1 ------------------------------------------------------------------------------
3 -- GNU ADA RUN-TIME LIBRARY (GNARL) COMPONENTS --
5 -- S Y S T E M . T A S K _ P R I M I T I V E S . O P E R A T I O N 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, 59 Temple Place - Suite 330, Boston, --
20 -- MA 02111-1307, USA. --
22 -- As a special exception, if other files instantiate generics from this --
23 -- unit, or you link this unit with other files to produce an executable, --
24 -- this unit does not by itself cause the resulting executable to be --
25 -- covered by the GNU General Public License. This exception does not --
26 -- however invalidate any other reasons why the executable file might be --
27 -- covered by the GNU Public License. --
29 -- GNARL was developed by the GNARL team at Florida State University. --
30 -- Extensive contributions were provided by Ada Core Technologies, Inc. --
32 ------------------------------------------------------------------------------
34 -- This is a NT (native) version of this package
36 -- This package contains all the GNULL primitives that interface directly
37 -- with the underlying OS.
40 -- Turn off polling, we do not want ATC polling to take place during
41 -- tasking operations. It causes infinite loops and other problems.
43 with System.Tasking.Debug;
44 -- used for Known_Tasks
50 with Interfaces.C.Strings;
53 with System.OS_Interface;
54 -- used for various type, constant, and operations
56 with System.Parameters;
60 -- used for Ada_Task_Control_Block
63 with System.Soft_Links;
64 -- used for Defer/Undefer_Abort
65 -- to initialize TSD for a C thread, in function Self
67 -- Note that we do not use System.Tasking.Initialization directly since
68 -- this is a higher level package that we shouldn't depend on. For example
69 -- when using the restricted run time, it is replaced by
70 -- System.Tasking.Restricted.Stages.
72 with System.OS_Primitives;
73 -- used for Delay_Modes
75 with System.Task_Info;
76 -- used for Unspecified_Task_Info
78 with Unchecked_Deallocation;
80 package body System.Task_Primitives.Operations is
82 use System.Tasking.Debug;
85 use Interfaces.C.Strings;
86 use System.OS_Interface;
87 use System.Parameters;
88 use System.OS_Primitives;
90 pragma Link_With ("-Xlinker --stack=0x800000,0x1000");
91 -- Change the stack size (8 MB) for tasking programs on Windows. This
92 -- permit to have more than 30 tasks running at the same time. Note that
93 -- we set the stack size for non tasking programs on System unit.
95 package SSL renames System.Soft_Links;
101 Environment_Task_Id : Task_Id;
102 -- A variable to hold Task_Id for the environment task
104 Single_RTS_Lock : aliased RTS_Lock;
105 -- This is a lock to allow only one thread of control in the RTS at
106 -- a time; it is used to execute in mutual exclusion from all other tasks.
107 -- Used mainly in Single_Lock mode, but also to protect All_Tasks_List
109 Time_Slice_Val : Integer;
110 pragma Import (C, Time_Slice_Val, "__gl_time_slice_val");
112 Dispatching_Policy : Character;
113 pragma Import (C, Dispatching_Policy, "__gl_task_dispatching_policy");
115 FIFO_Within_Priorities : constant Boolean := Dispatching_Policy = 'F';
116 -- Indicates whether FIFO_Within_Priorities is set
118 Foreign_Task_Elaborated : aliased Boolean := True;
119 -- Used to identified fake tasks (i.e., non-Ada Threads)
121 ------------------------------------
122 -- The thread local storage index --
123 ------------------------------------
126 pragma Export (Ada, TlsIndex);
127 -- To ensure that this variable won't be local to this package, since
128 -- in some cases, inlining forces this variable to be global anyway.
136 function Is_Valid_Task return Boolean;
137 pragma Inline (Is_Valid_Task);
138 -- Does executing thread have a TCB?
140 procedure Set (Self_Id : Task_Id);
142 -- Set the self id for the current task.
146 package body Specific is
148 function Is_Valid_Task return Boolean is
150 return TlsGetValue (TlsIndex) /= System.Null_Address;
153 procedure Set (Self_Id : Task_Id) is
156 Succeeded := TlsSetValue (TlsIndex, To_Address (Self_Id));
157 pragma Assert (Succeeded = True);
162 ---------------------------------
163 -- Support for foreign threads --
164 ---------------------------------
166 function Register_Foreign_Thread (Thread : Thread_Id) return Task_Id;
167 -- Allocate and Initialize a new ATCB for the current Thread.
169 function Register_Foreign_Thread
170 (Thread : Thread_Id) return Task_Id is separate;
172 ----------------------------------
173 -- Condition Variable Functions --
174 ----------------------------------
176 procedure Initialize_Cond (Cond : access Condition_Variable);
177 -- Initialize given condition variable Cond
179 procedure Finalize_Cond (Cond : access Condition_Variable);
180 -- Finalize given condition variable Cond.
182 procedure Cond_Signal (Cond : access Condition_Variable);
183 -- Signal condition variable Cond
186 (Cond : access Condition_Variable;
187 L : access RTS_Lock);
188 -- Wait on conditional variable Cond, using lock L
190 procedure Cond_Timed_Wait
191 (Cond : access Condition_Variable;
194 Timed_Out : out Boolean;
195 Status : out Integer);
196 -- Do timed wait on condition variable Cond using lock L. The duration
197 -- of the timed wait is given by Rel_Time. When the condition is
198 -- signalled, Timed_Out shows whether or not a time out occurred.
199 -- Status is only valid if Timed_Out is False, in which case it
200 -- shows whether Cond_Timed_Wait completed successfully.
202 ---------------------
203 -- Initialize_Cond --
204 ---------------------
206 procedure Initialize_Cond (Cond : access Condition_Variable) is
210 hEvent := CreateEvent (null, True, False, Null_Ptr);
211 pragma Assert (hEvent /= 0);
212 Cond.all := Condition_Variable (hEvent);
219 -- No such problem here, DosCloseEventSem has been derived.
220 -- What does such refer to in above comment???
222 procedure Finalize_Cond (Cond : access Condition_Variable) is
225 Result := CloseHandle (HANDLE (Cond.all));
226 pragma Assert (Result = True);
233 procedure Cond_Signal (Cond : access Condition_Variable) is
236 Result := SetEvent (HANDLE (Cond.all));
237 pragma Assert (Result = True);
244 -- Pre-assertion: Cond is posted
247 -- Post-assertion: Cond is posted
251 (Cond : access Condition_Variable;
258 -- Must reset Cond BEFORE L is unlocked.
260 Result_Bool := ResetEvent (HANDLE (Cond.all));
261 pragma Assert (Result_Bool = True);
264 -- No problem if we are interrupted here: if the condition is signaled,
265 -- WaitForSingleObject will simply not block
267 Result := WaitForSingleObject (HANDLE (Cond.all), Wait_Infinite);
268 pragma Assert (Result = 0);
273 ---------------------
274 -- Cond_Timed_Wait --
275 ---------------------
277 -- Pre-assertion: Cond is posted
280 -- Post-assertion: Cond is posted
283 procedure Cond_Timed_Wait
284 (Cond : access Condition_Variable;
287 Timed_Out : out Boolean;
288 Status : out Integer)
290 Time_Out_Max : constant DWORD := 16#FFFF0000#;
291 -- NT 4 cannot handle timeout values that are too large,
292 -- e.g. DWORD'Last - 1
299 -- Must reset Cond BEFORE L is unlocked.
301 Result := ResetEvent (HANDLE (Cond.all));
302 pragma Assert (Result = True);
305 -- No problem if we are interrupted here: if the condition is signaled,
306 -- WaitForSingleObject will simply not block
308 if Rel_Time <= 0.0 then
313 if Rel_Time >= Duration (Time_Out_Max) / 1000 then
314 Time_Out := Time_Out_Max;
316 Time_Out := DWORD (Rel_Time * 1000);
319 Wait_Result := WaitForSingleObject (HANDLE (Cond.all), Time_Out);
321 if Wait_Result = WAIT_TIMEOUT then
331 -- Ensure post-condition
334 Result := SetEvent (HANDLE (Cond.all));
335 pragma Assert (Result = True);
338 Status := Integer (Wait_Result);
345 -- The underlying thread system sets a guard page at the
346 -- bottom of a thread stack, so nothing is needed.
347 -- ??? Check the comment above
349 procedure Stack_Guard (T : ST.Task_Id; On : Boolean) is
350 pragma Warnings (Off, T);
351 pragma Warnings (Off, On);
361 function Get_Thread_Id (T : ST.Task_Id) return OSI.Thread_Id is
363 return T.Common.LL.Thread;
370 function Self return Task_Id is
371 Self_Id : constant Task_Id := To_Task_Id (TlsGetValue (TlsIndex));
373 if Self_Id = null then
374 return Register_Foreign_Thread (GetCurrentThread);
380 ---------------------
381 -- Initialize_Lock --
382 ---------------------
384 -- Note: mutexes and cond_variables needed per-task basis are
385 -- initialized in Intialize_TCB and the Storage_Error is handled.
386 -- Other mutexes (such as RTS_Lock, Memory_Lock...) used in
387 -- the RTS is initialized before any status change of RTS.
388 -- Therefore raising Storage_Error in the following routines
389 -- should be able to be handled safely.
391 procedure Initialize_Lock
392 (Prio : System.Any_Priority;
396 InitializeCriticalSection (L.Mutex'Access);
397 L.Owner_Priority := 0;
401 procedure Initialize_Lock (L : access RTS_Lock; Level : Lock_Level) is
402 pragma Unreferenced (Level);
404 InitializeCriticalSection (CRITICAL_SECTION (L.all)'Unrestricted_Access);
411 procedure Finalize_Lock (L : access Lock) is
413 DeleteCriticalSection (L.Mutex'Access);
416 procedure Finalize_Lock (L : access RTS_Lock) is
418 DeleteCriticalSection (CRITICAL_SECTION (L.all)'Unrestricted_Access);
425 procedure Write_Lock (L : access Lock; Ceiling_Violation : out Boolean) is
427 L.Owner_Priority := Get_Priority (Self);
429 if L.Priority < L.Owner_Priority then
430 Ceiling_Violation := True;
434 EnterCriticalSection (L.Mutex'Access);
436 Ceiling_Violation := False;
440 (L : access RTS_Lock;
441 Global_Lock : Boolean := False)
444 if not Single_Lock or else Global_Lock then
445 EnterCriticalSection (CRITICAL_SECTION (L.all)'Unrestricted_Access);
449 procedure Write_Lock (T : Task_Id) is
451 if not Single_Lock then
453 (CRITICAL_SECTION (T.Common.LL.L)'Unrestricted_Access);
461 procedure Read_Lock (L : access Lock; Ceiling_Violation : out Boolean) is
463 Write_Lock (L, Ceiling_Violation);
470 procedure Unlock (L : access Lock) is
472 LeaveCriticalSection (L.Mutex'Access);
475 procedure Unlock (L : access RTS_Lock; Global_Lock : Boolean := False) is
477 if not Single_Lock or else Global_Lock then
478 LeaveCriticalSection (CRITICAL_SECTION (L.all)'Unrestricted_Access);
482 procedure Unlock (T : Task_Id) is
484 if not Single_Lock then
486 (CRITICAL_SECTION (T.Common.LL.L)'Unrestricted_Access);
496 Reason : System.Tasking.Task_States)
498 pragma Unreferenced (Reason);
501 pragma Assert (Self_ID = Self);
504 Cond_Wait (Self_ID.Common.LL.CV'Access, Single_RTS_Lock'Access);
506 Cond_Wait (Self_ID.Common.LL.CV'Access, Self_ID.Common.LL.L'Access);
509 if Self_ID.Deferral_Level = 0
510 and then Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level
513 raise Standard'Abort_Signal;
521 -- This is for use within the run-time system, so abort is
522 -- assumed to be already deferred, and the caller should be
523 -- holding its own ATCB lock.
525 procedure Timed_Sleep
528 Mode : ST.Delay_Modes;
529 Reason : System.Tasking.Task_States;
530 Timedout : out Boolean;
531 Yielded : out Boolean)
533 pragma Unreferenced (Reason);
534 Check_Time : Duration := Monotonic_Clock;
539 Local_Timedout : Boolean;
545 if Mode = Relative then
547 Abs_Time := Duration'Min (Time, Max_Sensible_Delay) + Check_Time;
549 Rel_Time := Time - Check_Time;
553 if Rel_Time > 0.0 then
555 exit when Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level
556 or else Self_ID.Pending_Priority_Change;
559 Cond_Timed_Wait (Self_ID.Common.LL.CV'Access,
560 Single_RTS_Lock'Access, Rel_Time, Local_Timedout, Result);
562 Cond_Timed_Wait (Self_ID.Common.LL.CV'Access,
563 Self_ID.Common.LL.L'Access, Rel_Time, Local_Timedout, Result);
566 Check_Time := Monotonic_Clock;
567 exit when Abs_Time <= Check_Time;
569 if not Local_Timedout then
571 -- Somebody may have called Wakeup for us
577 Rel_Time := Abs_Time - Check_Time;
586 procedure Timed_Delay
589 Mode : ST.Delay_Modes)
591 Check_Time : Duration := Monotonic_Clock;
598 -- Only the little window between deferring abort and
599 -- locking Self_ID is the reason we need to
600 -- check for pending abort and priority change below!
608 Write_Lock (Self_ID);
610 if Mode = Relative then
612 Abs_Time := Time + Check_Time;
614 Rel_Time := Time - Check_Time;
618 if Rel_Time > 0.0 then
619 Self_ID.Common.State := Delay_Sleep;
622 if Self_ID.Pending_Priority_Change then
623 Self_ID.Pending_Priority_Change := False;
624 Self_ID.Common.Base_Priority := Self_ID.New_Base_Priority;
625 Set_Priority (Self_ID, Self_ID.Common.Base_Priority);
628 exit when Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level;
631 Cond_Timed_Wait (Self_ID.Common.LL.CV'Access,
632 Single_RTS_Lock'Access, Rel_Time, Timedout, Result);
634 Cond_Timed_Wait (Self_ID.Common.LL.CV'Access,
635 Self_ID.Common.LL.L'Access, Rel_Time, Timedout, Result);
638 Check_Time := Monotonic_Clock;
639 exit when Abs_Time <= Check_Time;
641 Rel_Time := Abs_Time - Check_Time;
644 Self_ID.Common.State := Runnable;
654 SSL.Abort_Undefer.all;
661 procedure Wakeup (T : Task_Id; Reason : System.Tasking.Task_States) is
662 pragma Unreferenced (Reason);
664 Cond_Signal (T.Common.LL.CV'Access);
671 procedure Yield (Do_Yield : Boolean := True) is
682 type Prio_Array_Type is array (System.Any_Priority) of Integer;
683 pragma Atomic_Components (Prio_Array_Type);
685 Prio_Array : Prio_Array_Type;
686 -- Global array containing the id of the currently running task for
689 -- Note: we assume that we are on a single processor with run-til-blocked
692 procedure Set_Priority
694 Prio : System.Any_Priority;
695 Loss_Of_Inheritance : Boolean := False)
698 Array_Item : Integer;
701 Res := SetThreadPriority
702 (T.Common.LL.Thread, Interfaces.C.int (Underlying_Priorities (Prio)));
703 pragma Assert (Res = True);
705 if FIFO_Within_Priorities then
707 -- Annex D requirement [RM D.2.2 par. 9]:
708 -- If the task drops its priority due to the loss of inherited
709 -- priority, it is added at the head of the ready queue for its
710 -- new active priority.
712 if Loss_Of_Inheritance
713 and then Prio < T.Common.Current_Priority
715 Array_Item := Prio_Array (T.Common.Base_Priority) + 1;
716 Prio_Array (T.Common.Base_Priority) := Array_Item;
719 -- Let some processes a chance to arrive
723 -- Then wait for our turn to proceed
725 exit when Array_Item = Prio_Array (T.Common.Base_Priority)
726 or else Prio_Array (T.Common.Base_Priority) = 1;
729 Prio_Array (T.Common.Base_Priority) :=
730 Prio_Array (T.Common.Base_Priority) - 1;
734 T.Common.Current_Priority := Prio;
741 function Get_Priority (T : Task_Id) return System.Any_Priority is
743 return T.Common.Current_Priority;
750 -- There were two paths were we needed to call Enter_Task :
751 -- 1) from System.Task_Primitives.Operations.Initialize
752 -- 2) from System.Tasking.Stages.Task_Wrapper
754 -- The thread initialisation has to be done only for the first case.
756 -- This is because the GetCurrentThread NT call does not return the
757 -- real thread handler but only a "pseudo" one. It is not possible to
758 -- release the thread handle and free the system ressources from this
759 -- "pseudo" handle. So we really want to keep the real thread handle
760 -- set in System.Task_Primitives.Operations.Create_Task during the
763 procedure Enter_Task (Self_ID : Task_Id) is
764 procedure Init_Float;
765 pragma Import (C, Init_Float, "__gnat_init_float");
766 -- Properly initializes the FPU for x86 systems.
769 Specific.Set (Self_ID);
772 Self_ID.Common.LL.Thread_Id := GetCurrentThreadId;
776 for J in Known_Tasks'Range loop
777 if Known_Tasks (J) = null then
778 Known_Tasks (J) := Self_ID;
779 Self_ID.Known_Tasks_Index := J;
791 function New_ATCB (Entry_Num : Task_Entry_Index) return Task_Id is
793 return new Ada_Task_Control_Block (Entry_Num);
800 function Is_Valid_Task return Boolean renames Specific.Is_Valid_Task;
802 -----------------------------
803 -- Register_Foreign_Thread --
804 -----------------------------
806 function Register_Foreign_Thread return Task_Id is
808 if Is_Valid_Task then
811 return Register_Foreign_Thread (GetCurrentThread);
813 end Register_Foreign_Thread;
819 procedure Initialize_TCB (Self_ID : Task_Id; Succeeded : out Boolean) is
821 -- Initialize thread ID to 0, this is needed to detect threads that
822 -- are not yet activated.
824 Self_ID.Common.LL.Thread := 0;
826 Initialize_Cond (Self_ID.Common.LL.CV'Access);
828 if not Single_Lock then
829 Initialize_Lock (Self_ID.Common.LL.L'Access, ATCB_Level);
839 procedure Create_Task
841 Wrapper : System.Address;
842 Stack_Size : System.Parameters.Size_Type;
843 Priority : System.Any_Priority;
844 Succeeded : out Boolean)
846 pragma Unreferenced (Stack_Size);
848 Initial_Stack_Size : constant := 1024;
849 -- We set the initial stack size to 1024. On Windows there is no way to
850 -- fix a task stack size. Only the initial stack size can be set, the
851 -- operating system will raise the task stack size if needed.
854 TaskId : aliased DWORD;
855 pTaskParameter : System.OS_Interface.PVOID;
857 Entry_Point : PTHREAD_START_ROUTINE;
860 pTaskParameter := To_Address (T);
862 Entry_Point := To_PTHREAD_START_ROUTINE (Wrapper);
864 hTask := CreateThread
869 DWORD (Create_Suspended),
870 TaskId'Unchecked_Access);
872 -- Step 1: Create the thread in blocked mode
878 -- Step 2: set its TCB
880 T.Common.LL.Thread := hTask;
882 -- Step 3: set its priority (child has inherited priority from parent)
884 Set_Priority (T, Priority);
886 if Time_Slice_Val = 0 or else FIFO_Within_Priorities then
887 -- Here we need Annex E semantics so we disable the NT priority
888 -- boost. A priority boost is temporarily given by the system to a
889 -- thread when it is taken out of a wait state.
891 SetThreadPriorityBoost (hTask, DisablePriorityBoost => True);
894 -- Step 4: Now, start it for good:
896 Result := ResumeThread (hTask);
897 pragma Assert (Result = 1);
899 Succeeded := Result = 1;
906 procedure Finalize_TCB (T : Task_Id) is
907 Self_ID : Task_Id := T;
910 Is_Self : constant Boolean := T = Self;
912 procedure Free is new
913 Unchecked_Deallocation (Ada_Task_Control_Block, Task_Id);
916 if not Single_Lock then
917 Finalize_Lock (T.Common.LL.L'Access);
920 Finalize_Cond (T.Common.LL.CV'Access);
922 if T.Known_Tasks_Index /= -1 then
923 Known_Tasks (T.Known_Tasks_Index) := null;
926 if Self_ID.Common.LL.Thread /= 0 then
928 -- This task has been activated. Wait for the thread to terminate
929 -- then close it. this is needed to release system ressources.
931 Result := WaitForSingleObject (T.Common.LL.Thread, Wait_Infinite);
932 pragma Assert (Result /= WAIT_FAILED);
933 Succeeded := CloseHandle (T.Common.LL.Thread);
934 pragma Assert (Succeeded = True);
948 procedure Exit_Task is
957 procedure Abort_Task (T : Task_Id) is
958 pragma Unreferenced (T);
963 ----------------------
964 -- Environment_Task --
965 ----------------------
967 function Environment_Task return Task_Id is
969 return Environment_Task_Id;
970 end Environment_Task;
976 procedure Lock_RTS is
978 Write_Lock (Single_RTS_Lock'Access, Global_Lock => True);
985 procedure Unlock_RTS is
987 Unlock (Single_RTS_Lock'Access, Global_Lock => True);
994 procedure Initialize (Environment_Task : Task_Id) is
996 pragma Unreferenced (Discard);
999 Environment_Task_Id := Environment_Task;
1001 if Time_Slice_Val = 0 or else FIFO_Within_Priorities then
1003 -- Here we need Annex E semantics, switch the current process to the
1004 -- High_Priority_Class.
1007 OS_Interface.SetPriorityClass
1008 (GetCurrentProcess, High_Priority_Class);
1010 -- ??? In theory it should be possible to use the priority class
1011 -- Realtime_Prioriry_Class but we suspect a bug in the NT scheduler
1012 -- which prevents (in some obscure cases) a thread to get on top of
1013 -- the running queue by another thread of lower priority. For
1014 -- example cxd8002 ACATS test freeze.
1017 TlsIndex := TlsAlloc;
1019 -- Initialize the lock used to synchronize chain of all ATCBs.
1021 Initialize_Lock (Single_RTS_Lock'Access, RTS_Lock_Level);
1023 Environment_Task.Common.LL.Thread := GetCurrentThread;
1024 Enter_Task (Environment_Task);
1027 ---------------------
1028 -- Monotonic_Clock --
1029 ---------------------
1031 function Monotonic_Clock return Duration
1032 renames System.OS_Primitives.Monotonic_Clock;
1038 function RT_Resolution return Duration is
1040 return 0.000_001; -- 1 micro-second
1047 -- Dummy versions. The only currently working versions is for solaris
1050 function Check_Exit (Self_ID : ST.Task_Id) return Boolean is
1051 pragma Unreferenced (Self_ID);
1056 --------------------
1057 -- Check_No_Locks --
1058 --------------------
1060 function Check_No_Locks (Self_ID : ST.Task_Id) return Boolean is
1061 pragma Unreferenced (Self_ID);
1070 function Suspend_Task
1072 Thread_Self : Thread_Id) return Boolean
1075 if T.Common.LL.Thread /= Thread_Self then
1076 return SuspendThread (T.Common.LL.Thread) = NO_ERROR;
1086 function Resume_Task
1088 Thread_Self : Thread_Id) return Boolean
1091 if T.Common.LL.Thread /= Thread_Self then
1092 return ResumeThread (T.Common.LL.Thread) = NO_ERROR;
1098 end System.Task_Primitives.Operations;