1 ------------------------------------------------------------------------------
3 -- GNAT 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) 1992-2006, 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 ------------------------------------------------------------------------------
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
46 with System
.OS_Primitives
;
47 -- used for Delay_Modes
53 with Interfaces
.C
.Strings
;
56 with System
.Task_Info
;
57 -- used for Unspecified_Task_Info
59 with Unchecked_Deallocation
;
61 package body System
.Task_Primitives
.Operations
is
63 use System
.Tasking
.Debug
;
66 use Interfaces
.C
.Strings
;
67 use System
.OS_Interface
;
68 use System
.Parameters
;
69 use System
.OS_Primitives
;
71 pragma Link_With
("-Xlinker --stack=0x200000,0x1000");
72 -- Change the default stack size (2 MB) for tasking programs on Windows.
73 -- This allows about 1000 tasks running at the same time. Note that
74 -- we set the stack size for non tasking programs on System unit.
75 -- Also note that under Windows XP, we use a Windows XP extension to
76 -- specify the stack size on a per task basis, as done under other OSes.
82 Environment_Task_Id
: Task_Id
;
83 -- A variable to hold Task_Id for the environment task
85 Single_RTS_Lock
: aliased RTS_Lock
;
86 -- This is a lock to allow only one thread of control in the RTS at
87 -- a time; it is used to execute in mutual exclusion from all other tasks.
88 -- Used mainly in Single_Lock mode, but also to protect All_Tasks_List
90 Time_Slice_Val
: Integer;
91 pragma Import
(C
, Time_Slice_Val
, "__gl_time_slice_val");
93 Dispatching_Policy
: Character;
94 pragma Import
(C
, Dispatching_Policy
, "__gl_task_dispatching_policy");
96 Foreign_Task_Elaborated
: aliased Boolean := True;
97 -- Used to identified fake tasks (i.e., non-Ada Threads)
99 ------------------------------------
100 -- The thread local storage index --
101 ------------------------------------
104 pragma Export
(Ada
, TlsIndex
);
105 -- To ensure that this variable won't be local to this package, since
106 -- in some cases, inlining forces this variable to be global anyway.
114 function Is_Valid_Task
return Boolean;
115 pragma Inline
(Is_Valid_Task
);
116 -- Does executing thread have a TCB?
118 procedure Set
(Self_Id
: Task_Id
);
120 -- Set the self id for the current task.
124 package body Specific
is
126 function Is_Valid_Task
return Boolean is
128 return TlsGetValue
(TlsIndex
) /= System
.Null_Address
;
131 procedure Set
(Self_Id
: Task_Id
) is
134 Succeeded
:= TlsSetValue
(TlsIndex
, To_Address
(Self_Id
));
135 pragma Assert
(Succeeded
= True);
140 ---------------------------------
141 -- Support for foreign threads --
142 ---------------------------------
144 function Register_Foreign_Thread
(Thread
: Thread_Id
) return Task_Id
;
145 -- Allocate and Initialize a new ATCB for the current Thread.
147 function Register_Foreign_Thread
148 (Thread
: Thread_Id
) return Task_Id
is separate;
150 ----------------------------------
151 -- Condition Variable Functions --
152 ----------------------------------
154 procedure Initialize_Cond
(Cond
: access Condition_Variable
);
155 -- Initialize given condition variable Cond
157 procedure Finalize_Cond
(Cond
: access Condition_Variable
);
158 -- Finalize given condition variable Cond.
160 procedure Cond_Signal
(Cond
: access Condition_Variable
);
161 -- Signal condition variable Cond
164 (Cond
: access Condition_Variable
;
165 L
: access RTS_Lock
);
166 -- Wait on conditional variable Cond, using lock L
168 procedure Cond_Timed_Wait
169 (Cond
: access Condition_Variable
;
172 Timed_Out
: out Boolean;
173 Status
: out Integer);
174 -- Do timed wait on condition variable Cond using lock L. The duration
175 -- of the timed wait is given by Rel_Time. When the condition is
176 -- signalled, Timed_Out shows whether or not a time out occurred.
177 -- Status is only valid if Timed_Out is False, in which case it
178 -- shows whether Cond_Timed_Wait completed successfully.
180 ---------------------
181 -- Initialize_Cond --
182 ---------------------
184 procedure Initialize_Cond
(Cond
: access Condition_Variable
) is
188 hEvent
:= CreateEvent
(null, True, False, Null_Ptr
);
189 pragma Assert
(hEvent
/= 0);
190 Cond
.all := Condition_Variable
(hEvent
);
197 -- No such problem here, DosCloseEventSem has been derived.
198 -- What does such refer to in above comment???
200 procedure Finalize_Cond
(Cond
: access Condition_Variable
) is
203 Result
:= CloseHandle
(HANDLE
(Cond
.all));
204 pragma Assert
(Result
= True);
211 procedure Cond_Signal
(Cond
: access Condition_Variable
) is
214 Result
:= SetEvent
(HANDLE
(Cond
.all));
215 pragma Assert
(Result
= True);
222 -- Pre-assertion: Cond is posted
225 -- Post-assertion: Cond is posted
229 (Cond
: access Condition_Variable
;
236 -- Must reset Cond BEFORE L is unlocked.
238 Result_Bool
:= ResetEvent
(HANDLE
(Cond
.all));
239 pragma Assert
(Result_Bool
= True);
242 -- No problem if we are interrupted here: if the condition is signaled,
243 -- WaitForSingleObject will simply not block
245 Result
:= WaitForSingleObject
(HANDLE
(Cond
.all), Wait_Infinite
);
246 pragma Assert
(Result
= 0);
251 ---------------------
252 -- Cond_Timed_Wait --
253 ---------------------
255 -- Pre-assertion: Cond is posted
258 -- Post-assertion: Cond is posted
261 procedure Cond_Timed_Wait
262 (Cond
: access Condition_Variable
;
265 Timed_Out
: out Boolean;
266 Status
: out Integer)
268 Time_Out_Max
: constant DWORD
:= 16#FFFF0000#
;
269 -- NT 4 cannot handle timeout values that are too large,
270 -- e.g. DWORD'Last - 1
277 -- Must reset Cond BEFORE L is unlocked.
279 Result
:= ResetEvent
(HANDLE
(Cond
.all));
280 pragma Assert
(Result
= True);
283 -- No problem if we are interrupted here: if the condition is signaled,
284 -- WaitForSingleObject will simply not block
286 if Rel_Time
<= 0.0 then
291 if Rel_Time
>= Duration (Time_Out_Max
) / 1000 then
292 Time_Out
:= Time_Out_Max
;
294 Time_Out
:= DWORD
(Rel_Time
* 1000);
297 Wait_Result
:= WaitForSingleObject
(HANDLE
(Cond
.all), Time_Out
);
299 if Wait_Result
= WAIT_TIMEOUT
then
309 -- Ensure post-condition
312 Result
:= SetEvent
(HANDLE
(Cond
.all));
313 pragma Assert
(Result
= True);
316 Status
:= Integer (Wait_Result
);
323 -- The underlying thread system sets a guard page at the
324 -- bottom of a thread stack, so nothing is needed.
325 -- ??? Check the comment above
327 procedure Stack_Guard
(T
: ST
.Task_Id
; On
: Boolean) is
328 pragma Warnings
(Off
, T
);
329 pragma Warnings
(Off
, On
);
339 function Get_Thread_Id
(T
: ST
.Task_Id
) return OSI
.Thread_Id
is
341 return T
.Common
.LL
.Thread
;
348 function Self
return Task_Id
is
349 Self_Id
: constant Task_Id
:= To_Task_Id
(TlsGetValue
(TlsIndex
));
351 if Self_Id
= null then
352 return Register_Foreign_Thread
(GetCurrentThread
);
358 ---------------------
359 -- Initialize_Lock --
360 ---------------------
362 -- Note: mutexes and cond_variables needed per-task basis are
363 -- initialized in Intialize_TCB and the Storage_Error is handled.
364 -- Other mutexes (such as RTS_Lock, Memory_Lock...) used in
365 -- the RTS is initialized before any status change of RTS.
366 -- Therefore raising Storage_Error in the following routines
367 -- should be able to be handled safely.
369 procedure Initialize_Lock
370 (Prio
: System
.Any_Priority
;
374 InitializeCriticalSection
(L
.Mutex
'Access);
375 L
.Owner_Priority
:= 0;
379 procedure Initialize_Lock
(L
: access RTS_Lock
; Level
: Lock_Level
) is
380 pragma Unreferenced
(Level
);
382 InitializeCriticalSection
(CRITICAL_SECTION
(L
.all)'Unrestricted_Access);
389 procedure Finalize_Lock
(L
: access Lock
) is
391 DeleteCriticalSection
(L
.Mutex
'Access);
394 procedure Finalize_Lock
(L
: access RTS_Lock
) is
396 DeleteCriticalSection
(CRITICAL_SECTION
(L
.all)'Unrestricted_Access);
403 procedure Write_Lock
(L
: access Lock
; Ceiling_Violation
: out Boolean) is
405 L
.Owner_Priority
:= Get_Priority
(Self
);
407 if L
.Priority
< L
.Owner_Priority
then
408 Ceiling_Violation
:= True;
412 EnterCriticalSection
(L
.Mutex
'Access);
414 Ceiling_Violation
:= False;
418 (L
: access RTS_Lock
;
419 Global_Lock
: Boolean := False)
422 if not Single_Lock
or else Global_Lock
then
423 EnterCriticalSection
(CRITICAL_SECTION
(L
.all)'Unrestricted_Access);
427 procedure Write_Lock
(T
: Task_Id
) is
429 if not Single_Lock
then
431 (CRITICAL_SECTION
(T
.Common
.LL
.L
)'Unrestricted_Access);
439 procedure Read_Lock
(L
: access Lock
; Ceiling_Violation
: out Boolean) is
441 Write_Lock
(L
, Ceiling_Violation
);
448 procedure Unlock
(L
: access Lock
) is
450 LeaveCriticalSection
(L
.Mutex
'Access);
453 procedure Unlock
(L
: access RTS_Lock
; Global_Lock
: Boolean := False) is
455 if not Single_Lock
or else Global_Lock
then
456 LeaveCriticalSection
(CRITICAL_SECTION
(L
.all)'Unrestricted_Access);
460 procedure Unlock
(T
: Task_Id
) is
462 if not Single_Lock
then
464 (CRITICAL_SECTION
(T
.Common
.LL
.L
)'Unrestricted_Access);
474 Reason
: System
.Tasking
.Task_States
)
476 pragma Unreferenced
(Reason
);
479 pragma Assert
(Self_ID
= Self
);
482 Cond_Wait
(Self_ID
.Common
.LL
.CV
'Access, Single_RTS_Lock
'Access);
484 Cond_Wait
(Self_ID
.Common
.LL
.CV
'Access, Self_ID
.Common
.LL
.L
'Access);
487 if Self_ID
.Deferral_Level
= 0
488 and then Self_ID
.Pending_ATC_Level
< Self_ID
.ATC_Nesting_Level
491 raise Standard
'Abort_Signal;
499 -- This is for use within the run-time system, so abort is
500 -- assumed to be already deferred, and the caller should be
501 -- holding its own ATCB lock.
503 procedure Timed_Sleep
506 Mode
: ST
.Delay_Modes
;
507 Reason
: System
.Tasking
.Task_States
;
508 Timedout
: out Boolean;
509 Yielded
: out Boolean)
511 pragma Unreferenced
(Reason
);
512 Check_Time
: Duration := Monotonic_Clock
;
517 Local_Timedout
: Boolean;
523 if Mode
= Relative
then
525 Abs_Time
:= Duration'Min (Time
, Max_Sensible_Delay
) + Check_Time
;
527 Rel_Time
:= Time
- Check_Time
;
531 if Rel_Time
> 0.0 then
533 exit when Self_ID
.Pending_ATC_Level
< Self_ID
.ATC_Nesting_Level
534 or else Self_ID
.Pending_Priority_Change
;
537 Cond_Timed_Wait
(Self_ID
.Common
.LL
.CV
'Access,
538 Single_RTS_Lock
'Access, Rel_Time
, Local_Timedout
, Result
);
540 Cond_Timed_Wait
(Self_ID
.Common
.LL
.CV
'Access,
541 Self_ID
.Common
.LL
.L
'Access, Rel_Time
, Local_Timedout
, Result
);
544 Check_Time
:= Monotonic_Clock
;
545 exit when Abs_Time
<= Check_Time
;
547 if not Local_Timedout
then
549 -- Somebody may have called Wakeup for us
555 Rel_Time
:= Abs_Time
- Check_Time
;
564 procedure Timed_Delay
567 Mode
: ST
.Delay_Modes
)
569 Check_Time
: Duration := Monotonic_Clock
;
580 Write_Lock
(Self_ID
);
582 if Mode
= Relative
then
584 Abs_Time
:= Time
+ Check_Time
;
586 Rel_Time
:= Time
- Check_Time
;
590 if Rel_Time
> 0.0 then
591 Self_ID
.Common
.State
:= Delay_Sleep
;
594 if Self_ID
.Pending_Priority_Change
then
595 Self_ID
.Pending_Priority_Change
:= False;
596 Self_ID
.Common
.Base_Priority
:= Self_ID
.New_Base_Priority
;
597 Set_Priority
(Self_ID
, Self_ID
.Common
.Base_Priority
);
600 exit when Self_ID
.Pending_ATC_Level
< Self_ID
.ATC_Nesting_Level
;
603 Cond_Timed_Wait
(Self_ID
.Common
.LL
.CV
'Access,
604 Single_RTS_Lock
'Access, Rel_Time
, Timedout
, Result
);
606 Cond_Timed_Wait
(Self_ID
.Common
.LL
.CV
'Access,
607 Self_ID
.Common
.LL
.L
'Access, Rel_Time
, Timedout
, Result
);
610 Check_Time
:= Monotonic_Clock
;
611 exit when Abs_Time
<= Check_Time
;
613 Rel_Time
:= Abs_Time
- Check_Time
;
616 Self_ID
.Common
.State
:= Runnable
;
632 procedure Wakeup
(T
: Task_Id
; Reason
: System
.Tasking
.Task_States
) is
633 pragma Unreferenced
(Reason
);
635 Cond_Signal
(T
.Common
.LL
.CV
'Access);
642 procedure Yield
(Do_Yield
: Boolean := True) is
653 type Prio_Array_Type
is array (System
.Any_Priority
) of Integer;
654 pragma Atomic_Components
(Prio_Array_Type
);
656 Prio_Array
: Prio_Array_Type
;
657 -- Global array containing the id of the currently running task for
660 -- Note: we assume that we are on a single processor with run-til-blocked
663 procedure Set_Priority
665 Prio
: System
.Any_Priority
;
666 Loss_Of_Inheritance
: Boolean := False)
669 Array_Item
: Integer;
672 Res
:= SetThreadPriority
673 (T
.Common
.LL
.Thread
, Interfaces
.C
.int
(Underlying_Priorities
(Prio
)));
674 pragma Assert
(Res
= True);
676 if Dispatching_Policy
= 'F' then
678 -- Annex D requirement [RM D.2.2 par. 9]:
679 -- If the task drops its priority due to the loss of inherited
680 -- priority, it is added at the head of the ready queue for its
681 -- new active priority.
683 if Loss_Of_Inheritance
684 and then Prio
< T
.Common
.Current_Priority
686 Array_Item
:= Prio_Array
(T
.Common
.Base_Priority
) + 1;
687 Prio_Array
(T
.Common
.Base_Priority
) := Array_Item
;
690 -- Let some processes a chance to arrive
694 -- Then wait for our turn to proceed
696 exit when Array_Item
= Prio_Array
(T
.Common
.Base_Priority
)
697 or else Prio_Array
(T
.Common
.Base_Priority
) = 1;
700 Prio_Array
(T
.Common
.Base_Priority
) :=
701 Prio_Array
(T
.Common
.Base_Priority
) - 1;
705 T
.Common
.Current_Priority
:= Prio
;
712 function Get_Priority
(T
: Task_Id
) return System
.Any_Priority
is
714 return T
.Common
.Current_Priority
;
721 -- There were two paths were we needed to call Enter_Task :
722 -- 1) from System.Task_Primitives.Operations.Initialize
723 -- 2) from System.Tasking.Stages.Task_Wrapper
725 -- The thread initialisation has to be done only for the first case.
727 -- This is because the GetCurrentThread NT call does not return the
728 -- real thread handler but only a "pseudo" one. It is not possible to
729 -- release the thread handle and free the system ressources from this
730 -- "pseudo" handle. So we really want to keep the real thread handle
731 -- set in System.Task_Primitives.Operations.Create_Task during the
734 procedure Enter_Task
(Self_ID
: Task_Id
) is
735 procedure Init_Float
;
736 pragma Import
(C
, Init_Float
, "__gnat_init_float");
737 -- Properly initializes the FPU for x86 systems.
740 Specific
.Set
(Self_ID
);
743 Self_ID
.Common
.LL
.Thread_Id
:= GetCurrentThreadId
;
747 for J
in Known_Tasks
'Range loop
748 if Known_Tasks
(J
) = null then
749 Known_Tasks
(J
) := Self_ID
;
750 Self_ID
.Known_Tasks_Index
:= J
;
762 function New_ATCB
(Entry_Num
: Task_Entry_Index
) return Task_Id
is
764 return new Ada_Task_Control_Block
(Entry_Num
);
771 function Is_Valid_Task
return Boolean renames Specific
.Is_Valid_Task
;
773 -----------------------------
774 -- Register_Foreign_Thread --
775 -----------------------------
777 function Register_Foreign_Thread
return Task_Id
is
779 if Is_Valid_Task
then
782 return Register_Foreign_Thread
(GetCurrentThread
);
784 end Register_Foreign_Thread
;
790 procedure Initialize_TCB
(Self_ID
: Task_Id
; Succeeded
: out Boolean) is
792 -- Initialize thread ID to 0, this is needed to detect threads that
793 -- are not yet activated.
795 Self_ID
.Common
.LL
.Thread
:= 0;
797 Initialize_Cond
(Self_ID
.Common
.LL
.CV
'Access);
799 if not Single_Lock
then
800 Initialize_Lock
(Self_ID
.Common
.LL
.L
'Access, ATCB_Level
);
810 procedure Create_Task
812 Wrapper
: System
.Address
;
813 Stack_Size
: System
.Parameters
.Size_Type
;
814 Priority
: System
.Any_Priority
;
815 Succeeded
: out Boolean)
817 Initial_Stack_Size
: constant := 1024;
818 -- We set the initial stack size to 1024. On Windows version prior to XP
819 -- there is no way to fix a task stack size. Only the initial stack size
820 -- can be set, the operating system will raise the task stack size if
823 function Is_Windows_XP
return Integer;
824 pragma Import
(C
, Is_Windows_XP
, "__gnat_is_windows_xp");
825 -- Returns 1 if running on Windows XP
828 TaskId
: aliased DWORD
;
829 pTaskParameter
: System
.OS_Interface
.PVOID
;
831 Entry_Point
: PTHREAD_START_ROUTINE
;
834 pTaskParameter
:= To_Address
(T
);
836 Entry_Point
:= To_PTHREAD_START_ROUTINE
(Wrapper
);
838 if Is_Windows_XP
= 1 then
839 hTask
:= CreateThread
844 DWORD
(Create_Suspended
) or
845 DWORD
(Stack_Size_Param_Is_A_Reservation
),
846 TaskId
'Unchecked_Access);
848 hTask
:= CreateThread
853 DWORD
(Create_Suspended
),
854 TaskId
'Unchecked_Access);
857 -- Step 1: Create the thread in blocked mode
863 -- Step 2: set its TCB
865 T
.Common
.LL
.Thread
:= hTask
;
867 -- Step 3: set its priority (child has inherited priority from parent)
869 Set_Priority
(T
, Priority
);
871 if Time_Slice_Val
= 0 or else Dispatching_Policy
= 'F' then
872 -- Here we need Annex E semantics so we disable the NT priority
873 -- boost. A priority boost is temporarily given by the system to a
874 -- thread when it is taken out of a wait state.
876 SetThreadPriorityBoost
(hTask
, DisablePriorityBoost
=> True);
879 -- Step 4: Now, start it for good:
881 Result
:= ResumeThread
(hTask
);
882 pragma Assert
(Result
= 1);
884 Succeeded
:= Result
= 1;
891 procedure Finalize_TCB
(T
: Task_Id
) is
892 Self_ID
: Task_Id
:= T
;
895 Is_Self
: constant Boolean := T
= Self
;
897 procedure Free
is new
898 Unchecked_Deallocation
(Ada_Task_Control_Block
, Task_Id
);
901 if not Single_Lock
then
902 Finalize_Lock
(T
.Common
.LL
.L
'Access);
905 Finalize_Cond
(T
.Common
.LL
.CV
'Access);
907 if T
.Known_Tasks_Index
/= -1 then
908 Known_Tasks
(T
.Known_Tasks_Index
) := null;
911 if Self_ID
.Common
.LL
.Thread
/= 0 then
913 -- This task has been activated. Wait for the thread to terminate
914 -- then close it. this is needed to release system ressources.
916 Result
:= WaitForSingleObject
(T
.Common
.LL
.Thread
, Wait_Infinite
);
917 pragma Assert
(Result
/= WAIT_FAILED
);
918 Succeeded
:= CloseHandle
(T
.Common
.LL
.Thread
);
919 pragma Assert
(Succeeded
= True);
933 procedure Exit_Task
is
942 procedure Abort_Task
(T
: Task_Id
) is
943 pragma Unreferenced
(T
);
948 ----------------------
949 -- Environment_Task --
950 ----------------------
952 function Environment_Task
return Task_Id
is
954 return Environment_Task_Id
;
955 end Environment_Task
;
961 procedure Lock_RTS
is
963 Write_Lock
(Single_RTS_Lock
'Access, Global_Lock
=> True);
970 procedure Unlock_RTS
is
972 Unlock
(Single_RTS_Lock
'Access, Global_Lock
=> True);
979 procedure Initialize
(Environment_Task
: Task_Id
) is
981 pragma Unreferenced
(Discard
);
984 Environment_Task_Id
:= Environment_Task
;
985 OS_Primitives
.Initialize
;
987 if Time_Slice_Val
= 0 or else Dispatching_Policy
= 'F' then
989 -- Here we need Annex D semantics, switch the current process to the
990 -- High_Priority_Class.
993 OS_Interface
.SetPriorityClass
994 (GetCurrentProcess
, High_Priority_Class
);
996 -- ??? In theory it should be possible to use the priority class
997 -- Realtime_Prioriry_Class but we suspect a bug in the NT scheduler
998 -- which prevents (in some obscure cases) a thread to get on top of
999 -- the running queue by another thread of lower priority. For
1000 -- example cxd8002 ACATS test freeze.
1003 TlsIndex
:= TlsAlloc
;
1005 -- Initialize the lock used to synchronize chain of all ATCBs.
1007 Initialize_Lock
(Single_RTS_Lock
'Access, RTS_Lock_Level
);
1009 Environment_Task
.Common
.LL
.Thread
:= GetCurrentThread
;
1010 Enter_Task
(Environment_Task
);
1013 ---------------------
1014 -- Monotonic_Clock --
1015 ---------------------
1017 function Monotonic_Clock
return Duration
1018 renames System
.OS_Primitives
.Monotonic_Clock
;
1024 function RT_Resolution
return Duration is
1026 return 0.000_001
; -- 1 micro-second
1033 procedure Initialize
(S
: in out Suspension_Object
) is
1035 -- Initialize internal state. It is always initialized to False (ARM
1041 -- Initialize internal mutex
1043 InitializeCriticalSection
(S
.L
'Access);
1045 -- Initialize internal condition variable
1047 S
.CV
:= CreateEvent
(null, True, False, Null_Ptr
);
1048 pragma Assert
(S
.CV
/= 0);
1055 procedure Finalize
(S
: in out Suspension_Object
) is
1058 -- Destroy internal mutex
1060 DeleteCriticalSection
(S
.L
'Access);
1062 -- Destroy internal condition variable
1064 Result
:= CloseHandle
(S
.CV
);
1065 pragma Assert
(Result
= True);
1072 function Current_State
(S
: Suspension_Object
) return Boolean is
1074 -- We do not want to use lock on this read operation. State is marked
1075 -- as Atomic so that we ensure that the value retrieved is correct.
1084 procedure Set_False
(S
: in out Suspension_Object
) is
1086 EnterCriticalSection
(S
.L
'Access);
1090 LeaveCriticalSection
(S
.L
'Access);
1097 procedure Set_True
(S
: in out Suspension_Object
) is
1100 EnterCriticalSection
(S
.L
'Access);
1102 -- If there is already a task waiting on this suspension object then
1103 -- we resume it, leaving the state of the suspension object to False,
1104 -- as it is specified in ARM D.10 par. 9. Otherwise, it just leaves
1105 -- the state to True.
1111 Result
:= SetEvent
(S
.CV
);
1112 pragma Assert
(Result
= True);
1117 LeaveCriticalSection
(S
.L
'Access);
1120 ------------------------
1121 -- Suspend_Until_True --
1122 ------------------------
1124 procedure Suspend_Until_True
(S
: in out Suspension_Object
) is
1128 EnterCriticalSection
(S
.L
'Access);
1131 -- Program_Error must be raised upon calling Suspend_Until_True
1132 -- if another task is already waiting on that suspension object
1133 -- (ARM D.10 par. 10).
1135 LeaveCriticalSection
(S
.L
'Access);
1137 raise Program_Error
;
1139 -- Suspend the task if the state is False. Otherwise, the task
1140 -- continues its execution, and the state of the suspension object
1141 -- is set to False (ARM D.10 par. 9).
1146 LeaveCriticalSection
(S
.L
'Access);
1150 -- Must reset CV BEFORE L is unlocked.
1152 Result_Bool
:= ResetEvent
(S
.CV
);
1153 pragma Assert
(Result_Bool
= True);
1155 LeaveCriticalSection
(S
.L
'Access);
1157 Result
:= WaitForSingleObject
(S
.CV
, Wait_Infinite
);
1158 pragma Assert
(Result
= 0);
1161 end Suspend_Until_True
;
1167 -- Dummy versions. The only currently working versions is for solaris
1170 function Check_Exit
(Self_ID
: ST
.Task_Id
) return Boolean is
1171 pragma Unreferenced
(Self_ID
);
1176 --------------------
1177 -- Check_No_Locks --
1178 --------------------
1180 function Check_No_Locks
(Self_ID
: ST
.Task_Id
) return Boolean is
1181 pragma Unreferenced
(Self_ID
);
1190 function Suspend_Task
1192 Thread_Self
: Thread_Id
) return Boolean
1195 if T
.Common
.LL
.Thread
/= Thread_Self
then
1196 return SuspendThread
(T
.Common
.LL
.Thread
) = NO_ERROR
;
1206 function Resume_Task
1208 Thread_Self
: Thread_Id
) return Boolean
1211 if T
.Common
.LL
.Thread
/= Thread_Self
then
1212 return ResumeThread
(T
.Common
.LL
.Thread
) = NO_ERROR
;
1218 end System
.Task_Primitives
.Operations
;