1 ------------------------------------------------------------------------------
3 -- GNAT 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) 1992-2005, 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, 51 Franklin Street, Fifth Floor, --
20 -- Boston, MA 02110-1301, 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 task
68 -- specific data. In the absence of tasking, these routines refer to global
69 -- data. In the presense of tasking, they must be replaced with pointers to
70 -- task-specific versions. Also used for Create_TSD, Destroy_TSD,
71 -- Get_Current_Excep, Finalize_Global_List, Task_Termination, Handler.
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
89 with System
.Tasking
.Queuing
;
90 -- Used for Dequeue_Head
92 with System
.Tasking
.Rendezvous
;
93 -- Used for Call_Simple
95 with System
.OS_Primitives
;
96 -- Used for Delay_Modes
98 with System
.Secondary_Stack
;
101 with System
.Storage_Elements
;
102 -- Used for Storage_Array
104 with System
.Restrictions
;
105 -- Used for Abort_Allowed
107 with System
.Standard_Library
;
108 -- Used for Exception_Trace
110 with System
.Traces
.Tasking
;
111 -- Used for Send_Trace_Info
113 with Unchecked_Deallocation
;
114 -- To recover from failure of ATCB initialization
116 with System
.Stack_Usage
;
118 package body System
.Tasking
.Stages
is
120 package STPO
renames System
.Task_Primitives
.Operations
;
121 package SSL
renames System
.Soft_Links
;
122 package SSE
renames System
.Storage_Elements
;
123 package SST
renames System
.Secondary_Stack
;
129 use Task_Primitives
.Operations
;
133 use System
.Traces
.Tasking
;
135 -----------------------
136 -- Local Subprograms --
137 -----------------------
139 procedure Free
is new
140 Unchecked_Deallocation
(Ada_Task_Control_Block
, Task_Id
);
142 procedure Trace_Unhandled_Exception_In_Task
(Self_Id
: Task_Id
);
143 -- This procedure outputs the task specific message for exception
146 procedure Task_Wrapper
(Self_ID
: Task_Id
);
147 pragma Convention
(C
, Task_Wrapper
);
148 -- This is the procedure that is called by the GNULL from the new context
149 -- when a task is created. It waits for activation and then calls the task
150 -- body procedure. When the task body procedure completes, it terminates
153 -- The Task_Wrapper's address will be provided to the underlying threads
154 -- library as the task entry point. Convention C is what makes most sense
155 -- for that purpose (Export C would make the function globally visible,
156 -- and affect the link name on which GDB depends). This will in addition
157 -- trigger an automatic stack alignment suitable for GCC's assumptions if
160 procedure Vulnerable_Complete_Task
(Self_ID
: Task_Id
);
161 -- Complete the calling task. This procedure must be called with
162 -- abort deferred. It should only be called by Complete_Task and
163 -- Finalizate_Global_Tasks (for the environment task).
165 procedure Vulnerable_Complete_Master
(Self_ID
: Task_Id
);
166 -- Complete the current master of the calling task. This procedure
167 -- must be called with abort deferred. It should only be called by
168 -- Vulnerable_Complete_Task and Complete_Master.
170 procedure Vulnerable_Complete_Activation
(Self_ID
: Task_Id
);
171 -- Signal to Self_ID's activator that Self_ID has completed activation.
172 -- This procedure must be called with abort deferred.
174 procedure Abort_Dependents
(Self_ID
: Task_Id
);
175 -- Abort all the direct dependents of Self at its current master
176 -- nesting level, plus all of their dependents, transitively.
177 -- RTS_Lock should be locked by the caller.
179 procedure Vulnerable_Free_Task
(T
: Task_Id
);
180 -- Recover all runtime system storage associated with the task T.
181 -- This should only be called after T has terminated and will no
182 -- longer be referenced.
184 -- For tasks created by an allocator that fails, due to an exception,
185 -- it is called from Expunge_Unactivated_Tasks.
187 -- It is also called from Unchecked_Deallocation, for objects that
188 -- are or contain tasks.
190 -- Different code is used at master completion, in Terminate_Dependents,
191 -- due to a need for tighter synchronization with the master.
193 ----------------------
194 -- Abort_Dependents --
195 ----------------------
197 procedure Abort_Dependents
(Self_ID
: Task_Id
) is
204 P
:= C
.Common
.Parent
;
208 -- ??? C is supposed to take care of its own dependents, so
209 -- there should be no need to worry about them. Need to double
212 if C
.Master_of_Task
= Self_ID
.Master_Within
then
213 Utilities
.Abort_One_Task
(Self_ID
, C
);
214 C
.Dependents_Aborted
:= True;
220 P
:= P
.Common
.Parent
;
223 C
:= C
.Common
.All_Tasks_Link
;
226 Self_ID
.Dependents_Aborted
:= True;
227 end Abort_Dependents
;
233 procedure Abort_Tasks
(Tasks
: Task_List
) is
235 Utilities
.Abort_Tasks
(Tasks
);
242 -- Note that locks of activator and activated task are both locked
243 -- here. This is necessary because C.Common.State and
244 -- Self.Common.Wait_Count have to be synchronized. This is safe from
245 -- deadlock because the activator is always created before the activated
246 -- task. That satisfies our in-order-of-creation ATCB locking policy.
248 -- At one point, we may also lock the parent, if the parent is
249 -- different from the activator. That is also consistent with the
250 -- lock ordering policy, since the activator cannot be created
251 -- before the parent.
253 -- Since we are holding both the activator's lock, and Task_Wrapper
254 -- locks that before it does anything more than initialize the
255 -- low-level ATCB components, it should be safe to wait to update
256 -- the counts until we see that the thread creation is successful.
258 -- If the thread creation fails, we do need to close the entries
259 -- of the task. The first phase, of dequeuing calls, only requires
260 -- locking the acceptor's ATCB, but the waking up of the callers
261 -- requires locking the caller's ATCB. We cannot safely do this
262 -- while we are holding other locks. Therefore, the queue-clearing
263 -- operation is done in a separate pass over the activation chain.
265 procedure Activate_Tasks
(Chain_Access
: Activation_Chain_Access
) is
266 Self_ID
: constant Task_Id
:= STPO
.Self
;
269 Next_C
, Last_C
: Task_Id
;
270 Activate_Prio
: System
.Any_Priority
;
272 All_Elaborated
: Boolean := True;
275 -- If pragma Detect_Blocking is active, then we must check whether this
276 -- potentially blocking operation is called from a protected action.
278 if System
.Tasking
.Detect_Blocking
279 and then Self_ID
.Common
.Protected_Action_Nesting
> 0
281 Ada
.Exceptions
.Raise_Exception
282 (Program_Error
'Identity, "potentially blocking operation");
286 (Debug
.Trace
(Self_ID
, "Activate_Tasks", 'C'));
288 Initialization
.Defer_Abort_Nestable
(Self_ID
);
290 pragma Assert
(Self_ID
.Common
.Wait_Count
= 0);
292 -- Lock RTS_Lock, to prevent activated tasks from racing ahead before
293 -- we finish activating the chain.
297 -- Check that all task bodies have been elaborated
299 C
:= Chain_Access
.T_ID
;
302 if C
.Common
.Elaborated
/= null
303 and then not C
.Common
.Elaborated
.all
305 All_Elaborated
:= False;
308 -- Reverse the activation chain so that tasks are
309 -- activated in the same order they're declared.
311 Next_C
:= C
.Common
.Activation_Link
;
312 C
.Common
.Activation_Link
:= Last_C
;
317 Chain_Access
.T_ID
:= Last_C
;
319 if not All_Elaborated
then
321 Initialization
.Undefer_Abort_Nestable
(Self_ID
);
323 (Program_Error
'Identity, "Some tasks have not been elaborated");
326 -- Activate all the tasks in the chain. Creation of the thread of
327 -- control was deferred until activation. So create it now.
329 C
:= Chain_Access
.T_ID
;
331 if C
.Common
.State
/= Terminated
then
332 pragma Assert
(C
.Common
.State
= Unactivated
);
334 P
:= C
.Common
.Parent
;
338 if C
.Common
.Base_Priority
< Get_Priority
(Self_ID
) then
339 Activate_Prio
:= Get_Priority
(Self_ID
);
341 Activate_Prio
:= C
.Common
.Base_Priority
;
344 System
.Task_Primitives
.Operations
.Create_Task
345 (C
, Task_Wrapper
'Address,
347 (C
.Common
.Compiler_Data
.Pri_Stack_Info
.Size
),
348 Activate_Prio
, Success
);
350 -- There would be a race between the created task and the
351 -- creator to do the following initialization, if we did not
352 -- have a Lock/Unlock_RTS pair in the task wrapper to prevent
353 -- it from racing ahead.
356 C
.Common
.State
:= Runnable
;
359 P
.Awake_Count
:= P
.Awake_Count
+ 1;
360 P
.Alive_Count
:= P
.Alive_Count
+ 1;
362 if P
.Common
.State
= Master_Completion_Sleep
and then
363 C
.Master_of_Task
= P
.Master_Within
365 pragma Assert
(Self_ID
/= P
);
366 P
.Common
.Wait_Count
:= P
.Common
.Wait_Count
+ 1;
373 -- No need to set Awake_Count, State, etc. here since the loop
374 -- below will do that for any Unactivated tasks.
378 Self_ID
.Common
.Activation_Failed
:= True;
382 C
:= C
.Common
.Activation_Link
;
385 if not Single_Lock
then
389 -- Close the entries of any tasks that failed thread creation,
390 -- and count those that have not finished activation.
392 Write_Lock
(Self_ID
);
393 Self_ID
.Common
.State
:= Activator_Sleep
;
395 C
:= Chain_Access
.T_ID
;
399 if C
.Common
.State
= Unactivated
then
400 C
.Common
.Activator
:= null;
401 C
.Common
.State
:= Terminated
;
403 Utilities
.Cancel_Queued_Entry_Calls
(C
);
405 elsif C
.Common
.Activator
/= null then
406 Self_ID
.Common
.Wait_Count
:= Self_ID
.Common
.Wait_Count
+ 1;
410 P
:= C
.Common
.Activation_Link
;
411 C
.Common
.Activation_Link
:= null;
415 -- Wait for the activated tasks to complete activation. It is
416 -- unsafe to abort any of these tasks until the count goes to zero.
419 Initialization
.Poll_Base_Priority_Change
(Self_ID
);
420 exit when Self_ID
.Common
.Wait_Count
= 0;
421 Sleep
(Self_ID
, Activator_Sleep
);
424 Self_ID
.Common
.State
:= Runnable
;
431 -- Remove the tasks from the chain
433 Chain_Access
.T_ID
:= null;
434 Initialization
.Undefer_Abort_Nestable
(Self_ID
);
436 if Self_ID
.Common
.Activation_Failed
then
437 Self_ID
.Common
.Activation_Failed
:= False;
438 Raise_Exception
(Tasking_Error
'Identity,
439 "Failure during activation");
443 -------------------------
444 -- Complete_Activation --
445 -------------------------
447 procedure Complete_Activation
is
448 Self_ID
: constant Task_Id
:= STPO
.Self
;
451 Initialization
.Defer_Abort_Nestable
(Self_ID
);
457 Vulnerable_Complete_Activation
(Self_ID
);
463 Initialization
.Undefer_Abort_Nestable
(Self_ID
);
466 -- Why do we need to allow for nested deferral here?
468 if Runtime_Traces
then
469 Send_Trace_Info
(T_Activate
);
471 end Complete_Activation
;
473 ---------------------
474 -- Complete_Master --
475 ---------------------
477 procedure Complete_Master
is
478 Self_ID
: constant Task_Id
:= STPO
.Self
;
480 pragma Assert
(Self_ID
.Deferral_Level
> 0);
481 Vulnerable_Complete_Master
(Self_ID
);
488 -- See comments on Vulnerable_Complete_Task for details
490 procedure Complete_Task
is
491 Self_ID
: constant Task_Id
:= STPO
.Self
;
494 pragma Assert
(Self_ID
.Deferral_Level
> 0);
496 Vulnerable_Complete_Task
(Self_ID
);
498 -- All of our dependents have terminated. Never undefer abort again!
506 -- Compiler interface only. Do not call from within the RTS.
507 -- This must be called to create a new task.
509 procedure Create_Task
511 Size
: System
.Parameters
.Size_Type
;
512 Task_Info
: System
.Task_Info
.Task_Info_Type
;
513 Num_Entries
: Task_Entry_Index
;
514 Master
: Master_Level
;
515 State
: Task_Procedure_Access
;
516 Discriminants
: System
.Address
;
517 Elaborated
: Access_Boolean
;
518 Chain
: in out Activation_Chain
;
520 Created_Task
: out Task_Id
)
523 Self_ID
: constant Task_Id
:= STPO
.Self
;
525 Base_Priority
: System
.Any_Priority
;
529 -- If pragma Detect_Blocking is active must be checked whether
530 -- this potentially blocking operation is called from a
533 if System
.Tasking
.Detect_Blocking
534 and then Self_ID
.Common
.Protected_Action_Nesting
> 0
536 Ada
.Exceptions
.Raise_Exception
537 (Program_Error
'Identity, "potentially blocking operation");
541 (Debug
.Trace
(Self_ID
, "Create_Task", 'C'));
543 if Priority
= Unspecified_Priority
then
544 Base_Priority
:= Self_ID
.Common
.Base_Priority
;
546 Base_Priority
:= System
.Any_Priority
(Priority
);
549 -- Find parent P of new Task, via master level number
554 while P
.Master_of_Task
>= Master
loop
555 P
:= P
.Common
.Parent
;
560 Initialization
.Defer_Abort_Nestable
(Self_ID
);
563 T
:= New_ATCB
(Num_Entries
);
566 Initialization
.Undefer_Abort_Nestable
(Self_ID
);
567 Raise_Exception
(Storage_Error
'Identity, "Cannot allocate task");
570 -- RTS_Lock is used by Abort_Dependents and Abort_Tasks.
571 -- Up to this point, it is possible that we may be part of
572 -- a family of tasks that is being aborted.
575 Write_Lock
(Self_ID
);
577 -- Now, we must check that we have not been aborted.
578 -- If so, we should give up on creating this task,
579 -- and simply return.
581 if not Self_ID
.Callable
then
582 pragma Assert
(Self_ID
.Pending_ATC_Level
= 0);
583 pragma Assert
(Self_ID
.Pending_Action
);
585 (Chain
.T_ID
= null or else Chain
.T_ID
.Common
.State
= Unactivated
);
589 Initialization
.Undefer_Abort_Nestable
(Self_ID
);
591 -- ??? Should never get here
593 pragma Assert
(False);
594 raise Standard
'Abort_Signal;
597 Initialize_ATCB
(Self_ID
, State
, Discriminants
, P
, Elaborated
,
598 Base_Priority
, Task_Info
, Size
, T
, Success
);
604 Initialization
.Undefer_Abort_Nestable
(Self_ID
);
606 (Storage_Error
'Identity, "Failed to initialize task");
609 T
.Master_of_Task
:= Master
;
610 T
.Master_Within
:= T
.Master_of_Task
+ 1;
612 for L
in T
.Entry_Calls
'Range loop
613 T
.Entry_Calls
(L
).Self
:= T
;
614 T
.Entry_Calls
(L
).Level
:= L
;
617 if Task_Image
'Length = 0 then
618 T
.Common
.Task_Image_Len
:= 0;
621 T
.Common
.Task_Image
(1) := Task_Image
(Task_Image
'First);
623 -- Remove unwanted blank space generated by 'Image
625 for J
in Task_Image
'First + 1 .. Task_Image
'Last loop
626 if Task_Image
(J
) /= ' '
627 or else Task_Image
(J
- 1) /= '('
630 T
.Common
.Task_Image
(Len
) := Task_Image
(J
);
631 exit when Len
= T
.Common
.Task_Image
'Last;
635 T
.Common
.Task_Image_Len
:= Len
;
641 -- Create TSD as early as possible in the creation of a task, since it
642 -- may be used by the operation of Ada code within the task.
644 SSL
.Create_TSD
(T
.Common
.Compiler_Data
);
645 T
.Common
.Activation_Link
:= Chain
.T_ID
;
647 Initialization
.Initialize_Attributes_Link
.all (T
);
649 Initialization
.Undefer_Abort_Nestable
(Self_ID
);
651 if Runtime_Traces
then
652 Send_Trace_Info
(T_Create
, T
);
660 function Current_Master
return Master_Level
is
662 return STPO
.Self
.Master_Within
;
669 procedure Enter_Master
is
670 Self_ID
: constant Task_Id
:= STPO
.Self
;
672 Self_ID
.Master_Within
:= Self_ID
.Master_Within
+ 1;
675 -------------------------------
676 -- Expunge_Unactivated_Tasks --
677 -------------------------------
679 -- See procedure Close_Entries for the general case
681 procedure Expunge_Unactivated_Tasks
(Chain
: in out Activation_Chain
) is
682 Self_ID
: constant Task_Id
:= STPO
.Self
;
684 Call
: Entry_Call_Link
;
689 (Debug
.Trace
(Self_ID
, "Expunge_Unactivated_Tasks", 'C'));
691 Initialization
.Defer_Abort_Nestable
(Self_ID
);
694 -- Experimentation has shown that abort is sometimes (but not
695 -- always) already deferred when this is called.
697 -- That may indicate an error. Find out what is going on
701 pragma Assert
(C
.Common
.State
= Unactivated
);
703 Temp
:= C
.Common
.Activation_Link
;
705 if C
.Common
.State
= Unactivated
then
709 for J
in 1 .. C
.Entry_Num
loop
710 Queuing
.Dequeue_Head
(C
.Entry_Queues
(J
), Call
);
711 pragma Assert
(Call
= null);
716 Initialization
.Remove_From_All_Tasks_List
(C
);
719 Vulnerable_Free_Task
(C
);
725 Initialization
.Undefer_Abort_Nestable
(Self_ID
);
726 end Expunge_Unactivated_Tasks
;
728 ---------------------------
729 -- Finalize_Global_Tasks --
730 ---------------------------
733 -- We have a potential problem here if finalization of global
734 -- objects does anything with signals or the timer server, since
735 -- by that time those servers have terminated.
737 -- It is hard to see how that would occur
739 -- However, a better solution might be to do all this finalization
740 -- using the global finalization chain.
742 procedure Finalize_Global_Tasks
is
743 Self_ID
: constant Task_Id
:= STPO
.Self
;
747 if Self_ID
.Deferral_Level
= 0 then
749 -- In principle, we should be able to predict whether
750 -- abort is already deferred here (and it should not be deferred
751 -- yet but in practice it seems Finalize_Global_Tasks is being
752 -- called sometimes, from RTS code for exceptions, with abort already
755 Initialization
.Defer_Abort_Nestable
(Self_ID
);
757 -- Never undefer again!!!
760 -- This code is only executed by the environment task
762 pragma Assert
(Self_ID
= Environment_Task
);
764 -- Set Environment_Task'Callable to false to notify library-level tasks
765 -- that it is waiting for them (cf 5619-003).
767 Self_ID
.Callable
:= False;
769 -- Exit level 2 master, for normal tasks in library-level packages
773 -- Force termination of "independent" library-level server tasks
777 Abort_Dependents
(Self_ID
);
779 if not Single_Lock
then
783 -- We need to explicitely wait for the task to be terminated here
784 -- because on true concurrent system, we may end this procedure
785 -- before the tasks are really terminated.
787 Write_Lock
(Self_ID
);
790 exit when Utilities
.Independent_Task_Count
= 0;
792 -- We used to yield here, but this did not take into account
793 -- low priority tasks that would cause dead lock in some cases.
797 (Self_ID
, 0.01, System
.OS_Primitives
.Relative
,
798 Self_ID
.Common
.State
, Ignore
, Ignore
);
801 -- ??? On multi-processor environments, it seems that the above loop
802 -- isn't sufficient, so we need to add an additional delay.
805 (Self_ID
, 0.01, System
.OS_Primitives
.Relative
,
806 Self_ID
.Common
.State
, Ignore
, Ignore
);
814 -- Complete the environment task
816 Vulnerable_Complete_Task
(Self_ID
);
818 -- Handle normal task termination by the environment task, but only
819 -- for the normal task termination. In the case of Abnormal and
820 -- Unhandled_Exception they must have been handled before, and the
821 -- task termination soft link must have been changed so the task
822 -- termination routine is not executed twice.
824 SSL
.Task_Termination_Handler
.all (Ada
.Exceptions
.Null_Occurrence
);
826 -- Finalize the global list for controlled objects if needed
828 SSL
.Finalize_Global_List
.all;
830 -- Reset the soft links to non-tasking
832 SSL
.Abort_Defer
:= SSL
.Abort_Defer_NT
'Access;
833 SSL
.Abort_Undefer
:= SSL
.Abort_Undefer_NT
'Access;
834 SSL
.Lock_Task
:= SSL
.Task_Lock_NT
'Access;
835 SSL
.Unlock_Task
:= SSL
.Task_Unlock_NT
'Access;
836 SSL
.Get_Jmpbuf_Address
:= SSL
.Get_Jmpbuf_Address_NT
'Access;
837 SSL
.Set_Jmpbuf_Address
:= SSL
.Set_Jmpbuf_Address_NT
'Access;
838 SSL
.Get_Sec_Stack_Addr
:= SSL
.Get_Sec_Stack_Addr_NT
'Access;
839 SSL
.Set_Sec_Stack_Addr
:= SSL
.Set_Sec_Stack_Addr_NT
'Access;
840 SSL
.Check_Abort_Status
:= SSL
.Check_Abort_Status_NT
'Access;
841 SSL
.Get_Stack_Info
:= SSL
.Get_Stack_Info_NT
'Access;
843 -- Don't bother trying to finalize Initialization.Global_Task_Lock
844 -- and System.Task_Primitives.RTS_Lock.
846 end Finalize_Global_Tasks
;
852 procedure Free_Task
(T
: Task_Id
) is
853 Self_Id
: constant Task_Id
:= Self
;
856 if T
.Common
.State
= Terminated
then
858 -- It is not safe to call Abort_Defer or Write_Lock at this stage
860 Initialization
.Task_Lock
(Self_Id
);
863 Initialization
.Remove_From_All_Tasks_List
(T
);
866 Initialization
.Task_Unlock
(Self_Id
);
868 System
.Task_Primitives
.Operations
.Finalize_TCB
(T
);
870 -- If the task is not terminated, then we simply ignore the call. This
871 -- happens when a user program attempts an unchecked deallocation on
872 -- a non-terminated task.
883 -- The task wrapper is a procedure that is called first for each task
884 -- task body, and which in turn calls the compiler-generated task body
885 -- procedure. The wrapper's main job is to do initialization for the task.
886 -- It also has some locally declared objects that server as per-task local
887 -- data. Task finalization is done by Complete_Task, which is called from
888 -- an at-end handler that the compiler generates.
890 procedure Task_Wrapper
(Self_ID
: Task_Id
) is
891 use type System
.Parameters
.Size_Type
;
892 use type SSE
.Storage_Offset
;
893 use System
.Standard_Library
;
894 use System
.Stack_Usage
;
896 Bottom_Of_Stack
: aliased Integer;
898 Secondary_Stack_Size
:
899 constant SSE
.Storage_Offset
:=
900 Self_ID
.Common
.Compiler_Data
.Pri_Stack_Info
.Size
*
901 SSE
.Storage_Offset
(Parameters
.Sec_Stack_Ratio
) / 100;
904 aliased SSE
.Storage_Array
905 (1 .. Secondary_Stack_Size
);
907 pragma Warnings
(Off
);
908 Secondary_Stack_Address
: System
.Address
:= Secondary_Stack
'Address;
910 Overflow_Guard
: constant := 16#
1_000#
;
913 Natural := Natural (Self_ID
.Common
.Compiler_Data
.Pri_Stack_Info
.Size
);
915 pragma Warnings
(On
);
916 -- Address of secondary stack. In the fixed secondary stack case, this
917 -- value is not modified, causing a warning, hence the bracketing with
918 -- Warnings (Off/On).
920 SEH_Table
: aliased SSE
.Storage_Array
(1 .. 8);
921 -- Structured Exception Registration table (2 words)
923 procedure Install_SEH_Handler
(Addr
: System
.Address
);
924 pragma Import
(C
, Install_SEH_Handler
, "__gnat_install_SEH_handler");
925 -- Install the SEH (Structured Exception Handling) handler
927 Cause
: Cause_Of_Termination
:= Normal
;
928 -- Indicates the reason why this task terminates. Normal corresponds to
929 -- a task terminating due to completing the last statement of its body,
930 -- or as a result of waiting on a terminate alternative. If the task
931 -- terminates because it is being aborted then Cause will be set to
932 -- Abnormal. If the task terminates because of an exception raised by
933 -- the execution of its task body, then Cause is set to
934 -- Unhandled_Exception.
936 EO
: Exception_Occurrence
;
937 -- If the task terminates because of an exception raised by the
938 -- execution of its task body, then EO will contain the associated
939 -- exception occurrence. Otherwise, it will contain Null_Occurrence.
941 procedure Search_Fall_Back_Handler
(ID
: Task_Id
);
942 -- Procedure that searches recursively a fall-back handler through the
943 -- master relationship.
945 procedure Search_Fall_Back_Handler
(ID
: Task_Id
) is
947 -- If there is a fall back handler, execute it
949 if ID
.Common
.Fall_Back_Handler
/= null then
950 ID
.Common
.Fall_Back_Handler
.all (Cause
, Self_ID
, EO
);
952 -- Otherwise look for a fall back handler in the parent
954 elsif ID
.Common
.Parent
/= null then
955 Search_Fall_Back_Handler
(ID
.Common
.Parent
);
957 -- Otherwise, do nothing
962 end Search_Fall_Back_Handler
;
965 pragma Assert
(Self_ID
.Deferral_Level
= 1);
967 if not Parameters
.Sec_Stack_Dynamic
then
968 Self_ID
.Common
.Compiler_Data
.Sec_Stack_Addr
:=
969 Secondary_Stack
'Address;
970 SST
.SS_Init
(Secondary_Stack_Address
, Integer (Secondary_Stack
'Last));
971 Size
:= Size
- Natural (Secondary_Stack_Size
);
974 Size
:= Size
- Overflow_Guard
;
976 if System
.Stack_Usage
.Is_Enabled
then
978 Initialize_Analyzer
(Self_ID
.Common
.Analyzer
,
979 Self_ID
.Common
.Task_Image
980 (1 .. Self_ID
.Common
.Task_Image_Len
),
982 SSE
.To_Integer
(Bottom_Of_Stack
'Address));
984 Fill_Stack
(Self_ID
.Common
.Analyzer
);
987 -- Set the guard page at the bottom of the stack. The call to unprotect
988 -- the page is done in Terminate_Task
990 Stack_Guard
(Self_ID
, True);
992 -- Initialize low-level TCB components, that cannot be initialized
993 -- by the creator. Enter_Task sets Self_ID.Known_Tasks_Index and
994 -- also Self_ID.LL.Thread
996 Enter_Task
(Self_ID
);
998 -- We setup the SEH (Structured Exception Handling) handler if supported
1001 Install_SEH_Handler
(SEH_Table
'Address);
1003 -- Initialize exception occurrence
1005 Save_Occurrence
(EO
, Ada
.Exceptions
.Null_Occurrence
);
1007 -- We lock RTS_Lock to wait for activator to finish activating the rest
1008 -- of the chain, so that everyone in the chain comes out in priority
1011 -- This also protects the value of
1012 -- Self_ID.Common.Activator.Common.Wait_Count.
1017 if not System
.Restrictions
.Abort_Allowed
then
1019 -- If Abort is not allowed, reset the deferral level since it will
1020 -- not get changed by the generated code. Keeping a default value
1021 -- of one would prevent some operations (e.g. select or delay) to
1022 -- proceed successfully.
1024 Self_ID
.Deferral_Level
:= 0;
1028 -- We are separating the following portion of the code in order to
1029 -- place the exception handlers in a different block. In this way,
1030 -- we do not call Set_Jmpbuf_Address (which needs Self) before we
1031 -- set Self in Enter_Task
1033 -- Call the task body procedure
1035 -- The task body is called with abort still deferred. That
1036 -- eliminates a dangerous window, for which we had to patch-up in
1039 -- During the expansion of the task body, we insert an RTS-call
1040 -- to Abort_Undefer, at the first point where abort should be
1043 Self_ID
.Common
.Task_Entry_Point
(Self_ID
.Common
.Task_Arg
);
1044 Initialization
.Defer_Abort_Nestable
(Self_ID
);
1047 -- We can't call Terminate_Task in the exception handlers below,
1048 -- since there may be (e.g. in the case of GCC exception handling)
1049 -- clean ups associated with the exception handler that need to
1050 -- access task specific data.
1052 -- Defer abort so that this task can't be aborted while exiting
1054 when Standard
'Abort_Signal =>
1055 Initialization
.Defer_Abort_Nestable
(Self_ID
);
1057 -- Update the cause that motivated the task termination so that
1058 -- the appropriate information is passed to the task termination
1059 -- procedure. Task termination as a result of waiting on a
1060 -- terminate alternative is a normal termination, although it is
1061 -- implemented using the abort mechanisms.
1063 if Self_ID
.Terminate_Alternative
then
1069 -- ??? Using an E : others here causes CD2C11A to fail on
1070 -- DEC Unix, see 7925-005.
1072 Initialization
.Defer_Abort_Nestable
(Self_ID
);
1074 -- Perform the task specific exception tracing duty. We handle
1075 -- these outputs here and not in the common notification routine
1076 -- because we need access to tasking related data and we don't
1077 -- want to drag dependencies against tasking related units in the
1078 -- the common notification units. Additionally, no trace is ever
1079 -- triggered from the common routine for the Unhandled_Raise case
1080 -- in tasks, since an exception never appears unhandled in this
1081 -- context because of this handler.
1083 if Exception_Trace
= Unhandled_Raise
then
1084 Trace_Unhandled_Exception_In_Task
(Self_ID
);
1087 -- Update the cause that motivated the task termination so that
1088 -- the appropriate information is passed to the task termination
1089 -- procedure, as well as the associated Exception_Occurrence.
1091 Cause
:= Unhandled_Exception
;
1092 Save_Occurrence
(EO
, SSL
.Get_Current_Excep
.all.all);
1095 -- Look for a task termination handler. This code is for all tasks but
1096 -- the environment task. The task termination code for the environment
1097 -- task is executed by SSL.Task_Termination_Handler.
1099 if Self_ID
.Common
.Specific_Handler
/= null then
1100 Self_ID
.Common
.Specific_Handler
.all (Cause
, Self_ID
, EO
);
1102 -- Look for a fall-back handler following the master relationship
1105 Search_Fall_Back_Handler
(Self_ID
);
1108 if System
.Stack_Usage
.Is_Enabled
then
1109 Compute_Result
(Self_ID
.Common
.Analyzer
);
1110 Report_Result
(Self_ID
.Common
.Analyzer
);
1113 Terminate_Task
(Self_ID
);
1116 --------------------
1117 -- Terminate_Task --
1118 --------------------
1120 -- Before we allow the thread to exit, we must clean up. This is a
1121 -- a delicate job. We must wake up the task's master, who may immediately
1122 -- try to deallocate the ATCB out from under the current task WHILE IT IS
1125 -- To avoid this, the parent task must be blocked up to the latest
1126 -- statement executed. The trouble is that we have another step that we
1127 -- also want to postpone to the very end, i.e., calling SSL.Destroy_TSD.
1128 -- We have to postpone that until the end because compiler-generated code
1129 -- is likely to try to access that data at just about any point.
1131 -- We can't call Destroy_TSD while we are holding any other locks, because
1132 -- it locks Global_Task_Lock, and our deadlock prevention rules require
1133 -- that to be the outermost lock. Our first "solution" was to just lock
1134 -- Global_Task_Lock in addition to the other locks, and force the parent to
1135 -- also lock this lock between its wakeup and its freeing of the ATCB. See
1136 -- Complete_Task for the parent-side of the code that has the matching
1137 -- calls to Task_Lock and Task_Unlock. That was not really a solution,
1138 -- since the operation Task_Unlock continued to access the ATCB after
1139 -- unlocking, after which the parent was observed to race ahead, deallocate
1140 -- the ATCB, and then reallocate it to another task. The call to
1141 -- Undefer_Abortion in Task_Unlock by the "terminated" task was overwriting
1142 -- the data of the new task that reused the ATCB! To solve this problem, we
1143 -- introduced the new operation Final_Task_Unlock.
1145 procedure Terminate_Task
(Self_ID
: Task_Id
) is
1146 Environment_Task
: constant Task_Id
:= STPO
.Environment_Task
;
1147 Master_of_Task
: Integer;
1150 Debug
.Task_Termination_Hook
;
1152 if Runtime_Traces
then
1153 Send_Trace_Info
(T_Terminate
);
1156 -- Since GCC cannot allocate stack chunks efficiently without reordering
1157 -- some of the allocations, we have to handle this unexpected situation
1158 -- here. We should normally never have to call Vulnerable_Complete_Task
1159 -- here. See 6602-003 for more details.
1161 if Self_ID
.Common
.Activator
/= null then
1162 Vulnerable_Complete_Task
(Self_ID
);
1165 Initialization
.Task_Lock
(Self_ID
);
1171 Master_of_Task
:= Self_ID
.Master_of_Task
;
1173 -- Check if the current task is an independent task If so, decrement
1174 -- the Independent_Task_Count value.
1176 if Master_of_Task
= 2 then
1178 Utilities
.Independent_Task_Count
:=
1179 Utilities
.Independent_Task_Count
- 1;
1181 Write_Lock
(Environment_Task
);
1182 Utilities
.Independent_Task_Count
:=
1183 Utilities
.Independent_Task_Count
- 1;
1184 Unlock
(Environment_Task
);
1188 -- Unprotect the guard page if needed
1190 Stack_Guard
(Self_ID
, False);
1192 Utilities
.Make_Passive
(Self_ID
, Task_Completed
=> True);
1198 pragma Assert
(Check_Exit
(Self_ID
));
1200 SSL
.Destroy_TSD
(Self_ID
.Common
.Compiler_Data
);
1201 Initialization
.Final_Task_Unlock
(Self_ID
);
1203 -- WARNING: past this point, this thread must assume that the ATCB
1204 -- has been deallocated. It should not be accessed again.
1206 if Master_of_Task
> 0 then
1215 function Terminated
(T
: Task_Id
) return Boolean is
1216 Self_ID
: constant Task_Id
:= STPO
.Self
;
1220 Initialization
.Defer_Abort_Nestable
(Self_ID
);
1227 Result
:= T
.Common
.State
= Terminated
;
1234 Initialization
.Undefer_Abort_Nestable
(Self_ID
);
1238 ----------------------------------------
1239 -- Trace_Unhandled_Exception_In_Task --
1240 ----------------------------------------
1242 procedure Trace_Unhandled_Exception_In_Task
(Self_Id
: Task_Id
) is
1243 procedure To_Stderr
(S
: String);
1244 pragma Import
(Ada
, To_Stderr
, "__gnat_to_stderr");
1246 use System
.Soft_Links
;
1247 use System
.Standard_Library
;
1249 function To_Address
is new
1250 Unchecked_Conversion
(Task_Id
, System
.Address
);
1252 function Tailored_Exception_Information
1253 (E
: Exception_Occurrence
) return String;
1255 (Ada
, Tailored_Exception_Information
,
1256 "__gnat_tailored_exception_information");
1258 Excep
: constant Exception_Occurrence_Access
:=
1259 SSL
.Get_Current_Excep
.all;
1262 -- This procedure is called by the task outermost handler in
1263 -- Task_Wrapper below, so only once the task stack has been fully
1264 -- unwound. The common notification routine has been called at the
1265 -- raise point already.
1267 To_Stderr
("task ");
1269 if Self_Id
.Common
.Task_Image_Len
/= 0 then
1271 (Self_Id
.Common
.Task_Image
(1 .. Self_Id
.Common
.Task_Image_Len
));
1275 To_Stderr
(System
.Address_Image
(To_Address
(Self_Id
)));
1276 To_Stderr
(" terminated by unhandled exception");
1277 To_Stderr
((1 => ASCII
.LF
));
1278 To_Stderr
(Tailored_Exception_Information
(Excep
.all));
1279 end Trace_Unhandled_Exception_In_Task
;
1281 ------------------------------------
1282 -- Vulnerable_Complete_Activation --
1283 ------------------------------------
1285 -- As in several other places, the locks of the activator and activated
1286 -- task are both locked here. This follows our deadlock prevention lock
1287 -- ordering policy, since the activated task must be created after the
1290 procedure Vulnerable_Complete_Activation
(Self_ID
: Task_Id
) is
1291 Activator
: constant Task_Id
:= Self_ID
.Common
.Activator
;
1294 pragma Debug
(Debug
.Trace
(Self_ID
, "V_Complete_Activation", 'C'));
1296 Write_Lock
(Activator
);
1297 Write_Lock
(Self_ID
);
1299 pragma Assert
(Self_ID
.Common
.Activator
/= null);
1301 -- Remove dangling reference to Activator, since a task may
1302 -- outlive its activator.
1304 Self_ID
.Common
.Activator
:= null;
1306 -- Wake up the activator, if it is waiting for a chain of tasks to
1307 -- activate, and we are the last in the chain to complete activation.
1309 if Activator
.Common
.State
= Activator_Sleep
then
1310 Activator
.Common
.Wait_Count
:= Activator
.Common
.Wait_Count
- 1;
1312 if Activator
.Common
.Wait_Count
= 0 then
1313 Wakeup
(Activator
, Activator_Sleep
);
1317 -- The activator raises a Tasking_Error if any task it is activating
1318 -- is completed before the activation is done. However, if the reason
1319 -- for the task completion is an abort, we do not raise an exception.
1322 if not Self_ID
.Callable
and then Self_ID
.Pending_ATC_Level
/= 0 then
1323 Activator
.Common
.Activation_Failed
:= True;
1329 -- After the activation, active priority should be the same
1330 -- as base priority. We must unlock the Activator first,
1331 -- though, since it should not wait if we have lower priority.
1333 if Get_Priority
(Self_ID
) /= Self_ID
.Common
.Base_Priority
then
1334 Write_Lock
(Self_ID
);
1335 Set_Priority
(Self_ID
, Self_ID
.Common
.Base_Priority
);
1338 end Vulnerable_Complete_Activation
;
1340 --------------------------------
1341 -- Vulnerable_Complete_Master --
1342 --------------------------------
1344 procedure Vulnerable_Complete_Master
(Self_ID
: Task_Id
) is
1347 CM
: constant Master_Level
:= Self_ID
.Master_Within
;
1348 T
: aliased Task_Id
;
1350 To_Be_Freed
: Task_Id
;
1351 -- This is a list of ATCBs to be freed, after we have released
1352 -- all RTS locks. This is necessary because of the locking order
1353 -- rules, since the storage manager uses Global_Task_Lock.
1355 pragma Warnings
(Off
);
1356 function Check_Unactivated_Tasks
return Boolean;
1357 pragma Warnings
(On
);
1358 -- Temporary error-checking code below. This is part of the checks
1359 -- added in the new run time. Call it only inside a pragma Assert.
1361 -----------------------------
1362 -- Check_Unactivated_Tasks --
1363 -----------------------------
1365 function Check_Unactivated_Tasks
return Boolean is
1367 if not Single_Lock
then
1371 Write_Lock
(Self_ID
);
1373 C
:= All_Tasks_List
;
1374 while C
/= null loop
1375 if C
.Common
.Activator
= Self_ID
then
1379 if C
.Common
.Parent
= Self_ID
and then C
.Master_of_Task
= CM
then
1382 if C
.Common
.State
= Unactivated
then
1389 C
:= C
.Common
.All_Tasks_Link
;
1394 if not Single_Lock
then
1399 end Check_Unactivated_Tasks
;
1401 -- Start of processing for Vulnerable_Complete_Master
1405 (Debug
.Trace
(Self_ID
, "V_Complete_Master", 'C'));
1407 pragma Assert
(Self_ID
.Common
.Wait_Count
= 0);
1408 pragma Assert
(Self_ID
.Deferral_Level
> 0);
1410 -- Count how many active dependent tasks this master currently
1411 -- has, and record this in Wait_Count.
1413 -- This count should start at zero, since it is initialized to
1414 -- zero for new tasks, and the task should not exit the
1415 -- sleep-loops that use this count until the count reaches zero.
1418 Write_Lock
(Self_ID
);
1420 C
:= All_Tasks_List
;
1421 while C
/= null loop
1422 if C
.Common
.Activator
= Self_ID
then
1423 pragma Assert
(C
.Common
.State
= Unactivated
);
1426 C
.Common
.Activator
:= null;
1427 C
.Common
.State
:= Terminated
;
1428 C
.Callable
:= False;
1429 Utilities
.Cancel_Queued_Entry_Calls
(C
);
1433 if C
.Common
.Parent
= Self_ID
and then C
.Master_of_Task
= CM
then
1436 if C
.Awake_Count
/= 0 then
1437 Self_ID
.Common
.Wait_Count
:= Self_ID
.Common
.Wait_Count
+ 1;
1443 C
:= C
.Common
.All_Tasks_Link
;
1446 Self_ID
.Common
.State
:= Master_Completion_Sleep
;
1449 if not Single_Lock
then
1453 -- Wait until dependent tasks are all terminated or ready to terminate.
1454 -- While waiting, the task may be awakened if the task's priority needs
1455 -- changing, or this master is aborted. In the latter case, we want
1456 -- to abort the dependents, and resume waiting until Wait_Count goes
1459 Write_Lock
(Self_ID
);
1462 Initialization
.Poll_Base_Priority_Change
(Self_ID
);
1463 exit when Self_ID
.Common
.Wait_Count
= 0;
1465 -- Here is a difference as compared to Complete_Master
1467 if Self_ID
.Pending_ATC_Level
< Self_ID
.ATC_Nesting_Level
1468 and then not Self_ID
.Dependents_Aborted
1471 Abort_Dependents
(Self_ID
);
1475 Abort_Dependents
(Self_ID
);
1477 Write_Lock
(Self_ID
);
1480 Sleep
(Self_ID
, Master_Completion_Sleep
);
1484 Self_ID
.Common
.State
:= Runnable
;
1487 -- Dependents are all terminated or on terminate alternatives.
1488 -- Now, force those on terminate alternatives to terminate, by
1491 pragma Assert
(Check_Unactivated_Tasks
);
1493 if Self_ID
.Alive_Count
> 1 then
1495 -- Consider finding a way to skip the following extra steps if there
1496 -- are no dependents with terminate alternatives. This could be done
1497 -- by adding another count to the ATCB, similar to Awake_Count, but
1498 -- keeping track of tasks that are on terminate alternatives.
1500 pragma Assert
(Self_ID
.Common
.Wait_Count
= 0);
1502 -- Force any remaining dependents to terminate by aborting them
1504 if not Single_Lock
then
1508 Abort_Dependents
(Self_ID
);
1510 -- Above, when we "abort" the dependents we are simply using this
1511 -- operation for convenience. We are not required to support the full
1512 -- abort-statement semantics; in particular, we are not required to
1513 -- immediately cancel any queued or in-service entry calls. That is
1514 -- good, because if we tried to cancel a call we would need to lock
1515 -- the caller, in order to wake the caller up. Our anti-deadlock
1516 -- rules prevent us from doing that without releasing the locks on C
1517 -- and Self_ID. Releasing and retaking those locks would be wasteful
1518 -- at best, and should not be considered further without more
1519 -- detailed analysis of potential concurrent accesses to the
1520 -- ATCBs of C and Self_ID.
1522 -- Count how many "alive" dependent tasks this master currently
1523 -- has, and record this in Wait_Count. This count should start at
1524 -- zero, since it is initialized to zero for new tasks, and the
1525 -- task should not exit the sleep-loops that use this count until
1526 -- the count reaches zero.
1528 pragma Assert
(Self_ID
.Common
.Wait_Count
= 0);
1530 Write_Lock
(Self_ID
);
1532 C
:= All_Tasks_List
;
1533 while C
/= null loop
1534 if C
.Common
.Parent
= Self_ID
and then C
.Master_of_Task
= CM
then
1537 pragma Assert
(C
.Awake_Count
= 0);
1539 if C
.Alive_Count
> 0 then
1540 pragma Assert
(C
.Terminate_Alternative
);
1541 Self_ID
.Common
.Wait_Count
:= Self_ID
.Common
.Wait_Count
+ 1;
1547 C
:= C
.Common
.All_Tasks_Link
;
1550 Self_ID
.Common
.State
:= Master_Phase_2_Sleep
;
1553 if not Single_Lock
then
1557 -- Wait for all counted tasks to finish terminating themselves
1559 Write_Lock
(Self_ID
);
1562 Initialization
.Poll_Base_Priority_Change
(Self_ID
);
1563 exit when Self_ID
.Common
.Wait_Count
= 0;
1564 Sleep
(Self_ID
, Master_Phase_2_Sleep
);
1567 Self_ID
.Common
.State
:= Runnable
;
1571 -- We don't wake up for abort here. We are already terminating just as
1572 -- fast as we can, so there is no point.
1574 -- Remove terminated tasks from the list of Self_ID's dependents, but
1575 -- don't free their ATCBs yet, because of lock order restrictions,
1576 -- which don't allow us to call "free" or "malloc" while holding any
1577 -- other locks. Instead, we put those ATCBs to be freed onto a
1578 -- temporary list, called To_Be_Freed.
1580 if not Single_Lock
then
1584 C
:= All_Tasks_List
;
1586 while C
/= null loop
1587 if C
.Common
.Parent
= Self_ID
and then C
.Master_of_Task
>= CM
then
1589 P
.Common
.All_Tasks_Link
:= C
.Common
.All_Tasks_Link
;
1591 All_Tasks_List
:= C
.Common
.All_Tasks_Link
;
1594 T
:= C
.Common
.All_Tasks_Link
;
1595 C
.Common
.All_Tasks_Link
:= To_Be_Freed
;
1601 C
:= C
.Common
.All_Tasks_Link
;
1607 -- Free all the ATCBs on the list To_Be_Freed
1609 -- The ATCBs in the list are no longer in All_Tasks_List, and after
1610 -- any interrupt entries are detached from them they should no longer
1613 -- Global_Task_Lock (Task_Lock/Unlock) is locked in the loop below to
1614 -- avoid a race between a terminating task and its parent. The parent
1615 -- might try to deallocate the ACTB out from underneath the exiting
1616 -- task. Note that Free will also lock Global_Task_Lock, but that is
1617 -- OK, since this is the *one* lock for which we have a mechanism to
1618 -- support nested locking. See Task_Wrapper and its finalizer for more
1622 -- The check "T.Common.Parent /= null ..." below is to prevent dangling
1623 -- references to terminated library-level tasks, which could
1624 -- otherwise occur during finalization of library-level objects.
1625 -- A better solution might be to hook task objects into the
1626 -- finalization chain and deallocate the ATCB when the task
1627 -- object is deallocated. However, this change is not likely
1628 -- to gain anything significant, since all this storage should
1629 -- be recovered en-masse when the process exits.
1631 while To_Be_Freed
/= null loop
1633 To_Be_Freed
:= T
.Common
.All_Tasks_Link
;
1635 -- ??? On SGI there is currently no Interrupt_Manager, that's
1636 -- why we need to check if the Interrupt_Manager_ID is null
1638 if T
.Interrupt_Entry
and Interrupt_Manager_ID
/= null then
1640 Detach_Interrupt_Entries_Index
: constant Task_Entry_Index
:= 1;
1641 -- Corresponds to the entry index of System.Interrupts.
1642 -- Interrupt_Manager.Detach_Interrupt_Entries.
1643 -- Be sure to update this value when changing
1644 -- Interrupt_Manager specs.
1646 type Param_Type
is access all Task_Id
;
1648 Param
: aliased Param_Type
:= T
'Access;
1651 System
.Tasking
.Rendezvous
.Call_Simple
1652 (Interrupt_Manager_ID
, Detach_Interrupt_Entries_Index
,
1657 if (T
.Common
.Parent
/= null
1658 and then T
.Common
.Parent
.Common
.Parent
/= null)
1659 or else T
.Master_of_Task
> 3
1661 Initialization
.Task_Lock
(Self_ID
);
1663 -- If Sec_Stack_Addr is not null, it means that Destroy_TSD
1664 -- has not been called yet (case of an unactivated task).
1666 if T
.Common
.Compiler_Data
.Sec_Stack_Addr
/= Null_Address
then
1667 SSL
.Destroy_TSD
(T
.Common
.Compiler_Data
);
1670 Vulnerable_Free_Task
(T
);
1671 Initialization
.Task_Unlock
(Self_ID
);
1675 -- It might seem nice to let the terminated task deallocate its own
1676 -- ATCB. That would not cover the case of unactivated tasks. It also
1677 -- would force us to keep the underlying thread around past termination,
1678 -- since references to the ATCB are possible past termination.
1679 -- Currently, we get rid of the thread as soon as the task terminates,
1680 -- and let the parent recover the ATCB later.
1682 -- Some day, if we want to recover the ATCB earlier, at task
1683 -- termination, we could consider using "fat task IDs", that include the
1684 -- serial number with the ATCB pointer, to catch references to tasks
1685 -- that no longer have ATCBs. It is not clear how much this would gain,
1686 -- since the user-level task object would still be occupying storage.
1688 -- Make next master level up active.
1689 -- We don't need to lock the ATCB, since the value is only updated by
1690 -- each task for itself.
1692 Self_ID
.Master_Within
:= CM
- 1;
1693 end Vulnerable_Complete_Master
;
1695 ------------------------------
1696 -- Vulnerable_Complete_Task --
1697 ------------------------------
1699 -- Complete the calling task
1701 -- This procedure must be called with abort deferred. (That's why the
1702 -- name has "Vulnerable" in it.) It should only be called by Complete_Task
1703 -- and Finalize_Global_Tasks (for the environment task).
1705 -- The effect is similar to that of Complete_Master. Differences include
1706 -- the closing of entries here, and computation of the number of active
1707 -- dependent tasks in Complete_Master.
1709 -- We don't lock Self_ID before the call to Vulnerable_Complete_Activation,
1710 -- because that does its own locking, and because we do not need the lock
1711 -- to test Self_ID.Common.Activator. That value should only be read and
1712 -- modified by Self.
1714 procedure Vulnerable_Complete_Task
(Self_ID
: Task_Id
) is
1716 pragma Assert
(Self_ID
.Deferral_Level
> 0);
1717 pragma Assert
(Self_ID
= Self
);
1718 pragma Assert
(Self_ID
.Master_Within
= Self_ID
.Master_of_Task
+ 1
1720 Self_ID
.Master_Within
= Self_ID
.Master_of_Task
+ 2);
1721 pragma Assert
(Self_ID
.Common
.Wait_Count
= 0);
1722 pragma Assert
(Self_ID
.Open_Accepts
= null);
1723 pragma Assert
(Self_ID
.ATC_Nesting_Level
= 1);
1725 pragma Debug
(Debug
.Trace
(Self_ID
, "V_Complete_Task", 'C'));
1731 Write_Lock
(Self_ID
);
1732 Self_ID
.Callable
:= False;
1734 -- In theory, Self should have no pending entry calls left on its
1735 -- call-stack. Each async. select statement should clean its own call,
1736 -- and blocking entry calls should defer abort until the calls are
1737 -- cancelled, then clean up.
1739 Utilities
.Cancel_Queued_Entry_Calls
(Self_ID
);
1742 if Self_ID
.Common
.Activator
/= null then
1743 Vulnerable_Complete_Activation
(Self_ID
);
1750 -- If Self_ID.Master_Within = Self_ID.Master_of_Task + 2
1751 -- we may have dependent tasks for which we need to wait.
1752 -- Otherwise, we can just exit.
1754 if Self_ID
.Master_Within
= Self_ID
.Master_of_Task
+ 2 then
1755 Vulnerable_Complete_Master
(Self_ID
);
1757 end Vulnerable_Complete_Task
;
1759 --------------------------
1760 -- Vulnerable_Free_Task --
1761 --------------------------
1763 -- Recover all runtime system storage associated with the task T.
1764 -- This should only be called after T has terminated and will no
1765 -- longer be referenced.
1767 -- For tasks created by an allocator that fails, due to an exception,
1768 -- it is called from Expunge_Unactivated_Tasks.
1770 -- For tasks created by elaboration of task object declarations it
1771 -- is called from the finalization code of the Task_Wrapper procedure.
1772 -- It is also called from Unchecked_Deallocation, for objects that
1773 -- are or contain tasks.
1775 procedure Vulnerable_Free_Task
(T
: Task_Id
) is
1777 pragma Debug
(Debug
.Trace
(Self
, "Vulnerable_Free_Task", 'C', T
));
1784 Initialization
.Finalize_Attributes_Link
.all (T
);
1791 System
.Task_Primitives
.Operations
.Finalize_TCB
(T
);
1792 end Vulnerable_Free_Task
;
1794 -- Package elaboration code
1797 -- Establish the Adafinal softlink
1799 -- This is not done inside the central RTS initialization routine
1800 -- to avoid with-ing this package from System.Tasking.Initialization.
1802 SSL
.Adafinal
:= Finalize_Global_Tasks
'Access;
1804 -- Establish soft links for subprograms that manipulate master_id's.
1805 -- This cannot be done when the RTS is initialized, because of various
1806 -- elaboration constraints.
1808 SSL
.Current_Master
:= Stages
.Current_Master
'Access;
1809 SSL
.Enter_Master
:= Stages
.Enter_Master
'Access;
1810 SSL
.Complete_Master
:= Stages
.Complete_Master
'Access;
1811 end System
.Tasking
.Stages
;