutexAlign) void[mutexClassInstanceSize] _slock;
__gshared align(mutexAlign) void[mutexClassInstanceSize] _criticalRegionLock;
static void initLocks()
{
_slock[] = typeid(Mutex).initializer[];
(cast(Mutex)_slock.ptr).__ctor();
_criticalRegionLock[] = typeid(Mutex).initializer[];
(cast(Mutex)_criticalRegionLock.ptr).__ctor();
}
static void termLocks()
{
(cast(Mutex)_slock.ptr).__dtor();
(cast(Mutex)_criticalRegionLock.ptr).__dtor();
}
__gshared Context* sm_cbeg;
__gshared Thread sm_tbeg;
__gshared size_t sm_tlen;
// can't use rt.util.array in public code
__gshared Thread* pAboutToStart;
__gshared size_t nAboutToStart;
//
// Used for ordering threads in the global thread list.
//
Thread prev;
Thread next;
///////////////////////////////////////////////////////////////////////////
// Global Context List Operations
///////////////////////////////////////////////////////////////////////////
//
// Add a context to the global context list.
//
static void add( Context* c ) nothrow @nogc
in
{
assert( c );
assert( !c.next && !c.prev );
}
body
{
slock.lock_nothrow();
scope(exit) slock.unlock_nothrow();
assert(!suspendDepth); // must be 0 b/c it's only set with slock held
if (sm_cbeg)
{
c.next = sm_cbeg;
sm_cbeg.prev = c;
}
sm_cbeg = c;
}
//
// Remove a context from the global context list.
//
// This assumes slock being acquired. This isn't done here to
// avoid double locking when called from remove(Thread)
static void remove( Context* c ) nothrow @nogc
in
{
assert( c );
assert( c.next || c.prev );
}
body
{
if ( c.prev )
c.prev.next = c.next;
if ( c.next )
c.next.prev = c.prev;
if ( sm_cbeg == c )
sm_cbeg = c.next;
// NOTE: Don't null out c.next or c.prev because opApply currently
// follows c.next after removing a node. This could be easily
// addressed by simply returning the next node from this
// function, however, a context should never be re-added to the
// list anyway and having next and prev be non-null is a good way
// to ensure that.
}
///////////////////////////////////////////////////////////////////////////
// Global Thread List Operations
///////////////////////////////////////////////////////////////////////////
//
// Add a thread to the global thread list.
//
static void add( Thread t, bool rmAboutToStart = true ) nothrow @nogc
in
{
assert( t );
assert( !t.next && !t.prev );
}
body
{
slock.lock_nothrow();
scope(exit) slock.unlock_nothrow();
assert(t.isRunning); // check this with slock to ensure pthread_create already returned
assert(!suspendDepth); // must be 0 b/c it's only set with slock held
if (rmAboutToStart)
{
size_t idx = -1;
foreach (i, thr; pAboutToStart[0 .. nAboutToStart])
{
if (thr is t)
{
idx = i;
break;
}
}
assert(idx != -1);
import core.stdc.string : memmove;
memmove(pAboutToStart + idx, pAboutToStart + idx + 1, Thread.sizeof * (nAboutToStart - idx - 1));
pAboutToStart =
cast(Thread*)realloc(pAboutToStart, Thread.sizeof * --nAboutToStart);
}
if (sm_tbeg)
{
t.next = sm_tbeg;
sm_tbeg.prev = t;
}
sm_tbeg = t;
++sm_tlen;
}
//
// Remove a thread from the global thread list.
//
static void remove( Thread t ) nothrow @nogc
in
{
assert( t );
}
body
{
// Thread was already removed earlier, might happen b/c of thread_detachInstance
if (!t.next && !t.prev)
return;
slock.lock_nothrow();
{
// NOTE: When a thread is removed from the global thread list its
// main context is invalid and should be removed as well.
// It is possible that t.m_curr could reference more
// than just the main context if the thread exited abnormally
// (if it was terminated), but we must assume that the user
// retains a reference to them and that they may be re-used
// elsewhere. Therefore, it is the responsibility of any
// object that creates contexts to clean them up properly
// when it is done with them.
remove( &t.m_main );
if ( t.prev )
t.prev.next = t.next;
if ( t.next )
t.next.prev = t.prev;
if ( sm_tbeg is t )
sm_tbeg = t.next;
t.prev = t.next = null;
--sm_tlen;
}
// NOTE: Don't null out t.next or t.prev because opApply currently
// follows t.next after removing a node. This could be easily
// addressed by simply returning the next node from this
// function, however, a thread should never be re-added to the
// list anyway and having next and prev be non-null is a good way
// to ensure that.
slock.unlock_nothrow();
}
}
///
unittest
{
class DerivedThread : Thread
{
this()
{
super(&run);
}
private:
void run()
{
// Derived thread running.
}
}
void threadFunc()
{
// Composed thread running.
}
// create and start instances of each type
auto derived = new DerivedThread().start();
auto composed = new Thread(&threadFunc).start();
new Thread({
// Codes to run in the newly created thread.
}).start();
}
unittest
{
int x = 0;
new Thread(
{
x++;
}).start().join();
assert( x == 1 );
}
unittest
{
enum MSG = "Test message.";
string caughtMsg;
try
{
new Thread(
{
throw new Exception( MSG );
}).start().join();
assert( false, "Expected rethrown exception." );
}
catch ( Throwable t )
{
assert( t.msg == MSG );
}
}
///////////////////////////////////////////////////////////////////////////////
// GC Support Routines
///////////////////////////////////////////////////////////////////////////////
version (CoreDdoc)
{
/**
* Instruct the thread module, when initialized, to use a different set of
* signals besides SIGUSR1 and SIGUSR2 for suspension and resumption of threads.
* This function should be called at most once, prior to thread_init().
* This function is Posix-only.
*/
extern (C) void thread_setGCSignals(int suspendSignalNo, int resumeSignalNo) nothrow @nogc
{
}
}
else version (Posix)
{
extern (C) void thread_setGCSignals(int suspendSignalNo, int resumeSignalNo) nothrow @nogc
in
{
assert(suspendSignalNumber == 0);
assert(resumeSignalNumber == 0);
assert(suspendSignalNo != 0);
assert(resumeSignalNo != 0);
}
out
{
assert(suspendSignalNumber != 0);
assert(resumeSignalNumber != 0);
}
body
{
suspendSignalNumber = suspendSignalNo;
resumeSignalNumber = resumeSignalNo;
}
}
version (Posix)
{
__gshared int suspendSignalNumber;
__gshared int resumeSignalNumber;
}
/**
* Initializes the thread module. This function must be called by the
* garbage collector on startup and before any other thread routines
* are called.
*/
extern (C) void thread_init()
{
// NOTE: If thread_init itself performs any allocations then the thread
// routines reserved for garbage collector use may be called while
// thread_init is being processed. However, since no memory should
// exist to be scanned at this point, it is sufficient for these
// functions to detect the condition and return immediately.
Thread.initLocks();
// The Android VM runtime intercepts SIGUSR1 and apparently doesn't allow
// its signal handler to run, so swap the two signals on Android, since
// thread_resumeHandler does nothing.
version (Android) thread_setGCSignals(SIGUSR2, SIGUSR1);
version (Darwin)
{
}
else version (Posix)
{
if ( suspendSignalNumber == 0 )
{
suspendSignalNumber = SIGUSR1;
}
if ( resumeSignalNumber == 0 )
{
resumeSignalNumber = SIGUSR2;
}
int status;
sigaction_t sigusr1 = void;
sigaction_t sigusr2 = void;
// This is a quick way to zero-initialize the structs without using
// memset or creating a link dependency on their static initializer.
(cast(byte*) &sigusr1)[0 .. sigaction_t.sizeof] = 0;
(cast(byte*) &sigusr2)[0 .. sigaction_t.sizeof] = 0;
// NOTE: SA_RESTART indicates that system calls should restart if they
// are interrupted by a signal, but this is not available on all
// Posix systems, even those that support multithreading.
static if ( __traits( compiles, SA_RESTART ) )
sigusr1.sa_flags = SA_RESTART;
else
sigusr1.sa_flags = 0;
sigusr1.sa_handler = &thread_suspendHandler;
// NOTE: We want to ignore all signals while in this handler, so fill
// sa_mask to indicate this.
status = sigfillset( &sigusr1.sa_mask );
assert( status == 0 );
// NOTE: Since resumeSignalNumber should only be issued for threads within the
// suspend handler, we don't want this signal to trigger a
// restart.
sigusr2.sa_flags = 0;
sigusr2.sa_handler = &thread_resumeHandler;
// NOTE: We want to ignore all signals while in this handler, so fill
// sa_mask to indicate this.
status = sigfillset( &sigusr2.sa_mask );
assert( status == 0 );
status = sigaction( suspendSignalNumber, &sigusr1, null );
assert( status == 0 );
status = sigaction( resumeSignalNumber, &sigusr2, null );
assert( status == 0 );
status = sem_init( &suspendCount, 0, 0 );
assert( status == 0 );
}
Thread.sm_main = thread_attachThis();
}
/**
* Terminates the thread module. No other thread routine may be called
* afterwards.
*/
extern (C) void thread_term()
{
assert(Thread.sm_tbeg && Thread.sm_tlen == 1);
assert(!Thread.nAboutToStart);
if (Thread.pAboutToStart) // in case realloc(p, 0) doesn't return null
{
free(Thread.pAboutToStart);
Thread.pAboutToStart = null;
}
Thread.termLocks();
}
/**
*
*/
extern (C) bool thread_isMainThread() nothrow @nogc
{
return Thread.getThis() is Thread.sm_main;
}
/**
* Registers the calling thread for use with the D Runtime. If this routine
* is called for a thread which is already registered, no action is performed.
*
* NOTE: This routine does not run thread-local static constructors when called.
* If full functionality as a D thread is desired, the following function
* must be called after thread_attachThis:
*
* extern (C) void rt_moduleTlsCtor();
*/
extern (C) Thread thread_attachThis()
{
GC.disable(); scope(exit) GC.enable();
if (auto t = Thread.getThis())
return t;
Thread thisThread = new Thread();
Thread.Context* thisContext = &thisThread.m_main;
assert( thisContext == thisThread.m_curr );
version (Windows)
{
thisThread.m_addr = GetCurrentThreadId();
thisThread.m_hndl = GetCurrentThreadHandle();
thisContext.bstack = getStackBottom();
thisContext.tstack = thisContext.bstack;
}
else version (Posix)
{
thisThread.m_addr = pthread_self();
thisContext.bstack = getStackBottom();
thisContext.tstack = thisContext.bstack;
atomicStore!(MemoryOrder.raw)(thisThread.m_isRunning, true);
}
thisThread.m_isDaemon = true;
thisThread.m_tlsgcdata = rt_tlsgc_init();
Thread.setThis( thisThread );
version (Darwin)
{
thisThread.m_tmach = pthread_mach_thread_np( thisThread.m_addr );
assert( thisThread.m_tmach != thisThread.m_tmach.init );
}
Thread.add( thisThread, false );
Thread.add( thisContext );
if ( Thread.sm_main !is null )
multiThreadedFlag = true;
return thisThread;
}
version (Windows)
{
// NOTE: These calls are not safe on Posix systems that use signals to
// perform garbage collection. The suspendHandler uses getThis()
// to get the thread handle so getThis() must be a simple call.
// Mutexes can't safely be acquired inside signal handlers, and
// even if they could, the mutex needed (Thread.slock) is held by
// thread_suspendAll(). So in short, these routines will remain
// Windows-specific. If they are truly needed elsewhere, the
// suspendHandler will need a way to call a version of getThis()
// that only does the TLS lookup without the fancy fallback stuff.
/// ditto
extern (C) Thread thread_attachByAddr( ThreadID addr )
{
return thread_attachByAddrB( addr, getThreadStackBottom( addr ) );
}
/// ditto
extern (C) Thread thread_attachByAddrB( ThreadID addr, void* bstack )
{
GC.disable(); scope(exit) GC.enable();
if (auto t = thread_findByAddr(addr))
return t;
Thread thisThread = new Thread();
Thread.Context* thisContext = &thisThread.m_main;
assert( thisContext == thisThread.m_curr );
thisThread.m_addr = addr;
thisContext.bstack = bstack;
thisContext.tstack = thisContext.bstack;
thisThread.m_isDaemon = true;
if ( addr == GetCurrentThreadId() )
{
thisThread.m_hndl = GetCurrentThreadHandle();
thisThread.m_tlsgcdata = rt_tlsgc_init();
Thread.setThis( thisThread );
}
else
{
thisThread.m_hndl = OpenThreadHandle( addr );
impersonate_thread(addr,
{
thisThread.m_tlsgcdata = rt_tlsgc_init();
Thread.setThis( thisThread );
});
}
Thread.add( thisThread, false );
Thread.add( thisContext );
if ( Thread.sm_main !is null )
multiThreadedFlag = true;
return thisThread;
}
}
/**
* Deregisters the calling thread from use with the runtime. If this routine
* is called for a thread which is not registered, the result is undefined.
*
* NOTE: This routine does not run thread-local static destructors when called.
* If full functionality as a D thread is desired, the following function
* must be called after thread_detachThis, particularly if the thread is
* being detached at some indeterminate time before program termination:
*
* $(D extern(C) void rt_moduleTlsDtor();)
*/
extern (C) void thread_detachThis() nothrow @nogc
{
if (auto t = Thread.getThis())
Thread.remove(t);
}
/**
* Deregisters the given thread from use with the runtime. If this routine
* is called for a thread which is not registered, the result is undefined.
*
* NOTE: This routine does not run thread-local static destructors when called.
* If full functionality as a D thread is desired, the following function
* must be called by the detached thread, particularly if the thread is
* being detached at some indeterminate time before program termination:
*
* $(D extern(C) void rt_moduleTlsDtor();)
*/
extern (C) void thread_detachByAddr( ThreadID addr )
{
if ( auto t = thread_findByAddr( addr ) )
Thread.remove( t );
}
/// ditto
extern (C) void thread_detachInstance( Thread t ) nothrow @nogc
{
Thread.remove( t );
}
unittest
{
import core.sync.semaphore;
auto sem = new Semaphore();
auto t = new Thread(
{
sem.notify();
Thread.sleep(100.msecs);
}).start();
sem.wait(); // thread cannot be detached while being started
thread_detachInstance(t);
foreach (t2; Thread)
assert(t !is t2);
t.join();
}
/**
* Search the list of all threads for a thread with the given thread identifier.
*
* Params:
* addr = The thread identifier to search for.
* Returns:
* The thread object associated with the thread identifier, null if not found.
*/
static Thread thread_findByAddr( ThreadID addr )
{
Thread.slock.lock_nothrow();
scope(exit) Thread.slock.unlock_nothrow();
// also return just spawned thread so that
// DLL_THREAD_ATTACH knows it's a D thread
foreach (t; Thread.pAboutToStart[0 .. Thread.nAboutToStart])
if (t.m_addr == addr)
return t;
foreach (t; Thread)
if (t.m_addr == addr)
return t;
return null;
}
/**
* Sets the current thread to a specific reference. Only to be used
* when dealing with externally-created threads (in e.g. C code).
* The primary use of this function is when Thread.getThis() must
* return a sensible value in, for example, TLS destructors. In
* other words, don't touch this unless you know what you're doing.
*
* Params:
* t = A reference to the current thread. May be null.
*/
extern (C) void thread_setThis(Thread t) nothrow @nogc
{
Thread.setThis(t);
}
/**
* Joins all non-daemon threads that are currently running. This is done by
* performing successive scans through the thread list until a scan consists
* of only daemon threads.
*/
extern (C) void thread_joinAll()
{
Lagain:
Thread.slock.lock_nothrow();
// wait for just spawned threads
if (Thread.nAboutToStart)
{
Thread.slock.unlock_nothrow();
Thread.yield();
goto Lagain;
}
// join all non-daemon threads, the main thread is also a daemon
auto t = Thread.sm_tbeg;
while (t)
{
if (!t.isRunning)
{
auto tn = t.next;
Thread.remove(t);
t = tn;
}
else if (t.isDaemon)
{
t = t.next;
}
else
{
Thread.slock.unlock_nothrow();
t.join(); // might rethrow
goto Lagain; // must restart iteration b/c of unlock
}
}
Thread.slock.unlock_nothrow();
}
/**
* Performs intermediate shutdown of the thread module.
*/
shared static ~this()
{
// NOTE: The functionality related to garbage collection must be minimally
// operable after this dtor completes. Therefore, only minimal
// cleanup may occur.
auto t = Thread.sm_tbeg;
while (t)
{
auto tn = t.next;
if (!t.isRunning)
Thread.remove(t);
t = tn;
}
}
// Used for needLock below.
private __gshared bool multiThreadedFlag = false;
version (PPC64) version = ExternStackShell;
version (ExternStackShell)
{
extern(D) public void callWithStackShell(scope void delegate(void* sp) nothrow fn) nothrow;
}
else
{
// Calls the given delegate, passing the current thread's stack pointer to it.
private void callWithStackShell(scope void delegate(void* sp) nothrow fn) nothrow
in
{
assert(fn);
}
body
{
// The purpose of the 'shell' is to ensure all the registers get
// put on the stack so they'll be scanned. We only need to push
// the callee-save registers.
void *sp = void;
version (GNU)
{
__builtin_unwind_init();
sp = &sp;
}
else version (AsmX86_Posix)
{
size_t[3] regs = void;
asm pure nothrow @nogc
{
mov [regs + 0 * 4], EBX;
mov [regs + 1 * 4], ESI;
mov [regs + 2 * 4], EDI;
mov sp[EBP], ESP;
}
}
else version (AsmX86_Windows)
{
size_t[3] regs = void;
asm pure nothrow @nogc
{
mov [regs + 0 * 4], EBX;
mov [regs + 1 * 4], ESI;
mov [regs + 2 * 4], EDI;
mov sp[EBP], ESP;
}
}
else version (AsmX86_64_Posix)
{
size_t[5] regs = void;
asm pure nothrow @nogc
{
mov [regs + 0 * 8], RBX;
mov [regs + 1 * 8], R12;
mov [regs + 2 * 8], R13;
mov [regs + 3 * 8], R14;
mov [regs + 4 * 8], R15;
mov sp[RBP], RSP;
}
}
else version (AsmX86_64_Windows)
{
size_t[7] regs = void;
asm pure nothrow @nogc
{
mov [regs + 0 * 8], RBX;
mov [regs + 1 * 8], RSI;
mov [regs + 2 * 8], RDI;
mov [regs + 3 * 8], R12;
mov [regs + 4 * 8], R13;
mov [regs + 5 * 8], R14;
mov [regs + 6 * 8], R15;
mov sp[RBP], RSP;
}
}
else
{
static assert(false, "Architecture not supported.");
}
fn(sp);
}
}
// Used for suspendAll/resumeAll below.
private __gshared uint suspendDepth = 0;
/**
* Suspend the specified thread and load stack and register information for
* use by thread_scanAll. If the supplied thread is the calling thread,
* stack and register information will be loaded but the thread will not
* be suspended. If the suspend operation fails and the thread is not
* running then it will be removed from the global thread list, otherwise
* an exception will be thrown.
*
* Params:
* t = The thread to suspend.
*
* Throws:
* ThreadError if the suspend operation fails for a running thread.
* Returns:
* Whether the thread is now suspended (true) or terminated (false).
*/
private bool suspend( Thread t ) nothrow
{
Duration waittime = dur!"usecs"(10);
Lagain:
if (!t.isRunning)
{
Thread.remove(t);
return false;
}
else if (t.m_isInCriticalRegion)
{
Thread.criticalRegionLock.unlock_nothrow();
Thread.sleep(waittime);
if (waittime < dur!"msecs"(10)) waittime *= 2;
Thread.criticalRegionLock.lock_nothrow();
goto Lagain;
}
version (Windows)
{
if ( t.m_addr != GetCurrentThreadId() && SuspendThread( t.m_hndl ) == 0xFFFFFFFF )
{
if ( !t.isRunning )
{
Thread.remove( t );
return false;
}
onThreadError( "Unable to suspend thread" );
}
CONTEXT context = void;
context.ContextFlags = CONTEXT_INTEGER | CONTEXT_CONTROL;
if ( !GetThreadContext( t.m_hndl, &context ) )
onThreadError( "Unable to load thread context" );
version (X86)
{
if ( !t.m_lock )
t.m_curr.tstack = cast(void*) context.Esp;
// eax,ebx,ecx,edx,edi,esi,ebp,esp
t.m_reg[0] = context.Eax;
t.m_reg[1] = context.Ebx;
t.m_reg[2] = context.Ecx;
t.m_reg[3] = context.Edx;
t.m_reg[4] = context.Edi;
t.m_reg[5] = context.Esi;
t.m_reg[6] = context.Ebp;
t.m_reg[7] = context.Esp;
}
else version (X86_64)
{
if ( !t.m_lock )
t.m_curr.tstack = cast(void*) context.Rsp;
// rax,rbx,rcx,rdx,rdi,rsi,rbp,rsp
t.m_reg[0] = context.Rax;
t.m_reg[1] = context.Rbx;
t.m_reg[2] = context.Rcx;
t.m_reg[3] = context.Rdx;
t.m_reg[4] = context.Rdi;
t.m_reg[5] = context.Rsi;
t.m_reg[6] = context.Rbp;
t.m_reg[7] = context.Rsp;
// r8,r9,r10,r11,r12,r13,r14,r15
t.m_reg[8] = context.R8;
t.m_reg[9] = context.R9;
t.m_reg[10] = context.R10;
t.m_reg[11] = context.R11;
t.m_reg[12] = context.R12;
t.m_reg[13] = context.R13;
t.m_reg[14] = context.R14;
t.m_reg[15] = context.R15;
}
else
{
static assert(false, "Architecture not supported." );
}
}
else version (Darwin)
{
if ( t.m_addr != pthread_self() && thread_suspend( t.m_tmach ) != KERN_SUCCESS )
{
if ( !t.isRunning )
{
Thread.remove( t );
return false;
}
onThreadError( "Unable to suspend thread" );
}
version (X86)
{
x86_thread_state32_t state = void;
mach_msg_type_number_t count = x86_THREAD_STATE32_COUNT;
if ( thread_get_state( t.m_tmach, x86_THREAD_STATE32, &state, &count ) != KERN_SUCCESS )
onThreadError( "Unable to load thread state" );
if ( !t.m_lock )
t.m_curr.tstack = cast(void*) state.esp;
// eax,ebx,ecx,edx,edi,esi,ebp,esp
t.m_reg[0] = state.eax;
t.m_reg[1] = state.ebx;
t.m_reg[2] = state.ecx;
t.m_reg[3] = state.edx;
t.m_reg[4] = state.edi;
t.m_reg[5] = state.esi;
t.m_reg[6] = state.ebp;
t.m_reg[7] = state.esp;
}
else version (X86_64)
{
x86_thread_state64_t state = void;
mach_msg_type_number_t count = x86_THREAD_STATE64_COUNT;
if ( thread_get_state( t.m_tmach, x86_THREAD_STATE64, &state, &count ) != KERN_SUCCESS )
onThreadError( "Unable to load thread state" );
if ( !t.m_lock )
t.m_curr.tstack = cast(void*) state.rsp;
// rax,rbx,rcx,rdx,rdi,rsi,rbp,rsp
t.m_reg[0] = state.rax;
t.m_reg[1] = state.rbx;
t.m_reg[2] = state.rcx;
t.m_reg[3] = state.rdx;
t.m_reg[4] = state.rdi;
t.m_reg[5] = state.rsi;
t.m_reg[6] = state.rbp;
t.m_reg[7] = state.rsp;
// r8,r9,r10,r11,r12,r13,r14,r15
t.m_reg[8] = state.r8;
t.m_reg[9] = state.r9;
t.m_reg[10] = state.r10;
t.m_reg[11] = state.r11;
t.m_reg[12] = state.r12;
t.m_reg[13] = state.r13;
t.m_reg[14] = state.r14;
t.m_reg[15] = state.r15;
}
else
{
static assert(false, "Architecture not supported." );
}
}
else version (Posix)
{
if ( t.m_addr != pthread_self() )
{
if ( pthread_kill( t.m_addr, suspendSignalNumber ) != 0 )
{
if ( !t.isRunning )
{
Thread.remove( t );
return false;
}
onThreadError( "Unable to suspend thread" );
}
}
else if ( !t.m_lock )
{
t.m_curr.tstack = getStackTop();
}
}
return true;
}
/**
* Suspend all threads but the calling thread for "stop the world" garbage
* collection runs. This function may be called multiple times, and must
* be followed by a matching number of calls to thread_resumeAll before
* processing is resumed.
*
* Throws:
* ThreadError if the suspend operation fails for a running thread.
*/
extern (C) void thread_suspendAll() nothrow
{
// NOTE: We've got an odd chicken & egg problem here, because while the GC
// is required to call thread_init before calling any other thread
// routines, thread_init may allocate memory which could in turn
// trigger a collection. Thus, thread_suspendAll, thread_scanAll,
// and thread_resumeAll must be callable before thread_init
// completes, with the assumption that no other GC memory has yet
// been allocated by the system, and thus there is no risk of losing
// data if the global thread list is empty. The check of
// Thread.sm_tbeg below is done to ensure thread_init has completed,
// and therefore that calling Thread.getThis will not result in an
// error. For the short time when Thread.sm_tbeg is null, there is
// no reason not to simply call the multithreaded code below, with
// the expectation that the foreach loop will never be entered.
if ( !multiThreadedFlag && Thread.sm_tbeg )
{
if ( ++suspendDepth == 1 )
suspend( Thread.getThis() );
return;
}
Thread.slock.lock_nothrow();
{
if ( ++suspendDepth > 1 )
return;
Thread.criticalRegionLock.lock_nothrow();
scope (exit) Thread.criticalRegionLock.unlock_nothrow();
size_t cnt;
auto t = Thread.sm_tbeg;
while (t)
{
auto tn = t.next;
if (suspend(t))
++cnt;
t = tn;
}
version (Darwin)
{}
else version (Posix)
{
// subtract own thread
assert(cnt >= 1);
--cnt;
Lagain:
// wait for semaphore notifications
for (; cnt; --cnt)
{
while (sem_wait(&suspendCount) != 0)
{
if (errno != EINTR)
onThreadError("Unable to wait for semaphore");
errno = 0;
}
}
version (FreeBSD)
{
// avoid deadlocks, see Issue 13416
t = Thread.sm_tbeg;
while (t)
{
auto tn = t.next;
if (t.m_suspendagain && suspend(t))
++cnt;
t = tn;
}
if (cnt)
goto Lagain;
}
}
}
}
/**
* Resume the specified thread and unload stack and register information.
* If the supplied thread is the calling thread, stack and register
* information will be unloaded but the thread will not be resumed. If
* the resume operation fails and the thread is not running then it will
* be removed from the global thread list, otherwise an exception will be
* thrown.
*
* Params:
* t = The thread to resume.
*
* Throws:
* ThreadError if the resume fails for a running thread.
*/
private void resume( Thread t ) nothrow
{
version (Windows)
{
if ( t.m_addr != GetCurrentThreadId() && ResumeThread( t.m_hndl ) == 0xFFFFFFFF )
{
if ( !t.isRunning )
{
Thread.remove( t );
return;
}
onThreadError( "Unable to resume thread" );
}
if ( !t.m_lock )
t.m_curr.tstack = t.m_curr.bstack;
t.m_reg[0 .. $] = 0;
}
else version (Darwin)
{
if ( t.m_addr != pthread_self() && thread_resume( t.m_tmach ) != KERN_SUCCESS )
{
if ( !t.isRunning )
{
Thread.remove( t );
return;
}
onThreadError( "Unable to resume thread" );
}
if ( !t.m_lock )
t.m_curr.tstack = t.m_curr.bstack;
t.m_reg[0 .. $] = 0;
}
else version (Posix)
{
if ( t.m_addr != pthread_self() )
{
if ( pthread_kill( t.m_addr, resumeSignalNumber ) != 0 )
{
if ( !t.isRunning )
{
Thread.remove( t );
return;
}
onThreadError( "Unable to resume thread" );
}
}
else if ( !t.m_lock )
{
t.m_curr.tstack = t.m_curr.bstack;
}
}
}
/**
* Resume all threads but the calling thread for "stop the world" garbage
* collection runs. This function must be called once for each preceding
* call to thread_suspendAll before the threads are actually resumed.
*
* In:
* This routine must be preceded by a call to thread_suspendAll.
*
* Throws:
* ThreadError if the resume operation fails for a running thread.
*/
extern (C) void thread_resumeAll() nothrow
in
{
assert( suspendDepth > 0 );
}
body
{
// NOTE: See thread_suspendAll for the logic behind this.
if ( !multiThreadedFlag && Thread.sm_tbeg )
{
if ( --suspendDepth == 0 )
resume( Thread.getThis() );
return;
}
scope(exit) Thread.slock.unlock_nothrow();
{
if ( --suspendDepth > 0 )
return;
for ( Thread t = Thread.sm_tbeg; t; t = t.next )
{
// NOTE: We do not need to care about critical regions at all
// here. thread_suspendAll takes care of everything.
resume( t );
}
}
}
/**
* Indicates the kind of scan being performed by $(D thread_scanAllType).
*/
enum ScanType
{
stack, /// The stack and/or registers are being scanned.
tls, /// TLS data is being scanned.
}
alias ScanAllThreadsFn = void delegate(void*, void*) nothrow; /// The scanning function.
alias ScanAllThreadsTypeFn = void delegate(ScanType, void*, void*) nothrow; /// ditto
/**
* The main entry point for garbage collection. The supplied delegate
* will be passed ranges representing both stack and register values.
*
* Params:
* scan = The scanner function. It should scan from p1 through p2 - 1.
*
* In:
* This routine must be preceded by a call to thread_suspendAll.
*/
extern (C) void thread_scanAllType( scope ScanAllThreadsTypeFn scan ) nothrow
in
{
assert( suspendDepth > 0 );
}
body
{
callWithStackShell(sp => scanAllTypeImpl(scan, sp));
}
private void scanAllTypeImpl( scope ScanAllThreadsTypeFn scan, void* curStackTop ) nothrow
{
Thread thisThread = null;
void* oldStackTop = null;
if ( Thread.sm_tbeg )
{
thisThread = Thread.getThis();
if ( !thisThread.m_lock )
{
oldStackTop = thisThread.m_curr.tstack;
thisThread.m_curr.tstack = curStackTop;
}
}
scope( exit )
{
if ( Thread.sm_tbeg )
{
if ( !thisThread.m_lock )
{
thisThread.m_curr.tstack = oldStackTop;
}
}
}
// NOTE: Synchronizing on Thread.slock is not needed because this
// function may only be called after all other threads have
// been suspended from within the same lock.
if (Thread.nAboutToStart)
scan(ScanType.stack, Thread.pAboutToStart, Thread.pAboutToStart + Thread.nAboutToStart);
for ( Thread.Context* c = Thread.sm_cbeg; c; c = c.next )
{
version (StackGrowsDown)
{
// NOTE: We can't index past the bottom of the stack
// so don't do the "+1" for StackGrowsDown.
if ( c.tstack && c.tstack < c.bstack )
scan( ScanType.stack, c.tstack, c.bstack );
}
else
{
if ( c.bstack && c.bstack < c.tstack )
scan( ScanType.stack, c.bstack, c.tstack + 1 );
}
}
for ( Thread t = Thread.sm_tbeg; t; t = t.next )
{
version (Windows)
{
// Ideally, we'd pass ScanType.regs or something like that, but this
// would make portability annoying because it only makes sense on Windows.
scan( ScanType.stack, t.m_reg.ptr, t.m_reg.ptr + t.m_reg.length );
}
if (t.m_tlsgcdata !is null)
rt_tlsgc_scan(t.m_tlsgcdata, (p1, p2) => scan(ScanType.tls, p1, p2));
}
}
/**
* The main entry point for garbage collection. The supplied delegate
* will be passed ranges representing both stack and register values.
*
* Params:
* scan = The scanner function. It should scan from p1 through p2 - 1.
*
* In:
* This routine must be preceded by a call to thread_suspendAll.
*/
extern (C) void thread_scanAll( scope ScanAllThreadsFn scan ) nothrow
{
thread_scanAllType((type, p1, p2) => scan(p1, p2));
}
/**
* Signals that the code following this call is a critical region. Any code in
* this region must finish running before the calling thread can be suspended
* by a call to thread_suspendAll.
*
* This function is, in particular, meant to help maintain garbage collector
* invariants when a lock is not used.
*
* A critical region is exited with thread_exitCriticalRegion.
*
* $(RED Warning):
* Using critical regions is extremely error-prone. For instance, using locks
* inside a critical region can easily result in a deadlock when another thread
* holding the lock already got suspended.
*
* The term and concept of a 'critical region' comes from
* $(LINK2 https://github.com/mono/mono/blob/521f4a198e442573c400835ef19bbb36b60b0ebb/mono/metadata/sgen-gc.h#L925 Mono's SGen garbage collector).
*
* In:
* The calling thread must be attached to the runtime.
*/
extern (C) void thread_enterCriticalRegion() @nogc
in
{
assert(Thread.getThis());
}
body
{
synchronized (Thread.criticalRegionLock)
Thread.getThis().m_isInCriticalRegion = true;
}
/**
* Signals that the calling thread is no longer in a critical region. Following
* a call to this function, the thread can once again be suspended.
*
* In:
* The calling thread must be attached to the runtime.
*/
extern (C) void thread_exitCriticalRegion() @nogc
in
{
assert(Thread.getThis());
}
body
{
synchronized (Thread.criticalRegionLock)
Thread.getThis().m_isInCriticalRegion = false;
}
/**
* Returns true if the current thread is in a critical region; otherwise, false.
*
* In:
* The calling thread must be attached to the runtime.
*/
extern (C) bool thread_inCriticalRegion() @nogc
in
{
assert(Thread.getThis());
}
body
{
synchronized (Thread.criticalRegionLock)
return Thread.getThis().m_isInCriticalRegion;
}
/**
* A callback for thread errors in D during collections. Since an allocation is not possible
* a preallocated ThreadError will be used as the Error instance
*
* Throws:
* ThreadError.
*/
private void onThreadError(string msg = null, Throwable next = null) nothrow
{
__gshared ThreadError error = new ThreadError(null);
error.msg = msg;
error.next = next;
import core.exception : SuppressTraceInfo;
error.info = SuppressTraceInfo.instance;
throw error;
}
unittest
{
assert(!thread_inCriticalRegion());
{
thread_enterCriticalRegion();
scope (exit)
thread_exitCriticalRegion();
assert(thread_inCriticalRegion());
}
assert(!thread_inCriticalRegion());
}
unittest
{
// NOTE: This entire test is based on the assumption that no
// memory is allocated after the child thread is
// started. If an allocation happens, a collection could
// trigger, which would cause the synchronization below
// to cause a deadlock.
// NOTE: DO NOT USE LOCKS IN CRITICAL REGIONS IN NORMAL CODE.
import core.sync.semaphore;
auto sema = new Semaphore(),
semb = new Semaphore();
auto thr = new Thread(
{
thread_enterCriticalRegion();
assert(thread_inCriticalRegion());
sema.notify();
semb.wait();
assert(thread_inCriticalRegion());
thread_exitCriticalRegion();
assert(!thread_inCriticalRegion());
sema.notify();
semb.wait();
assert(!thread_inCriticalRegion());
});
thr.start();
sema.wait();
synchronized (Thread.criticalRegionLock)
assert(thr.m_isInCriticalRegion);
semb.notify();
sema.wait();
synchronized (Thread.criticalRegionLock)
assert(!thr.m_isInCriticalRegion);
semb.notify();
thr.join();
}
unittest
{
import core.sync.semaphore;
shared bool inCriticalRegion;
auto sema = new Semaphore(),
semb = new Semaphore();
auto thr = new Thread(
{
thread_enterCriticalRegion();
inCriticalRegion = true;
sema.notify();
semb.wait();
Thread.sleep(dur!"msecs"(1));
inCriticalRegion = false;
thread_exitCriticalRegion();
});
thr.start();
sema.wait();
assert(inCriticalRegion);
semb.notify();
thread_suspendAll();
assert(!inCriticalRegion);
thread_resumeAll();
}
/**
* Indicates whether an address has been marked by the GC.
*/
enum IsMarked : int
{
no, /// Address is not marked.
yes, /// Address is marked.
unknown, /// Address is not managed by the GC.
}
alias IsMarkedDg = int delegate( void* addr ) nothrow; /// The isMarked callback function.
/**
* This routine allows the runtime to process any special per-thread handling
* for the GC. This is needed for taking into account any memory that is
* referenced by non-scanned pointers but is about to be freed. That currently
* means the array append cache.
*
* Params:
* isMarked = The function used to check if $(D addr) is marked.
*
* In:
* This routine must be called just prior to resuming all threads.
*/
extern(C) void thread_processGCMarks( scope IsMarkedDg isMarked ) nothrow
{
for ( Thread t = Thread.sm_tbeg; t; t = t.next )
{
/* Can be null if collection was triggered between adding a
* thread and calling rt_tlsgc_init.
*/
if (t.m_tlsgcdata !is null)
rt_tlsgc_processGCMarks(t.m_tlsgcdata, isMarked);
}
}
extern (C) @nogc nothrow
{
version (CRuntime_Glibc) int pthread_getattr_np(pthread_t thread, pthread_attr_t* attr);
version (FreeBSD) int pthread_attr_get_np(pthread_t thread, pthread_attr_t* attr);
version (NetBSD) int pthread_attr_get_np(pthread_t thread, pthread_attr_t* attr);
version (OpenBSD) int pthread_stackseg_np(pthread_t thread, stack_t* sinfo);
version (DragonFlyBSD) int pthread_attr_get_np(pthread_t thread, pthread_attr_t* attr);
version (Solaris) int thr_stksegment(stack_t* stk);
version (CRuntime_Bionic) int pthread_getattr_np(pthread_t thid, pthread_attr_t* attr);
version (CRuntime_Musl) int pthread_getattr_np(pthread_t, pthread_attr_t*);
version (CRuntime_UClibc) int pthread_getattr_np(pthread_t thread, pthread_attr_t* attr);
}
private void* getStackTop() nothrow @nogc
{
version (D_InlineAsm_X86)
asm pure nothrow @nogc { naked; mov EAX, ESP; ret; }
else version (D_InlineAsm_X86_64)
asm pure nothrow @nogc { naked; mov RAX, RSP; ret; }
else version (GNU)
return __builtin_frame_address(0);
else
static assert(false, "Architecture not supported.");
}
private void* getStackBottom() nothrow @nogc
{
version (Windows)
{
version (D_InlineAsm_X86)
asm pure nothrow @nogc { naked; mov EAX, FS:4; ret; }
else version (D_InlineAsm_X86_64)
asm pure nothrow @nogc
{ naked;
mov RAX, 8;
mov RAX, GS:[RAX];
ret;
}
else version (GNU_InlineAsm)
{
void *bottom;
version (X86)
asm pure nothrow @nogc { "movl %%fs:4, %0;" : "=r" bottom; }
else version (X86_64)
asm pure nothrow @nogc { "movq %%gs:8, %0;" : "=r" bottom; }
else
static assert(false, "Platform not supported.");
return bottom;
}
else
static assert(false, "Architecture not supported.");
}
else version (Darwin)
{
import core.sys.darwin.pthread;
return pthread_get_stackaddr_np(pthread_self());
}
else version (CRuntime_Glibc)
{
pthread_attr_t attr;
void* addr; size_t size;
pthread_getattr_np(pthread_self(), &attr);
pthread_attr_getstack(&attr, &addr, &size);
pthread_attr_destroy(&attr);
version (StackGrowsDown)
addr += size;
return addr;
}
else version (FreeBSD)
{
pthread_attr_t attr;
void* addr; size_t size;
pthread_attr_init(&attr);
pthread_attr_get_np(pthread_self(), &attr);
pthread_attr_getstack(&attr, &addr, &size);
pthread_attr_destroy(&attr);
version (StackGrowsDown)
addr += size;
return addr;
}
else version (NetBSD)
{
pthread_attr_t attr;
void* addr; size_t size;
pthread_attr_init(&attr);
pthread_attr_get_np(pthread_self(), &attr);
pthread_attr_getstack(&attr, &addr, &size);
pthread_attr_destroy(&attr);
version (StackGrowsDown)
addr += size;
return addr;
}
else version (OpenBSD)
{
stack_t stk;
pthread_stackseg_np(pthread_self(), &stk);
return stk.ss_sp;
}
else version (DragonFlyBSD)
{
pthread_attr_t attr;
void* addr; size_t size;
pthread_attr_init(&attr);
pthread_attr_get_np(pthread_self(), &attr);
pthread_attr_getstack(&attr, &addr, &size);
pthread_attr_destroy(&attr);
version (StackGrowsDown)
addr += size;
return addr;
}
else version (Solaris)
{
stack_t stk;
thr_stksegment(&stk);
return stk.ss_sp;
}
else version (CRuntime_Bionic)
{
pthread_attr_t attr;
void* addr; size_t size;
pthread_getattr_np(pthread_self(), &attr);
pthread_attr_getstack(&attr, &addr, &size);
pthread_attr_destroy(&attr);
version (StackGrowsDown)
addr += size;
return addr;
}
else version (CRuntime_Musl)
{
pthread_attr_t attr;
void* addr; size_t size;
pthread_getattr_np(pthread_self(), &attr);
pthread_attr_getstack(&attr, &addr, &size);
pthread_attr_destroy(&attr);
version (StackGrowsDown)
addr += size;
return addr;
}
else version (CRuntime_UClibc)
{
pthread_attr_t attr;
void* addr; size_t size;
pthread_getattr_np(pthread_self(), &attr);
pthread_attr_getstack(&attr, &addr, &size);
pthread_attr_destroy(&attr);
version (StackGrowsDown)
addr += size;
return addr;
}
else
static assert(false, "Platform not supported.");
}
/**
* Returns the stack top of the currently active stack within the calling
* thread.
*
* In:
* The calling thread must be attached to the runtime.
*
* Returns:
* The address of the stack top.
*/
extern (C) void* thread_stackTop() nothrow @nogc
in
{
// Not strictly required, but it gives us more flexibility.
assert(Thread.getThis());
}
body
{
return getStackTop();
}
/**
* Returns the stack bottom of the currently active stack within the calling
* thread.
*
* In:
* The calling thread must be attached to the runtime.
*
* Returns:
* The address of the stack bottom.
*/
extern (C) void* thread_stackBottom() nothrow @nogc
in
{
assert(Thread.getThis());
}
body
{
return Thread.getThis().topContext().bstack;
}
///////////////////////////////////////////////////////////////////////////////
// Thread Group
///////////////////////////////////////////////////////////////////////////////
/**
* This class is intended to simplify certain common programming techniques.
*/
class ThreadGroup
{
/**
* Creates and starts a new Thread object that executes fn and adds it to
* the list of tracked threads.
*
* Params:
* fn = The thread function.
*
* Returns:
* A reference to the newly created thread.
*/
final Thread create( void function() fn )
{
Thread t = new Thread( fn ).start();
synchronized( this )
{
m_all[t] = t;
}
return t;
}
/**
* Creates and starts a new Thread object that executes dg and adds it to
* the list of tracked threads.
*
* Params:
* dg = The thread function.
*
* Returns:
* A reference to the newly created thread.
*/
final Thread create( void delegate() dg )
{
Thread t = new Thread( dg ).start();
synchronized( this )
{
m_all[t] = t;
}
return t;
}
/**
* Add t to the list of tracked threads if it is not already being tracked.
*
* Params:
* t = The thread to add.
*
* In:
* t must not be null.
*/
final void add( Thread t )
in
{
assert( t );
}
body
{
synchronized( this )
{
m_all[t] = t;
}
}
/**
* Removes t from the list of tracked threads. No operation will be
* performed if t is not currently being tracked by this object.
*
* Params:
* t = The thread to remove.
*
* In:
* t must not be null.
*/
final void remove( Thread t )
in
{
assert( t );
}
body
{
synchronized( this )
{
m_all.remove( t );
}
}
/**
* Operates on all threads currently tracked by this object.
*/
final int opApply( scope int delegate( ref Thread ) dg )
{
synchronized( this )
{
int ret = 0;
// NOTE: This loop relies on the knowledge that m_all uses the
// Thread object for both the key and the mapped value.
foreach ( Thread t; m_all.keys )
{
ret = dg( t );
if ( ret )
break;
}
return ret;
}
}
/**
* Iteratively joins all tracked threads. This function will block add,
* remove, and opApply until it completes.
*
* Params:
* rethrow = Rethrow any unhandled exception which may have caused the
* current thread to terminate.
*
* Throws:
* Any exception not handled by the joined threads.
*/
final void joinAll( bool rethrow = true )
{
synchronized( this )
{
// NOTE: This loop relies on the knowledge that m_all uses the
// Thread object for both the key and the mapped value.
foreach ( Thread t; m_all.keys )
{
t.join( rethrow );
}
}
}
private:
Thread[Thread] m_all;
}
///////////////////////////////////////////////////////////////////////////////
// Fiber Platform Detection and Memory Allocation
///////////////////////////////////////////////////////////////////////////////
private
{
version (D_InlineAsm_X86)
{
version (Windows)
version = AsmX86_Windows;
else version (Posix)
version = AsmX86_Posix;
version (Darwin)
version = AlignFiberStackTo16Byte;
}
else version (D_InlineAsm_X86_64)
{
version (Windows)
{
version = AsmX86_64_Windows;
version = AlignFiberStackTo16Byte;
}
else version (Posix)
{
version = AsmX86_64_Posix;
version = AlignFiberStackTo16Byte;
}
}
else version (X86)
{
version = AsmExternal;
version (MinGW)
{
version = GNU_AsmX86_Windows;
version = AlignFiberStackTo16Byte;
}
else version (Posix)
{
version = AsmX86_Posix;
version (OSX)
version = AlignFiberStackTo16Byte;
}
}
else version (X86_64)
{
version (D_X32)
{
// let X32 be handled by ucontext swapcontext
}
else
{
version = AsmExternal;
version = AlignFiberStackTo16Byte;
version (MinGW)
version = GNU_AsmX86_64_Windows;
else version (Posix)
version = AsmX86_64_Posix;
}
}
else version (PPC)
{
version (Posix)
{
version = AsmPPC_Posix;
version = AsmExternal;
}
}
else version (PPC64)
{
version (Posix)
{
version = AlignFiberStackTo16Byte;
}
}
else version (MIPS_O32)
{
version (Posix)
{
version = AsmMIPS_O32_Posix;
version = AsmExternal;
}
}
else version (AArch64)
{
version (Posix)
{
version = AsmAArch64_Posix;
version = AsmExternal;
version = AlignFiberStackTo16Byte;
}
}
else version (ARM)
{
version (Posix)
{
version = AsmARM_Posix;
version = AsmExternal;
}
}
else version (SPARC)
{
// NOTE: The SPARC ABI specifies only doubleword alignment.
version = AlignFiberStackTo16Byte;
}
else version (SPARC64)
{
version = AlignFiberStackTo16Byte;
}
version (Posix)
{
import core.sys.posix.unistd; // for sysconf
version (AsmX86_Windows) {} else
version (AsmX86_Posix) {} else
version (AsmX86_64_Windows) {} else
version (AsmX86_64_Posix) {} else
version (AsmExternal) {} else
{
// NOTE: The ucontext implementation requires architecture specific
// data definitions to operate so testing for it must be done
// by checking for the existence of ucontext_t rather than by
// a version identifier. Please note that this is considered
// an obsolescent feature according to the POSIX spec, so a
// custom solution is still preferred.
import core.sys.posix.ucontext;
}
}
static immutable size_t PAGESIZE;
version (Posix) static immutable size_t PTHREAD_STACK_MIN;
}
shared static this()
{
version (Windows)
{
SYSTEM_INFO info;
GetSystemInfo(&info);
PAGESIZE = info.dwPageSize;
assert(PAGESIZE < int.max);
}
else version (Posix)
{
PAGESIZE = cast(size_t)sysconf(_SC_PAGESIZE);
PTHREAD_STACK_MIN = cast(size_t)sysconf(_SC_THREAD_STACK_MIN);
}
else
{
static assert(0, "unimplemented");
}
}
///////////////////////////////////////////////////////////////////////////////
// Fiber Entry Point and Context Switch
///////////////////////////////////////////////////////////////////////////////
private
{
extern (C) void fiber_entryPoint() nothrow
{
Fiber obj = Fiber.getThis();
assert( obj );
assert( Thread.getThis().m_curr is obj.m_ctxt );
atomicStore!(MemoryOrder.raw)(*cast(shared)&Thread.getThis().m_lock, false);
obj.m_ctxt.tstack = obj.m_ctxt.bstack;
obj.m_state = Fiber.State.EXEC;
try
{
obj.run();
}
catch ( Throwable t )
{
obj.m_unhandled = t;
}
static if ( __traits( compiles, ucontext_t ) )
obj.m_ucur = &obj.m_utxt;
obj.m_state = Fiber.State.TERM;
obj.switchOut();
}
// Look above the definition of 'class Fiber' for some information about the implementation of this routine
version (AsmExternal)
{
extern (C) void fiber_switchContext( void** oldp, void* newp ) nothrow @nogc;
version (AArch64)
extern (C) void fiber_trampoline() nothrow;
}
else
extern (C) void fiber_switchContext( void** oldp, void* newp ) nothrow @nogc
{
// NOTE: The data pushed and popped in this routine must match the
// default stack created by Fiber.initStack or the initial
// switch into a new context will fail.
version (AsmX86_Windows)
{
asm pure nothrow @nogc
{
naked;
// save current stack state
push EBP;
mov EBP, ESP;
push EDI;
push ESI;
push EBX;
push dword ptr FS:[0];
push dword ptr FS:[4];
push dword ptr FS:[8];
push EAX;
// store oldp again with more accurate address
mov EAX, dword ptr 8[EBP];
mov [EAX], ESP;
// load newp to begin context switch
mov ESP, dword ptr 12[EBP];
// load saved state from new stack
pop EAX;
pop dword ptr FS:[8];
pop dword ptr FS:[4];
pop dword ptr FS:[0];
pop EBX;
pop ESI;
pop EDI;
pop EBP;
// 'return' to complete switch
pop ECX;
jmp ECX;
}
}
else version (AsmX86_64_Windows)
{
asm pure nothrow @nogc
{
naked;
// save current stack state
// NOTE: When changing the layout of registers on the stack,
// make sure that the XMM registers are still aligned.
// On function entry, the stack is guaranteed to not
// be aligned to 16 bytes because of the return address
// on the stack.
push RBP;
mov RBP, RSP;
push R12;
push R13;
push R14;
push R15;
push RDI;
push RSI;
// 7 registers = 56 bytes; stack is now aligned to 16 bytes
sub RSP, 160;
movdqa [RSP + 144], XMM6;
movdqa [RSP + 128], XMM7;
movdqa [RSP + 112], XMM8;
movdqa [RSP + 96], XMM9;
movdqa [RSP + 80], XMM10;
movdqa [RSP + 64], XMM11;
movdqa [RSP + 48], XMM12;
movdqa [RSP + 32], XMM13;
movdqa [RSP + 16], XMM14;
movdqa [RSP], XMM15;
push RBX;
xor RAX,RAX;
push qword ptr GS:[RAX];
push qword ptr GS:8[RAX];
push qword ptr GS:16[RAX];
// store oldp
mov [RCX], RSP;
// load newp to begin context switch
mov RSP, RDX;
// load saved state from new stack
pop qword ptr GS:16[RAX];
pop qword ptr GS:8[RAX];
pop qword ptr GS:[RAX];
pop RBX;
movdqa XMM15, [RSP];
movdqa XMM14, [RSP + 16];
movdqa XMM13, [RSP + 32];
movdqa XMM12, [RSP + 48];
movdqa XMM11, [RSP + 64];
movdqa XMM10, [RSP + 80];
movdqa XMM9, [RSP + 96];
movdqa XMM8, [RSP + 112];
movdqa XMM7, [RSP + 128];
movdqa XMM6, [RSP + 144];
add RSP, 160;
pop RSI;
pop RDI;
pop R15;
pop R14;
pop R13;
pop R12;
pop RBP;
// 'return' to complete switch
pop RCX;
jmp RCX;
}
}
else version (AsmX86_Posix)
{
asm pure nothrow @nogc
{
naked;
// save current stack state
push EBP;
mov EBP, ESP;
push EDI;
push ESI;
push EBX;
push EAX;
// store oldp again with more accurate address
mov EAX, dword ptr 8[EBP];
mov [EAX], ESP;
// load newp to begin context switch
mov ESP, dword ptr 12[EBP];
// load saved state from new stack
pop EAX;
pop EBX;
pop ESI;
pop EDI;
pop EBP;
// 'return' to complete switch
pop ECX;
jmp ECX;
}
}
else version (AsmX86_64_Posix)
{
asm pure nothrow @nogc
{
naked;
// save current stack state
push RBP;
mov RBP, RSP;
push RBX;
push R12;
push R13;
push R14;
push R15;
// store oldp
mov [RDI], RSP;
// load newp to begin context switch
mov RSP, RSI;
// load saved state from new stack
pop R15;
pop R14;
pop R13;
pop R12;
pop RBX;
pop RBP;
// 'return' to complete switch
pop RCX;
jmp RCX;
}
}
else static if ( __traits( compiles, ucontext_t ) )
{
Fiber cfib = Fiber.getThis();
void* ucur = cfib.m_ucur;
*oldp = &ucur;
swapcontext( **(cast(ucontext_t***) oldp),
*(cast(ucontext_t**) newp) );
}
else
static assert(0, "Not implemented");
}
}
///////////////////////////////////////////////////////////////////////////////
// Fiber
///////////////////////////////////////////////////////////////////////////////
/*
* Documentation of Fiber internals:
*
* The main routines to implement when porting Fibers to new architectures are
* fiber_switchContext and initStack. Some version constants have to be defined
* for the new platform as well, search for "Fiber Platform Detection and Memory Allocation".
*
* Fibers are based on a concept called 'Context'. A Context describes the execution
* state of a Fiber or main thread which is fully described by the stack, some
* registers and a return address at which the Fiber/Thread should continue executing.
* Please note that not only each Fiber has a Context, but each thread also has got a
* Context which describes the threads stack and state. If you call Fiber fib; fib.call
* the first time in a thread you switch from Threads Context into the Fibers Context.
* If you call fib.yield in that Fiber you switch out of the Fibers context and back
* into the Thread Context. (However, this is not always the case. You can call a Fiber
* from within another Fiber, then you switch Contexts between the Fibers and the Thread
* Context is not involved)
*
* In all current implementations the registers and the return address are actually
* saved on a Contexts stack.
*
* The fiber_switchContext routine has got two parameters:
* void** a: This is the _location_ where we have to store the current stack pointer,
* the stack pointer of the currently executing Context (Fiber or Thread).
* void* b: This is the pointer to the stack of the Context which we want to switch into.
* Note that we get the same pointer here as the one we stored into the void** a
* in a previous call to fiber_switchContext.
*
* In the simplest case, a fiber_switchContext rountine looks like this:
* fiber_switchContext:
* push {return Address}
* push {registers}
* copy {stack pointer} into {location pointed to by a}
* //We have now switch to the stack of a different Context!
* copy {b} into {stack pointer}
* pop {registers}
* pop {return Address}
* jump to {return Address}
*
* The GC uses the value returned in parameter a to scan the Fibers stack. It scans from
* the stack base to that value. As the GC dislikes false pointers we can actually optimize
* this a little: By storing registers which can not contain references to memory managed
* by the GC outside of the region marked by the stack base pointer and the stack pointer
* saved in fiber_switchContext we can prevent the GC from scanning them.
* Such registers are usually floating point registers and the return address. In order to
* implement this, we return a modified stack pointer from fiber_switchContext. However,
* we have to remember that when we restore the registers from the stack!
*
* --------------------------- <= Stack Base
* | Frame | <= Many other stack frames
* | Frame |
* |-------------------------| <= The last stack frame. This one is created by fiber_switchContext
* | registers with pointers |
* | | <= Stack pointer. GC stops scanning here
* | return address |
* |floating point registers |
* --------------------------- <= Real Stack End
*
* fiber_switchContext:
* push {registers with pointers}
* copy {stack pointer} into {location pointed to by a}
* push {return Address}
* push {Floating point registers}
* //We have now switch to the stack of a different Context!
* copy {b} into {stack pointer}
* //We now have to adjust the stack pointer to point to 'Real Stack End' so we can pop
* //the FP registers
* //+ or - depends on if your stack grows downwards or upwards
* {stack pointer} = {stack pointer} +- ({FPRegisters}.sizeof + {return address}.sizeof}
* pop {Floating point registers}
* pop {return Address}
* pop {registers with pointers}
* jump to {return Address}
*
* So the question now is which registers need to be saved? This depends on the specific
* architecture ABI of course, but here are some general guidelines:
* - If a register is callee-save (if the callee modifies the register it must saved and
* restored by the callee) it needs to be saved/restored in switchContext
* - If a register is caller-save it needn't be saved/restored. (Calling fiber_switchContext
* is a function call and the compiler therefore already must save these registers before
* calling fiber_switchContext)
* - Argument registers used for passing parameters to functions needn't be saved/restored
* - The return register needn't be saved/restored (fiber_switchContext hasn't got a return type)
* - All scratch registers needn't be saved/restored
* - The link register usually needn't be saved/restored (but sometimes it must be cleared -
* see below for details)
* - The frame pointer register - if it exists - is usually callee-save
* - All current implementations do not save control registers
*
* What happens on the first switch into a Fiber? We never saved a state for this fiber before,
* but the initial state is prepared in the initStack routine. (This routine will also be called
* when a Fiber is being resetted). initStack must produce exactly the same stack layout as the
* part of fiber_switchContext which saves the registers. Pay special attention to set the stack
* pointer correctly if you use the GC optimization mentioned before. the return Address saved in
* initStack must be the address of fiber_entrypoint.
*
* There's now a small but important difference between the first context switch into a fiber and
* further context switches. On the first switch, Fiber.call is used and the returnAddress in
* fiber_switchContext will point to fiber_entrypoint. The important thing here is that this jump
* is a _function call_, we call fiber_entrypoint by jumping before it's function prologue. On later
* calls, the user used yield() in a function, and therefore the return address points into a user
* function, after the yield call. So here the jump in fiber_switchContext is a _function return_,
* not a function call!
*
* The most important result of this is that on entering a function, i.e. fiber_entrypoint, we
* would have to provide a return address / set the link register once fiber_entrypoint
* returns. Now fiber_entrypoint does never return and therefore the actual value of the return
* address / link register is never read/used and therefore doesn't matter. When fiber_switchContext
* performs a _function return_ the value in the link register doesn't matter either.
* However, the link register will still be saved to the stack in fiber_entrypoint and some
* exception handling / stack unwinding code might read it from this stack location and crash.
* The exact solution depends on your architecture, but see the ARM implementation for a way
* to deal with this issue.
*
* The ARM implementation is meant to be used as a kind of documented example implementation.
* Look there for a concrete example.
*
* FIXME: fiber_entrypoint might benefit from a @noreturn attribute, but D doesn't have one.
*/
/**
* This class provides a cooperative concurrency mechanism integrated with the
* threading and garbage collection functionality. Calling a fiber may be
* considered a blocking operation that returns when the fiber yields (via
* Fiber.yield()). Execution occurs within the context of the calling thread
* so synchronization is not necessary to guarantee memory visibility so long
* as the same thread calls the fiber each time. Please note that there is no
* requirement that a fiber be bound to one specific thread. Rather, fibers
* may be freely passed between threads so long as they are not currently
* executing. Like threads, a new fiber thread may be created using either
* derivation or composition, as in the following example.
*
* Warning:
* Status registers are not saved by the current implementations. This means
* floating point exception status bits (overflow, divide by 0), rounding mode
* and similar stuff is set per-thread, not per Fiber!
*
* Warning:
* On ARM FPU registers are not saved if druntime was compiled as ARM_SoftFloat.
* If such a build is used on a ARM_SoftFP system which actually has got a FPU
* and other libraries are using the FPU registers (other code is compiled
* as ARM_SoftFP) this can cause problems. Druntime must be compiled as
* ARM_SoftFP in this case.
*
* Example:
* ----------------------------------------------------------------------
*
* class DerivedFiber : Fiber
* {
* this()
* {
* super( &run );
* }
*
* private :
* void run()
* {
* printf( "Derived fiber running.\n" );
* }
* }
*
* void fiberFunc()
* {
* printf( "Composed fiber running.\n" );
* Fiber.yield();
* printf( "Composed fiber running.\n" );
* }
*
* // create instances of each type
* Fiber derived = new DerivedFiber();
* Fiber composed = new Fiber( &fiberFunc );
*
* // call both fibers once
* derived.call();
* composed.call();
* printf( "Execution returned to calling context.\n" );
* composed.call();
*
* // since each fiber has run to completion, each should have state TERM
* assert( derived.state == Fiber.State.TERM );
* assert( composed.state == Fiber.State.TERM );
*
* ----------------------------------------------------------------------
*
* Authors: Based on a design by Mikola Lysenko.
*/
class Fiber
{
///////////////////////////////////////////////////////////////////////////
// Initialization
///////////////////////////////////////////////////////////////////////////
/**
* Initializes a fiber object which is associated with a static
* D function.
*
* Params:
* fn = The fiber function.
* sz = The stack size for this fiber.
* guardPageSize = size of the guard page to trap fiber's stack
* overflows
*
* In:
* fn must not be null.
*/
this( void function() fn, size_t sz = PAGESIZE*4,
size_t guardPageSize = PAGESIZE ) nothrow
in
{
assert( fn );
}
body
{
allocStack( sz, guardPageSize );
reset( fn );
}
/**
* Initializes a fiber object which is associated with a dynamic
* D function.
*
* Params:
* dg = The fiber function.
* sz = The stack size for this fiber.
* guardPageSize = size of the guard page to trap fiber's stack
* overflows
*
* In:
* dg must not be null.
*/
this( void delegate() dg, size_t sz = PAGESIZE*4,
size_t guardPageSize = PAGESIZE ) nothrow
in
{
assert( dg );
}
body
{
allocStack( sz, guardPageSize);
reset( dg );
}
/**
* Cleans up any remaining resources used by this object.
*/
~this() nothrow @nogc
{
// NOTE: A live reference to this object will exist on its associated
// stack from the first time its call() method has been called
// until its execution completes with State.TERM. Thus, the only
// times this dtor should be called are either if the fiber has
// terminated (and therefore has no active stack) or if the user
// explicitly deletes this object. The latter case is an error
// but is not easily tested for, since State.HOLD may imply that
// the fiber was just created but has never been run. There is
// not a compelling case to create a State.INIT just to offer a
// means of ensuring the user isn't violating this object's
// contract, so for now this requirement will be enforced by
// documentation only.
freeStack();
}
///////////////////////////////////////////////////////////////////////////
// General Actions
///////////////////////////////////////////////////////////////////////////
/**
* Transfers execution to this fiber object. The calling context will be
* suspended until the fiber calls Fiber.yield() or until it terminates
* via an unhandled exception.
*
* Params:
* rethrow = Rethrow any unhandled exception which may have caused this
* fiber to terminate.
*
* In:
* This fiber must be in state HOLD.
*
* Throws:
* Any exception not handled by the joined thread.
*
* Returns:
* Any exception not handled by this fiber if rethrow = false, null
* otherwise.
*/
// Not marked with any attributes, even though `nothrow @nogc` works
// because it calls arbitrary user code. Most of the implementation
// is already `@nogc nothrow`, but in order for `Fiber.call` to
// propagate the attributes of the user's function, the Fiber
// class needs to be templated.
final Throwable call( Rethrow rethrow = Rethrow.yes )
{
return rethrow ? call!(Rethrow.yes)() : call!(Rethrow.no);
}
/// ditto
final Throwable call( Rethrow rethrow )()
{
callImpl();
if ( m_unhandled )
{
Throwable t = m_unhandled;
m_unhandled = null;
static if ( rethrow )
throw t;
else
return t;
}
return null;
}
/// ditto
deprecated("Please pass Fiber.Rethrow.yes or .no instead of a boolean.")
final Throwable call( bool rethrow )
{
return rethrow ? call!(Rethrow.yes)() : call!(Rethrow.no);
}
private void callImpl() nothrow @nogc
in
{
assert( m_state == State.HOLD );
}
body
{
Fiber cur = getThis();
static if ( __traits( compiles, ucontext_t ) )
m_ucur = cur ? &cur.m_utxt : &Fiber.sm_utxt;
setThis( this );
this.switchIn();
setThis( cur );
static if ( __traits( compiles, ucontext_t ) )
m_ucur = null;
// NOTE: If the fiber has terminated then the stack pointers must be
// reset. This ensures that the stack for this fiber is not
// scanned if the fiber has terminated. This is necessary to
// prevent any references lingering on the stack from delaying
// the collection of otherwise dead objects. The most notable
// being the current object, which is referenced at the top of
// fiber_entryPoint.
if ( m_state == State.TERM )
{
m_ctxt.tstack = m_ctxt.bstack;
}
}
/// Flag to control rethrow behavior of $(D $(LREF call))
enum Rethrow : bool { no, yes }
/**
* Resets this fiber so that it may be re-used, optionally with a
* new function/delegate. This routine should only be called for
* fibers that have terminated, as doing otherwise could result in
* scope-dependent functionality that is not executed.
* Stack-based classes, for example, may not be cleaned up
* properly if a fiber is reset before it has terminated.
*
* In:
* This fiber must be in state TERM or HOLD.
*/
final void reset() nothrow @nogc
in
{
assert( m_state == State.TERM || m_state == State.HOLD );
}
body
{
m_ctxt.tstack = m_ctxt.bstack;
m_state = State.HOLD;
initStack();
m_unhandled = null;
}
/// ditto
final void reset( void function() fn ) nothrow @nogc
{
reset();
m_fn = fn;
m_call = Call.FN;
}
/// ditto
final void reset( void delegate() dg ) nothrow @nogc
{
reset();
m_dg = dg;
m_call = Call.DG;
}
///////////////////////////////////////////////////////////////////////////
// General Properties
///////////////////////////////////////////////////////////////////////////
/**
* A fiber may occupy one of three states: HOLD, EXEC, and TERM. The HOLD
* state applies to any fiber that is suspended and ready to be called.
* The EXEC state will be set for any fiber that is currently executing.
* And the TERM state is set when a fiber terminates. Once a fiber
* terminates, it must be reset before it may be called again.
*/
enum State
{
HOLD, ///
EXEC, ///
TERM ///
}
/**
* Gets the current state of this fiber.
*
* Returns:
* The state of this fiber as an enumerated value.
*/
final @property State state() const @safe pure nothrow @nogc
{
return m_state;
}
///////////////////////////////////////////////////////////////////////////
// Actions on Calling Fiber
///////////////////////////////////////////////////////////////////////////
/**
* Forces a context switch to occur away from the calling fiber.
*/
static void yield() nothrow @nogc
{
Fiber cur = getThis();
assert( cur, "Fiber.yield() called with no active fiber" );
assert( cur.m_state == State.EXEC );
static if ( __traits( compiles, ucontext_t ) )
cur.m_ucur = &cur.m_utxt;
cur.m_state = State.HOLD;
cur.switchOut();
cur.m_state = State.EXEC;
}
/**
* Forces a context switch to occur away from the calling fiber and then
* throws obj in the calling fiber.
*
* Params:
* t = The object to throw.
*
* In:
* t must not be null.
*/
static void yieldAndThrow( Throwable t ) nothrow @nogc
in
{
assert( t );
}
body
{
Fiber cur = getThis();
assert( cur, "Fiber.yield() called with no active fiber" );
assert( cur.m_state == State.EXEC );
static if ( __traits( compiles, ucontext_t ) )
cur.m_ucur = &cur.m_utxt;
cur.m_unhandled = t;
cur.m_state = State.HOLD;
cur.switchOut();
cur.m_state = State.EXEC;
}
///////////////////////////////////////////////////////////////////////////
// Fiber Accessors
///////////////////////////////////////////////////////////////////////////
/**
* Provides a reference to the calling fiber or null if no fiber is
* currently active.
*
* Returns:
* The fiber object representing the calling fiber or null if no fiber
* is currently active within this thread. The result of deleting this object is undefined.
*/
static Fiber getThis() @safe nothrow @nogc
{
return sm_this;
}
///////////////////////////////////////////////////////////////////////////
// Static Initialization
///////////////////////////////////////////////////////////////////////////
version (Posix)
{
static this()
{
static if ( __traits( compiles, ucontext_t ) )
{
int status = getcontext( &sm_utxt );
assert( status == 0 );
}
}
}
private:
//
// Initializes a fiber object which has no associated executable function.
//
this() @safe pure nothrow @nogc
{
m_call = Call.NO;
}
//
// Fiber entry point. Invokes the function or delegate passed on
// construction (if any).
//
final void run()
{
switch ( m_call )
{
case Call.FN:
m_fn();
break;
case Call.DG:
m_dg();
break;
default:
break;
}
}
private:
//
// The type of routine passed on fiber construction.
//
enum Call
{
NO,
FN,
DG
}
//
// Standard fiber data
//
Call m_call;
union
{
void function() m_fn;
void delegate() m_dg;
}
bool m_isRunning;
Throwable m_unhandled;
State m_state;
private:
///////////////////////////////////////////////////////////////////////////
// Stack Management
///////////////////////////////////////////////////////////////////////////
//
// Allocate a new stack for this fiber.
//
final void allocStack( size_t sz, size_t guardPageSize ) nothrow
in
{
assert( !m_pmem && !m_ctxt );
}
body
{
// adjust alloc size to a multiple of PAGESIZE
sz += PAGESIZE - 1;
sz -= sz % PAGESIZE;
// NOTE: This instance of Thread.Context is dynamic so Fiber objects
// can be collected by the GC so long as no user level references
// to the object exist. If m_ctxt were not dynamic then its
// presence in the global context list would be enough to keep
// this object alive indefinitely. An alternative to allocating
// room for this struct explicitly would be to mash it into the
// base of the stack being allocated below. However, doing so
// requires too much special logic to be worthwhile.
m_ctxt = new Thread.Context;
static if ( __traits( compiles, VirtualAlloc ) )
{
// reserve memory for stack
m_pmem = VirtualAlloc( null,
sz + guardPageSize,
MEM_RESERVE,
PAGE_NOACCESS );
if ( !m_pmem )
onOutOfMemoryError();
version (StackGrowsDown)
{
void* stack = m_pmem + guardPageSize;
void* guard = m_pmem;
void* pbase = stack + sz;
}
else
{
void* stack = m_pmem;
void* guard = m_pmem + sz;
void* pbase = stack;
}
// allocate reserved stack segment
stack = VirtualAlloc( stack,
sz,
MEM_COMMIT,
PAGE_READWRITE );
if ( !stack )
onOutOfMemoryError();
if (guardPageSize)
{
// allocate reserved guard page
guard = VirtualAlloc( guard,
guardPageSize,
MEM_COMMIT,
PAGE_READWRITE | PAGE_GUARD );
if ( !guard )
onOutOfMemoryError();
}
m_ctxt.bstack = pbase;
m_ctxt.tstack = pbase;
m_size = sz;
}
else
{
version (Posix) import core.sys.posix.sys.mman; // mmap
version (FreeBSD) import core.sys.freebsd.sys.mman : MAP_ANON;
version (NetBSD) import core.sys.netbsd.sys.mman : MAP_ANON;
version (OpenBSD) import core.sys.openbsd.sys.mman : MAP_ANON;
version (DragonFlyBSD) import core.sys.dragonflybsd.sys.mman : MAP_ANON;
version (CRuntime_Glibc) import core.sys.linux.sys.mman : MAP_ANON;
version (Darwin) import core.sys.darwin.sys.mman : MAP_ANON;
version (CRuntime_UClibc) import core.sys.linux.sys.mman : MAP_ANON;
static if ( __traits( compiles, mmap ) )
{
// Allocate more for the memory guard
sz += guardPageSize;
m_pmem = mmap( null,
sz,
PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANON,
-1,
0 );
if ( m_pmem == MAP_FAILED )
m_pmem = null;
}
else static if ( __traits( compiles, valloc ) )
{
m_pmem = valloc( sz );
}
else static if ( __traits( compiles, malloc ) )
{
m_pmem = malloc( sz );
}
else
{
m_pmem = null;
}
if ( !m_pmem )
onOutOfMemoryError();
version (StackGrowsDown)
{
m_ctxt.bstack = m_pmem + sz;
m_ctxt.tstack = m_pmem + sz;
void* guard = m_pmem;
}
else
{
m_ctxt.bstack = m_pmem;
m_ctxt.tstack = m_pmem;
void* guard = m_pmem + sz - guardPageSize;
}
m_size = sz;
static if ( __traits( compiles, mmap ) )
{
if (guardPageSize)
{
// protect end of stack
if ( mprotect(guard, guardPageSize, PROT_NONE) == -1 )
abort();
}
}
else
{
// Supported only for mmap allocated memory - results are
// undefined if applied to memory not obtained by mmap
}
}
Thread.add( m_ctxt );
}
//
// Free this fiber's stack.
//
final void freeStack() nothrow @nogc
in
{
assert( m_pmem && m_ctxt );
}
body
{
// NOTE: m_ctxt is guaranteed to be alive because it is held in the
// global context list.
Thread.slock.lock_nothrow();
scope(exit) Thread.slock.unlock_nothrow();
Thread.remove( m_ctxt );
static if ( __traits( compiles, VirtualAlloc ) )
{
VirtualFree( m_pmem, 0, MEM_RELEASE );
}
else
{
import core.sys.posix.sys.mman; // munmap
static if ( __traits( compiles, mmap ) )
{
munmap( m_pmem, m_size );
}
else static if ( __traits( compiles, valloc ) )
{
free( m_pmem );
}
else static if ( __traits( compiles, malloc ) )
{
free( m_pmem );
}
}
m_pmem = null;
m_ctxt = null;
}
//
// Initialize the allocated stack.
// Look above the definition of 'class Fiber' for some information about the implementation of this routine
//
final void initStack() nothrow @nogc
in
{
assert( m_ctxt.tstack && m_ctxt.tstack == m_ctxt.bstack );
assert( cast(size_t) m_ctxt.bstack % (void*).sizeof == 0 );
}
body
{
void* pstack = m_ctxt.tstack;
scope( exit ) m_ctxt.tstack = pstack;
void push( size_t val ) nothrow
{
version (StackGrowsDown)
{
pstack -= size_t.sizeof;
*(cast(size_t*) pstack) = val;
}
else
{
pstack += size_t.sizeof;
*(cast(size_t*) pstack) = val;
}
}
// NOTE: On OS X the stack must be 16-byte aligned according
// to the IA-32 call spec. For x86_64 the stack also needs to
// be aligned to 16-byte according to SysV AMD64 ABI.
version (AlignFiberStackTo16Byte)
{
version (StackGrowsDown)
{
pstack = cast(void*)(cast(size_t)(pstack) - (cast(size_t)(pstack) & 0x0F));
}
else
{
pstack = cast(void*)(cast(size_t)(pstack) + (cast(size_t)(pstack) & 0x0F));
}
}
version (AsmX86_Windows)
{
version (StackGrowsDown) {} else static assert( false );
// On Windows Server 2008 and 2008 R2, an exploit mitigation
// technique known as SEHOP is activated by default. To avoid
// hijacking of the exception handler chain, the presence of a
// Windows-internal handler (ntdll.dll!FinalExceptionHandler) at
// its end is tested by RaiseException. If it is not present, all
// handlers are disregarded, and the program is thus aborted
// (see http://blogs.technet.com/b/srd/archive/2009/02/02/
// preventing-the-exploitation-of-seh-overwrites-with-sehop.aspx).
// For new threads, this handler is installed by Windows immediately
// after creation. To make exception handling work in fibers, we
// have to insert it for our new stacks manually as well.
//
// To do this, we first determine the handler by traversing the SEH
// chain of the current thread until its end, and then construct a
// registration block for the last handler on the newly created
// thread. We then continue to push all the initial register values
// for the first context switch as for the other implementations.
//
// Note that this handler is never actually invoked, as we install
// our own one on top of it in the fiber entry point function.
// Thus, it should not have any effects on OSes not implementing
// exception chain verification.
alias fp_t = void function(); // Actual signature not relevant.
static struct EXCEPTION_REGISTRATION
{
EXCEPTION_REGISTRATION* next; // sehChainEnd if last one.
fp_t handler;
}
enum sehChainEnd = cast(EXCEPTION_REGISTRATION*) 0xFFFFFFFF;
__gshared static fp_t finalHandler = null;
if ( finalHandler is null )
{
static EXCEPTION_REGISTRATION* fs0() nothrow
{
asm pure nothrow @nogc
{
naked;
mov EAX, FS:[0];
ret;
}
}
auto reg = fs0();
while ( reg.next != sehChainEnd ) reg = reg.next;
// Benign races are okay here, just to avoid re-lookup on every
// fiber creation.
finalHandler = reg.handler;
}
// When linking with /safeseh (supported by LDC, but not DMD)
// the exception chain must not extend to the very top
// of the stack, otherwise the exception chain is also considered
// invalid. Reserving additional 4 bytes at the top of the stack will
// keep the EXCEPTION_REGISTRATION below that limit
size_t reserve = EXCEPTION_REGISTRATION.sizeof + 4;
pstack -= reserve;
*(cast(EXCEPTION_REGISTRATION*)pstack) =
EXCEPTION_REGISTRATION( sehChainEnd, finalHandler );
push( cast(size_t) &fiber_entryPoint ); // EIP
push( cast(size_t) m_ctxt.bstack - reserve ); // EBP
push( 0x00000000 ); // EDI
push( 0x00000000 ); // ESI
push( 0x00000000 ); // EBX
push( cast(size_t) m_ctxt.bstack - reserve ); // FS:[0]
push( cast(size_t) m_ctxt.bstack ); // FS:[4]
push( cast(size_t) m_ctxt.bstack - m_size ); // FS:[8]
push( 0x00000000 ); // EAX
}
else version (AsmX86_64_Windows)
{
// Using this trampoline instead of the raw fiber_entryPoint
// ensures that during context switches, source and destination
// stacks have the same alignment. Otherwise, the stack would need
// to be shifted by 8 bytes for the first call, as fiber_entryPoint
// is an actual function expecting a stack which is not aligned
// to 16 bytes.
static void trampoline()
{
asm pure nothrow @nogc
{
naked;
sub RSP, 32; // Shadow space (Win64 calling convention)
call fiber_entryPoint;
xor RCX, RCX; // This should never be reached, as
jmp RCX; // fiber_entryPoint must never return.
}
}
push( cast(size_t) &trampoline ); // RIP
push( 0x00000000_00000000 ); // RBP
push( 0x00000000_00000000 ); // R12
push( 0x00000000_00000000 ); // R13
push( 0x00000000_00000000 ); // R14
push( 0x00000000_00000000 ); // R15
push( 0x00000000_00000000 ); // RDI
push( 0x00000000_00000000 ); // RSI
push( 0x00000000_00000000 ); // XMM6 (high)
push( 0x00000000_00000000 ); // XMM6 (low)
push( 0x00000000_00000000 ); // XMM7 (high)
push( 0x00000000_00000000 ); // XMM7 (low)
push( 0x00000000_00000000 ); // XMM8 (high)
push( 0x00000000_00000000 ); // XMM8 (low)
push( 0x00000000_00000000 ); // XMM9 (high)
push( 0x00000000_00000000 ); // XMM9 (low)
push( 0x00000000_00000000 ); // XMM10 (high)
push( 0x00000000_00000000 ); // XMM10 (low)
push( 0x00000000_00000000 ); // XMM11 (high)
push( 0x00000000_00000000 ); // XMM11 (low)
push( 0x00000000_00000000 ); // XMM12 (high)
push( 0x00000000_00000000 ); // XMM12 (low)
push( 0x00000000_00000000 ); // XMM13 (high)
push( 0x00000000_00000000 ); // XMM13 (low)
push( 0x00000000_00000000 ); // XMM14 (high)
push( 0x00000000_00000000 ); // XMM14 (low)
push( 0x00000000_00000000 ); // XMM15 (high)
push( 0x00000000_00000000 ); // XMM15 (low)
push( 0x00000000_00000000 ); // RBX
push( 0xFFFFFFFF_FFFFFFFF ); // GS:[0]
version (StackGrowsDown)
{
push( cast(size_t) m_ctxt.bstack ); // GS:[8]
push( cast(size_t) m_ctxt.bstack - m_size ); // GS:[16]
}
else
{
push( cast(size_t) m_ctxt.bstack ); // GS:[8]
push( cast(size_t) m_ctxt.bstack + m_size ); // GS:[16]
}
}
else version (AsmX86_Posix)
{
push( 0x00000000 ); // Return address of fiber_entryPoint call
push( cast(size_t) &fiber_entryPoint ); // EIP
push( cast(size_t) m_ctxt.bstack ); // EBP
push( 0x00000000 ); // EDI
push( 0x00000000 ); // ESI
push( 0x00000000 ); // EBX
push( 0x00000000 ); // EAX
}
else version (AsmX86_64_Posix)
{
push( 0x00000000_00000000 ); // Return address of fiber_entryPoint call
push( cast(size_t) &fiber_entryPoint ); // RIP
push( cast(size_t) m_ctxt.bstack ); // RBP
push( 0x00000000_00000000 ); // RBX
push( 0x00000000_00000000 ); // R12
push( 0x00000000_00000000 ); // R13
push( 0x00000000_00000000 ); // R14
push( 0x00000000_00000000 ); // R15
}
else version (AsmPPC_Posix)
{
version (StackGrowsDown)
{
pstack -= int.sizeof * 5;
}
else
{
pstack += int.sizeof * 5;
}
push( cast(size_t) &fiber_entryPoint ); // link register
push( 0x00000000 ); // control register
push( 0x00000000 ); // old stack pointer
// GPR values
version (StackGrowsDown)
{
pstack -= int.sizeof * 20;
}
else
{
pstack += int.sizeof * 20;
}
assert( (cast(size_t) pstack & 0x0f) == 0 );
}
else version (AsmMIPS_O32_Posix)
{
version (StackGrowsDown) {}
else static assert(0);
/* We keep the FP registers and the return address below
* the stack pointer, so they don't get scanned by the
* GC. The last frame before swapping the stack pointer is
* organized like the following.
*
* |-----------|<= frame pointer
* | $gp |
* | $s0-8 |
* |-----------|<= stack pointer
* | $ra |
* | align(8) |
* | $f20-30 |
* |-----------|
*
*/
enum SZ_GP = 10 * size_t.sizeof; // $gp + $s0-8
enum SZ_RA = size_t.sizeof; // $ra
version (MIPS_HardFloat)
{
enum SZ_FP = 6 * 8; // $f20-30
enum ALIGN = -(SZ_FP + SZ_RA) & (8 - 1);
}
else
{
enum SZ_FP = 0;
enum ALIGN = 0;
}
enum BELOW = SZ_FP + ALIGN + SZ_RA;
enum ABOVE = SZ_GP;
enum SZ = BELOW + ABOVE;
(cast(ubyte*)pstack - SZ)[0 .. SZ] = 0;
pstack -= ABOVE;
*cast(size_t*)(pstack - SZ_RA) = cast(size_t)&fiber_entryPoint;
}
else version (AsmAArch64_Posix)
{
// Like others, FP registers and return address (lr) are kept
// below the saved stack top (tstack) to hide from GC scanning.
// fiber_switchContext expects newp sp to look like this:
// 19: x19
// ...
// 9: x29 (fp) <-- newp tstack
// 8: x30 (lr) [&fiber_entryPoint]
// 7: d8
// ...
// 0: d15
version (StackGrowsDown) {}
else
static assert(false, "Only full descending stacks supported on AArch64");
// Only need to set return address (lr). Everything else is fine
// zero initialized.
pstack -= size_t.sizeof * 11; // skip past x19-x29
push(cast(size_t) &fiber_trampoline); // see threadasm.S for docs
pstack += size_t.sizeof; // adjust sp (newp) above lr
}
else version (AsmARM_Posix)
{
/* We keep the FP registers and the return address below
* the stack pointer, so they don't get scanned by the
* GC. The last frame before swapping the stack pointer is
* organized like the following.
*
* | |-----------|<= 'frame starts here'
* | | fp | (the actual frame pointer, r11 isn't
* | | r10-r4 | updated and still points to the previous frame)
* | |-----------|<= stack pointer
* | | lr |
* | | 4byte pad |
* | | d15-d8 |(if FP supported)
* | |-----------|
* Y
* stack grows down: The pointer value here is smaller than some lines above
*/
// frame pointer can be zero, r10-r4 also zero initialized
version (StackGrowsDown)
pstack -= int.sizeof * 8;
else
static assert(false, "Only full descending stacks supported on ARM");
// link register
push( cast(size_t) &fiber_entryPoint );
/*
* We do not push padding and d15-d8 as those are zero initialized anyway
* Position the stack pointer above the lr register
*/
pstack += int.sizeof * 1;
}
else version (GNU_AsmX86_Windows)
{
version (StackGrowsDown) {} else static assert( false );
// Currently, MinGW doesn't utilize SEH exceptions.
// See DMD AsmX86_Windows If this code ever becomes fails and SEH is used.
push( 0x00000000 ); // Return address of fiber_entryPoint call
push( cast(size_t) &fiber_entryPoint ); // EIP
push( 0x00000000 ); // EBP
push( 0x00000000 ); // EDI
push( 0x00000000 ); // ESI
push( 0x00000000 ); // EBX
push( 0xFFFFFFFF ); // FS:[0] - Current SEH frame
push( cast(size_t) m_ctxt.bstack ); // FS:[4] - Top of stack
push( cast(size_t) m_ctxt.bstack - m_size ); // FS:[8] - Bottom of stack
push( 0x00000000 ); // EAX
}
else version (GNU_AsmX86_64_Windows)
{
push( 0x00000000_00000000 ); // Return address of fiber_entryPoint call
push( cast(size_t) &fiber_entryPoint ); // RIP
push( 0x00000000_00000000 ); // RBP
push( 0x00000000_00000000 ); // RBX
push( 0x00000000_00000000 ); // R12
push( 0x00000000_00000000 ); // R13
push( 0x00000000_00000000 ); // R14
push( 0x00000000_00000000 ); // R15
push( 0xFFFFFFFF_FFFFFFFF ); // GS:[0] - Current SEH frame
version (StackGrowsDown)
{
push( cast(size_t) m_ctxt.bstack ); // GS:[8] - Top of stack
push( cast(size_t) m_ctxt.bstack - m_size ); // GS:[16] - Bottom of stack
}
else
{
push( cast(size_t) m_ctxt.bstack ); // GS:[8] - Top of stack
push( cast(size_t) m_ctxt.bstack + m_size ); // GS:[16] - Bottom of stack
}
}
else static if ( __traits( compiles, ucontext_t ) )
{
getcontext( &m_utxt );
m_utxt.uc_stack.ss_sp = m_pmem;
m_utxt.uc_stack.ss_size = m_size;
makecontext( &m_utxt, &fiber_entryPoint, 0 );
// NOTE: If ucontext is being used then the top of the stack will
// be a pointer to the ucontext_t struct for that fiber.
push( cast(size_t) &m_utxt );
}
else
static assert(0, "Not implemented");
}
Thread.Context* m_ctxt;
size_t m_size;
void* m_pmem;
static if ( __traits( compiles, ucontext_t ) )
{
// NOTE: The static ucontext instance is used to represent the context
// of the executing thread.
static ucontext_t sm_utxt = void;
ucontext_t m_utxt = void;
ucontext_t* m_ucur = null;
}
private:
///////////////////////////////////////////////////////////////////////////
// Storage of Active Fiber
///////////////////////////////////////////////////////////////////////////
//
// Sets a thread-local reference to the current fiber object.
//
static void setThis( Fiber f ) nothrow @nogc
{
sm_this = f;
}
static Fiber sm_this;
private:
///////////////////////////////////////////////////////////////////////////
// Context Switching
///////////////////////////////////////////////////////////////////////////
//
// Switches into the stack held by this fiber.
//
final void switchIn() nothrow @nogc
{
Thread tobj = Thread.getThis();
void** oldp = &tobj.m_curr.tstack;
void* newp = m_ctxt.tstack;
// NOTE: The order of operations here is very important. The current
// stack top must be stored before m_lock is set, and pushContext
// must not be called until after m_lock is set. This process
// is intended to prevent a race condition with the suspend
// mechanism used for garbage collection. If it is not followed,
// a badly timed collection could cause the GC to scan from the
// bottom of one stack to the top of another, or to miss scanning
// a stack that still contains valid data. The old stack pointer
// oldp will be set again before the context switch to guarantee
// that it points to exactly the correct stack location so the
// successive pop operations will succeed.
*oldp = getStackTop();
atomicStore!(MemoryOrder.raw)(*cast(shared)&tobj.m_lock, true);
tobj.pushContext( m_ctxt );
fiber_switchContext( oldp, newp );
// NOTE: As above, these operations must be performed in a strict order
// to prevent Bad Things from happening.
tobj.popContext();
atomicStore!(MemoryOrder.raw)(*cast(shared)&tobj.m_lock, false);
tobj.m_curr.tstack = tobj.m_curr.bstack;
}
//
// Switches out of the current stack and into the enclosing stack.
//
final void switchOut() nothrow @nogc
{
Thread tobj = Thread.getThis();
void** oldp = &m_ctxt.tstack;
void* newp = tobj.m_curr.within.tstack;
// NOTE: The order of operations here is very important. The current
// stack top must be stored before m_lock is set, and pushContext
// must not be called until after m_lock is set. This process
// is intended to prevent a race condition with the suspend
// mechanism used for garbage collection. If it is not followed,
// a badly timed collection could cause the GC to scan from the
// bottom of one stack to the top of another, or to miss scanning
// a stack that still contains valid data. The old stack pointer
// oldp will be set again before the context switch to guarantee
// that it points to exactly the correct stack location so the
// successive pop operations will succeed.
*oldp = getStackTop();
atomicStore!(MemoryOrder.raw)(*cast(shared)&tobj.m_lock, true);
fiber_switchContext( oldp, newp );
// NOTE: As above, these operations must be performed in a strict order
// to prevent Bad Things from happening.
// NOTE: If use of this fiber is multiplexed across threads, the thread
// executing here may be different from the one above, so get the
// current thread handle before unlocking, etc.
tobj = Thread.getThis();
atomicStore!(MemoryOrder.raw)(*cast(shared)&tobj.m_lock, false);
tobj.m_curr.tstack = tobj.m_curr.bstack;
}
}
version (unittest)
{
class TestFiber : Fiber
{
this()
{
super(&run);
}
void run()
{
foreach (i; 0 .. 1000)
{
sum += i;
Fiber.yield();
}
}
enum expSum = 1000 * 999 / 2;
size_t sum;
}
void runTen()
{
TestFiber[10] fibs;
foreach (ref fib; fibs)
fib = new TestFiber();
bool cont;
do {
cont = false;
foreach (fib; fibs) {
if (fib.state == Fiber.State.HOLD)
{
fib.call();
cont |= fib.state != Fiber.State.TERM;
}
}
} while (cont);
foreach (fib; fibs)
{
assert(fib.sum == TestFiber.expSum);
}
}
}
// Single thread running separate fibers
unittest
{
runTen();
}
// Multiple threads running separate fibers
unittest
{
auto group = new ThreadGroup();
foreach (_; 0 .. 4)
{
group.create(&runTen);
}
group.joinAll();
}
// Multiple threads running shared fibers
unittest
{
shared bool[10] locks;
TestFiber[10] fibs;
void runShared()
{
bool cont;
do {
cont = false;
foreach (idx; 0 .. 10)
{
if (cas(&locks[idx], false, true))
{
if (fibs[idx].state == Fiber.State.HOLD)
{
fibs[idx].call();
cont |= fibs[idx].state != Fiber.State.TERM;
}
locks[idx] = false;
}
else
{
cont = true;
}
}
} while (cont);
}
foreach (ref fib; fibs)
{
fib = new TestFiber();
}
auto group = new ThreadGroup();
foreach (_; 0 .. 4)
{
group.create(&runShared);
}
group.joinAll();
foreach (fib; fibs)
{
assert(fib.sum == TestFiber.expSum);
}
}
// Test exception handling inside fibers.
version (Win32) {
// broken on win32 under windows server 2012: bug 13821
} else unittest {
enum MSG = "Test message.";
string caughtMsg;
(new Fiber({
try
{
throw new Exception(MSG);
}
catch (Exception e)
{
caughtMsg = e.msg;
}
})).call();
assert(caughtMsg == MSG);
}
unittest
{
int x = 0;
(new Fiber({
x++;
})).call();
assert( x == 1 );
}
nothrow unittest
{
new Fiber({}).call!(Fiber.Rethrow.no)();
}
unittest
{
new Fiber({}).call(Fiber.Rethrow.yes);
new Fiber({}).call(Fiber.Rethrow.no);
}
deprecated unittest
{
new Fiber({}).call(true);
new Fiber({}).call(false);
}
version (Win32) {
// broken on win32 under windows server 2012: bug 13821
} else unittest {
enum MSG = "Test message.";
try
{
(new Fiber({
throw new Exception( MSG );
})).call();
assert( false, "Expected rethrown exception." );
}
catch ( Throwable t )
{
assert( t.msg == MSG );
}
}
// Test exception chaining when switching contexts in finally blocks.
unittest
{
static void throwAndYield(string msg) {
try {
throw new Exception(msg);
} finally {
Fiber.yield();
}
}
static void fiber(string name) {
try {
try {
throwAndYield(name ~ ".1");
} finally {
throwAndYield(name ~ ".2");
}
} catch (Exception e) {
assert(e.msg == name ~ ".1");
assert(e.next);
assert(e.next.msg == name ~ ".2");
assert(!e.next.next);
}
}
auto first = new Fiber(() => fiber("first"));
auto second = new Fiber(() => fiber("second"));
first.call();
second.call();
first.call();
second.call();
first.call();
second.call();
assert(first.state == Fiber.State.TERM);
assert(second.state == Fiber.State.TERM);
}
// Test Fiber resetting
unittest
{
static string method;
static void foo()
{
method = "foo";
}
void bar()
{
method = "bar";
}
static void expect(Fiber fib, string s)
{
assert(fib.state == Fiber.State.HOLD);
fib.call();
assert(fib.state == Fiber.State.TERM);
assert(method == s); method = null;
}
auto fib = new Fiber(&foo);
expect(fib, "foo");
fib.reset();
expect(fib, "foo");
fib.reset(&foo);
expect(fib, "foo");
fib.reset(&bar);
expect(fib, "bar");
fib.reset(function void(){method = "function";});
expect(fib, "function");
fib.reset(delegate void(){method = "delegate";});
expect(fib, "delegate");
}
// Test unsafe reset in hold state
unittest
{
auto fib = new Fiber(function {ubyte[2048] buf = void; Fiber.yield();}, 4096);
foreach (_; 0 .. 10)
{
fib.call();
assert(fib.state == Fiber.State.HOLD);
fib.reset();
}
}
// stress testing GC stack scanning
unittest
{
import core.memory;
static void unreferencedThreadObject()
{
static void sleep() { Thread.sleep(dur!"msecs"(100)); }
auto thread = new Thread(&sleep).start();
}
unreferencedThreadObject();
GC.collect();
static class Foo
{
this(int value)
{
_value = value;
}
int bar()
{
return _value;
}
int _value;
}
static void collect()
{
auto foo = new Foo(2);
assert(foo.bar() == 2);
GC.collect();
Fiber.yield();
GC.collect();
assert(foo.bar() == 2);
}
auto fiber = new Fiber(&collect);
fiber.call();
GC.collect();
fiber.call();
// thread reference
auto foo = new Foo(2);
void collect2()
{
assert(foo.bar() == 2);
GC.collect();
Fiber.yield();
GC.collect();
assert(foo.bar() == 2);
}
fiber = new Fiber(&collect2);
fiber.call();
GC.collect();
fiber.call();
static void recurse(size_t cnt)
{
--cnt;
Fiber.yield();
if (cnt)
{
auto fib = new Fiber(() { recurse(cnt); });
fib.call();
GC.collect();
fib.call();
}
}
fiber = new Fiber(() { recurse(20); });
fiber.call();
}
version (AsmX86_64_Windows)
{
// Test Windows x64 calling convention
unittest
{
void testNonvolatileRegister(alias REG)()
{
auto zeroRegister = new Fiber(() {
mixin("asm pure nothrow @nogc { naked; xor "~REG~", "~REG~"; ret; }");
});
long after;
mixin("asm pure nothrow @nogc { mov "~REG~", 0xFFFFFFFFFFFFFFFF; }");
zeroRegister.call();
mixin("asm pure nothrow @nogc { mov after, "~REG~"; }");
assert(after == -1);
}
void testNonvolatileRegisterSSE(alias REG)()
{
auto zeroRegister = new Fiber(() {
mixin("asm pure nothrow @nogc { naked; xorpd "~REG~", "~REG~"; ret; }");
});
long[2] before = [0xFFFFFFFF_FFFFFFFF, 0xFFFFFFFF_FFFFFFFF], after;
mixin("asm pure nothrow @nogc { movdqu "~REG~", before; }");
zeroRegister.call();
mixin("asm pure nothrow @nogc { movdqu after, "~REG~"; }");
assert(before == after);
}
testNonvolatileRegister!("R12")();
testNonvolatileRegister!("R13")();
testNonvolatileRegister!("R14")();
testNonvolatileRegister!("R15")();
testNonvolatileRegister!("RDI")();
testNonvolatileRegister!("RSI")();
testNonvolatileRegister!("RBX")();
testNonvolatileRegisterSSE!("XMM6")();
testNonvolatileRegisterSSE!("XMM7")();
testNonvolatileRegisterSSE!("XMM8")();
testNonvolatileRegisterSSE!("XMM9")();
testNonvolatileRegisterSSE!("XMM10")();
testNonvolatileRegisterSSE!("XMM11")();
testNonvolatileRegisterSSE!("XMM12")();
testNonvolatileRegisterSSE!("XMM13")();
testNonvolatileRegisterSSE!("XMM14")();
testNonvolatileRegisterSSE!("XMM15")();
}
}
version (D_InlineAsm_X86_64)
{
unittest
{
void testStackAlignment()
{
void* pRSP;
asm pure nothrow @nogc
{
mov pRSP, RSP;
}
assert((cast(size_t)pRSP & 0xF) == 0);
}
auto fib = new Fiber(&testStackAlignment);
fib.call();
}
}
// regression test for Issue 13416
version (FreeBSD) unittest
{
static void loop()
{
pthread_attr_t attr;
pthread_attr_init(&attr);
auto thr = pthread_self();
foreach (i; 0 .. 50)
pthread_attr_get_np(thr, &attr);
pthread_attr_destroy(&attr);
}
auto thr = new Thread(&loop).start();
foreach (i; 0 .. 50)
{
thread_suspendAll();
thread_resumeAll();
}
thr.join();
}
version (DragonFlyBSD) unittest
{
static void loop()
{
pthread_attr_t attr;
pthread_attr_init(&attr);
auto thr = pthread_self();
foreach (i; 0 .. 50)
pthread_attr_get_np(thr, &attr);
pthread_attr_destroy(&attr);
}
auto thr = new Thread(&loop).start();
foreach (i; 0 .. 50)
{
thread_suspendAll();
thread_resumeAll();
}
thr.join();
}
unittest
{
// use >PAGESIZE to avoid stack overflow (e.g. in an syscall)
auto thr = new Thread(function{}, 4096 + 1).start();
thr.join();
}
/**
* Represents the ID of a thread, as returned by $(D Thread.)$(LREF id).
* The exact type varies from platform to platform.
*/
version (Windows)
alias ThreadID = uint;
else
version (Posix)
alias ThreadID = pthread_t;