| ------------------------------------------------------------------------------ |
| -- -- |
| -- 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 -- |
| -- -- |
| -- B o d y -- |
| -- -- |
| -- Copyright (C) 1992-2005, 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, 51 Franklin Street, Fifth Floor, -- |
| -- Boston, MA 02110-1301, 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 ordering check, since we group soft link |
| -- bodies and dummy soft link bodies together separately in this unit. |
| |
| pragma Polling (Off); |
| -- Turn polling off for this package. We don't need polling during any |
| -- of the routines in this package, and more to the point, if we try |
| -- to poll it can cause infinite loops. |
| |
| with Ada.Exceptions; |
| -- Used for Exception_Occurrence_Access |
| |
| with System.Task_Primitives; |
| -- Used for Lock |
| |
| with System.Task_Primitives.Operations; |
| -- Used for Set_Priority |
| -- Write_Lock |
| -- Unlock |
| -- Initialize_Lock |
| |
| 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. |
| |
| with System.Soft_Links.Tasking; |
| -- Used for Init_Tasking_Soft_Links |
| |
| with System.Tasking.Debug; |
| -- Used for Trace |
| |
| with System.Stack_Checking; |
| |
| with System.Parameters; |
| -- used for Single_Lock |
| |
| package body System.Tasking.Initialization is |
| |
| package STPO renames System.Task_Primitives.Operations; |
| package SSL renames System.Soft_Links; |
| package AE renames Ada.Exceptions; |
| |
| use Parameters; |
| use Task_Primitives.Operations; |
| |
| 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, |
| -- Task_Unlock, and Final_Task_Unlock. |
| |
| function Current_Target_Exception return AE.Exception_Occurrence; |
| pragma Import |
| (Ada, Current_Target_Exception, "__gnat_current_target_exception"); |
| -- Import this subprogram from the private part of Ada.Exceptions |
| |
| ---------------------------------------------------------------------- |
| -- Tasking versions of some services needed by non-tasking programs -- |
| ---------------------------------------------------------------------- |
| |
| procedure Abort_Defer; |
| -- NON-INLINE versions without Self_ID for soft links |
| |
| procedure Abort_Undefer; |
| -- NON-INLINE versions without Self_ID for soft links |
| |
| 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. |
| |
| function Get_Stack_Info return Stack_Checking.Stack_Access; |
| -- Get access to the current task's Stack_Info |
| |
| procedure Update_Exception |
| (X : AE.Exception_Occurrence := Current_Target_Exception); |
| -- Handle exception setting and check for pending actions |
| |
| function Task_Name return String; |
| -- Returns current task's name |
| |
| ------------------------ |
| -- Local Subprograms -- |
| ------------------------ |
| |
| ---------------------------- |
| -- Tasking Initialization -- |
| ---------------------------- |
| |
| procedure Init_RTS; |
| -- This procedure completes the initialization of the GNARL. The first |
| -- part of the initialization is done in the body of System.Tasking. |
| -- It consists of initializing global locks, and installing tasking |
| -- versions of certain operations used by the compiler. Init_RTS is called |
| -- during elaboration. |
| |
| -------------------------- |
| -- Change_Base_Priority -- |
| -------------------------- |
| |
| -- Call only with abort deferred and holding Self_ID locked |
| |
| procedure Change_Base_Priority (T : Task_Id) is |
| begin |
| if T.Common.Base_Priority /= T.New_Base_Priority then |
| T.Common.Base_Priority := T.New_Base_Priority; |
| Set_Priority (T, T.Common.Base_Priority); |
| end if; |
| end Change_Base_Priority; |
| |
| ------------------------ |
| -- Check_Abort_Status -- |
| ------------------------ |
| |
| function Check_Abort_Status return Integer is |
| Self_ID : constant Task_Id := Self; |
| begin |
| if Self_ID /= null and then Self_ID.Deferral_Level = 0 |
| and then Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level |
| then |
| return 1; |
| else |
| return 0; |
| end if; |
| end Check_Abort_Status; |
| |
| ----------------- |
| -- Defer_Abort -- |
| ----------------- |
| |
| procedure Defer_Abort (Self_ID : Task_Id) is |
| begin |
| if No_Abort and then not Dynamic_Priority_Support then |
| return; |
| end if; |
| |
| pragma Assert (Self_ID.Deferral_Level = 0); |
| |
| -- pragma Assert |
| -- (Self_ID.Pending_ATC_Level >= Self_ID.ATC_Nesting_Level); |
| |
| -- The above check has been useful in detecting mismatched defer/undefer |
| -- pairs. You may uncomment it when testing on systems that support |
| -- preemptive abort. |
| |
| -- If the OS supports preemptive abort (e.g. pthread_kill), it should |
| -- have happened already. A problem is with systems that do not support |
| -- preemptive abort, and so rely on polling. On such systems we may get |
| -- false failures of the assertion, since polling for pending abort does |
| -- no occur until the abort undefer operation. |
| |
| -- Even on systems that only poll for abort, the assertion may be useful |
| -- for catching missed abort completion polling points. The operations |
| -- that undefer abort poll for pending aborts. This covers most of the |
| -- places where the core Ada semantics require abort to be caught, |
| -- without any special attention. However, this generally happens on |
| -- exit from runtime system call, which means a pending abort will not |
| -- be noticed on the way into the runtime system. We considered adding a |
| -- check for pending aborts at this point, but chose not to, because of |
| -- the overhead. Instead, we searched for RTS calls where abort |
| -- completion is required and a task could go farther than Ada allows |
| -- before undeferring abort; we then modified the code to ensure the |
| -- abort would be detected. |
| |
| Self_ID.Deferral_Level := Self_ID.Deferral_Level + 1; |
| end Defer_Abort; |
| |
| -------------------------- |
| -- Defer_Abort_Nestable -- |
| -------------------------- |
| |
| procedure Defer_Abort_Nestable (Self_ID : Task_Id) is |
| begin |
| if No_Abort and then not Dynamic_Priority_Support then |
| return; |
| end if; |
| |
| -- pragma Assert |
| -- ((Self_ID.Pending_ATC_Level >= Self_ID.ATC_Nesting_Level or else |
| -- Self_ID.Deferral_Level > 0)); |
| |
| -- See comment in Defer_Abort on the situations in which it may be |
| -- useful to uncomment the above assertion. |
| |
| Self_ID.Deferral_Level := Self_ID.Deferral_Level + 1; |
| end Defer_Abort_Nestable; |
| |
| ----------------- |
| -- Abort_Defer -- |
| ----------------- |
| |
| procedure Abort_Defer is |
| Self_ID : Task_Id; |
| begin |
| if No_Abort and then not Dynamic_Priority_Support then |
| return; |
| end if; |
| |
| Self_ID := STPO.Self; |
| Self_ID.Deferral_Level := Self_ID.Deferral_Level + 1; |
| end Abort_Defer; |
| |
| ----------------------- |
| -- Do_Pending_Action -- |
| ----------------------- |
| |
| -- Call only when holding no locks |
| |
| procedure Do_Pending_Action (Self_ID : Task_Id) is |
| use type Ada.Exceptions.Exception_Id; |
| |
| begin |
| pragma Assert (Self_ID = Self and then Self_ID.Deferral_Level = 0); |
| |
| -- Needs loop to recheck for pending action in case a new one occurred |
| -- while we had abort deferred below. |
| |
| loop |
| -- Temporarily defer abort so that we can lock Self_ID |
| |
| Self_ID.Deferral_Level := Self_ID.Deferral_Level + 1; |
| |
| if Single_Lock then |
| Lock_RTS; |
| end if; |
| |
| Write_Lock (Self_ID); |
| Self_ID.Pending_Action := False; |
| Poll_Base_Priority_Change (Self_ID); |
| Unlock (Self_ID); |
| |
| if Single_Lock then |
| Unlock_RTS; |
| end if; |
| |
| -- Restore the original Deferral value |
| |
| Self_ID.Deferral_Level := Self_ID.Deferral_Level - 1; |
| |
| if not Self_ID.Pending_Action then |
| if Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level then |
| if not Self_ID.Aborting then |
| Self_ID.Aborting := True; |
| pragma Debug |
| (Debug.Trace (Self_ID, "raise Abort_Signal", 'B')); |
| raise Standard'Abort_Signal; |
| |
| pragma Assert (not Self_ID.ATC_Hack); |
| |
| elsif Self_ID.ATC_Hack then |
| -- The solution really belongs in the Abort_Signal handler |
| -- for async. entry calls. The present hack is very |
| -- fragile. It relies that the very next point after |
| -- Exit_One_ATC_Level at which the task becomes abortable |
| -- will be the call to Undefer_Abort in the |
| -- Abort_Signal handler. |
| |
| Self_ID.ATC_Hack := False; |
| |
| pragma Debug |
| (Debug.Trace |
| (Self_ID, "raise Abort_Signal (ATC hack)", 'B')); |
| raise Standard'Abort_Signal; |
| end if; |
| end if; |
| |
| return; |
| end if; |
| end loop; |
| end Do_Pending_Action; |
| |
| ----------------------- |
| -- Final_Task_Unlock -- |
| ----------------------- |
| |
| -- 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 Final_Task_Unlock (Self_ID : Task_Id) is |
| begin |
| pragma Assert (Self_ID.Common.Global_Task_Lock_Nesting = 1); |
| Unlock (Global_Task_Lock'Access, Global_Lock => True); |
| end Final_Task_Unlock; |
| |
| -------------- |
| -- Init_RTS -- |
| -------------- |
| |
| procedure Init_RTS is |
| Self_Id : Task_Id; |
| begin |
| Tasking.Initialize; |
| |
| -- Terminate run time (regular vs restricted) specific initialization |
| -- of the environment task. |
| |
| Self_Id := Environment_Task; |
| Self_Id.Master_of_Task := Environment_Task_Level; |
| Self_Id.Master_Within := Self_Id.Master_of_Task + 1; |
| |
| for L in Self_Id.Entry_Calls'Range loop |
| Self_Id.Entry_Calls (L).Self := Self_Id; |
| Self_Id.Entry_Calls (L).Level := L; |
| end loop; |
| |
| Self_Id.Awake_Count := 1; |
| Self_Id.Alive_Count := 1; |
| |
| Self_Id.Master_Within := Library_Task_Level; |
| -- Normally, a task starts out with internal master nesting level |
| -- one larger than external master nesting level. It is incremented |
| -- to one by Enter_Master, which is called in the task body only if |
| -- the compiler thinks the task may have dependent tasks. There is no |
| -- corresponding call to Enter_Master for the environment task, so we |
| -- would need to increment it to 2 here. Instead, we set it to 3. |
| -- By doing this we reserve the level 2 for server tasks of the runtime |
| -- system. The environment task does not need to wait for these server |
| |
| -- Initialize lock used to implement mutual exclusion between all tasks |
| |
| 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. |
| |
| if not No_Abort or else Dynamic_Priority_Support then |
| SSL.Abort_Defer := Abort_Defer'Access; |
| SSL.Abort_Undefer := Abort_Undefer'Access; |
| end if; |
| |
| SSL.Update_Exception := Update_Exception'Access; |
| SSL.Lock_Task := Task_Lock'Access; |
| SSL.Unlock_Task := Task_Unlock'Access; |
| SSL.Check_Abort_Status := Check_Abort_Status'Access; |
| SSL.Get_Stack_Info := Get_Stack_Info'Access; |
| SSL.Task_Name := Task_Name'Access; |
| |
| -- Initialize the tasking soft links (if not done yet) that are common |
| -- to the full and the restricted run times. |
| |
| SSL.Tasking.Init_Tasking_Soft_Links; |
| |
| -- Abort is deferred in a new ATCB, so we need to undefer abort |
| -- at this stage to make the environment task abortable. |
| |
| Undefer_Abort (Environment_Task); |
| end Init_RTS; |
| |
| --------------------------- |
| -- Locked_Abort_To_Level-- |
| --------------------------- |
| |
| -- Abort a task to the specified ATC nesting level. |
| -- Call this only with T locked. |
| |
| -- An earlier version of this code contained a call to Wakeup. That |
| -- should not be necessary here, if Abort_Task is implemented correctly, |
| -- since Abort_Task should include the effect of Wakeup. However, the |
| -- above call was in earlier versions of this file, and at least for |
| -- some targets Abort_Task has not beek doing Wakeup. It should not |
| -- hurt to uncomment the above call, until the error is corrected for |
| -- all targets. |
| |
| -- See extended comments in package body System.Tasking.Abort for the |
| -- overall design of the implementation of task abort. |
| -- ??? there is no such package ??? |
| |
| -- If the task is sleeping it will be in an abort-deferred region, and |
| -- will not have Abort_Signal raised by Abort_Task. Such an "abort |
| -- deferral" is just to protect the RTS internals, and not necessarily |
| -- required to enforce Ada semantics. Abort_Task should wake the task up |
| -- and let it decide if it wants to complete the aborted construct |
| -- immediately. |
| |
| -- Note that the effect of the lowl-level Abort_Task is not persistent. |
| -- If the target task is not blocked, this wakeup will be missed. |
| |
| -- We don't bother calling Abort_Task if this task is aborting itself, |
| -- since we are inside the RTS and have abort deferred. Similarly, We |
| -- don't bother to call Abort_Task if T is terminated, since there is |
| -- no need to abort a terminated task, and it could be dangerous to try |
| -- if the task has stopped executing. |
| |
| -- Note that an earlier version of this code had some false reasoning |
| -- about being able to reliably wake up a task that had suspended on |
| -- a blocking system call that does not atomically relase the task's |
| -- lock (e.g., UNIX nanosleep, which we once thought could be used to |
| -- implement delays). That still left the possibility of missed |
| -- wakeups. |
| |
| -- We cannot safely call Vulnerable_Complete_Activation here, since that |
| -- requires locking Self_ID.Parent. The anti-deadlock lock ordering rules |
| -- would then require us to release the lock on Self_ID first, which would |
| -- create a timing window for other tasks to lock Self_ID. This is |
| -- significant for tasks that may be aborted before their execution can |
| -- enter the task body, and so they do not get a chance to call |
| -- Complete_Task. The actual work for this case is done in Terminate_Task. |
| |
| procedure Locked_Abort_To_Level |
| (Self_ID : Task_Id; |
| T : Task_Id; |
| L : ATC_Level) |
| is |
| begin |
| if not T.Aborting and then T /= Self_ID then |
| case T.Common.State is |
| when Unactivated | Terminated => |
| pragma Assert (False); |
| null; |
| |
| when Runnable => |
| -- This is needed to cancel an asynchronous protected entry |
| -- call during a requeue with abort. |
| |
| T.Entry_Calls |
| (T.ATC_Nesting_Level).Cancellation_Attempted := True; |
| |
| when Interrupt_Server_Blocked_On_Event_Flag => |
| null; |
| |
| when Delay_Sleep | |
| Async_Select_Sleep | |
| Interrupt_Server_Idle_Sleep | |
| Interrupt_Server_Blocked_Interrupt_Sleep | |
| Timer_Server_Sleep | |
| AST_Server_Sleep => |
| Wakeup (T, T.Common.State); |
| |
| when Acceptor_Sleep => |
| T.Open_Accepts := null; |
| Wakeup (T, T.Common.State); |
| |
| when Entry_Caller_Sleep => |
| T.Entry_Calls |
| (T.ATC_Nesting_Level).Cancellation_Attempted := True; |
| Wakeup (T, T.Common.State); |
| |
| when Activator_Sleep | |
| Master_Completion_Sleep | |
| Master_Phase_2_Sleep | |
| Asynchronous_Hold => |
| null; |
| end case; |
| end if; |
| |
| if T.Pending_ATC_Level > L then |
| T.Pending_ATC_Level := L; |
| T.Pending_Action := True; |
| |
| if L = 0 then |
| T.Callable := False; |
| end if; |
| |
| -- This prevents aborted task from accepting calls |
| |
| if T.Aborting then |
| |
| -- The test above is just a heuristic, to reduce wasteful |
| -- calls to Abort_Task. We are holding T locked, and this |
| -- value will not be set to False except with T also locked, |
| -- inside Exit_One_ATC_Level, so we should not miss wakeups. |
| |
| if T.Common.State = Acceptor_Sleep then |
| T.Open_Accepts := null; |
| end if; |
| |
| elsif T /= Self_ID and then |
| (T.Common.State = Runnable |
| or else T.Common.State = Interrupt_Server_Blocked_On_Event_Flag) |
| -- The task is blocked on a system call waiting for the |
| -- completion event. In this case Abort_Task may need to take |
| -- special action in order to succeed. Example system: VMS. |
| |
| then |
| Abort_Task (T); |
| end if; |
| end if; |
| end Locked_Abort_To_Level; |
| |
| ------------------------------- |
| -- Poll_Base_Priority_Change -- |
| ------------------------------- |
| |
| -- Poll for pending base priority change and for held tasks. |
| -- This should always be called with (only) Self_ID locked. |
| -- It may temporarily release Self_ID's lock. |
| |
| -- The call to Yield is to force enqueuing at the |
| -- tail of the dispatching queue. |
| |
| -- We must unlock Self_ID for this to take effect, |
| -- since we are inheriting high active priority from the lock. |
| |
| -- See also Poll_Base_Priority_Change_At_Entry_Call, |
| -- in package System.Tasking.Entry_Calls. |
| |
| -- In this version, we check if the task is held too because |
| -- doing this only in Do_Pending_Action is not enough. |
| |
| procedure Poll_Base_Priority_Change (Self_ID : Task_Id) is |
| begin |
| if Dynamic_Priority_Support and then Self_ID.Pending_Priority_Change then |
| |
| -- Check for ceiling violations ??? |
| |
| Self_ID.Pending_Priority_Change := False; |
| |
| if Self_ID.Common.Base_Priority = Self_ID.New_Base_Priority then |
| if Single_Lock then |
| Unlock_RTS; |
| Yield; |
| Lock_RTS; |
| else |
| Unlock (Self_ID); |
| Yield; |
| Write_Lock (Self_ID); |
| end if; |
| |
| elsif Self_ID.Common.Base_Priority < Self_ID.New_Base_Priority then |
| Self_ID.Common.Base_Priority := Self_ID.New_Base_Priority; |
| Set_Priority (Self_ID, Self_ID.Common.Base_Priority); |
| |
| else |
| -- Lowering priority |
| |
| Self_ID.Common.Base_Priority := Self_ID.New_Base_Priority; |
| Set_Priority (Self_ID, Self_ID.Common.Base_Priority); |
| |
| if Single_Lock then |
| Unlock_RTS; |
| Yield; |
| Lock_RTS; |
| else |
| Unlock (Self_ID); |
| Yield; |
| Write_Lock (Self_ID); |
| end if; |
| end if; |
| end if; |
| end Poll_Base_Priority_Change; |
| |
| -------------------------------- |
| -- Remove_From_All_Tasks_List -- |
| -------------------------------- |
| |
| procedure Remove_From_All_Tasks_List (T : Task_Id) is |
| C : Task_Id; |
| Previous : Task_Id; |
| |
| begin |
| pragma Debug |
| (Debug.Trace (Self, "Remove_From_All_Tasks_List", 'C')); |
| |
| Previous := Null_Task; |
| C := All_Tasks_List; |
| |
| while C /= Null_Task loop |
| if C = T then |
| if Previous = Null_Task then |
| All_Tasks_List := |
| All_Tasks_List.Common.All_Tasks_Link; |
| else |
| Previous.Common.All_Tasks_Link := C.Common.All_Tasks_Link; |
| end if; |
| |
| return; |
| end if; |
| |
| Previous := C; |
| C := C.Common.All_Tasks_Link; |
| end loop; |
| |
| pragma Assert (False); |
| end Remove_From_All_Tasks_List; |
| |
| --------------- |
| -- Task_Lock -- |
| --------------- |
| |
| procedure Task_Lock (Self_ID : Task_Id) is |
| begin |
| Self_ID.Common.Global_Task_Lock_Nesting := |
| Self_ID.Common.Global_Task_Lock_Nesting + 1; |
| |
| if Self_ID.Common.Global_Task_Lock_Nesting = 1 then |
| Defer_Abort_Nestable (Self_ID); |
| Write_Lock (Global_Task_Lock'Access, Global_Lock => True); |
| end if; |
| end Task_Lock; |
| |
| procedure Task_Lock is |
| begin |
| Task_Lock (STPO.Self); |
| end Task_Lock; |
| |
| --------------- |
| -- Task_Name -- |
| --------------- |
| |
| function Task_Name return String is |
| Self_Id : constant Task_Id := STPO.Self; |
| |
| begin |
| return Self_Id.Common.Task_Image (1 .. Self_Id.Common.Task_Image_Len); |
| end Task_Name; |
| |
| ----------------- |
| -- Task_Unlock -- |
| ----------------- |
| |
| procedure Task_Unlock (Self_ID : Task_Id) is |
| begin |
| pragma Assert (Self_ID.Common.Global_Task_Lock_Nesting > 0); |
| Self_ID.Common.Global_Task_Lock_Nesting := |
| Self_ID.Common.Global_Task_Lock_Nesting - 1; |
| |
| if Self_ID.Common.Global_Task_Lock_Nesting = 0 then |
| Unlock (Global_Task_Lock'Access, Global_Lock => True); |
| Undefer_Abort_Nestable (Self_ID); |
| end if; |
| end Task_Unlock; |
| |
| procedure Task_Unlock is |
| begin |
| Task_Unlock (STPO.Self); |
| end Task_Unlock; |
| |
| ------------------- |
| -- Undefer_Abort -- |
| ------------------- |
| |
| -- Precondition : Self does not hold any locks! |
| |
| -- Undefer_Abort is called on any abort completion point (aka. |
| -- synchronization point). It performs the following actions if they |
| -- are pending: (1) change the base priority, (2) abort the task. |
| |
| -- The priority change has to occur before abort. Otherwise, it would |
| -- take effect no earlier than the next abort completion point. |
| |
| procedure Undefer_Abort (Self_ID : Task_Id) is |
| begin |
| if No_Abort and then not Dynamic_Priority_Support then |
| return; |
| end if; |
| |
| pragma Assert (Self_ID.Deferral_Level = 1); |
| |
| Self_ID.Deferral_Level := Self_ID.Deferral_Level - 1; |
| |
| if Self_ID.Deferral_Level = 0 then |
| pragma Assert (Check_No_Locks (Self_ID)); |
| |
| if Self_ID.Pending_Action then |
| Do_Pending_Action (Self_ID); |
| end if; |
| end if; |
| end Undefer_Abort; |
| |
| ---------------------------- |
| -- Undefer_Abort_Nestable -- |
| ---------------------------- |
| |
| -- An earlier version would re-defer abort if an abort is in progress. |
| -- Then, we modified the effect of the raise statement so that it defers |
| -- abort until control reaches a handler. That was done to prevent |
| -- "skipping over" a handler if another asynchronous abort occurs during |
| -- the propagation of the abort to the handler. |
| |
| -- There has been talk of reversing that decision, based on a newer |
| -- implementation of exception propagation. Care must be taken to evaluate |
| -- how such a change would interact with the above code and all the places |
| -- where abort-deferral is used to bridge over critical transitions, such |
| -- as entry to the scope of a region with a finalizer and entry into the |
| -- body of an accept-procedure. |
| |
| procedure Undefer_Abort_Nestable (Self_ID : Task_Id) is |
| begin |
| if No_Abort and then not Dynamic_Priority_Support then |
| return; |
| end if; |
| |
| pragma Assert (Self_ID.Deferral_Level > 0); |
| |
| Self_ID.Deferral_Level := Self_ID.Deferral_Level - 1; |
| |
| if Self_ID.Deferral_Level = 0 then |
| |
| pragma Assert (Check_No_Locks (Self_ID)); |
| |
| if Self_ID.Pending_Action then |
| Do_Pending_Action (Self_ID); |
| end if; |
| end if; |
| end Undefer_Abort_Nestable; |
| |
| ------------------- |
| -- Abort_Undefer -- |
| ------------------- |
| |
| procedure Abort_Undefer is |
| Self_ID : Task_Id; |
| begin |
| if No_Abort and then not Dynamic_Priority_Support then |
| return; |
| end if; |
| |
| Self_ID := STPO.Self; |
| |
| if Self_ID.Deferral_Level = 0 then |
| |
| -- In case there are different views on whether Abort is supported |
| -- between the expander and the run time, we may end up with |
| -- Self_ID.Deferral_Level being equal to zero, when called from |
| -- the procedure created by the expander that corresponds to a |
| -- task body. |
| |
| -- In this case, there's nothing to be done |
| |
| -- See related code in System.Tasking.Stages.Create_Task resetting |
| -- Deferral_Level when System.Restrictions.Abort_Allowed is False. |
| |
| return; |
| end if; |
| |
| pragma Assert (Self_ID.Deferral_Level > 0); |
| Self_ID.Deferral_Level := Self_ID.Deferral_Level - 1; |
| |
| if Self_ID.Deferral_Level = 0 then |
| pragma Assert (Check_No_Locks (Self_ID)); |
| |
| if Self_ID.Pending_Action then |
| Do_Pending_Action (Self_ID); |
| end if; |
| end if; |
| end Abort_Undefer; |
| |
| ---------------------- |
| -- Update_Exception -- |
| ---------------------- |
| |
| -- Call only when holding no locks |
| |
| procedure Update_Exception |
| (X : AE.Exception_Occurrence := Current_Target_Exception) |
| is |
| Self_Id : constant Task_Id := Self; |
| use Ada.Exceptions; |
| |
| begin |
| Save_Occurrence (Self_Id.Common.Compiler_Data.Current_Excep, X); |
| |
| if Self_Id.Deferral_Level = 0 then |
| if Self_Id.Pending_Action then |
| Self_Id.Pending_Action := False; |
| Self_Id.Deferral_Level := Self_Id.Deferral_Level + 1; |
| |
| if Single_Lock then |
| Lock_RTS; |
| end if; |
| |
| Write_Lock (Self_Id); |
| Self_Id.Pending_Action := False; |
| Poll_Base_Priority_Change (Self_Id); |
| Unlock (Self_Id); |
| |
| if Single_Lock then |
| Unlock_RTS; |
| end if; |
| |
| Self_Id.Deferral_Level := Self_Id.Deferral_Level - 1; |
| |
| if Self_Id.Pending_ATC_Level < Self_Id.ATC_Nesting_Level then |
| if not Self_Id.Aborting then |
| Self_Id.Aborting := True; |
| raise Standard'Abort_Signal; |
| end if; |
| end if; |
| end if; |
| end if; |
| end Update_Exception; |
| |
| -------------------------- |
| -- 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 it |
| -- is on Entry_Caller_Sleep. It assumes that the call is already off-queue. |
| |
| -- (This enforces the rule that a task must be off-queue if its state is |
| -- Done or Cancelled.) 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 o |
| -- an async. select, or on a time delay, |
| -- if Entry_Call.State >= Was_Abortable. |
| |
| procedure Wakeup_Entry_Caller |
| (Self_ID : Task_Id; |
| Entry_Call : Entry_Call_Link; |
| New_State : Entry_Call_State) |
| is |
| Caller : constant Task_Id := Entry_Call.Self; |
| |
| begin |
| pragma Debug (Debug.Trace |
| (Self_ID, "Wakeup_Entry_Caller", 'E', Caller)); |
| pragma Assert (New_State = Done or else New_State = Cancelled); |
| |
| pragma Assert |
| (Caller.Common.State /= Terminated |
| and then Caller.Common.State /= Unactivated); |
| |
| Entry_Call.State := New_State; |
| |
| if Entry_Call.Mode = Asynchronous_Call then |
| |
| -- Abort the caller in his abortable part, |
| -- but do so only if call has been queued abortably |
| |
| if Entry_Call.State >= Was_Abortable or else New_State = Done then |
| Locked_Abort_To_Level (Self_ID, Caller, Entry_Call.Level - 1); |
| end if; |
| |
| elsif Caller.Common.State = Entry_Caller_Sleep then |
| Wakeup (Caller, Entry_Caller_Sleep); |
| end if; |
| end Wakeup_Entry_Caller; |
| |
| ---------------------- |
| -- Soft-Link Bodies -- |
| ---------------------- |
| |
| function Get_Stack_Info return Stack_Checking.Stack_Access is |
| begin |
| return STPO.Self.Common.Compiler_Data.Pri_Stack_Info'Access; |
| end Get_Stack_Info; |
| |
| ----------------------- |
| -- Soft-Link Dummies -- |
| ----------------------- |
| |
| -- These are dummies for subprograms that are only needed by certain |
| -- optional run-time system packages. If they are needed, the soft |
| -- links will be redirected to the real subprogram by elaboration of |
| -- the subprogram body where the real subprogram is declared. |
| |
| procedure Finalize_Attributes (T : Task_Id) is |
| pragma Warnings (Off, T); |
| |
| begin |
| null; |
| end Finalize_Attributes; |
| |
| procedure Initialize_Attributes (T : Task_Id) is |
| pragma Warnings (Off, T); |
| |
| begin |
| null; |
| end Initialize_Attributes; |
| |
| begin |
| Init_RTS; |
| end System.Tasking.Initialization; |
