1 ------------------------------------------------------------------------------
3 -- GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS --
5 -- S Y S T E M . T A S K I N G . P R O T E C T E D _ O B J E C T S . --
6 -- O P E R A T I O N S --
10 -- Copyright (C) 1998-2007, Free Software Foundation, Inc. --
12 -- GNARL is free software; you can redistribute it and/or modify it under --
13 -- terms of the GNU General Public License as published by the Free Soft- --
14 -- ware Foundation; either version 2, or (at your option) any later ver- --
15 -- sion. GNARL is distributed in the hope that it will be useful, but WITH- --
16 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
17 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
18 -- for more details. You should have received a copy of the GNU General --
19 -- Public License distributed with GNARL; see file COPYING. If not, write --
20 -- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, --
21 -- Boston, MA 02110-1301, USA. --
23 -- As a special exception, if other files instantiate generics from this --
24 -- unit, or you link this unit with other files to produce an executable, --
25 -- this unit does not by itself cause the resulting executable to be --
26 -- covered by the GNU General Public License. This exception does not --
27 -- however invalidate any other reasons why the executable file might be --
28 -- covered by the GNU Public License. --
30 -- GNARL was developed by the GNARL team at Florida State University. --
31 -- Extensive contributions were provided by Ada Core Technologies, Inc. --
33 ------------------------------------------------------------------------------
35 -- This package contains all the extended primitives related to
36 -- Protected_Objects with entries.
38 -- The handling of protected objects with no entries is done in
39 -- System.Tasking.Protected_Objects, the simple routines for protected
40 -- objects with entries in System.Tasking.Protected_Objects.Entries.
42 -- The split between Entries and Operations is needed to break circular
43 -- dependencies inside the run time.
45 -- This package contains all primitives related to Protected_Objects.
46 -- Note: the compiler generates direct calls to this interface, via Rtsfind.
48 with System.Task_Primitives.Operations;
49 -- used for Initialize_Lock
55 with System.Tasking.Entry_Calls;
56 -- used for Wait_For_Completion
57 -- Wait_Until_Abortable
58 -- Wait_For_Completion_With_Timeout
60 with System.Tasking.Initialization;
61 -- Used for Defer_Abort,
63 -- Change_Base_Priority
65 pragma Elaborate_All (System.Tasking.Initialization);
66 -- This insures that tasking is initialized if any protected objects are
69 with System.Tasking.Queuing;
71 -- Broadcast_Program_Error
72 -- Select_Protected_Entry_Call
76 with System.Tasking.Rendezvous;
77 -- used for Task_Do_Or_Queue
79 with System.Tasking.Utilities;
80 -- used for Exit_One_ATC_Level
82 with System.Tasking.Debug;
85 with System.Parameters;
86 -- used for Single_Lock
89 with System.Traces.Tasking;
90 -- used for Send_Trace_Info
92 with System.Restrictions;
93 -- used for Run_Time_Restrictions
95 package body System.Tasking.Protected_Objects.Operations is
97 package STPO renames System.Task_Primitives.Operations;
104 use System.Restrictions;
105 use System.Restrictions.Rident;
107 use System.Traces.Tasking;
109 -----------------------
110 -- Local Subprograms --
111 -----------------------
113 procedure Update_For_Queue_To_PO
114 (Entry_Call : Entry_Call_Link;
115 With_Abort : Boolean);
116 pragma Inline (Update_For_Queue_To_PO);
117 -- Update the state of an existing entry call to reflect
118 -- the fact that it is being enqueued, based on
119 -- whether the current queuing action is with or without abort.
120 -- Call this only while holding the PO's lock.
121 -- It returns with the PO's lock still held.
123 procedure Requeue_Call
125 Object : Protection_Entries_Access;
126 Entry_Call : Entry_Call_Link);
127 -- Handle requeue of Entry_Call.
128 -- In particular, queue the call if needed, or service it immediately
131 ---------------------------------
132 -- Cancel_Protected_Entry_Call --
133 ---------------------------------
135 -- Compiler interface only. Do not call from within the RTS.
136 -- This should have analogous effect to Cancel_Task_Entry_Call,
137 -- setting the value of Block.Cancelled instead of returning
138 -- the parameter value Cancelled.
140 -- The effect should be idempotent, since the call may already
141 -- have been dequeued.
154 -- X : protected_entry_index := 1;
155 -- B80b : communication_block;
156 -- communication_blockIP (B80b);
161 -- procedure _clean is
163 -- if enqueued (B80b) then
164 -- cancel_protected_entry_call (B80b);
169 -- protected_entry_call (rTV!(r)._object'unchecked_access, X,
170 -- null_address, asynchronous_call, B80b, objectF => 0);
171 -- if enqueued (B80b) then
178 -- when _abort_signal =>
179 -- abort_undefer.all;
182 -- if not cancelled (B80b) then
187 -- If the entry call completes after we get into the abortable part,
188 -- Abort_Signal should be raised and ATC will take us to the at-end
189 -- handler, which will call _clean.
191 -- If the entry call returns with the call already completed,
192 -- we can skip this, and use the "if enqueued()" to go past
193 -- the at-end handler, but we will still call _clean.
195 -- If the abortable part completes before the entry call is Done,
196 -- it will call _clean.
198 -- If the entry call or the abortable part raises an exception,
199 -- we will still call _clean, but the value of Cancelled should not matter.
201 -- Whoever calls _clean first gets to decide whether the call
202 -- has been "cancelled".
204 -- Enqueued should be true if there is any chance that the call
205 -- is still on a queue. It seems to be safe to make it True if
206 -- the call was Onqueue at some point before return from
207 -- Protected_Entry_Call.
209 -- Cancelled should be true iff the abortable part completed
210 -- and succeeded in cancelling the entry call before it completed.
213 -- The need for Enqueued is less obvious.
214 -- The "if enqueued ()" tests are not necessary, since both
215 -- Cancel_Protected_Entry_Call and Protected_Entry_Call must
216 -- do the same test internally, with locking. The one that
217 -- makes cancellation conditional may be a useful heuristic
218 -- since at least 1/2 the time the call should be off-queue
219 -- by that point. The other one seems totally useless, since
220 -- Protected_Entry_Call must do the same check and then
221 -- possibly wait for the call to be abortable, internally.
223 -- We can check Call.State here without locking the caller's mutex,
224 -- since the call must be over after returning from Wait_For_Completion.
225 -- No other task can access the call record at this point.
227 procedure Cancel_Protected_Entry_Call
228 (Block : in out Communication_Block) is
230 Entry_Calls.Try_To_Cancel_Entry_Call (Block.Cancelled);
231 end Cancel_Protected_Entry_Call;
237 function Cancelled (Block : Communication_Block) return Boolean is
239 return Block.Cancelled;
242 -------------------------
243 -- Complete_Entry_Body --
244 -------------------------
246 procedure Complete_Entry_Body (Object : Protection_Entries_Access) is
248 Exceptional_Complete_Entry_Body (Object, Ada.Exceptions.Null_Id);
249 end Complete_Entry_Body;
255 function Enqueued (Block : Communication_Block) return Boolean is
257 return Block.Enqueued;
260 -------------------------------------
261 -- Exceptional_Complete_Entry_Body --
262 -------------------------------------
264 procedure Exceptional_Complete_Entry_Body
265 (Object : Protection_Entries_Access;
266 Ex : Ada.Exceptions.Exception_Id)
268 procedure Transfer_Occurrence
269 (Target : Ada.Exceptions.Exception_Occurrence_Access;
270 Source : Ada.Exceptions.Exception_Occurrence);
271 pragma Import (C, Transfer_Occurrence, "__gnat_transfer_occurrence");
273 Entry_Call : constant Entry_Call_Link := Object.Call_In_Progress;
278 (Debug.Trace (STPO.Self, "Exceptional_Complete_Entry_Body", 'P'));
280 -- We must have abort deferred, since we are inside
281 -- a protected operation.
283 if Entry_Call /= null then
284 -- The call was not requeued.
286 Entry_Call.Exception_To_Raise := Ex;
288 if Ex /= Ada.Exceptions.Null_Id then
289 -- An exception was raised and abort was deferred, so adjust
290 -- before propagating, otherwise the task will stay with deferral
291 -- enabled for its remaining life.
293 Self_Id := STPO.Self;
294 Initialization.Undefer_Abort_Nestable (Self_Id);
296 (Entry_Call.Self.Common.Compiler_Data.Current_Excep'Access,
297 Self_Id.Common.Compiler_Data.Current_Excep);
300 -- Wakeup_Entry_Caller will be called from PO_Do_Or_Queue or
301 -- PO_Service_Entries on return.
304 if Runtime_Traces then
305 Send_Trace_Info (PO_Done, Entry_Call.Self);
307 end Exceptional_Complete_Entry_Body;
313 procedure PO_Do_Or_Queue
315 Object : Protection_Entries_Access;
316 Entry_Call : Entry_Call_Link)
318 E : constant Protected_Entry_Index :=
319 Protected_Entry_Index (Entry_Call.E);
320 Barrier_Value : Boolean;
323 -- When the Action procedure for an entry body returns, it is either
324 -- completed (having called [Exceptional_]Complete_Entry_Body) or it
325 -- is queued, having executed a requeue statement.
328 Object.Entry_Bodies (
329 Object.Find_Body_Index (Object.Compiler_Info, E)).
330 Barrier (Object.Compiler_Info, E);
332 if Barrier_Value then
334 -- Not abortable while service is in progress.
336 if Entry_Call.State = Now_Abortable then
337 Entry_Call.State := Was_Abortable;
340 Object.Call_In_Progress := Entry_Call;
343 (Debug.Trace (Self_ID, "PODOQ: start entry body", 'P'));
344 Object.Entry_Bodies (
345 Object.Find_Body_Index (Object.Compiler_Info, E)).Action (
346 Object.Compiler_Info, Entry_Call.Uninterpreted_Data, E);
348 if Object.Call_In_Progress /= null then
350 -- Body of current entry served call to completion
352 Object.Call_In_Progress := null;
358 STPO.Write_Lock (Entry_Call.Self);
359 Initialization.Wakeup_Entry_Caller (Self_ID, Entry_Call, Done);
360 STPO.Unlock (Entry_Call.Self);
367 Requeue_Call (Self_ID, Object, Entry_Call);
370 elsif Entry_Call.Mode /= Conditional_Call
371 or else not Entry_Call.With_Abort
374 if Run_Time_Restrictions.Set (Max_Entry_Queue_Length)
376 Run_Time_Restrictions.Value (Max_Entry_Queue_Length) <=
377 Queuing.Count_Waiting (Object.Entry_Queues (E))
379 -- This violates the Max_Entry_Queue_Length restriction,
380 -- raise Program_Error.
382 Entry_Call.Exception_To_Raise := Program_Error'Identity;
388 STPO.Write_Lock (Entry_Call.Self);
389 Initialization.Wakeup_Entry_Caller (Self_ID, Entry_Call, Done);
390 STPO.Unlock (Entry_Call.Self);
396 Queuing.Enqueue (Object.Entry_Queues (E), Entry_Call);
397 Update_For_Queue_To_PO (Entry_Call, Entry_Call.With_Abort);
400 -- Conditional_Call and With_Abort
406 STPO.Write_Lock (Entry_Call.Self);
407 pragma Assert (Entry_Call.State >= Was_Abortable);
408 Initialization.Wakeup_Entry_Caller (Self_ID, Entry_Call, Cancelled);
409 STPO.Unlock (Entry_Call.Self);
418 Queuing.Broadcast_Program_Error (Self_ID, Object, Entry_Call);
421 ------------------------
422 -- PO_Service_Entries --
423 ------------------------
425 procedure PO_Service_Entries
427 Object : Entries.Protection_Entries_Access;
428 Unlock_Object : Boolean := True)
430 E : Protected_Entry_Index;
432 Entry_Call : Entry_Call_Link;
436 Queuing.Select_Protected_Entry_Call (Self_ID, Object, Entry_Call);
438 exit when Entry_Call = null;
440 E := Protected_Entry_Index (Entry_Call.E);
442 -- Not abortable while service is in progress.
444 if Entry_Call.State = Now_Abortable then
445 Entry_Call.State := Was_Abortable;
448 Object.Call_In_Progress := Entry_Call;
451 if Runtime_Traces then
452 Send_Trace_Info (PO_Run, Self_ID,
453 Entry_Call.Self, Entry_Index (E));
457 (Debug.Trace (Self_ID, "POSE: start entry body", 'P'));
458 Object.Entry_Bodies (
459 Object.Find_Body_Index (Object.Compiler_Info, E)).Action (
460 Object.Compiler_Info, Entry_Call.Uninterpreted_Data, E);
463 Queuing.Broadcast_Program_Error
464 (Self_ID, Object, Entry_Call);
467 if Object.Call_In_Progress = null then
468 Requeue_Call (Self_ID, Object, Entry_Call);
469 exit when Entry_Call.State = Cancelled;
472 Object.Call_In_Progress := null;
473 Caller := Entry_Call.Self;
479 STPO.Write_Lock (Caller);
480 Initialization.Wakeup_Entry_Caller (Self_ID, Entry_Call, Done);
481 STPO.Unlock (Caller);
489 if Unlock_Object then
490 Unlock_Entries (Object);
492 end PO_Service_Entries;
494 ---------------------
495 -- Protected_Count --
496 ---------------------
498 function Protected_Count
499 (Object : Protection_Entries'Class;
500 E : Protected_Entry_Index)
504 return Queuing.Count_Waiting (Object.Entry_Queues (E));
507 --------------------------
508 -- Protected_Entry_Call --
509 --------------------------
511 -- Compiler interface only. Do not call from within the RTS.
520 -- X : protected_entry_index := 1;
521 -- B85b : communication_block;
522 -- communication_blockIP (B85b);
524 -- protected_entry_call (rTV!(r)._object'unchecked_access, X,
525 -- null_address, conditional_call, B85b, objectF => 0);
526 -- if cancelled (B85b) then
533 -- See also Cancel_Protected_Entry_Call for code expansion of asynchronous
536 -- The initial part of this procedure does not need to lock the the calling
537 -- task's ATCB, up to the point where the call record first may be queued
538 -- (PO_Do_Or_Queue), since before that no other task will have access to
541 -- If this is a call made inside of an abort deferred region, the call
542 -- should be never abortable.
544 -- If the call was not queued abortably, we need to wait until it is before
545 -- proceeding with the abortable part.
547 -- There are some heuristics here, just to save time for frequently
548 -- occurring cases. For example, we check Initially_Abortable to try to
549 -- avoid calling the procedure Wait_Until_Abortable, since the normal case
550 -- for async. entry calls is to be queued abortably.
552 -- Another heuristic uses the Block.Enqueued to try to avoid calling
553 -- Cancel_Protected_Entry_Call if the call can be served immediately.
555 procedure Protected_Entry_Call
556 (Object : Protection_Entries_Access;
557 E : Protected_Entry_Index;
558 Uninterpreted_Data : System.Address;
560 Block : out Communication_Block)
562 Self_ID : constant Task_Id := STPO.Self;
563 Entry_Call : Entry_Call_Link;
564 Initially_Abortable : Boolean;
565 Ceiling_Violation : Boolean;
569 (Debug.Trace (Self_ID, "Protected_Entry_Call", 'P'));
571 if Runtime_Traces then
572 Send_Trace_Info (PO_Call, Entry_Index (E));
575 if Self_ID.ATC_Nesting_Level = ATC_Level'Last then
577 (Storage_Error'Identity, "not enough ATC nesting levels");
580 -- If pragma Detect_Blocking is active then Program_Error must be
581 -- raised if this potentially blocking operation is called from a
585 and then Self_ID.Common.Protected_Action_Nesting > 0
587 Ada.Exceptions.Raise_Exception
588 (Program_Error'Identity, "potentially blocking operation");
591 -- Self_ID.Deferral_Level should be 0, except when called from Finalize,
592 -- where abort is already deferred.
594 Initialization.Defer_Abort_Nestable (Self_ID);
595 Lock_Entries (Object, Ceiling_Violation);
597 if Ceiling_Violation then
599 -- Failed ceiling check
601 Initialization.Undefer_Abort_Nestable (Self_ID);
605 Block.Self := Self_ID;
606 Self_ID.ATC_Nesting_Level := Self_ID.ATC_Nesting_Level + 1;
608 (Debug.Trace (Self_ID, "PEC: entered ATC level: " &
609 ATC_Level'Image (Self_ID.ATC_Nesting_Level), 'A'));
611 Self_ID.Entry_Calls (Self_ID.ATC_Nesting_Level)'Access;
612 Entry_Call.Next := null;
613 Entry_Call.Mode := Mode;
614 Entry_Call.Cancellation_Attempted := False;
616 if Self_ID.Deferral_Level > 1 then
617 Entry_Call.State := Never_Abortable;
619 Entry_Call.State := Now_Abortable;
622 Entry_Call.E := Entry_Index (E);
623 Entry_Call.Prio := STPO.Get_Priority (Self_ID);
624 Entry_Call.Uninterpreted_Data := Uninterpreted_Data;
625 Entry_Call.Called_PO := To_Address (Object);
626 Entry_Call.Called_Task := null;
627 Entry_Call.Exception_To_Raise := Ada.Exceptions.Null_Id;
628 Entry_Call.With_Abort := True;
630 PO_Do_Or_Queue (Self_ID, Object, Entry_Call);
631 Initially_Abortable := Entry_Call.State = Now_Abortable;
632 PO_Service_Entries (Self_ID, Object);
634 -- Try to prevent waiting later (in Try_To_Cancel_Protected_Entry_Call)
635 -- for completed or cancelled calls. (This is a heuristic, only.)
637 if Entry_Call.State >= Done then
639 -- Once State >= Done it will not change any more.
645 STPO.Write_Lock (Self_ID);
646 Utilities.Exit_One_ATC_Level (Self_ID);
647 STPO.Unlock (Self_ID);
653 Block.Enqueued := False;
654 Block.Cancelled := Entry_Call.State = Cancelled;
655 Initialization.Undefer_Abort_Nestable (Self_ID);
656 Entry_Calls.Check_Exception (Self_ID, Entry_Call);
660 -- In this case we cannot conclude anything,
661 -- since State can change concurrently.
665 -- Now for the general case.
667 if Mode = Asynchronous_Call then
669 -- Try to avoid an expensive call.
671 if not Initially_Abortable then
674 Entry_Calls.Wait_Until_Abortable (Self_ID, Entry_Call);
677 Entry_Calls.Wait_Until_Abortable (Self_ID, Entry_Call);
681 elsif Mode < Asynchronous_Call then
683 -- Simple_Call or Conditional_Call
687 Entry_Calls.Wait_For_Completion (Entry_Call);
690 STPO.Write_Lock (Self_ID);
691 Entry_Calls.Wait_For_Completion (Entry_Call);
692 STPO.Unlock (Self_ID);
695 Block.Cancelled := Entry_Call.State = Cancelled;
698 pragma Assert (False);
702 Initialization.Undefer_Abort_Nestable (Self_ID);
703 Entry_Calls.Check_Exception (Self_ID, Entry_Call);
704 end Protected_Entry_Call;
710 procedure Requeue_Call
712 Object : Protection_Entries_Access;
713 Entry_Call : Entry_Call_Link)
715 New_Object : Protection_Entries_Access;
716 Ceiling_Violation : Boolean;
718 E : Protected_Entry_Index;
721 New_Object := To_Protection (Entry_Call.Called_PO);
723 if New_Object = null then
725 -- Call is to be requeued to a task entry
731 Result := Rendezvous.Task_Do_Or_Queue (Self_Id, Entry_Call);
734 Queuing.Broadcast_Program_Error
735 (Self_Id, Object, Entry_Call, RTS_Locked => True);
743 -- Call should be requeued to a PO
745 if Object /= New_Object then
747 -- Requeue is to different PO
749 Lock_Entries (New_Object, Ceiling_Violation);
751 if Ceiling_Violation then
752 Object.Call_In_Progress := null;
753 Queuing.Broadcast_Program_Error
754 (Self_Id, Object, Entry_Call);
757 PO_Do_Or_Queue (Self_Id, New_Object, Entry_Call);
758 PO_Service_Entries (Self_Id, New_Object);
762 -- Requeue is to same protected object
764 -- ??? Try to compensate apparent failure of the
765 -- scheduler on some OS (e.g VxWorks) to give higher
766 -- priority tasks a chance to run (see CXD6002).
770 if Entry_Call.With_Abort
771 and then Entry_Call.Cancellation_Attempted
773 -- If this is a requeue with abort and someone tried
774 -- to cancel this call, cancel it at this point.
776 Entry_Call.State := Cancelled;
780 if not Entry_Call.With_Abort
781 or else Entry_Call.Mode /= Conditional_Call
783 E := Protected_Entry_Index (Entry_Call.E);
785 if Run_Time_Restrictions.Set (Max_Entry_Queue_Length)
787 Run_Time_Restrictions.Value (Max_Entry_Queue_Length) <=
788 Queuing.Count_Waiting (Object.Entry_Queues (E))
790 -- This violates the Max_Entry_Queue_Length restriction,
791 -- raise Program_Error.
793 Entry_Call.Exception_To_Raise := Program_Error'Identity;
799 STPO.Write_Lock (Entry_Call.Self);
800 Initialization.Wakeup_Entry_Caller
801 (Self_Id, Entry_Call, Done);
802 STPO.Unlock (Entry_Call.Self);
809 (New_Object.Entry_Queues (E), Entry_Call);
810 Update_For_Queue_To_PO (Entry_Call, Entry_Call.With_Abort);
814 PO_Do_Or_Queue (Self_Id, New_Object, Entry_Call);
820 ----------------------------
821 -- Protected_Entry_Caller --
822 ----------------------------
824 function Protected_Entry_Caller
825 (Object : Protection_Entries'Class) return Task_Id is
827 return Object.Call_In_Progress.Self;
828 end Protected_Entry_Caller;
830 -----------------------------
831 -- Requeue_Protected_Entry --
832 -----------------------------
834 -- Compiler interface only. Do not call from within the RTS.
843 -- procedure rPT__E10b (O : address; P : address; E :
844 -- protected_entry_index) is
845 -- type rTVP is access rTV;
847 -- _object : rTVP := rTVP!(O);
850 -- rR : protection renames _object._object;
851 -- vP : integer renames _object.v;
852 -- bP : boolean renames _object.b;
856 -- requeue_protected_entry (rR'unchecked_access, rR'
857 -- unchecked_access, 2, false, objectF => 0, new_objectF =>
861 -- complete_entry_body (_object._object'unchecked_access, objectF =>
866 -- abort_undefer.all;
867 -- exceptional_complete_entry_body (_object._object'
868 -- unchecked_access, current_exception, objectF => 0);
872 procedure Requeue_Protected_Entry
873 (Object : Protection_Entries_Access;
874 New_Object : Protection_Entries_Access;
875 E : Protected_Entry_Index;
876 With_Abort : Boolean)
878 Entry_Call : constant Entry_Call_Link := Object.Call_In_Progress;
882 (Debug.Trace (STPO.Self, "Requeue_Protected_Entry", 'P'));
883 pragma Assert (STPO.Self.Deferral_Level > 0);
885 Entry_Call.E := Entry_Index (E);
886 Entry_Call.Called_PO := To_Address (New_Object);
887 Entry_Call.Called_Task := null;
888 Entry_Call.With_Abort := With_Abort;
889 Object.Call_In_Progress := null;
890 end Requeue_Protected_Entry;
892 -------------------------------------
893 -- Requeue_Task_To_Protected_Entry --
894 -------------------------------------
896 -- Compiler interface only.
906 -- accept_call (1, A79b);
908 -- requeue_task_to_protected_entry (rTV!(r)._object'
909 -- unchecked_access, 2, false, new_objectF => 0);
912 -- complete_rendezvous;
914 -- when all others =>
915 -- exceptional_complete_rendezvous (get_gnat_exception);
918 procedure Requeue_Task_To_Protected_Entry
919 (New_Object : Protection_Entries_Access;
920 E : Protected_Entry_Index;
921 With_Abort : Boolean)
923 Self_ID : constant Task_Id := STPO.Self;
924 Entry_Call : constant Entry_Call_Link := Self_ID.Common.Call;
927 Initialization.Defer_Abort (Self_ID);
929 -- We do not need to lock Self_ID here since the call is not abortable
930 -- at this point, and therefore, the caller cannot cancel the call.
932 Entry_Call.Needs_Requeue := True;
933 Entry_Call.With_Abort := With_Abort;
934 Entry_Call.Called_PO := To_Address (New_Object);
935 Entry_Call.Called_Task := null;
936 Entry_Call.E := Entry_Index (E);
937 Initialization.Undefer_Abort (Self_ID);
938 end Requeue_Task_To_Protected_Entry;
940 ---------------------
941 -- Service_Entries --
942 ---------------------
944 procedure Service_Entries (Object : Protection_Entries_Access) is
945 Self_ID : constant Task_Id := STPO.Self;
947 PO_Service_Entries (Self_ID, Object);
950 --------------------------------
951 -- Timed_Protected_Entry_Call --
952 --------------------------------
954 -- Compiler interface only. Do not call from within the RTS.
956 procedure Timed_Protected_Entry_Call
957 (Object : Protection_Entries_Access;
958 E : Protected_Entry_Index;
959 Uninterpreted_Data : System.Address;
962 Entry_Call_Successful : out Boolean)
964 Self_Id : constant Task_Id := STPO.Self;
965 Entry_Call : Entry_Call_Link;
966 Ceiling_Violation : Boolean;
970 if Self_Id.ATC_Nesting_Level = ATC_Level'Last then
971 Raise_Exception (Storage_Error'Identity,
972 "not enough ATC nesting levels");
975 -- If pragma Detect_Blocking is active then Program_Error must be
976 -- raised if this potentially blocking operation is called from a
980 and then Self_Id.Common.Protected_Action_Nesting > 0
982 Ada.Exceptions.Raise_Exception
983 (Program_Error'Identity, "potentially blocking operation");
986 if Runtime_Traces then
987 Send_Trace_Info (POT_Call, Entry_Index (E), Timeout);
990 Initialization.Defer_Abort (Self_Id);
991 Lock_Entries (Object, Ceiling_Violation);
993 if Ceiling_Violation then
994 Initialization.Undefer_Abort (Self_Id);
998 Self_Id.ATC_Nesting_Level := Self_Id.ATC_Nesting_Level + 1;
1000 (Debug.Trace (Self_Id, "TPEC: exited to ATC level: " &
1001 ATC_Level'Image (Self_Id.ATC_Nesting_Level), 'A'));
1003 Self_Id.Entry_Calls (Self_Id.ATC_Nesting_Level)'Access;
1004 Entry_Call.Next := null;
1005 Entry_Call.Mode := Timed_Call;
1006 Entry_Call.Cancellation_Attempted := False;
1008 if Self_Id.Deferral_Level > 1 then
1009 Entry_Call.State := Never_Abortable;
1011 Entry_Call.State := Now_Abortable;
1014 Entry_Call.E := Entry_Index (E);
1015 Entry_Call.Prio := STPO.Get_Priority (Self_Id);
1016 Entry_Call.Uninterpreted_Data := Uninterpreted_Data;
1017 Entry_Call.Called_PO := To_Address (Object);
1018 Entry_Call.Called_Task := null;
1019 Entry_Call.Exception_To_Raise := Ada.Exceptions.Null_Id;
1020 Entry_Call.With_Abort := True;
1022 PO_Do_Or_Queue (Self_Id, Object, Entry_Call);
1023 PO_Service_Entries (Self_Id, Object);
1028 STPO.Write_Lock (Self_Id);
1031 -- Try to avoid waiting for completed or cancelled calls.
1033 if Entry_Call.State >= Done then
1034 Utilities.Exit_One_ATC_Level (Self_Id);
1039 STPO.Unlock (Self_Id);
1042 Entry_Call_Successful := Entry_Call.State = Done;
1043 Initialization.Undefer_Abort (Self_Id);
1044 Entry_Calls.Check_Exception (Self_Id, Entry_Call);
1048 Entry_Calls.Wait_For_Completion_With_Timeout
1049 (Entry_Call, Timeout, Mode, Yielded);
1054 STPO.Unlock (Self_Id);
1057 -- ??? Do we need to yield in case Yielded is False
1059 Initialization.Undefer_Abort (Self_Id);
1060 Entry_Call_Successful := Entry_Call.State = Done;
1061 Entry_Calls.Check_Exception (Self_Id, Entry_Call);
1062 end Timed_Protected_Entry_Call;
1064 ----------------------------
1065 -- Update_For_Queue_To_PO --
1066 ----------------------------
1068 -- Update the state of an existing entry call, based on
1069 -- whether the current queuing action is with or without abort.
1070 -- Call this only while holding the server's lock.
1071 -- It returns with the server's lock released.
1073 New_State : constant array (Boolean, Entry_Call_State)
1074 of Entry_Call_State :=
1076 (Never_Abortable => Never_Abortable,
1077 Not_Yet_Abortable => Now_Abortable,
1078 Was_Abortable => Now_Abortable,
1079 Now_Abortable => Now_Abortable,
1081 Cancelled => Cancelled),
1083 (Never_Abortable => Never_Abortable,
1084 Not_Yet_Abortable => Not_Yet_Abortable,
1085 Was_Abortable => Was_Abortable,
1086 Now_Abortable => Now_Abortable,
1088 Cancelled => Cancelled)
1091 procedure Update_For_Queue_To_PO
1092 (Entry_Call : Entry_Call_Link;
1093 With_Abort : Boolean)
1095 Old : constant Entry_Call_State := Entry_Call.State;
1098 pragma Assert (Old < Done);
1100 Entry_Call.State := New_State (With_Abort, Entry_Call.State);
1102 if Entry_Call.Mode = Asynchronous_Call then
1103 if Old < Was_Abortable and then
1104 Entry_Call.State = Now_Abortable
1110 STPO.Write_Lock (Entry_Call.Self);
1112 if Entry_Call.Self.Common.State = Async_Select_Sleep then
1113 STPO.Wakeup (Entry_Call.Self, Async_Select_Sleep);
1116 STPO.Unlock (Entry_Call.Self);
1124 elsif Entry_Call.Mode = Conditional_Call then
1125 pragma Assert (Entry_Call.State < Was_Abortable);
1128 end Update_For_Queue_To_PO;
1130 end System.Tasking.Protected_Objects.Operations;