| ------------------------------------------------------------------------------ |
| -- -- |
| -- GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS -- |
| -- -- |
| -- S Y S T E M . T A S K I N G . I N I T I A L I Z A T I O N -- |
| -- -- |
| -- S p e c -- |
| -- -- |
| -- Copyright (C) 1992-2023, 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 3, or (at your option) any later ver- -- |
| -- sion. GNAT 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. -- |
| -- -- |
| -- As a special exception under Section 7 of GPL version 3, you are granted -- |
| -- additional permissions described in the GCC Runtime Library Exception, -- |
| -- version 3.1, as published by the Free Software Foundation. -- |
| -- -- |
| -- You should have received a copy of the GNU General Public License and -- |
| -- a copy of the GCC Runtime Library Exception along with this program; -- |
| -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see -- |
| -- <http://www.gnu.org/licenses/>. -- |
| -- -- |
| -- GNARL was developed by the GNARL team at Florida State University. -- |
| -- Extensive contributions were provided by Ada Core Technologies, Inc. -- |
| -- -- |
| ------------------------------------------------------------------------------ |
| |
| -- This package provides overall initialization of the tasking portion of the |
| -- RTS. This package must be elaborated before any tasking features are used. |
| |
| package System.Tasking.Initialization is |
| |
| procedure Remove_From_All_Tasks_List (T : Task_Id); |
| -- Remove T from All_Tasks_List. Call this function with RTS_Lock taken |
| |
| procedure Finalize_Attributes (T : Task_Id); |
| -- Finalize all attributes from T. This is to be called just before the |
| -- ATCB is deallocated. It relies on the caller holding T.L write-lock |
| -- on entry. |
| |
| --------------------------------- |
| -- Tasking-Specific Soft Links -- |
| --------------------------------- |
| |
| ------------------------- |
| -- Abort Defer/Undefer -- |
| ------------------------- |
| |
| -- Defer_Abort defers the effects of low-level abort and priority change |
| -- in the calling task until a matching Undefer_Abort call is executed. |
| |
| -- Undefer_Abort DOES MORE than just undo the effects of one call to |
| -- Defer_Abort. It is the universal "polling point" for deferred |
| -- processing, including the following: |
| |
| -- 1) base priority changes |
| |
| -- 2) abort/ATC |
| |
| -- Abort deferral MAY be nested (Self_ID.Deferral_Level is a count), but |
| -- to avoid waste and undetected errors, it generally SHOULD NOT be |
| -- nested. The symptom of over-deferring abort is that an exception may |
| -- fail to be raised, or an abort may fail to take place. |
| |
| -- Therefore, there are two sets of the inlineable defer/undefer routines, |
| -- which are the ones to be used inside GNARL. One set allows nesting. The |
| -- other does not. People who maintain the GNARL should try to avoid using |
| -- the nested versions, or at least look very critically at the places |
| -- where they are used. |
| |
| -- In general, any GNARL call that is potentially blocking, or whose |
| -- semantics require that it sometimes raise an exception, or that is |
| -- required to be an abort completion point, must be made with abort |
| -- Deferral_Level = 1. |
| |
| -- In general, non-blocking GNARL calls, which may be made from inside a |
| -- protected action, are likely to need to allow nested abort deferral. |
| |
| -- With some critical exceptions (which are supposed to be documented), |
| -- internal calls to the tasking runtime system assume abort is already |
| -- deferred, and do not modify the deferral level. |
| |
| -- There is also a set of non-inlineable defer/undefer routines, for direct |
| -- call from the compiler. These are not inlineable because they may need |
| -- to be called via pointers ("soft links"). For the sake of efficiency, |
| -- the version with Self_ID as parameter should used wherever possible. |
| -- These are all nestable. |
| |
| -- Non-nestable inline versions |
| |
| procedure Defer_Abort (Self_ID : Task_Id); |
| pragma Inline (Defer_Abort); |
| |
| procedure Undefer_Abort (Self_ID : Task_Id); |
| pragma Inline (Undefer_Abort); |
| |
| -- Nestable inline versions |
| |
| procedure Defer_Abort_Nestable (Self_ID : Task_Id); |
| pragma Inline (Defer_Abort_Nestable); |
| |
| procedure Undefer_Abort_Nestable (Self_ID : Task_Id); |
| pragma Inline (Undefer_Abort_Nestable); |
| |
| procedure Do_Pending_Action (Self_ID : Task_Id); |
| -- Only call with no locks, and when Self_ID.Pending_Action = True Perform |
| -- necessary pending actions (e.g. abort, priority change). This procedure |
| -- is usually called when needed as a result of calling Undefer_Abort, |
| -- although in the case of e.g. No_Abort restriction, it can be necessary |
| -- to force execution of pending actions. |
| |
| function Check_Abort_Status return Integer; |
| -- Returns Boolean'Pos (True) iff abort signal should raise |
| -- Standard'Abort_Signal. Only used by RTEMS currently. |
| |
| -------------------------- |
| -- Change Base Priority -- |
| -------------------------- |
| |
| procedure Change_Base_Priority (T : Task_Id); |
| -- Change the base priority of T. Has to be called with the affected |
| -- task's ATCB write-locked. May temporarily release the lock. |
| |
| ---------------------- |
| -- Task Lock/Unlock -- |
| ---------------------- |
| |
| procedure Task_Lock (Self_ID : Task_Id); |
| pragma Inline (Task_Lock); |
| |
| procedure Task_Unlock (Self_ID : Task_Id); |
| pragma Inline (Task_Unlock); |
| -- These are versions of Lock_Task and Unlock_Task created for use |
| -- within the GNARL. |
| |
| procedure Final_Task_Unlock (Self_ID : Task_Id); |
| -- This version is only for use in Terminate_Task, when the task is |
| -- relinquishing further rights to its own ATCB. There is a very |
| -- interesting potential race condition there, where the old task may run |
| -- concurrently with a new task that is allocated the old tasks (now |
| -- reused) ATCB. The critical thing here is to not make any reference to |
| -- the ATCB after the lock is released. See also comments on |
| -- Terminate_Task and Unlock. |
| |
| procedure Wakeup_Entry_Caller |
| (Self_ID : Task_Id; |
| Entry_Call : Entry_Call_Link; |
| New_State : Entry_Call_State); |
| pragma Inline (Wakeup_Entry_Caller); |
| -- This is called at the end of service of an entry call, to abort the |
| -- caller if he is in an abortable part, and to wake up the caller if he |
| -- is on Entry_Caller_Sleep. Call it holding the lock of Entry_Call.Self. |
| -- |
| -- Timed_Call or Simple_Call: |
| -- The caller is waiting on Entry_Caller_Sleep, in Wait_For_Completion, |
| -- or Wait_For_Completion_With_Timeout. |
| -- |
| -- Conditional_Call: |
| -- The caller might be in Wait_For_Completion, |
| -- waiting for a rendezvous (possibly requeued without abort) to |
| -- complete. |
| -- |
| -- Asynchronous_Call: |
| -- The caller may be executing in the abortable part an async. select, |
| -- or on a time delay, if Entry_Call.State >= Was_Abortable. |
| |
| procedure Locked_Abort_To_Level |
| (Self_ID : Task_Id; |
| T : Task_Id; |
| L : ATC_Level_Base); |
| pragma Inline (Locked_Abort_To_Level); |
| -- Abort a task to a specified ATC level. Call this only with T locked |
| |
| end System.Tasking.Initialization; |
