* lto.c (do_stream_out): Add PART parameter; open dump file.
[official-gcc.git] / gcc / ada / libgnarl / s-taenca.adb
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1 ------------------------------------------------------------------------------
2 -- --
3 -- GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS --
4 -- --
5 -- S Y S T E M . T A S K I N G . E N T R Y _ C A L L S --
6 -- --
7 -- B o d y --
8 -- --
9 -- Copyright (C) 1992-2018, Free Software Foundation, Inc. --
10 -- --
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 3, or (at your option) any later ver- --
14 -- sion. GNAT 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. --
17 -- --
18 -- As a special exception under Section 7 of GPL version 3, you are granted --
19 -- additional permissions described in the GCC Runtime Library Exception, --
20 -- version 3.1, as published by the Free Software Foundation. --
21 -- --
22 -- You should have received a copy of the GNU General Public License and --
23 -- a copy of the GCC Runtime Library Exception along with this program; --
24 -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
25 -- <http://www.gnu.org/licenses/>. --
26 -- --
27 -- GNARL was developed by the GNARL team at Florida State University. --
28 -- Extensive contributions were provided by Ada Core Technologies, Inc. --
29 -- --
30 ------------------------------------------------------------------------------
32 with System.Task_Primitives.Operations;
33 with System.Tasking.Initialization;
34 with System.Tasking.Protected_Objects.Entries;
35 with System.Tasking.Protected_Objects.Operations;
36 with System.Tasking.Queuing;
37 with System.Tasking.Utilities;
38 with System.Parameters;
40 package body System.Tasking.Entry_Calls is
42 package STPO renames System.Task_Primitives.Operations;
44 use Parameters;
45 use Protected_Objects.Entries;
46 use Protected_Objects.Operations;
48 -- DO NOT use Protected_Objects.Lock or Protected_Objects.Unlock
49 -- internally. Those operations will raise Program_Error, which
50 -- we are not prepared to handle inside the RTS. Instead, use
51 -- System.Task_Primitives lock operations directly on Protection.L.
53 -----------------------
54 -- Local Subprograms --
55 -----------------------
57 procedure Lock_Server (Entry_Call : Entry_Call_Link);
59 -- This locks the server targeted by Entry_Call
61 -- This may be a task or a protected object, depending on the target of the
62 -- original call or any subsequent requeues.
64 -- This routine is needed because the field specifying the server for this
65 -- call must be protected by the server's mutex. If it were protected by
66 -- the caller's mutex, accessing the server's queues would require locking
67 -- the caller to get the server, locking the server, and then accessing the
68 -- queues. This involves holding two ATCB locks at once, something which we
69 -- can guarantee that it will always be done in the same order, or locking
70 -- a protected object while we hold an ATCB lock, something which is not
71 -- permitted. Since the server cannot be obtained reliably, it must be
72 -- obtained unreliably and then checked again once it has been locked.
74 -- If Single_Lock and server is a PO, release RTS_Lock
76 -- This should only be called by the Entry_Call.Self.
77 -- It should be holding no other ATCB locks at the time.
79 procedure Unlock_Server (Entry_Call : Entry_Call_Link);
80 -- STPO.Unlock the server targeted by Entry_Call. The server must
81 -- be locked before calling this.
83 -- If Single_Lock and server is a PO, take RTS_Lock on exit.
85 procedure Unlock_And_Update_Server
86 (Self_ID : Task_Id;
87 Entry_Call : Entry_Call_Link);
88 -- Similar to Unlock_Server, but services entry calls if the
89 -- server is a protected object.
91 -- If Single_Lock and server is a PO, take RTS_Lock on exit.
93 procedure Check_Pending_Actions_For_Entry_Call
94 (Self_ID : Task_Id;
95 Entry_Call : Entry_Call_Link);
96 -- This procedure performs priority change of a queued call and dequeuing
97 -- of an entry call when the call is cancelled. If the call is dequeued the
98 -- state should be set to Cancelled. Call only with abort deferred and
99 -- holding lock of Self_ID. This is a bit of common code for all entry
100 -- calls. The effect is to do any deferred base priority change operation,
101 -- in case some other task called STPO.Set_Priority while the current task
102 -- had abort deferred, and to dequeue the call if the call has been
103 -- aborted.
105 procedure Poll_Base_Priority_Change_At_Entry_Call
106 (Self_ID : Task_Id;
107 Entry_Call : Entry_Call_Link);
108 pragma Inline (Poll_Base_Priority_Change_At_Entry_Call);
109 -- A specialized version of Poll_Base_Priority_Change, that does the
110 -- optional entry queue reordering. Has to be called with the Self_ID's
111 -- ATCB write-locked. May temporarily release the lock.
113 ---------------------
114 -- Check_Exception --
115 ---------------------
117 procedure Check_Exception
118 (Self_ID : Task_Id;
119 Entry_Call : Entry_Call_Link)
121 pragma Warnings (Off, Self_ID);
123 use type Ada.Exceptions.Exception_Id;
125 procedure Internal_Raise (X : Ada.Exceptions.Exception_Id);
126 pragma Import (C, Internal_Raise, "__gnat_raise_with_msg");
128 E : constant Ada.Exceptions.Exception_Id :=
129 Entry_Call.Exception_To_Raise;
130 begin
131 -- pragma Assert (Self_ID.Deferral_Level = 0);
133 -- The above may be useful for debugging, but the Florist packages
134 -- contain critical sections that defer abort and then do entry calls,
135 -- which causes the above Assert to trip.
137 if E /= Ada.Exceptions.Null_Id then
138 Internal_Raise (E);
139 end if;
140 end Check_Exception;
142 ------------------------------------------
143 -- Check_Pending_Actions_For_Entry_Call --
144 ------------------------------------------
146 procedure Check_Pending_Actions_For_Entry_Call
147 (Self_ID : Task_Id;
148 Entry_Call : Entry_Call_Link)
150 begin
151 pragma Assert (Self_ID = Entry_Call.Self);
153 Poll_Base_Priority_Change_At_Entry_Call (Self_ID, Entry_Call);
155 if Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level
156 and then Entry_Call.State = Now_Abortable
157 then
158 STPO.Unlock (Self_ID);
159 Lock_Server (Entry_Call);
161 if Queuing.Onqueue (Entry_Call)
162 and then Entry_Call.State = Now_Abortable
163 then
164 Queuing.Dequeue_Call (Entry_Call);
165 Entry_Call.State :=
166 (if Entry_Call.Cancellation_Attempted then Cancelled else Done);
167 Unlock_And_Update_Server (Self_ID, Entry_Call);
169 else
170 Unlock_Server (Entry_Call);
171 end if;
173 STPO.Write_Lock (Self_ID);
174 end if;
175 end Check_Pending_Actions_For_Entry_Call;
177 -----------------
178 -- Lock_Server --
179 -----------------
181 procedure Lock_Server (Entry_Call : Entry_Call_Link) is
182 Test_Task : Task_Id;
183 Test_PO : Protection_Entries_Access;
184 Ceiling_Violation : Boolean;
185 Failures : Integer := 0;
187 begin
188 Test_Task := Entry_Call.Called_Task;
190 loop
191 if Test_Task = null then
193 -- Entry_Call was queued on a protected object, or in transition,
194 -- when we last fetched Test_Task.
196 Test_PO := To_Protection (Entry_Call.Called_PO);
198 if Test_PO = null then
200 -- We had very bad luck, interleaving with TWO different
201 -- requeue operations. Go around the loop and try again.
203 if Single_Lock then
204 STPO.Unlock_RTS;
205 STPO.Yield;
206 STPO.Lock_RTS;
207 else
208 STPO.Yield;
209 end if;
211 else
212 if Single_Lock then
213 STPO.Unlock_RTS;
214 end if;
216 Lock_Entries_With_Status (Test_PO, Ceiling_Violation);
218 -- ???
220 -- The following code allows Lock_Server to be called when
221 -- cancelling a call, to allow for the possibility that the
222 -- priority of the caller has been raised beyond that of the
223 -- protected entry call by Ada.Dynamic_Priorities.Set_Priority.
225 -- If the current task has a higher priority than the ceiling
226 -- of the protected object, temporarily lower it. It will
227 -- be reset in Unlock.
229 if Ceiling_Violation then
230 declare
231 Current_Task : constant Task_Id := STPO.Self;
232 Old_Base_Priority : System.Any_Priority;
234 begin
235 if Single_Lock then
236 STPO.Lock_RTS;
237 end if;
239 STPO.Write_Lock (Current_Task);
240 Old_Base_Priority := Current_Task.Common.Base_Priority;
241 Current_Task.New_Base_Priority := Test_PO.Ceiling;
242 System.Tasking.Initialization.Change_Base_Priority
243 (Current_Task);
244 STPO.Unlock (Current_Task);
246 if Single_Lock then
247 STPO.Unlock_RTS;
248 end if;
250 -- Following lock should not fail
252 Lock_Entries (Test_PO);
254 Test_PO.Old_Base_Priority := Old_Base_Priority;
255 Test_PO.Pending_Action := True;
256 end;
257 end if;
259 exit when To_Address (Test_PO) = Entry_Call.Called_PO;
260 Unlock_Entries (Test_PO);
262 if Single_Lock then
263 STPO.Lock_RTS;
264 end if;
265 end if;
267 else
268 STPO.Write_Lock (Test_Task);
269 exit when Test_Task = Entry_Call.Called_Task;
270 STPO.Unlock (Test_Task);
271 end if;
273 Test_Task := Entry_Call.Called_Task;
274 Failures := Failures + 1;
275 pragma Assert (Failures <= 5);
276 end loop;
277 end Lock_Server;
279 ---------------------------------------------
280 -- Poll_Base_Priority_Change_At_Entry_Call --
281 ---------------------------------------------
283 procedure Poll_Base_Priority_Change_At_Entry_Call
284 (Self_ID : Task_Id;
285 Entry_Call : Entry_Call_Link)
287 begin
288 if Self_ID.Pending_Priority_Change then
290 -- Check for ceiling violations ???
292 Self_ID.Pending_Priority_Change := False;
294 -- Requeue the entry call at the new priority. We need to requeue
295 -- even if the new priority is the same than the previous (see ACATS
296 -- test cxd4006).
298 STPO.Unlock (Self_ID);
299 Lock_Server (Entry_Call);
300 Queuing.Requeue_Call_With_New_Prio
301 (Entry_Call, STPO.Get_Priority (Self_ID));
302 Unlock_And_Update_Server (Self_ID, Entry_Call);
303 STPO.Write_Lock (Self_ID);
304 end if;
305 end Poll_Base_Priority_Change_At_Entry_Call;
307 --------------------
308 -- Reset_Priority --
309 --------------------
311 procedure Reset_Priority
312 (Acceptor : Task_Id;
313 Acceptor_Prev_Priority : Rendezvous_Priority)
315 begin
316 pragma Assert (Acceptor = STPO.Self);
318 -- Since we limit this kind of "active" priority change to be done
319 -- by the task for itself, we don't need to lock Acceptor.
321 if Acceptor_Prev_Priority /= Priority_Not_Boosted then
322 STPO.Set_Priority (Acceptor, Acceptor_Prev_Priority,
323 Loss_Of_Inheritance => True);
324 end if;
325 end Reset_Priority;
327 ------------------------------
328 -- Try_To_Cancel_Entry_Call --
329 ------------------------------
331 procedure Try_To_Cancel_Entry_Call (Succeeded : out Boolean) is
332 Entry_Call : Entry_Call_Link;
333 Self_ID : constant Task_Id := STPO.Self;
335 use type Ada.Exceptions.Exception_Id;
337 begin
338 Entry_Call := Self_ID.Entry_Calls (Self_ID.ATC_Nesting_Level)'Access;
340 -- Experimentation has shown that abort is sometimes (but not
341 -- always) already deferred when Cancel_xxx_Entry_Call is called.
342 -- That may indicate an error. Find out what is going on. ???
344 pragma Assert (Entry_Call.Mode = Asynchronous_Call);
345 Initialization.Defer_Abort_Nestable (Self_ID);
347 if Single_Lock then
348 STPO.Lock_RTS;
349 end if;
351 STPO.Write_Lock (Self_ID);
352 Entry_Call.Cancellation_Attempted := True;
354 if Self_ID.Pending_ATC_Level >= Entry_Call.Level then
355 Self_ID.Pending_ATC_Level := Entry_Call.Level - 1;
356 end if;
358 Entry_Calls.Wait_For_Completion (Entry_Call);
359 STPO.Unlock (Self_ID);
361 if Single_Lock then
362 STPO.Unlock_RTS;
363 end if;
365 Succeeded := Entry_Call.State = Cancelled;
367 Initialization.Undefer_Abort_Nestable (Self_ID);
369 -- Ideally, abort should no longer be deferred at this point, so we
370 -- should be able to call Check_Exception. The loop below should be
371 -- considered temporary, to work around the possibility that abort
372 -- may be deferred more than one level deep ???
374 if Entry_Call.Exception_To_Raise /= Ada.Exceptions.Null_Id then
375 while Self_ID.Deferral_Level > 0 loop
376 System.Tasking.Initialization.Undefer_Abort_Nestable (Self_ID);
377 end loop;
379 Entry_Calls.Check_Exception (Self_ID, Entry_Call);
380 end if;
381 end Try_To_Cancel_Entry_Call;
383 ------------------------------
384 -- Unlock_And_Update_Server --
385 ------------------------------
387 procedure Unlock_And_Update_Server
388 (Self_ID : Task_Id;
389 Entry_Call : Entry_Call_Link)
391 Called_PO : Protection_Entries_Access;
392 Caller : Task_Id;
394 begin
395 if Entry_Call.Called_Task /= null then
396 STPO.Unlock (Entry_Call.Called_Task);
397 else
398 Called_PO := To_Protection (Entry_Call.Called_PO);
399 PO_Service_Entries (Self_ID, Called_PO, False);
401 if Called_PO.Pending_Action then
402 Called_PO.Pending_Action := False;
403 Caller := STPO.Self;
405 if Single_Lock then
406 STPO.Lock_RTS;
407 end if;
409 STPO.Write_Lock (Caller);
410 Caller.New_Base_Priority := Called_PO.Old_Base_Priority;
411 Initialization.Change_Base_Priority (Caller);
412 STPO.Unlock (Caller);
414 if Single_Lock then
415 STPO.Unlock_RTS;
416 end if;
417 end if;
419 Unlock_Entries (Called_PO);
421 if Single_Lock then
422 STPO.Lock_RTS;
423 end if;
424 end if;
425 end Unlock_And_Update_Server;
427 -------------------
428 -- Unlock_Server --
429 -------------------
431 procedure Unlock_Server (Entry_Call : Entry_Call_Link) is
432 Caller : Task_Id;
433 Called_PO : Protection_Entries_Access;
435 begin
436 if Entry_Call.Called_Task /= null then
437 STPO.Unlock (Entry_Call.Called_Task);
438 else
439 Called_PO := To_Protection (Entry_Call.Called_PO);
441 if Called_PO.Pending_Action then
442 Called_PO.Pending_Action := False;
443 Caller := STPO.Self;
445 if Single_Lock then
446 STPO.Lock_RTS;
447 end if;
449 STPO.Write_Lock (Caller);
450 Caller.New_Base_Priority := Called_PO.Old_Base_Priority;
451 Initialization.Change_Base_Priority (Caller);
452 STPO.Unlock (Caller);
454 if Single_Lock then
455 STPO.Unlock_RTS;
456 end if;
457 end if;
459 Unlock_Entries (Called_PO);
461 if Single_Lock then
462 STPO.Lock_RTS;
463 end if;
464 end if;
465 end Unlock_Server;
467 -------------------------
468 -- Wait_For_Completion --
469 -------------------------
471 procedure Wait_For_Completion (Entry_Call : Entry_Call_Link) is
472 Self_Id : constant Task_Id := Entry_Call.Self;
474 begin
475 -- If this is a conditional call, it should be cancelled when it
476 -- becomes abortable. This is checked in the loop below.
478 Self_Id.Common.State := Entry_Caller_Sleep;
480 -- Try to remove calls to Sleep in the loop below by letting the caller
481 -- a chance of getting ready immediately, using Unlock & Yield.
482 -- See similar action in Wait_For_Call & Timed_Selective_Wait.
484 if Single_Lock then
485 STPO.Unlock_RTS;
486 else
487 STPO.Unlock (Self_Id);
488 end if;
490 if Entry_Call.State < Done then
491 STPO.Yield;
492 end if;
494 if Single_Lock then
495 STPO.Lock_RTS;
496 else
497 STPO.Write_Lock (Self_Id);
498 end if;
500 loop
501 Check_Pending_Actions_For_Entry_Call (Self_Id, Entry_Call);
503 exit when Entry_Call.State >= Done;
505 STPO.Sleep (Self_Id, Entry_Caller_Sleep);
506 end loop;
508 Self_Id.Common.State := Runnable;
509 Utilities.Exit_One_ATC_Level (Self_Id);
511 end Wait_For_Completion;
513 --------------------------------------
514 -- Wait_For_Completion_With_Timeout --
515 --------------------------------------
517 procedure Wait_For_Completion_With_Timeout
518 (Entry_Call : Entry_Call_Link;
519 Wakeup_Time : Duration;
520 Mode : Delay_Modes;
521 Yielded : out Boolean)
523 Self_Id : constant Task_Id := Entry_Call.Self;
524 Timedout : Boolean := False;
526 begin
527 -- This procedure waits for the entry call to be served, with a timeout.
528 -- It tries to cancel the call if the timeout expires before the call is
529 -- served.
531 -- If we wake up from the timed sleep operation here, it may be for
532 -- several possible reasons:
534 -- 1) The entry call is done being served.
535 -- 2) There is an abort or priority change to be served.
536 -- 3) The timeout has expired (Timedout = True)
537 -- 4) There has been a spurious wakeup.
539 -- Once the timeout has expired we may need to continue to wait if the
540 -- call is already being serviced. In that case, we want to go back to
541 -- sleep, but without any timeout. The variable Timedout is used to
542 -- control this. If the Timedout flag is set, we do not need to
543 -- STPO.Sleep with a timeout. We just sleep until we get a wakeup for
544 -- some status change.
546 -- The original call may have become abortable after waking up. We want
547 -- to check Check_Pending_Actions_For_Entry_Call again in any case.
549 pragma Assert (Entry_Call.Mode = Timed_Call);
551 Yielded := False;
552 Self_Id.Common.State := Entry_Caller_Sleep;
554 -- Looping is necessary in case the task wakes up early from the timed
555 -- sleep, due to a "spurious wakeup". Spurious wakeups are a weakness of
556 -- POSIX condition variables. A thread waiting for a condition variable
557 -- is allowed to wake up at any time, not just when the condition is
558 -- signaled. See same loop in the ordinary Wait_For_Completion, above.
560 loop
561 Check_Pending_Actions_For_Entry_Call (Self_Id, Entry_Call);
562 exit when Entry_Call.State >= Done;
564 STPO.Timed_Sleep (Self_Id, Wakeup_Time, Mode,
565 Entry_Caller_Sleep, Timedout, Yielded);
567 if Timedout then
568 -- Try to cancel the call (see Try_To_Cancel_Entry_Call for
569 -- corresponding code in the ATC case).
571 Entry_Call.Cancellation_Attempted := True;
573 -- Reset Entry_Call.State so that the call is marked as cancelled
574 -- by Check_Pending_Actions_For_Entry_Call below.
576 if Entry_Call.State < Was_Abortable then
577 Entry_Call.State := Now_Abortable;
578 end if;
580 if Self_Id.Pending_ATC_Level >= Entry_Call.Level then
581 Self_Id.Pending_ATC_Level := Entry_Call.Level - 1;
582 end if;
584 -- The following loop is the same as the loop and exit code
585 -- from the ordinary Wait_For_Completion. If we get here, we
586 -- have timed out but we need to keep waiting until the call
587 -- has actually completed or been cancelled successfully.
589 loop
590 Check_Pending_Actions_For_Entry_Call (Self_Id, Entry_Call);
591 exit when Entry_Call.State >= Done;
592 STPO.Sleep (Self_Id, Entry_Caller_Sleep);
593 end loop;
595 Self_Id.Common.State := Runnable;
596 Utilities.Exit_One_ATC_Level (Self_Id);
598 return;
599 end if;
600 end loop;
602 -- This last part is the same as ordinary Wait_For_Completion,
603 -- and is only executed if the call completed without timing out.
605 Self_Id.Common.State := Runnable;
606 Utilities.Exit_One_ATC_Level (Self_Id);
607 end Wait_For_Completion_With_Timeout;
609 --------------------------
610 -- Wait_Until_Abortable --
611 --------------------------
613 procedure Wait_Until_Abortable
614 (Self_ID : Task_Id;
615 Call : Entry_Call_Link)
617 begin
618 pragma Assert (Self_ID.ATC_Nesting_Level > 0);
619 pragma Assert (Call.Mode = Asynchronous_Call);
621 STPO.Write_Lock (Self_ID);
622 Self_ID.Common.State := Entry_Caller_Sleep;
624 loop
625 Check_Pending_Actions_For_Entry_Call (Self_ID, Call);
626 exit when Call.State >= Was_Abortable;
627 STPO.Sleep (Self_ID, Async_Select_Sleep);
628 end loop;
630 Self_ID.Common.State := Runnable;
631 STPO.Unlock (Self_ID);
633 end Wait_Until_Abortable;
635 end System.Tasking.Entry_Calls;