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-- --
-- --
-- S Y S T E M . T A S K I N G . R E S T R I C T E D . S T A G E S --
-- --
-- B o d y --
-- --
-- Copyright (C) 1999-2002, Free Software Foundation, Inc. --
-- --
-- GNARL is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
-- ware Foundation; either version 2, or (at your option) any later ver- --
-- sion. GNARL is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
-- for more details. You should have received a copy of the GNU General --
-- Public License distributed with GNARL; see file COPYING. If not, write --
-- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
-- MA 02111-1307, USA. --
-- --
-- As a special exception, if other files instantiate generics from this --
-- unit, or you link this unit with other files to produce an executable, --
-- this unit does not by itself cause the resulting executable to be --
-- covered by the GNU General Public License. This exception does not --
-- however invalidate any other reasons why the executable file might be --
-- covered by the GNU Public License. --
-- --
-- GNARL was developed by the GNARL team at Florida State University. --
-- Extensive contributions were provided by Ada Core Technologies, Inc. --
-- --
pragma Style_Checks (All_Checks);
-- Turn off subprogram alpha order check, since we group soft link
-- bodies and also separate off subprograms for restricted GNARLI.
-- This is a simplified version of the System.Tasking.Stages package,
-- intended to be used in a restricted run time.
-- This package represents the high level tasking interface used by the
-- compiler to expand Ada 95 tasking constructs into simpler run time calls.
pragma Polling (Off);
-- Turn off polling, we do not want ATC polling to take place during
-- tasking operations. It causes infinite loops and other problems.
with System.Parameters;
-- used for Size_Type
-- Single_Lock
with System.Task_Info;
-- used for Task_Info_Type
with System.Task_Primitives.Operations;
-- used for Enter_Task
-- Write_Lock
-- Unlock
-- Wakeup
-- Get_Priority
with System.Soft_Links;
-- used for the non-tasking routines (*_NT) that refer to global data.
-- They are needed here before the tasking run time has been elaborated.
-- used for Create_TSD
-- This package also provides initialization routines for task specific data.
-- The GNARL must call these to be sure that all non-tasking
-- Ada constructs will work.
with System.Secondary_Stack;
-- used for SS_Init;
with System.Storage_Elements;
-- used for Storage_Array;
package body System.Tasking.Restricted.Stages is
package STPO renames System.Task_Primitives.Operations;
package SSL renames System.Soft_Links;
package SSE renames System.Storage_Elements;
package SST renames System.Secondary_Stack;
use Parameters;
use Task_Primitives.Operations;
use Task_Info;
Global_Task_Lock : aliased System.Task_Primitives.RTS_Lock;
-- This is a global lock; it is used to execute in mutual exclusion
-- from all other tasks. It is only used by Task_Lock and Task_Unlock.
-- Tasking versions of services needed by non-tasking programs --
procedure Task_Lock;
-- Locks out other tasks. Preceding a section of code by Task_Lock and
-- following it by Task_Unlock creates a critical region. This is used
-- for ensuring that a region of non-tasking code (such as code used to
-- allocate memory) is tasking safe. Note that it is valid for calls to
-- Task_Lock/Task_Unlock to be nested, and this must work properly, i.e.
-- only the corresponding outer level Task_Unlock will actually unlock.
procedure Task_Unlock;
-- Releases lock previously set by call to Task_Lock. In the nested case,
-- all nested locks must be released before other tasks competing for the
-- tasking lock are released.
-- See s-tasini.adb for more information on the following functions.
function Get_Jmpbuf_Address return Address;
procedure Set_Jmpbuf_Address (Addr : Address);
function Get_Sec_Stack_Addr return Address;
procedure Set_Sec_Stack_Addr (Addr : Address);
function Get_Machine_State_Addr return Address;
procedure Set_Machine_State_Addr (Addr : Address);
function Get_Current_Excep return SSL.EOA;
procedure Timed_Delay_T (Time : Duration; Mode : Integer);
-- Local Subprograms --
procedure Task_Wrapper (Self_ID : Task_ID);
-- This is the procedure that is called by the GNULL from the
-- new context when a task is created. It waits for activation
-- and then calls the task body procedure. When the task body
-- procedure completes, it terminates the task.
procedure Terminate_Task (Self_ID : Task_ID);
-- Terminate the calling task.
-- This should only be called by the Task_Wrapper procedure.
procedure Init_RTS;
-- This procedure performs the initialization of the GNARL.
-- It consists of initializing the environment task, global locks, and
-- installing tasking versions of certain operations used by the compiler.
-- Init_RTS is called during elaboration.
-- Task_Lock --
procedure Task_Lock is
STPO.Write_Lock (Global_Task_Lock'Access, Global_Lock => True);
end Task_Lock;
-- Task_Unlock --
procedure Task_Unlock is
STPO.Unlock (Global_Task_Lock'Access, Global_Lock => True);
end Task_Unlock;
-- Soft-Link Bodies --
function Get_Current_Excep return SSL.EOA is
return STPO.Self.Common.Compiler_Data.Current_Excep'Access;
end Get_Current_Excep;
function Get_Jmpbuf_Address return Address is
return STPO.Self.Common.Compiler_Data.Jmpbuf_Address;
end Get_Jmpbuf_Address;
function Get_Machine_State_Addr return Address is
return STPO.Self.Common.Compiler_Data.Machine_State_Addr;
end Get_Machine_State_Addr;
function Get_Sec_Stack_Addr return Address is
return STPO.Self.Common.Compiler_Data.Sec_Stack_Addr;
end Get_Sec_Stack_Addr;
procedure Set_Jmpbuf_Address (Addr : Address) is
STPO.Self.Common.Compiler_Data.Jmpbuf_Address := Addr;
end Set_Jmpbuf_Address;
procedure Set_Machine_State_Addr (Addr : Address) is
STPO.Self.Common.Compiler_Data.Machine_State_Addr := Addr;
end Set_Machine_State_Addr;
procedure Set_Sec_Stack_Addr (Addr : Address) is
STPO.Self.Common.Compiler_Data.Sec_Stack_Addr := Addr;
end Set_Sec_Stack_Addr;
-- Task_Wrapper --
-- The task wrapper is a procedure that is called first for each task
-- task body, and which in turn calls the compiler-generated task body
-- procedure. The wrapper's main job is to do initialization for the task.
-- The variable ID in the task wrapper is used to implement the Self
-- function on targets where there is a fast way to find the stack base
-- of the current thread, since it should be at a fixed offset from the
-- stack base.
procedure Task_Wrapper (Self_ID : Task_ID) is
ID : Task_ID := Self_ID;
pragma Volatile (ID);
pragma Warnings (Off, ID);
-- Turn off warnings (stand alone volatile constant has to be
-- imported, so we cannot just make ID constant).
-- Do not delete this variable.
-- In some targets, we need this variable to implement a fast Self.
use type System.Parameters.Size_Type;
use type SSE.Storage_Offset;
Secondary_Stack : aliased SSE.Storage_Array
(1 .. Self_ID.Common.Compiler_Data.Pri_Stack_Info.Size *
SSE.Storage_Offset (Parameters.Sec_Stack_Ratio) / 100);
Secondary_Stack_Address : System.Address := Secondary_Stack'Address;
if not Parameters.Sec_Stack_Dynamic then
Self_ID.Common.Compiler_Data.Sec_Stack_Addr :=
SST.SS_Init (Secondary_Stack_Address, Integer (Secondary_Stack'Last));
end if;
-- Initialize low-level TCB components, that
-- cannot be initialized by the creator.
Enter_Task (Self_ID);
-- Call the task body procedure.
-- We are separating the following portion of the code in order to
-- place the exception handlers in a different block.
-- In this way we do not call Set_Jmpbuf_Address (which needs
-- Self) before we set Self in Enter_Task.
-- Note that in the case of Ravenscar HI-E where there are no
-- exception handlers, the exception handler is suppressed.
-- Call the task body procedure.
Self_ID.Common.Task_Entry_Point (Self_ID.Common.Task_Arg);
Terminate_Task (Self_ID);
when others =>
Terminate_Task (Self_ID);
end Task_Wrapper;
-- Timed_Delay_T --
procedure Timed_Delay_T (Time : Duration; Mode : Integer) is
STPO.Timed_Delay (STPO.Self, Time, Mode);
end Timed_Delay_T;
-- Restricted GNARLI --
-- Activate_Restricted_Tasks --
-- Note that locks of activator and activated task are both locked
-- here. This is necessary because C.State and Self.Wait_Count
-- have to be synchronized. This is safe from deadlock because
-- the activator is always created before the activated task.
-- That satisfies our in-order-of-creation ATCB locking policy.
procedure Activate_Restricted_Tasks
(Chain_Access : Activation_Chain_Access)
Self_ID : constant Task_ID := STPO.Self;
C : Task_ID;
Activate_Prio : System.Any_Priority;
Success : Boolean;
pragma Assert (Self_ID = Environment_Task);
pragma Assert (Self_ID.Common.Wait_Count = 0);
if Single_Lock then
end if;
-- Lock self, to prevent activated tasks
-- from racing ahead before we finish activating the chain.
Write_Lock (Self_ID);
-- Activate all the tasks in the chain.
-- Creation of the thread of control was deferred until
-- activation. So create it now.
C := Chain_Access.T_ID;
while C /= null loop
if C.Common.State /= Terminated then
pragma Assert (C.Common.State = Unactivated);
Write_Lock (C);
if C.Common.Base_Priority < Get_Priority (Self_ID) then
Activate_Prio := Get_Priority (Self_ID);
Activate_Prio := C.Common.Base_Priority;
end if;
(C, Task_Wrapper'Address,
Activate_Prio, Success);
Self_ID.Common.Wait_Count := Self_ID.Common.Wait_Count + 1;
if Success then
C.Common.State := Runnable;
raise Program_Error;
end if;
Unlock (C);
end if;
C := C.Common.Activation_Link;
end loop;
Self_ID.Common.State := Activator_Sleep;
-- Wait for the activated tasks to complete activation.
-- It is unsafe to abort any of these tasks until the count goes to
-- zero.
exit when Self_ID.Common.Wait_Count = 0;
Sleep (Self_ID, Activator_Sleep);
end loop;
Self_ID.Common.State := Runnable;
Unlock (Self_ID);
if Single_Lock then
end if;
-- Remove the tasks from the chain.
Chain_Access.T_ID := null;
end Activate_Restricted_Tasks;
-- Complete_Restricted_Activation --
-- As in several other places, the locks of the activator and activated
-- task are both locked here. This follows our deadlock prevention lock
-- ordering policy, since the activated task must be created after the
-- activator.
procedure Complete_Restricted_Activation is
Self_ID : constant Task_ID := STPO.Self;
Activator : constant Task_ID := Self_ID.Common.Activator;
if Single_Lock then
end if;
Write_Lock (Activator);
Write_Lock (Self_ID);
-- Remove dangling reference to Activator,
-- since a task may outlive its activator.
Self_ID.Common.Activator := null;
-- Wake up the activator, if it is waiting for a chain
-- of tasks to activate, and we are the last in the chain
-- to complete activation
if Activator.Common.State = Activator_Sleep then
Activator.Common.Wait_Count := Activator.Common.Wait_Count - 1;
if Activator.Common.Wait_Count = 0 then
Wakeup (Activator, Activator_Sleep);
end if;
end if;
Unlock (Self_ID);
Unlock (Activator);
if Single_Lock then
end if;
-- After the activation, active priority should be the same
-- as base priority. We must unlock the Activator first,
-- though, since it should not wait if we have lower priority.
if Get_Priority (Self_ID) /= Self_ID.Common.Base_Priority then
Set_Priority (Self_ID, Self_ID.Common.Base_Priority);
end if;
end Complete_Restricted_Activation;
-- Complete_Restricted_Task --
procedure Complete_Restricted_Task is
STPO.Self.Common.State := Terminated;
end Complete_Restricted_Task;
-- Create_Restricted_Task --
procedure Create_Restricted_Task
(Priority : Integer;
Size : System.Parameters.Size_Type;
Task_Info : System.Task_Info.Task_Info_Type;
State : Task_Procedure_Access;
Discriminants : System.Address;
Elaborated : Access_Boolean;
Chain : in out Activation_Chain;
Task_Image : String;
Created_Task : out Task_ID)
T : Task_ID;
Self_ID : constant Task_ID := STPO.Self;
Base_Priority : System.Any_Priority;
Success : Boolean;
if Priority = Unspecified_Priority then
Base_Priority := Self_ID.Common.Base_Priority;
Base_Priority := System.Any_Priority (Priority);
end if;
T := New_ATCB (0);
if Single_Lock then
end if;
Write_Lock (Self_ID);
-- With no task hierarchy, the parent of all non-Environment tasks that
-- are created must be the Environment task
(Self_ID, State, Discriminants, Self_ID, Elaborated, Base_Priority,
Task_Info, Size, T, Success);
-- If we do our job right then there should never be any failures,
-- which was probably said about the Titanic; so just to be safe,
-- let's retain this code for now
if not Success then
Unlock (Self_ID);
if Single_Lock then
end if;
raise Program_Error;
end if;
T.Entry_Calls (1).Self := T;
T.Common.Task_Image_Len :=
Integer'Min (T.Common.Task_Image'Length, Task_Image'Length);
T.Common.Task_Image (1 .. T.Common.Task_Image_Len) := Task_Image;
Unlock (Self_ID);
if Single_Lock then
end if;
-- Create TSD as early as possible in the creation of a task, since it
-- may be used by the operation of Ada code within the task.
SSL.Create_TSD (T.Common.Compiler_Data);
T.Common.Activation_Link := Chain.T_ID;
Chain.T_ID := T;
Created_Task := T;
end Create_Restricted_Task;
-- Finalize_Global_Tasks --
-- This is needed to support the compiler interface; it will only be called
-- by the Environment task. Instead, it will cause the Environment to block
-- forever, since none of the dependent tasks are expected to terminate
procedure Finalize_Global_Tasks is
Self_ID : constant Task_ID := STPO.Self;
pragma Assert (Self_ID = STPO.Environment_Task);
if Single_Lock then
end if;
Write_Lock (Self_ID);
Sleep (Self_ID, Master_Completion_Sleep);
Unlock (Self_ID);
if Single_Lock then
end if;
-- Should never return from Master Completion Sleep
raise Program_Error;
end Finalize_Global_Tasks;
-- Restricted_Terminated --
function Restricted_Terminated (T : Task_ID) return Boolean is
return T.Common.State = Terminated;
end Restricted_Terminated;
-- Terminate_Task --
procedure Terminate_Task (Self_ID : Task_ID) is
Self_ID.Common.State := Terminated;
end Terminate_Task;
-- Init_RTS --
procedure Init_RTS is
-- Initialize lock used to implement mutual exclusion between all tasks
STPO.Initialize_Lock (Global_Task_Lock'Access, STPO.Global_Task_Level);
-- Notify that the tasking run time has been elaborated so that
-- the tasking version of the soft links can be used.
SSL.Lock_Task := Task_Lock'Access;
SSL.Unlock_Task := Task_Unlock'Access;
SSL.Get_Jmpbuf_Address := Get_Jmpbuf_Address'Access;
SSL.Set_Jmpbuf_Address := Set_Jmpbuf_Address'Access;
SSL.Get_Machine_State_Addr := Get_Machine_State_Addr'Access;
SSL.Set_Machine_State_Addr := Set_Machine_State_Addr'Access;
SSL.Get_Current_Excep := Get_Current_Excep'Access;
SSL.Set_Jmpbuf_Address (SSL.Get_Jmpbuf_Address_NT);
SSL.Set_Machine_State_Addr (SSL.Get_Machine_State_Addr_NT);
SSL.Get_Sec_Stack_Addr := Get_Sec_Stack_Addr'Access;
SSL.Set_Sec_Stack_Addr := Set_Sec_Stack_Addr'Access;
-- No need to create a new Secondary Stack, since we will use the
-- default one created in s-secsta.adb
Set_Sec_Stack_Addr (SSL.Get_Sec_Stack_Addr_NT);
SSL.Timed_Delay := Timed_Delay_T'Access;
SSL.Adafinal := Finalize_Global_Tasks'Access;
end Init_RTS;
end System.Tasking.Restricted.Stages;