1 ------------------------------------------------------------------------------
3 -- GNU ADA RUN-TIME LIBRARY (GNARL) COMPONENTS --
5 -- S Y S T E M . T A S K I N G . S T A G E S --
9 -- Copyright (C) 1992-2004, Free Software Foundation, Inc. --
11 -- GNARL is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 2, or (at your option) any later ver- --
14 -- sion. GNARL is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNARL; see file COPYING. If not, write --
19 -- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
20 -- MA 02111-1307, USA. --
22 -- As a special exception, if other files instantiate generics from this --
23 -- unit, or you link this unit with other files to produce an executable, --
24 -- this unit does not by itself cause the resulting executable to be --
25 -- covered by the GNU General Public License. This exception does not --
26 -- however invalidate any other reasons why the executable file might be --
27 -- covered by the GNU Public License. --
29 -- GNARL was developed by the GNARL team at Florida State University. --
30 -- Extensive contributions were provided by Ada Core Technologies, Inc. --
32 ------------------------------------------------------------------------------
35 -- Turn off polling, we do not want ATC polling to take place during
36 -- tasking operations. It causes infinite loops and other problems.
39 -- used for Raise_Exception
41 with System
.Tasking
.Debug
;
42 -- used for enabling tasking facilities with gdb
44 with System
.Address_Image
;
45 -- used for the function itself.
47 with System
.Parameters
;
52 with System
.Task_Info
;
53 -- used for Task_Info_Type
55 with System
.Task_Primitives
.Operations
;
56 -- used for Finalize_Lock
66 with System
.Soft_Links
;
67 -- These are procedure pointers to non-tasking routines that use
68 -- task specific data. In the absence of tasking, these routines
69 -- refer to global data. In the presense of tasking, they must be
70 -- replaced with pointers to task-specific versions.
71 -- Also used for Create_TSD, Destroy_TSD, Get_Current_Excep
73 with System
.Tasking
.Initialization
;
74 -- Used for Remove_From_All_Tasks_List
77 -- Initialization.Poll_Base_Priority_Change
78 -- Finalize_Attributes_Link
79 -- Initialize_Attributes_Link
81 pragma Elaborate_All
(System
.Tasking
.Initialization
);
82 -- This insures that tasking is initialized if any tasks are created.
84 with System
.Tasking
.Utilities
;
85 -- Used for Make_Passive
88 with System
.Tasking
.Queuing
;
89 -- Used for Dequeue_Head
91 with System
.Tasking
.Rendezvous
;
92 -- Used for Call_Simple
94 with System
.OS_Primitives
;
95 -- Used for Delay_Modes
97 with System
.Finalization_Implementation
;
98 -- Used for System.Finalization_Implementation.Finalize_Global_List
100 with System
.Secondary_Stack
;
103 with System
.Storage_Elements
;
104 -- used for Storage_Array
106 with System
.Standard_Library
;
107 -- used for Exception_Trace
109 with System
.Traces
.Tasking
;
110 -- used for Send_Trace_Info
112 with Unchecked_Deallocation
;
113 -- To recover from failure of ATCB initialization.
115 package body System
.Tasking
.Stages
is
117 package STPO
renames System
.Task_Primitives
.Operations
;
118 package SSL
renames System
.Soft_Links
;
119 package SSE
renames System
.Storage_Elements
;
120 package SST
renames System
.Secondary_Stack
;
126 use Task_Primitives
.Operations
;
130 use System
.Traces
.Tasking
;
132 -----------------------
133 -- Local Subprograms --
134 -----------------------
136 procedure Free
is new
137 Unchecked_Deallocation
(Ada_Task_Control_Block
, Task_Id
);
139 procedure Trace_Unhandled_Exception_In_Task
(Self_Id
: Task_Id
);
140 -- This procedure outputs the task specific message for exception
143 procedure Task_Wrapper
(Self_ID
: Task_Id
);
144 pragma Convention
(C
, Task_Wrapper
);
145 -- This is the procedure that is called by the GNULL from the new context
146 -- when a task is created. It waits for activation and then calls the task
147 -- body procedure. When the task body procedure completes, it terminates
150 -- The Task_Wrapper's address will be provided to the underlying threads
151 -- library as the task entry point. Convention C is what makes most sense
152 -- for that purpose (Export C would make the function globally visible,
153 -- and affect the link name on which GDB depends). This will in addition
154 -- trigger an automatic stack alignment suitable for GCC's assumptions if
157 procedure Vulnerable_Complete_Task
(Self_ID
: Task_Id
);
158 -- Complete the calling task. This procedure must be called with
159 -- abort deferred. It should only be called by Complete_Task and
160 -- Finalizate_Global_Tasks (for the environment task).
162 procedure Vulnerable_Complete_Master
(Self_ID
: Task_Id
);
163 -- Complete the current master of the calling task. This procedure
164 -- must be called with abort deferred. It should only be called by
165 -- Vulnerable_Complete_Task and Complete_Master.
167 procedure Vulnerable_Complete_Activation
(Self_ID
: Task_Id
);
168 -- Signal to Self_ID's activator that Self_ID has completed activation.
169 -- This procedure must be called with abort deferred.
171 procedure Abort_Dependents
(Self_ID
: Task_Id
);
172 -- Abort all the direct dependents of Self at its current master
173 -- nesting level, plus all of their dependents, transitively.
174 -- RTS_Lock should be locked by the caller.
176 procedure Vulnerable_Free_Task
(T
: Task_Id
);
177 -- Recover all runtime system storage associated with the task T.
178 -- This should only be called after T has terminated and will no
179 -- longer be referenced.
181 -- For tasks created by an allocator that fails, due to an exception,
182 -- it is called from Expunge_Unactivated_Tasks.
184 -- It is also called from Unchecked_Deallocation, for objects that
185 -- are or contain tasks.
187 -- Different code is used at master completion, in Terminate_Dependents,
188 -- due to a need for tighter synchronization with the master.
190 ----------------------
191 -- Abort_Dependents --
192 ----------------------
194 procedure Abort_Dependents
(Self_ID
: Task_Id
) is
201 P
:= C
.Common
.Parent
;
205 -- ??? C is supposed to take care of its own dependents, so
206 -- there should be no need to worry about them. Need to double
209 if C
.Master_of_Task
= Self_ID
.Master_Within
then
210 Utilities
.Abort_One_Task
(Self_ID
, C
);
211 C
.Dependents_Aborted
:= True;
217 P
:= P
.Common
.Parent
;
220 C
:= C
.Common
.All_Tasks_Link
;
223 Self_ID
.Dependents_Aborted
:= True;
224 end Abort_Dependents
;
230 procedure Abort_Tasks
(Tasks
: Task_List
) is
232 -- If pragma Detect_Blocking is active then Program_Error must be
233 -- raised if this potentially blocking operation is called from a
236 if System
.Tasking
.Detect_Blocking
237 and then STPO
.Self
.Common
.Protected_Action_Nesting
> 0
239 Ada
.Exceptions
.Raise_Exception
240 (Program_Error
'Identity, "potentially blocking operation");
243 Utilities
.Abort_Tasks
(Tasks
);
250 -- Note that locks of activator and activated task are both locked
251 -- here. This is necessary because C.Common.State and
252 -- Self.Common.Wait_Count have to be synchronized. This is safe from
253 -- deadlock because the activator is always created before the activated
254 -- task. That satisfies our in-order-of-creation ATCB locking policy.
256 -- At one point, we may also lock the parent, if the parent is
257 -- different from the activator. That is also consistent with the
258 -- lock ordering policy, since the activator cannot be created
259 -- before the parent.
261 -- Since we are holding both the activator's lock, and Task_Wrapper
262 -- locks that before it does anything more than initialize the
263 -- low-level ATCB components, it should be safe to wait to update
264 -- the counts until we see that the thread creation is successful.
266 -- If the thread creation fails, we do need to close the entries
267 -- of the task. The first phase, of dequeuing calls, only requires
268 -- locking the acceptor's ATCB, but the waking up of the callers
269 -- requires locking the caller's ATCB. We cannot safely do this
270 -- while we are holding other locks. Therefore, the queue-clearing
271 -- operation is done in a separate pass over the activation chain.
273 procedure Activate_Tasks
(Chain_Access
: Activation_Chain_Access
) is
274 Self_ID
: constant Task_Id
:= STPO
.Self
;
277 Next_C
, Last_C
: Task_Id
;
278 Activate_Prio
: System
.Any_Priority
;
280 All_Elaborated
: Boolean := True;
283 -- If pragma Detect_Blocking is active, then we must check whether this
284 -- potentially blocking operation is called from a protected action.
286 if System
.Tasking
.Detect_Blocking
287 and then Self_ID
.Common
.Protected_Action_Nesting
> 0
289 Ada
.Exceptions
.Raise_Exception
290 (Program_Error
'Identity, "potentially blocking operation");
294 (Debug
.Trace
(Self_ID
, "Activate_Tasks", 'C'));
296 Initialization
.Defer_Abort_Nestable
(Self_ID
);
298 pragma Assert
(Self_ID
.Common
.Wait_Count
= 0);
300 -- Lock RTS_Lock, to prevent activated tasks from racing ahead before
301 -- we finish activating the chain.
305 -- Check that all task bodies have been elaborated
307 C
:= Chain_Access
.T_ID
;
310 if C
.Common
.Elaborated
/= null
311 and then not C
.Common
.Elaborated
.all
313 All_Elaborated
:= False;
316 -- Reverse the activation chain so that tasks are
317 -- activated in the same order they're declared.
319 Next_C
:= C
.Common
.Activation_Link
;
320 C
.Common
.Activation_Link
:= Last_C
;
325 Chain_Access
.T_ID
:= Last_C
;
327 if not All_Elaborated
then
329 Initialization
.Undefer_Abort_Nestable
(Self_ID
);
331 (Program_Error
'Identity, "Some tasks have not been elaborated");
334 -- Activate all the tasks in the chain. Creation of the thread of
335 -- control was deferred until activation. So create it now.
337 C
:= Chain_Access
.T_ID
;
339 if C
.Common
.State
/= Terminated
then
340 pragma Assert
(C
.Common
.State
= Unactivated
);
342 P
:= C
.Common
.Parent
;
346 if C
.Common
.Base_Priority
< Get_Priority
(Self_ID
) then
347 Activate_Prio
:= Get_Priority
(Self_ID
);
349 Activate_Prio
:= C
.Common
.Base_Priority
;
352 System
.Task_Primitives
.Operations
.Create_Task
353 (C
, Task_Wrapper
'Address,
355 (C
.Common
.Compiler_Data
.Pri_Stack_Info
.Size
),
356 Activate_Prio
, Success
);
358 -- There would be a race between the created task and the
359 -- creator to do the following initialization, if we did not
360 -- have a Lock/Unlock_RTS pair in the task wrapper to prevent
361 -- it from racing ahead.
364 C
.Common
.State
:= Runnable
;
367 P
.Awake_Count
:= P
.Awake_Count
+ 1;
368 P
.Alive_Count
:= P
.Alive_Count
+ 1;
370 if P
.Common
.State
= Master_Completion_Sleep
and then
371 C
.Master_of_Task
= P
.Master_Within
373 pragma Assert
(Self_ID
/= P
);
374 P
.Common
.Wait_Count
:= P
.Common
.Wait_Count
+ 1;
381 -- No need to set Awake_Count, State, etc. here since the loop
382 -- below will do that for any Unactivated tasks.
386 Self_ID
.Common
.Activation_Failed
:= True;
390 C
:= C
.Common
.Activation_Link
;
393 if not Single_Lock
then
397 -- Close the entries of any tasks that failed thread creation,
398 -- and count those that have not finished activation.
400 Write_Lock
(Self_ID
);
401 Self_ID
.Common
.State
:= Activator_Sleep
;
403 C
:= Chain_Access
.T_ID
;
407 if C
.Common
.State
= Unactivated
then
408 C
.Common
.Activator
:= null;
409 C
.Common
.State
:= Terminated
;
411 Utilities
.Cancel_Queued_Entry_Calls
(C
);
413 elsif C
.Common
.Activator
/= null then
414 Self_ID
.Common
.Wait_Count
:= Self_ID
.Common
.Wait_Count
+ 1;
418 P
:= C
.Common
.Activation_Link
;
419 C
.Common
.Activation_Link
:= null;
423 -- Wait for the activated tasks to complete activation. It is
424 -- unsafe to abort any of these tasks until the count goes to zero.
427 Initialization
.Poll_Base_Priority_Change
(Self_ID
);
428 exit when Self_ID
.Common
.Wait_Count
= 0;
429 Sleep
(Self_ID
, Activator_Sleep
);
432 Self_ID
.Common
.State
:= Runnable
;
439 -- Remove the tasks from the chain
441 Chain_Access
.T_ID
:= null;
442 Initialization
.Undefer_Abort_Nestable
(Self_ID
);
444 if Self_ID
.Common
.Activation_Failed
then
445 Self_ID
.Common
.Activation_Failed
:= False;
446 Raise_Exception
(Tasking_Error
'Identity,
447 "Failure during activation");
451 -------------------------
452 -- Complete_Activation --
453 -------------------------
455 procedure Complete_Activation
is
456 Self_ID
: constant Task_Id
:= STPO
.Self
;
459 Initialization
.Defer_Abort_Nestable
(Self_ID
);
465 Vulnerable_Complete_Activation
(Self_ID
);
471 Initialization
.Undefer_Abort_Nestable
(Self_ID
);
474 -- Why do we need to allow for nested deferral here?
476 if Runtime_Traces
then
477 Send_Trace_Info
(T_Activate
);
479 end Complete_Activation
;
481 ---------------------
482 -- Complete_Master --
483 ---------------------
485 procedure Complete_Master
is
486 Self_ID
: constant Task_Id
:= STPO
.Self
;
488 pragma Assert
(Self_ID
.Deferral_Level
> 0);
489 Vulnerable_Complete_Master
(Self_ID
);
496 -- See comments on Vulnerable_Complete_Task for details
498 procedure Complete_Task
is
499 Self_ID
: constant Task_Id
:= STPO
.Self
;
502 pragma Assert
(Self_ID
.Deferral_Level
> 0);
504 Vulnerable_Complete_Task
(Self_ID
);
506 -- All of our dependents have terminated. Never undefer abort again!
514 -- Compiler interface only. Do not call from within the RTS.
515 -- This must be called to create a new task.
517 procedure Create_Task
519 Size
: System
.Parameters
.Size_Type
;
520 Task_Info
: System
.Task_Info
.Task_Info_Type
;
521 Num_Entries
: Task_Entry_Index
;
522 Master
: Master_Level
;
523 State
: Task_Procedure_Access
;
524 Discriminants
: System
.Address
;
525 Elaborated
: Access_Boolean
;
526 Chain
: in out Activation_Chain
;
528 Created_Task
: out Task_Id
)
531 Self_ID
: constant Task_Id
:= STPO
.Self
;
533 Base_Priority
: System
.Any_Priority
;
537 -- If pragma Detect_Blocking is active must be checked whether
538 -- this potentially blocking operation is called from a
541 if System
.Tasking
.Detect_Blocking
542 and then Self_ID
.Common
.Protected_Action_Nesting
> 0
544 Ada
.Exceptions
.Raise_Exception
545 (Program_Error
'Identity, "potentially blocking operation");
549 (Debug
.Trace
(Self_ID
, "Create_Task", 'C'));
551 if Priority
= Unspecified_Priority
then
552 Base_Priority
:= Self_ID
.Common
.Base_Priority
;
554 Base_Priority
:= System
.Any_Priority
(Priority
);
557 -- Find parent P of new Task, via master level number
562 while P
.Master_of_Task
>= Master
loop
563 P
:= P
.Common
.Parent
;
568 Initialization
.Defer_Abort_Nestable
(Self_ID
);
571 T
:= New_ATCB
(Num_Entries
);
574 Initialization
.Undefer_Abort_Nestable
(Self_ID
);
575 Raise_Exception
(Storage_Error
'Identity, "Cannot allocate task");
578 -- RTS_Lock is used by Abort_Dependents and Abort_Tasks.
579 -- Up to this point, it is possible that we may be part of
580 -- a family of tasks that is being aborted.
583 Write_Lock
(Self_ID
);
585 -- Now, we must check that we have not been aborted.
586 -- If so, we should give up on creating this task,
587 -- and simply return.
589 if not Self_ID
.Callable
then
590 pragma Assert
(Self_ID
.Pending_ATC_Level
= 0);
591 pragma Assert
(Self_ID
.Pending_Action
);
593 (Chain
.T_ID
= null or else Chain
.T_ID
.Common
.State
= Unactivated
);
597 Initialization
.Undefer_Abort_Nestable
(Self_ID
);
599 -- ??? Should never get here
601 pragma Assert
(False);
602 raise Standard
'Abort_Signal;
605 Initialize_ATCB
(Self_ID
, State
, Discriminants
, P
, Elaborated
,
606 Base_Priority
, Task_Info
, Size
, T
, Success
);
612 Initialization
.Undefer_Abort_Nestable
(Self_ID
);
614 (Storage_Error
'Identity, "Failed to initialize task");
617 T
.Master_of_Task
:= Master
;
618 T
.Master_Within
:= T
.Master_of_Task
+ 1;
620 for L
in T
.Entry_Calls
'Range loop
621 T
.Entry_Calls
(L
).Self
:= T
;
622 T
.Entry_Calls
(L
).Level
:= L
;
625 if Task_Image
'Length = 0 then
626 T
.Common
.Task_Image_Len
:= 0;
629 T
.Common
.Task_Image
(1) := Task_Image
(Task_Image
'First);
631 -- Remove unwanted blank space generated by 'Image
633 for J
in Task_Image
'First + 1 .. Task_Image
'Last loop
634 if Task_Image
(J
) /= ' '
635 or else Task_Image
(J
- 1) /= '('
638 T
.Common
.Task_Image
(Len
) := Task_Image
(J
);
639 exit when Len
= T
.Common
.Task_Image
'Last;
643 T
.Common
.Task_Image_Len
:= Len
;
649 -- Create TSD as early as possible in the creation of a task, since it
650 -- may be used by the operation of Ada code within the task.
652 SSL
.Create_TSD
(T
.Common
.Compiler_Data
);
653 T
.Common
.Activation_Link
:= Chain
.T_ID
;
655 Initialization
.Initialize_Attributes_Link
.all (T
);
657 Initialization
.Undefer_Abort_Nestable
(Self_ID
);
659 if Runtime_Traces
then
660 Send_Trace_Info
(T_Create
, T
);
668 function Current_Master
return Master_Level
is
670 return STPO
.Self
.Master_Within
;
677 procedure Enter_Master
is
678 Self_ID
: constant Task_Id
:= STPO
.Self
;
680 Self_ID
.Master_Within
:= Self_ID
.Master_Within
+ 1;
683 -------------------------------
684 -- Expunge_Unactivated_Tasks --
685 -------------------------------
687 -- See procedure Close_Entries for the general case
689 procedure Expunge_Unactivated_Tasks
(Chain
: in out Activation_Chain
) is
690 Self_ID
: constant Task_Id
:= STPO
.Self
;
692 Call
: Entry_Call_Link
;
697 (Debug
.Trace
(Self_ID
, "Expunge_Unactivated_Tasks", 'C'));
699 Initialization
.Defer_Abort_Nestable
(Self_ID
);
702 -- Experimentation has shown that abort is sometimes (but not
703 -- always) already deferred when this is called.
705 -- That may indicate an error. Find out what is going on
709 pragma Assert
(C
.Common
.State
= Unactivated
);
711 Temp
:= C
.Common
.Activation_Link
;
713 if C
.Common
.State
= Unactivated
then
717 for J
in 1 .. C
.Entry_Num
loop
718 Queuing
.Dequeue_Head
(C
.Entry_Queues
(J
), Call
);
719 pragma Assert
(Call
= null);
724 Initialization
.Remove_From_All_Tasks_List
(C
);
727 Vulnerable_Free_Task
(C
);
733 Initialization
.Undefer_Abort_Nestable
(Self_ID
);
734 end Expunge_Unactivated_Tasks
;
736 ---------------------------
737 -- Finalize_Global_Tasks --
738 ---------------------------
741 -- We have a potential problem here if finalization of global
742 -- objects does anything with signals or the timer server, since
743 -- by that time those servers have terminated.
745 -- It is hard to see how that would occur
747 -- However, a better solution might be to do all this finalization
748 -- using the global finalization chain.
750 procedure Finalize_Global_Tasks
is
751 Self_ID
: constant Task_Id
:= STPO
.Self
;
755 if Self_ID
.Deferral_Level
= 0 then
757 -- In principle, we should be able to predict whether
758 -- abort is already deferred here (and it should not be deferred
759 -- yet but in practice it seems Finalize_Global_Tasks is being
760 -- called sometimes, from RTS code for exceptions, with abort already
763 Initialization
.Defer_Abort_Nestable
(Self_ID
);
765 -- Never undefer again!!!
768 -- This code is only executed by the environment task
770 pragma Assert
(Self_ID
= Environment_Task
);
772 -- Set Environment_Task'Callable to false to notify library-level tasks
773 -- that it is waiting for them (cf 5619-003).
775 Self_ID
.Callable
:= False;
777 -- Exit level 2 master, for normal tasks in library-level packages.
781 -- Force termination of "independent" library-level server tasks.
785 Abort_Dependents
(Self_ID
);
787 if not Single_Lock
then
791 -- We need to explicitely wait for the task to be terminated here
792 -- because on true concurrent system, we may end this procedure
793 -- before the tasks are really terminated.
795 Write_Lock
(Self_ID
);
798 exit when Utilities
.Independent_Task_Count
= 0;
800 -- We used to yield here, but this did not take into account
801 -- low priority tasks that would cause dead lock in some cases.
805 (Self_ID
, 0.01, System
.OS_Primitives
.Relative
,
806 Self_ID
.Common
.State
, Ignore
, Ignore
);
809 -- ??? On multi-processor environments, it seems that the above loop
810 -- isn't sufficient, so we need to add an additional delay.
813 (Self_ID
, 0.01, System
.OS_Primitives
.Relative
,
814 Self_ID
.Common
.State
, Ignore
, Ignore
);
822 -- Complete the environment task
824 Vulnerable_Complete_Task
(Self_ID
);
826 System
.Finalization_Implementation
.Finalize_Global_List
;
828 SSL
.Abort_Defer
:= SSL
.Abort_Defer_NT
'Access;
829 SSL
.Abort_Undefer
:= SSL
.Abort_Undefer_NT
'Access;
830 SSL
.Lock_Task
:= SSL
.Task_Lock_NT
'Access;
831 SSL
.Unlock_Task
:= SSL
.Task_Unlock_NT
'Access;
832 SSL
.Get_Jmpbuf_Address
:= SSL
.Get_Jmpbuf_Address_NT
'Access;
833 SSL
.Set_Jmpbuf_Address
:= SSL
.Set_Jmpbuf_Address_NT
'Access;
834 SSL
.Get_Sec_Stack_Addr
:= SSL
.Get_Sec_Stack_Addr_NT
'Access;
835 SSL
.Set_Sec_Stack_Addr
:= SSL
.Set_Sec_Stack_Addr_NT
'Access;
836 SSL
.Get_Exc_Stack_Addr
:= SSL
.Get_Exc_Stack_Addr_NT
'Access;
837 SSL
.Set_Exc_Stack_Addr
:= SSL
.Set_Exc_Stack_Addr_NT
'Access;
838 SSL
.Check_Abort_Status
:= SSL
.Check_Abort_Status_NT
'Access;
839 SSL
.Get_Stack_Info
:= SSL
.Get_Stack_Info_NT
'Access;
841 -- Don't bother trying to finalize Initialization.Global_Task_Lock
842 -- and System.Task_Primitives.RTS_Lock.
844 end Finalize_Global_Tasks
;
850 procedure Free_Task
(T
: Task_Id
) is
851 Self_Id
: constant Task_Id
:= Self
;
854 if T
.Common
.State
= Terminated
then
856 -- It is not safe to call Abort_Defer or Write_Lock at this stage
858 Initialization
.Task_Lock
(Self_Id
);
861 Initialization
.Remove_From_All_Tasks_List
(T
);
864 Initialization
.Task_Unlock
(Self_Id
);
866 System
.Task_Primitives
.Operations
.Finalize_TCB
(T
);
868 -- If the task is not terminated, then we simply ignore the call. This
869 -- happens when a user program attempts an unchecked deallocation on
870 -- a non-terminated task.
881 -- The task wrapper is a procedure that is called first for each task
882 -- task body, and which in turn calls the compiler-generated task body
883 -- procedure. The wrapper's main job is to do initialization for the task.
884 -- It also has some locally declared objects that server as per-task local
885 -- data. Task finalization is done by Complete_Task, which is called from
886 -- an at-end handler that the compiler generates.
888 procedure Task_Wrapper
(Self_ID
: Task_Id
) is
889 use type System
.Parameters
.Size_Type
;
890 use type SSE
.Storage_Offset
;
891 use System
.Standard_Library
;
894 aliased SSE
.Storage_Array
895 (1 .. Self_ID
.Common
.Compiler_Data
.Pri_Stack_Info
.Size
*
896 SSE
.Storage_Offset
(Parameters
.Sec_Stack_Ratio
) / 100);
898 Secondary_Stack_Address
: System
.Address
:= Secondary_Stack
'Address;
901 pragma Assert
(Self_ID
.Deferral_Level
= 1);
903 if not Parameters
.Sec_Stack_Dynamic
then
904 Self_ID
.Common
.Compiler_Data
.Sec_Stack_Addr
:=
905 Secondary_Stack
'Address;
906 SST
.SS_Init
(Secondary_Stack_Address
, Integer (Secondary_Stack
'Last));
909 -- Set the guard page at the bottom of the stack. The call to
910 -- unprotect the page is done in Terminate_Task
912 Stack_Guard
(Self_ID
, True);
914 -- Initialize low-level TCB components, that cannot be initialized
915 -- by the creator. Enter_Task sets Self_ID.Known_Tasks_Index and
916 -- also Self_ID.LL.Thread
918 Enter_Task
(Self_ID
);
920 -- We lock RTS_Lock to wait for activator to finish activating
921 -- the rest of the chain, so that everyone in the chain comes out
922 -- in priority order.
924 -- This also protects the value of
925 -- Self_ID.Common.Activator.Common.Wait_Count.
931 -- We are separating the following portion of the code in order to
932 -- place the exception handlers in a different block. In this way,
933 -- we do not call Set_Jmpbuf_Address (which needs Self) before we
934 -- set Self in Enter_Task
936 -- Call the task body procedure
938 -- The task body is called with abort still deferred. That
939 -- eliminates a dangerous window, for which we had to patch-up in
942 -- During the expansion of the task body, we insert an RTS-call
943 -- to Abort_Undefer, at the first point where abort should be
946 Self_ID
.Common
.Task_Entry_Point
(Self_ID
.Common
.Task_Arg
);
947 Initialization
.Defer_Abort_Nestable
(Self_ID
);
950 -- We can't call Terminate_Task in the exception handlers below,
951 -- since there may be (e.g. in the case of GCC exception handling)
952 -- clean ups associated with the exception handler that need to
953 -- access task specific data.
955 -- Defer abortion so that this task can't be aborted while exiting
957 when Standard
'Abort_Signal =>
958 Initialization
.Defer_Abort_Nestable
(Self_ID
);
961 -- ??? Using an E : others here causes CD2C11A to fail on
962 -- DEC Unix, see 7925-005.
964 Initialization
.Defer_Abort_Nestable
(Self_ID
);
966 -- Perform the task specific exception tracing duty. We handle
967 -- these outputs here and not in the common notification routine
968 -- because we need access to tasking related data and we don't
969 -- want to drag dependencies against tasking related units in the
970 -- the common notification units. Additionally, no trace is ever
971 -- triggered from the common routine for the Unhandled_Raise case
972 -- in tasks, since an exception never appears unhandled in this
973 -- context because of this handler.
975 if Exception_Trace
= Unhandled_Raise
then
976 Trace_Unhandled_Exception_In_Task
(Self_ID
);
980 Terminate_Task
(Self_ID
);
987 -- Before we allow the thread to exit, we must clean up. This is a
988 -- a delicate job. We must wake up the task's master, who may immediately
989 -- try to deallocate the ATCB out from under the current task WHILE IT IS
992 -- To avoid this, the parent task must be blocked up to the latest
993 -- statement executed. The trouble is that we have another step that we
994 -- also want to postpone to the very end, i.e., calling SSL.Destroy_TSD.
995 -- We have to postpone that until the end because compiler-generated code
996 -- is likely to try to access that data at just about any point.
998 -- We can't call Destroy_TSD while we are holding any other locks, because
999 -- it locks Global_Task_Lock, and our deadlock prevention rules require
1000 -- that to be the outermost lock. Our first "solution" was to just lock
1001 -- Global_Task_Lock in addition to the other locks, and force the parent
1002 -- to also lock this lock between its wakeup and its freeing of the ATCB.
1003 -- See Complete_Task for the parent-side of the code that has the matching
1004 -- calls to Task_Lock and Task_Unlock. That was not really a solution,
1005 -- since the operation Task_Unlock continued to access the ATCB after
1006 -- unlocking, after which the parent was observed to race ahead,
1007 -- deallocate the ATCB, and then reallocate it to another task. The
1008 -- call to Undefer_Abortion in Task_Unlock by the "terminated" task was
1009 -- overwriting the data of the new task that reused the ATCB! To solve
1010 -- this problem, we introduced the new operation Final_Task_Unlock.
1012 procedure Terminate_Task
(Self_ID
: Task_Id
) is
1013 Environment_Task
: constant Task_Id
:= STPO
.Environment_Task
;
1014 Master_of_Task
: Integer;
1017 Debug
.Task_Termination_Hook
;
1019 if Runtime_Traces
then
1020 Send_Trace_Info
(T_Terminate
);
1023 -- Since GCC cannot allocate stack chunks efficiently without reordering
1024 -- some of the allocations, we have to handle this unexpected situation
1025 -- here. We should normally never have to call Vulnerable_Complete_Task
1026 -- here. See 6602-003 for more details.
1028 if Self_ID
.Common
.Activator
/= null then
1029 Vulnerable_Complete_Task
(Self_ID
);
1032 Initialization
.Task_Lock
(Self_ID
);
1038 Master_of_Task
:= Self_ID
.Master_of_Task
;
1040 -- Check if the current task is an independent task If so, decrement
1041 -- the Independent_Task_Count value.
1043 if Master_of_Task
= 2 then
1045 Utilities
.Independent_Task_Count
:=
1046 Utilities
.Independent_Task_Count
- 1;
1048 Write_Lock
(Environment_Task
);
1049 Utilities
.Independent_Task_Count
:=
1050 Utilities
.Independent_Task_Count
- 1;
1051 Unlock
(Environment_Task
);
1055 -- Unprotect the guard page if needed
1057 Stack_Guard
(Self_ID
, False);
1059 Utilities
.Make_Passive
(Self_ID
, Task_Completed
=> True);
1065 pragma Assert
(Check_Exit
(Self_ID
));
1067 SSL
.Destroy_TSD
(Self_ID
.Common
.Compiler_Data
);
1068 Initialization
.Final_Task_Unlock
(Self_ID
);
1070 -- WARNING: past this point, this thread must assume that the ATCB
1071 -- has been deallocated. It should not be accessed again.
1073 if Master_of_Task
> 0 then
1082 function Terminated
(T
: Task_Id
) return Boolean is
1083 Self_ID
: constant Task_Id
:= STPO
.Self
;
1087 Initialization
.Defer_Abort_Nestable
(Self_ID
);
1094 Result
:= T
.Common
.State
= Terminated
;
1101 Initialization
.Undefer_Abort_Nestable
(Self_ID
);
1105 ----------------------------------------
1106 -- Trace_Unhandled_Exception_In_Task --
1107 ----------------------------------------
1109 procedure Trace_Unhandled_Exception_In_Task
(Self_Id
: Task_Id
) is
1110 procedure To_Stderr
(S
: String);
1111 pragma Import
(Ada
, To_Stderr
, "__gnat_to_stderr");
1113 use System
.Task_Info
;
1114 use System
.Soft_Links
;
1115 use System
.Standard_Library
;
1117 function To_Address
is new
1118 Unchecked_Conversion
(Task_Id
, System
.Address
);
1120 function Tailored_Exception_Information
1121 (E
: Exception_Occurrence
) return String;
1123 (Ada
, Tailored_Exception_Information
,
1124 "__gnat_tailored_exception_information");
1126 Excep
: constant Exception_Occurrence_Access
:=
1127 SSL
.Get_Current_Excep
.all;
1130 -- This procedure is called by the task outermost handler in
1131 -- Task_Wrapper below, so only once the task stack has been fully
1132 -- unwound. The common notification routine has been called at the
1133 -- raise point already.
1135 To_Stderr
("task ");
1137 if Self_Id
.Common
.Task_Image_Len
/= 0 then
1139 (Self_Id
.Common
.Task_Image
(1 .. Self_Id
.Common
.Task_Image_Len
));
1143 To_Stderr
(System
.Address_Image
(To_Address
(Self_Id
)));
1144 To_Stderr
(" terminated by unhandled exception");
1145 To_Stderr
((1 => ASCII
.LF
));
1146 To_Stderr
(Tailored_Exception_Information
(Excep
.all));
1147 end Trace_Unhandled_Exception_In_Task
;
1149 ------------------------------------
1150 -- Vulnerable_Complete_Activation --
1151 ------------------------------------
1153 -- As in several other places, the locks of the activator and activated
1154 -- task are both locked here. This follows our deadlock prevention lock
1155 -- ordering policy, since the activated task must be created after the
1158 procedure Vulnerable_Complete_Activation
(Self_ID
: Task_Id
) is
1159 Activator
: constant Task_Id
:= Self_ID
.Common
.Activator
;
1162 pragma Debug
(Debug
.Trace
(Self_ID
, "V_Complete_Activation", 'C'));
1164 Write_Lock
(Activator
);
1165 Write_Lock
(Self_ID
);
1167 pragma Assert
(Self_ID
.Common
.Activator
/= null);
1169 -- Remove dangling reference to Activator, since a task may
1170 -- outlive its activator.
1172 Self_ID
.Common
.Activator
:= null;
1174 -- Wake up the activator, if it is waiting for a chain of tasks to
1175 -- activate, and we are the last in the chain to complete activation.
1177 if Activator
.Common
.State
= Activator_Sleep
then
1178 Activator
.Common
.Wait_Count
:= Activator
.Common
.Wait_Count
- 1;
1180 if Activator
.Common
.Wait_Count
= 0 then
1181 Wakeup
(Activator
, Activator_Sleep
);
1185 -- The activator raises a Tasking_Error if any task it is activating
1186 -- is completed before the activation is done. However, if the reason
1187 -- for the task completion is an abortion, we do not raise an exception.
1190 if not Self_ID
.Callable
and then Self_ID
.Pending_ATC_Level
/= 0 then
1191 Activator
.Common
.Activation_Failed
:= True;
1197 -- After the activation, active priority should be the same
1198 -- as base priority. We must unlock the Activator first,
1199 -- though, since it should not wait if we have lower priority.
1201 if Get_Priority
(Self_ID
) /= Self_ID
.Common
.Base_Priority
then
1202 Write_Lock
(Self_ID
);
1203 Set_Priority
(Self_ID
, Self_ID
.Common
.Base_Priority
);
1206 end Vulnerable_Complete_Activation
;
1208 --------------------------------
1209 -- Vulnerable_Complete_Master --
1210 --------------------------------
1212 procedure Vulnerable_Complete_Master
(Self_ID
: Task_Id
) is
1215 CM
: constant Master_Level
:= Self_ID
.Master_Within
;
1216 T
: aliased Task_Id
;
1218 To_Be_Freed
: Task_Id
;
1219 -- This is a list of ATCBs to be freed, after we have released
1220 -- all RTS locks. This is necessary because of the locking order
1221 -- rules, since the storage manager uses Global_Task_Lock.
1223 pragma Warnings
(Off
);
1224 function Check_Unactivated_Tasks
return Boolean;
1225 pragma Warnings
(On
);
1226 -- Temporary error-checking code below. This is part of the checks
1227 -- added in the new run time. Call it only inside a pragma Assert.
1229 -----------------------------
1230 -- Check_Unactivated_Tasks --
1231 -----------------------------
1233 function Check_Unactivated_Tasks
return Boolean is
1235 if not Single_Lock
then
1239 Write_Lock
(Self_ID
);
1241 C
:= All_Tasks_List
;
1242 while C
/= null loop
1243 if C
.Common
.Activator
= Self_ID
then
1247 if C
.Common
.Parent
= Self_ID
and then C
.Master_of_Task
= CM
then
1250 if C
.Common
.State
= Unactivated
then
1257 C
:= C
.Common
.All_Tasks_Link
;
1262 if not Single_Lock
then
1267 end Check_Unactivated_Tasks
;
1269 -- Start of processing for Vulnerable_Complete_Master
1273 (Debug
.Trace
(Self_ID
, "V_Complete_Master", 'C'));
1275 pragma Assert
(Self_ID
.Common
.Wait_Count
= 0);
1276 pragma Assert
(Self_ID
.Deferral_Level
> 0);
1278 -- Count how many active dependent tasks this master currently
1279 -- has, and record this in Wait_Count.
1281 -- This count should start at zero, since it is initialized to
1282 -- zero for new tasks, and the task should not exit the
1283 -- sleep-loops that use this count until the count reaches zero.
1286 Write_Lock
(Self_ID
);
1288 C
:= All_Tasks_List
;
1289 while C
/= null loop
1290 if C
.Common
.Activator
= Self_ID
then
1291 pragma Assert
(C
.Common
.State
= Unactivated
);
1294 C
.Common
.Activator
:= null;
1295 C
.Common
.State
:= Terminated
;
1296 C
.Callable
:= False;
1297 Utilities
.Cancel_Queued_Entry_Calls
(C
);
1301 if C
.Common
.Parent
= Self_ID
and then C
.Master_of_Task
= CM
then
1304 if C
.Awake_Count
/= 0 then
1305 Self_ID
.Common
.Wait_Count
:= Self_ID
.Common
.Wait_Count
+ 1;
1311 C
:= C
.Common
.All_Tasks_Link
;
1314 Self_ID
.Common
.State
:= Master_Completion_Sleep
;
1317 if not Single_Lock
then
1321 -- Wait until dependent tasks are all terminated or ready to terminate.
1322 -- While waiting, the task may be awakened if the task's priority needs
1323 -- changing, or this master is aborted. In the latter case, we want
1324 -- to abort the dependents, and resume waiting until Wait_Count goes
1327 Write_Lock
(Self_ID
);
1330 Initialization
.Poll_Base_Priority_Change
(Self_ID
);
1331 exit when Self_ID
.Common
.Wait_Count
= 0;
1333 -- Here is a difference as compared to Complete_Master
1335 if Self_ID
.Pending_ATC_Level
< Self_ID
.ATC_Nesting_Level
1336 and then not Self_ID
.Dependents_Aborted
1339 Abort_Dependents
(Self_ID
);
1343 Abort_Dependents
(Self_ID
);
1345 Write_Lock
(Self_ID
);
1348 Sleep
(Self_ID
, Master_Completion_Sleep
);
1352 Self_ID
.Common
.State
:= Runnable
;
1355 -- Dependents are all terminated or on terminate alternatives.
1356 -- Now, force those on terminate alternatives to terminate, by
1359 pragma Assert
(Check_Unactivated_Tasks
);
1361 if Self_ID
.Alive_Count
> 1 then
1363 -- Consider finding a way to skip the following extra steps if there
1364 -- are no dependents with terminate alternatives. This could be done
1365 -- by adding another count to the ATCB, similar to Awake_Count, but
1366 -- keeping track of tasks that are on terminate alternatives.
1368 pragma Assert
(Self_ID
.Common
.Wait_Count
= 0);
1370 -- Force any remaining dependents to terminate, by aborting them.
1372 if not Single_Lock
then
1376 Abort_Dependents
(Self_ID
);
1378 -- Above, when we "abort" the dependents we are simply using this
1379 -- operation for convenience. We are not required to support the full
1380 -- abort-statement semantics; in particular, we are not required to
1381 -- immediately cancel any queued or in-service entry calls. That is
1382 -- good, because if we tried to cancel a call we would need to lock
1383 -- the caller, in order to wake the caller up. Our anti-deadlock
1384 -- rules prevent us from doing that without releasing the locks on C
1385 -- and Self_ID. Releasing and retaking those locks would be wasteful
1386 -- at best, and should not be considered further without more
1387 -- detailed analysis of potential concurrent accesses to the
1388 -- ATCBs of C and Self_ID.
1390 -- Count how many "alive" dependent tasks this master currently
1391 -- has, and record this in Wait_Count. This count should start at
1392 -- zero, since it is initialized to zero for new tasks, and the
1393 -- task should not exit the sleep-loops that use this count until
1394 -- the count reaches zero.
1396 pragma Assert
(Self_ID
.Common
.Wait_Count
= 0);
1398 Write_Lock
(Self_ID
);
1400 C
:= All_Tasks_List
;
1401 while C
/= null loop
1402 if C
.Common
.Parent
= Self_ID
and then C
.Master_of_Task
= CM
then
1405 pragma Assert
(C
.Awake_Count
= 0);
1407 if C
.Alive_Count
> 0 then
1408 pragma Assert
(C
.Terminate_Alternative
);
1409 Self_ID
.Common
.Wait_Count
:= Self_ID
.Common
.Wait_Count
+ 1;
1415 C
:= C
.Common
.All_Tasks_Link
;
1418 Self_ID
.Common
.State
:= Master_Phase_2_Sleep
;
1421 if not Single_Lock
then
1425 -- Wait for all counted tasks to finish terminating themselves
1427 Write_Lock
(Self_ID
);
1430 Initialization
.Poll_Base_Priority_Change
(Self_ID
);
1431 exit when Self_ID
.Common
.Wait_Count
= 0;
1432 Sleep
(Self_ID
, Master_Phase_2_Sleep
);
1435 Self_ID
.Common
.State
:= Runnable
;
1439 -- We don't wake up for abortion here. We are already terminating
1440 -- just as fast as we can, so there is no point.
1442 -- Remove terminated tasks from the list of Self_ID's dependents, but
1443 -- don't free their ATCBs yet, because of lock order restrictions,
1444 -- which don't allow us to call "free" or "malloc" while holding any
1445 -- other locks. Instead, we put those ATCBs to be freed onto a
1446 -- temporary list, called To_Be_Freed.
1448 if not Single_Lock
then
1452 C
:= All_Tasks_List
;
1454 while C
/= null loop
1455 if C
.Common
.Parent
= Self_ID
and then C
.Master_of_Task
>= CM
then
1457 P
.Common
.All_Tasks_Link
:= C
.Common
.All_Tasks_Link
;
1459 All_Tasks_List
:= C
.Common
.All_Tasks_Link
;
1462 T
:= C
.Common
.All_Tasks_Link
;
1463 C
.Common
.All_Tasks_Link
:= To_Be_Freed
;
1469 C
:= C
.Common
.All_Tasks_Link
;
1475 -- Free all the ATCBs on the list To_Be_Freed
1477 -- The ATCBs in the list are no longer in All_Tasks_List, and after
1478 -- any interrupt entries are detached from them they should no longer
1481 -- Global_Task_Lock (Task_Lock/Unlock) is locked in the loop below to
1482 -- avoid a race between a terminating task and its parent. The parent
1483 -- might try to deallocate the ACTB out from underneath the exiting
1484 -- task. Note that Free will also lock Global_Task_Lock, but that is
1485 -- OK, since this is the *one* lock for which we have a mechanism to
1486 -- support nested locking. See Task_Wrapper and its finalizer for more
1490 -- The check "T.Common.Parent /= null ..." below is to prevent dangling
1491 -- references to terminated library-level tasks, which could
1492 -- otherwise occur during finalization of library-level objects.
1493 -- A better solution might be to hook task objects into the
1494 -- finalization chain and deallocate the ATCB when the task
1495 -- object is deallocated. However, this change is not likely
1496 -- to gain anything significant, since all this storage should
1497 -- be recovered en-masse when the process exits.
1499 while To_Be_Freed
/= null loop
1501 To_Be_Freed
:= T
.Common
.All_Tasks_Link
;
1503 -- ??? On SGI there is currently no Interrupt_Manager, that's
1504 -- why we need to check if the Interrupt_Manager_ID is null
1506 if T
.Interrupt_Entry
and Interrupt_Manager_ID
/= null then
1508 Detach_Interrupt_Entries_Index
: constant Task_Entry_Index
:= 1;
1509 -- Corresponds to the entry index of System.Interrupts.
1510 -- Interrupt_Manager.Detach_Interrupt_Entries.
1511 -- Be sure to update this value when changing
1512 -- Interrupt_Manager specs.
1514 type Param_Type
is access all Task_Id
;
1516 Param
: aliased Param_Type
:= T
'Access;
1519 System
.Tasking
.Rendezvous
.Call_Simple
1520 (Interrupt_Manager_ID
, Detach_Interrupt_Entries_Index
,
1525 if (T
.Common
.Parent
/= null
1526 and then T
.Common
.Parent
.Common
.Parent
/= null)
1527 or else T
.Master_of_Task
> 3
1529 Initialization
.Task_Lock
(Self_ID
);
1531 -- If Sec_Stack_Addr is not null, it means that Destroy_TSD
1532 -- has not been called yet (case of an unactivated task).
1534 if T
.Common
.Compiler_Data
.Sec_Stack_Addr
/= Null_Address
then
1535 SSL
.Destroy_TSD
(T
.Common
.Compiler_Data
);
1538 Vulnerable_Free_Task
(T
);
1539 Initialization
.Task_Unlock
(Self_ID
);
1543 -- It might seem nice to let the terminated task deallocate its own
1544 -- ATCB. That would not cover the case of unactivated tasks. It also
1545 -- would force us to keep the underlying thread around past termination,
1546 -- since references to the ATCB are possible past termination.
1547 -- Currently, we get rid of the thread as soon as the task terminates,
1548 -- and let the parent recover the ATCB later.
1550 -- Some day, if we want to recover the ATCB earlier, at task
1551 -- termination, we could consider using "fat task IDs", that include the
1552 -- serial number with the ATCB pointer, to catch references to tasks
1553 -- that no longer have ATCBs. It is not clear how much this would gain,
1554 -- since the user-level task object would still be occupying storage.
1556 -- Make next master level up active.
1557 -- We don't need to lock the ATCB, since the value is only updated by
1558 -- each task for itself.
1560 Self_ID
.Master_Within
:= CM
- 1;
1561 end Vulnerable_Complete_Master
;
1563 ------------------------------
1564 -- Vulnerable_Complete_Task --
1565 ------------------------------
1567 -- Complete the calling task
1569 -- This procedure must be called with abort deferred. (That's why the
1570 -- name has "Vulnerable" in it.) It should only be called by Complete_Task
1571 -- and Finalize_Global_Tasks (for the environment task).
1573 -- The effect is similar to that of Complete_Master. Differences include
1574 -- the closing of entries here, and computation of the number of active
1575 -- dependent tasks in Complete_Master.
1577 -- We don't lock Self_ID before the call to Vulnerable_Complete_Activation,
1578 -- because that does its own locking, and because we do not need the lock
1579 -- to test Self_ID.Common.Activator. That value should only be read and
1580 -- modified by Self.
1582 procedure Vulnerable_Complete_Task
(Self_ID
: Task_Id
) is
1584 pragma Assert
(Self_ID
.Deferral_Level
> 0);
1585 pragma Assert
(Self_ID
= Self
);
1586 pragma Assert
(Self_ID
.Master_Within
= Self_ID
.Master_of_Task
+ 1
1588 Self_ID
.Master_Within
= Self_ID
.Master_of_Task
+ 2);
1589 pragma Assert
(Self_ID
.Common
.Wait_Count
= 0);
1590 pragma Assert
(Self_ID
.Open_Accepts
= null);
1591 pragma Assert
(Self_ID
.ATC_Nesting_Level
= 1);
1593 pragma Debug
(Debug
.Trace
(Self_ID
, "V_Complete_Task", 'C'));
1599 Write_Lock
(Self_ID
);
1600 Self_ID
.Callable
:= False;
1602 -- In theory, Self should have no pending entry calls left on its
1603 -- call-stack. Each async. select statement should clean its own call,
1604 -- and blocking entry calls should defer abort until the calls are
1605 -- cancelled, then clean up.
1607 Utilities
.Cancel_Queued_Entry_Calls
(Self_ID
);
1610 if Self_ID
.Common
.Activator
/= null then
1611 Vulnerable_Complete_Activation
(Self_ID
);
1618 -- If Self_ID.Master_Within = Self_ID.Master_of_Task + 2
1619 -- we may have dependent tasks for which we need to wait.
1620 -- Otherwise, we can just exit.
1622 if Self_ID
.Master_Within
= Self_ID
.Master_of_Task
+ 2 then
1623 Vulnerable_Complete_Master
(Self_ID
);
1625 end Vulnerable_Complete_Task
;
1627 --------------------------
1628 -- Vulnerable_Free_Task --
1629 --------------------------
1631 -- Recover all runtime system storage associated with the task T.
1632 -- This should only be called after T has terminated and will no
1633 -- longer be referenced.
1635 -- For tasks created by an allocator that fails, due to an exception,
1636 -- it is called from Expunge_Unactivated_Tasks.
1638 -- For tasks created by elaboration of task object declarations it
1639 -- is called from the finalization code of the Task_Wrapper procedure.
1640 -- It is also called from Unchecked_Deallocation, for objects that
1641 -- are or contain tasks.
1643 procedure Vulnerable_Free_Task
(T
: Task_Id
) is
1645 pragma Debug
(Debug
.Trace
(Self
, "Vulnerable_Free_Task", 'C', T
));
1652 Initialization
.Finalize_Attributes_Link
.all (T
);
1659 System
.Task_Primitives
.Operations
.Finalize_TCB
(T
);
1660 end Vulnerable_Free_Task
;
1662 -- Package elaboration code
1665 -- Establish the Adafinal softlink.
1667 -- This is not done inside the central RTS initialization routine
1668 -- to avoid with-ing this package from System.Tasking.Initialization.
1670 SSL
.Adafinal
:= Finalize_Global_Tasks
'Access;
1672 -- Establish soft links for subprograms that manipulate master_id's.
1673 -- This cannot be done when the RTS is initialized, because of various
1674 -- elaboration constraints.
1676 SSL
.Current_Master
:= Stages
.Current_Master
'Access;
1677 SSL
.Enter_Master
:= Stages
.Enter_Master
'Access;
1678 SSL
.Complete_Master
:= Stages
.Complete_Master
'Access;
1679 end System
.Tasking
.Stages
;