gcc/ada/5wtaprop.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                GNU ADA RUN-TIME LIBRARY (GNARL) COMPONENTS               --
   4 --                                                                          --
   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    --
   6 --                                                                          --
   7 --                                  B o d y                                 --
   8 --                                                                          --
   9 --                                                                          --
  10 --         Copyright (C) 1992-2002, Free Software Foundation, Inc.          --
  11 --                                                                          --
  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,  59 Temple Place - Suite 330,  Boston, --
  21 -- MA 02111-1307, USA.                                                      --
  22 --                                                                          --
  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.                                      --
  29 --                                                                          --
  30 -- GNARL was developed by the GNARL team at Florida State University. It is --
  31 -- now maintained by Ada Core Technologies, Inc. (http://www.gnat.com).     --
  32 --                                                                          --
  33 ------------------------------------------------------------------------------
  34
  35 --  This is a NT (native) version of this package.
  36
  37 --  This package contains all the GNULL primitives that interface directly
  38 --  with the underlying OS.
  39
  40 pragma Polling (Off);
  41 --  Turn off polling, we do not want ATC polling to take place during
  42 --  tasking operations. It causes infinite loops and other problems.
  43
  44 with System.Tasking.Debug;
  45 --  used for Known_Tasks
  46
  47 with Interfaces.C;
  48 --  used for int
  49 --           size_t
  50
  51 with Interfaces.C.Strings;
  52 --  used for Null_Ptr
  53
  54 with System.OS_Interface;
  55 --  used for various type, constant, and operations
  56
  57 with System.Parameters;
  58 --  used for Size_Type
  59
  60 with System.Tasking;
  61 --  used for Ada_Task_Control_Block
  62 --           Task_ID
  63
  64 with System.Soft_Links;
  65 --  used for Defer/Undefer_Abort
  66 --       to initialize TSD for a C thread, in function Self
  67
  68 --  Note that we do not use System.Tasking.Initialization directly since
  69 --  this is a higher level package that we shouldn't depend on. For example
  70 --  when using the restricted run time, it is replaced by
  71 --  System.Tasking.Restricted.Initialization
  72
  73 with System.OS_Primitives;
  74 --  used for Delay_Modes
  75
  76 with System.Task_Info;
  77 --  used for Unspecified_Task_Info
  78
  79 with Unchecked_Conversion;
  80 with Unchecked_Deallocation;
  81
  82 package body System.Task_Primitives.Operations is
  83
  84    use System.Tasking.Debug;
  85    use System.Tasking;
  86    use Interfaces.C;
  87    use Interfaces.C.Strings;
  88    use System.OS_Interface;
  89    use System.Parameters;
  90    use System.OS_Primitives;
  91
  92    pragma Link_With ("-Xlinker --stack=0x800000,0x1000");
  93    --  Change the stack size (8 MB) for tasking programs on Windows. This
  94    --  permit to have more than 30 tasks running at the same time. Note that
  95    --  we set the stack size for non tasking programs on System unit.
  96
  97    package SSL renames System.Soft_Links;
  98
  99    ------------------
 100    --  Local Data  --
 101    ------------------
 102
 103    Environment_Task_ID : Task_ID;
 104    --  A variable to hold Task_ID for the environment task.
 105
 106    Single_RTS_Lock : aliased RTS_Lock;
 107    --  This is a lock to allow only one thread of control in the RTS at
 108    --  a time; it is used to execute in mutual exclusion from all other tasks.
 109    --  Used mainly in Single_Lock mode, but also to protect All_Tasks_List
 110
 111    Time_Slice_Val : Integer;
 112    pragma Import (C, Time_Slice_Val, "__gl_time_slice_val");
 113
 114    Dispatching_Policy : Character;
 115    pragma Import (C, Dispatching_Policy, "__gl_task_dispatching_policy");
 116
 117    FIFO_Within_Priorities : constant Boolean := Dispatching_Policy = 'F';
 118    --  Indicates whether FIFO_Within_Priorities is set.
 119
 120    ---------------------------------
 121    --  Foreign Threads Detection  --
 122    ---------------------------------
 123
 124    --  The following are used to allow the Self function to
 125    --  automatically generate ATCB's for C threads that happen to call
 126    --  Ada procedure, which in turn happen to call the Ada run-time system.
 127
 128    type Fake_ATCB;
 129    type Fake_ATCB_Ptr is access Fake_ATCB;
 130    type Fake_ATCB is record
 131       Stack_Base : Interfaces.C.unsigned := 0;
 132       --  A value of zero indicates the node is not in use.
 133       Next       : Fake_ATCB_Ptr;
 134       Real_ATCB  : aliased Ada_Task_Control_Block (0);
 135    end record;
 136
 137    Fake_ATCB_List : Fake_ATCB_Ptr;
 138    --  A linear linked list.
 139    --  The list is protected by Single_RTS_Lock;
 140    --  Nodes are added to this list from the front.
 141    --  Once a node is added to this list, it is never removed.
 142
 143    Fake_Task_Elaborated : aliased Boolean := True;
 144    --  Used to identified fake tasks (i.e., non-Ada Threads).
 145
 146    Next_Fake_ATCB : Fake_ATCB_Ptr;
 147    --  Used to allocate one Fake_ATCB in advance. See comment in New_Fake_ATCB
 148
 149    ---------------------------------
 150    --  Support for New_Fake_ATCB  --
 151    ---------------------------------
 152
 153    function New_Fake_ATCB return Task_ID;
 154    --  Allocate and Initialize a new ATCB. This code can safely be called from
 155    --  a foreign thread, as it doesn't access implicitly or explicitly
 156    --  "self" before having initialized the new ATCB.
 157
 158    ------------------------------------
 159    -- The thread local storage index --
 160    ------------------------------------
 161
 162    TlsIndex : DWORD;
 163    pragma Export (Ada, TlsIndex);
 164    --  To ensure that this variable won't be local to this package, since
 165    --  in some cases, inlining forces this variable to be global anyway.
 166
 167    ----------------------------------
 168    -- Utility Conversion Functions --
 169    ----------------------------------
 170
 171    function To_Task_Id is new Unchecked_Conversion (System.Address, Task_ID);
 172
 173    function To_Address is new Unchecked_Conversion (Task_ID, System.Address);
 174
 175    -------------------
 176    -- New_Fake_ATCB --
 177    -------------------
 178
 179    function New_Fake_ATCB return Task_ID is
 180       Self_ID   : Task_ID;
 181       P, Q      : Fake_ATCB_Ptr;
 182       Succeeded : Boolean;
 183       Res       : BOOL;
 184
 185    begin
 186       --  This section is ticklish.
 187       --  We dare not call anything that might require an ATCB, until
 188       --  we have the new ATCB in place.
 189
 190       Lock_RTS;
 191       Q := null;
 192       P := Fake_ATCB_List;
 193
 194       while P /= null loop
 195          if P.Stack_Base = 0 then
 196             Q := P;
 197          end if;
 198
 199          P := P.Next;
 200       end loop;
 201
 202       if Q = null then
 203
 204          --  Create a new ATCB with zero entries.
 205
 206          Self_ID := Next_Fake_ATCB.Real_ATCB'Access;
 207          Next_Fake_ATCB.Stack_Base := 1;
 208          Next_Fake_ATCB.Next := Fake_ATCB_List;
 209          Fake_ATCB_List := Next_Fake_ATCB;
 210          Next_Fake_ATCB := null;
 211
 212       else
 213          --  Reuse an existing fake ATCB.
 214
 215          Self_ID := Q.Real_ATCB'Access;
 216          Q.Stack_Base := 1;
 217       end if;
 218
 219       --  Record this as the Task_ID for the current thread.
 220
 221       Self_ID.Common.LL.Thread := GetCurrentThread;
 222
 223       Res := TlsSetValue (TlsIndex, To_Address (Self_ID));
 224       pragma Assert (Res = True);
 225
 226       --  Do the standard initializations
 227
 228       System.Tasking.Initialize_ATCB
 229         (Self_ID, null, Null_Address, Null_Task, Fake_Task_Elaborated'Access,
 230          System.Priority'First, Task_Info.Unspecified_Task_Info, 0, Self_ID,
 231          Succeeded);
 232       pragma Assert (Succeeded);
 233
 234       --  Finally, it is safe to use an allocator in this thread.
 235
 236       if Next_Fake_ATCB = null then
 237          Next_Fake_ATCB := new Fake_ATCB;
 238       end if;
 239
 240       Self_ID.Master_of_Task := 0;
 241       Self_ID.Master_Within := Self_ID.Master_of_Task + 1;
 242
 243       for L in Self_ID.Entry_Calls'Range loop
 244          Self_ID.Entry_Calls (L).Self := Self_ID;
 245          Self_ID.Entry_Calls (L).Level := L;
 246       end loop;
 247
 248       Self_ID.Common.State := Runnable;
 249       Self_ID.Awake_Count := 1;
 250
 251       --  Since this is not an ordinary Ada task, we will start out undeferred
 252
 253       Self_ID.Deferral_Level := 0;
 254
 255       System.Soft_Links.Create_TSD (Self_ID.Common.Compiler_Data);
 256
 257       --  ????
 258       --  The following call is commented out to avoid dependence on
 259       --  the System.Tasking.Initialization package.
 260       --  It seems that if we want Ada.Task_Attributes to work correctly
 261       --  for C threads we will need to raise the visibility of this soft
 262       --  link to System.Soft_Links.
 263       --  We are putting that off until this new functionality is otherwise
 264       --  stable.
 265       --  System.Tasking.Initialization.Initialize_Attributes_Link.all (T);
 266
 267       --  Must not unlock until Next_ATCB is again allocated.
 268
 269       Unlock_RTS;
 270       return Self_ID;
 271    end New_Fake_ATCB;
 272
 273    ----------------------------------
 274    -- Condition Variable Functions --
 275    ----------------------------------
 276
 277    procedure Initialize_Cond (Cond : access Condition_Variable);
 278    --  Initialize given condition variable Cond
 279
 280    procedure Finalize_Cond (Cond : access Condition_Variable);
 281    --  Finalize given condition variable Cond.
 282
 283    procedure Cond_Signal (Cond : access Condition_Variable);
 284    --  Signal condition variable Cond
 285
 286    procedure Cond_Wait
 287      (Cond : access Condition_Variable;
 288       L    : access RTS_Lock);
 289    --  Wait on conditional variable Cond, using lock L
 290
 291    procedure Cond_Timed_Wait
 292      (Cond      : access Condition_Variable;
 293       L         : access RTS_Lock;
 294       Rel_Time  : Duration;
 295       Timed_Out : out Boolean;
 296       Status    : out Integer);
 297    --  Do timed wait on condition variable Cond using lock L. The duration
 298    --  of the timed wait is given by Rel_Time. When the condition is
 299    --  signalled, Timed_Out shows whether or not a time out occurred.
 300    --  Status shows whether Cond_Timed_Wait completed successfully.
 301
 302    ---------------------
 303    -- Initialize_Cond --
 304    ---------------------
 305
 306    procedure Initialize_Cond (Cond : access Condition_Variable) is
 307       hEvent : HANDLE;
 308
 309    begin
 310       hEvent := CreateEvent (null, True, False, Null_Ptr);
 311       pragma Assert (hEvent /= 0);
 312       Cond.all := Condition_Variable (hEvent);
 313    end Initialize_Cond;
 314
 315    -------------------
 316    -- Finalize_Cond --
 317    -------------------
 318
 319    --  No such problem here, DosCloseEventSem has been derived.
 320    --  What does such refer to in above comment???
 321
 322    procedure Finalize_Cond (Cond : access Condition_Variable) is
 323       Result : BOOL;
 324
 325    begin
 326       Result := CloseHandle (HANDLE (Cond.all));
 327       pragma Assert (Result = True);
 328    end Finalize_Cond;
 329
 330    -----------------
 331    -- Cond_Signal --
 332    -----------------
 333
 334    procedure Cond_Signal (Cond : access Condition_Variable) is
 335       Result : BOOL;
 336
 337    begin
 338       Result := SetEvent (HANDLE (Cond.all));
 339       pragma Assert (Result = True);
 340    end Cond_Signal;
 341
 342    ---------------
 343    -- Cond_Wait --
 344    ---------------
 345
 346    --  Pre-assertion: Cond is posted
 347    --                 L is locked.
 348
 349    --  Post-assertion: Cond is posted
 350    --                  L is locked.
 351
 352    procedure Cond_Wait
 353      (Cond : access Condition_Variable;
 354       L    : access RTS_Lock)
 355    is
 356       Result      : DWORD;
 357       Result_Bool : BOOL;
 358
 359    begin
 360       --  Must reset Cond BEFORE L is unlocked.
 361
 362       Result_Bool := ResetEvent (HANDLE (Cond.all));
 363       pragma Assert (Result_Bool = True);
 364       Unlock (L);
 365
 366       --  No problem if we are interrupted here: if the condition is signaled,
 367       --  WaitForSingleObject will simply not block
 368
 369       Result := WaitForSingleObject (HANDLE (Cond.all), Wait_Infinite);
 370       pragma Assert (Result = 0);
 371
 372       Write_Lock (L);
 373    end Cond_Wait;
 374
 375    ---------------------
 376    -- Cond_Timed_Wait --
 377    ---------------------
 378
 379    --  Pre-assertion: Cond is posted
 380    --                 L is locked.
 381
 382    --  Post-assertion: Cond is posted
 383    --                  L is locked.
 384
 385    procedure Cond_Timed_Wait
 386      (Cond      : access Condition_Variable;
 387       L         : access RTS_Lock;
 388       Rel_Time  : Duration;
 389       Timed_Out : out Boolean;
 390       Status    : out Integer)
 391    is
 392       Time_Out : DWORD;
 393       Result   : BOOL;
 394
 395       Int_Rel_Time : DWORD;
 396       Wait_Result  : DWORD;
 397
 398    begin
 399       --  Must reset Cond BEFORE L is unlocked.
 400
 401       Result := ResetEvent (HANDLE (Cond.all));
 402       pragma Assert (Result = True);
 403       Unlock (L);
 404
 405       --  No problem if we are interrupted here: if the condition is signaled,
 406       --  WaitForSingleObject will simply not block
 407
 408       if Rel_Time <= 0.0 then
 409          Timed_Out := True;
 410       else
 411          Int_Rel_Time := DWORD (Rel_Time);
 412          Time_Out := Int_Rel_Time * 1000 +
 413                      DWORD ((Rel_Time - Duration (Int_Rel_Time)) * 1000.0);
 414          Wait_Result := WaitForSingleObject (HANDLE (Cond.all), Time_Out);
 415
 416          if Wait_Result = WAIT_TIMEOUT then
 417             Timed_Out := True;
 418             Wait_Result := 0;
 419          else
 420             Timed_Out := False;
 421          end if;
 422       end if;
 423
 424       Write_Lock (L);
 425
 426       --  Ensure post-condition
 427
 428       if Timed_Out then
 429          Result := SetEvent (HANDLE (Cond.all));
 430          pragma Assert (Result = True);
 431       end if;
 432
 433       Status := Integer (Wait_Result);
 434    end Cond_Timed_Wait;
 435
 436    ------------------
 437    -- Stack_Guard  --
 438    ------------------
 439
 440    --  The underlying thread system sets a guard page at the
 441    --  bottom of a thread stack, so nothing is needed.
 442    --  ??? Check the comment above
 443
 444    procedure Stack_Guard (T : ST.Task_ID; On : Boolean) is
 445    begin
 446       null;
 447    end Stack_Guard;
 448
 449    --------------------
 450    -- Get_Thread_Id  --
 451    --------------------
 452
 453    function Get_Thread_Id (T : ST.Task_ID) return OSI.Thread_Id is
 454    begin
 455       return T.Common.LL.Thread;
 456    end Get_Thread_Id;
 457
 458    ----------
 459    -- Self --
 460    ----------
 461
 462    function Self return Task_ID is
 463       Self_Id : Task_ID;
 464
 465    begin
 466       Self_Id := To_Task_Id (TlsGetValue (TlsIndex));
 467
 468       if Self_Id = null then
 469          return New_Fake_ATCB;
 470       end if;
 471
 472       return Self_Id;
 473    end Self;
 474
 475    ---------------------
 476    -- Initialize_Lock --
 477    ---------------------
 478
 479    --  Note: mutexes and cond_variables needed per-task basis are
 480    --  initialized in Initialize_TCB and the Storage_Error is handled.
 481    --  Other mutexes (such as RTS_Lock, Memory_Lock...) used in
 482    --  the RTS is initialized before any status change of RTS.
 483    --  Therefore raising Storage_Error in the following routines
 484    --  should be able to be handled safely.
 485
 486    procedure Initialize_Lock
 487      (Prio : System.Any_Priority;
 488       L    : access Lock) is
 489    begin
 490       InitializeCriticalSection (L.Mutex'Access);
 491       L.Owner_Priority := 0;
 492       L.Priority := Prio;
 493    end Initialize_Lock;
 494
 495    procedure Initialize_Lock (L : access RTS_Lock; Level : Lock_Level) is
 496    begin
 497       InitializeCriticalSection (CRITICAL_SECTION (L.all)'Unrestricted_Access);
 498    end Initialize_Lock;
 499
 500    -------------------
 501    -- Finalize_Lock --
 502    -------------------
 503
 504    procedure Finalize_Lock (L : access Lock) is
 505    begin
 506       DeleteCriticalSection (L.Mutex'Access);
 507    end Finalize_Lock;
 508
 509    procedure Finalize_Lock (L : access RTS_Lock) is
 510    begin
 511       DeleteCriticalSection (CRITICAL_SECTION (L.all)'Unrestricted_Access);
 512    end Finalize_Lock;
 513
 514    ----------------
 515    -- Write_Lock --
 516    ----------------
 517
 518    procedure Write_Lock (L : access Lock; Ceiling_Violation : out Boolean) is
 519    begin
 520       L.Owner_Priority := Get_Priority (Self);
 521
 522       if L.Priority < L.Owner_Priority then
 523          Ceiling_Violation := True;
 524          return;
 525       end if;
 526
 527       EnterCriticalSection (L.Mutex'Access);
 528
 529       Ceiling_Violation := False;
 530    end Write_Lock;
 531
 532    procedure Write_Lock
 533      (L : access RTS_Lock; Global_Lock : Boolean := False) is
 534    begin
 535       if not Single_Lock or else Global_Lock then
 536          EnterCriticalSection (CRITICAL_SECTION (L.all)'Unrestricted_Access);
 537       end if;
 538    end Write_Lock;
 539
 540    procedure Write_Lock (T : Task_ID) is
 541    begin
 542       if not Single_Lock then
 543          EnterCriticalSection
 544            (CRITICAL_SECTION (T.Common.LL.L)'Unrestricted_Access);
 545       end if;
 546    end Write_Lock;
 547
 548    ---------------
 549    -- Read_Lock --
 550    ---------------
 551
 552    procedure Read_Lock (L : access Lock; Ceiling_Violation : out Boolean) is
 553    begin
 554       Write_Lock (L, Ceiling_Violation);
 555    end Read_Lock;
 556
 557    ------------
 558    -- Unlock --
 559    ------------
 560
 561    procedure Unlock (L : access Lock) is
 562    begin
 563       LeaveCriticalSection (L.Mutex'Access);
 564    end Unlock;
 565
 566    procedure Unlock (L : access RTS_Lock; Global_Lock : Boolean := False) is
 567    begin
 568       if not Single_Lock or else Global_Lock then
 569          LeaveCriticalSection (CRITICAL_SECTION (L.all)'Unrestricted_Access);
 570       end if;
 571    end Unlock;
 572
 573    procedure Unlock (T : Task_ID) is
 574    begin
 575       if not Single_Lock then
 576          LeaveCriticalSection
 577            (CRITICAL_SECTION (T.Common.LL.L)'Unrestricted_Access);
 578       end if;
 579    end Unlock;
 580
 581    -----------
 582    -- Sleep --
 583    -----------
 584
 585    procedure Sleep
 586      (Self_ID : Task_ID;
 587       Reason  : System.Tasking.Task_States) is
 588    begin
 589       pragma Assert (Self_ID = Self);
 590
 591       if Single_Lock then
 592          Cond_Wait (Self_ID.Common.LL.CV'Access, Single_RTS_Lock'Access);
 593       else
 594          Cond_Wait (Self_ID.Common.LL.CV'Access, Self_ID.Common.LL.L'Access);
 595       end if;
 596
 597       if Self_ID.Deferral_Level = 0
 598         and then Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level
 599       then
 600          Unlock (Self_ID);
 601          raise Standard'Abort_Signal;
 602       end if;
 603    end Sleep;
 604
 605    -----------------
 606    -- Timed_Sleep --
 607    -----------------
 608
 609    --  This is for use within the run-time system, so abort is
 610    --  assumed to be already deferred, and the caller should be
 611    --  holding its own ATCB lock.
 612
 613    procedure Timed_Sleep
 614      (Self_ID  : Task_ID;
 615       Time     : Duration;
 616       Mode     : ST.Delay_Modes;
 617       Reason   : System.Tasking.Task_States;
 618       Timedout : out Boolean;
 619       Yielded  : out Boolean)
 620    is
 621       Check_Time : constant Duration := Monotonic_Clock;
 622       Rel_Time   : Duration;
 623       Abs_Time   : Duration;
 624       Result     : Integer;
 625
 626       Local_Timedout : Boolean;
 627
 628    begin
 629       Timedout := True;
 630       Yielded  := False;
 631
 632       if Mode = Relative then
 633          Rel_Time := Time;
 634          Abs_Time := Duration'Min (Time, Max_Sensible_Delay) + Check_Time;
 635       else
 636          Rel_Time := Time - Check_Time;
 637          Abs_Time := Time;
 638       end if;
 639
 640       if Rel_Time > 0.0 then
 641          loop
 642             exit when Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level
 643               or else Self_ID.Pending_Priority_Change;
 644
 645             if Single_Lock then
 646                Cond_Timed_Wait (Self_ID.Common.LL.CV'Access,
 647                  Single_RTS_Lock'Access, Rel_Time, Local_Timedout, Result);
 648             else
 649                Cond_Timed_Wait (Self_ID.Common.LL.CV'Access,
 650                  Self_ID.Common.LL.L'Access, Rel_Time, Local_Timedout, Result);
 651             end if;
 652
 653             exit when Abs_Time <= Monotonic_Clock;
 654
 655             if not Local_Timedout then
 656                --  somebody may have called Wakeup for us
 657                Timedout := False;
 658                exit;
 659             end if;
 660
 661             Rel_Time := Abs_Time - Monotonic_Clock;
 662          end loop;
 663       end if;
 664    end Timed_Sleep;
 665
 666    -----------------
 667    -- Timed_Delay --
 668    -----------------
 669
 670    procedure Timed_Delay
 671      (Self_ID  : Task_ID;
 672       Time     : Duration;
 673       Mode     : ST.Delay_Modes)
 674    is
 675       Check_Time : constant Duration := Monotonic_Clock;
 676       Rel_Time   : Duration;
 677       Abs_Time   : Duration;
 678       Result     : Integer;
 679       Timedout   : Boolean;
 680
 681    begin
 682       --  Only the little window between deferring abort and
 683       --  locking Self_ID is the reason we need to
 684       --  check for pending abort and priority change below!
 685
 686       SSL.Abort_Defer.all;
 687
 688       if Single_Lock then
 689          Lock_RTS;
 690       end if;
 691
 692       Write_Lock (Self_ID);
 693
 694       if Mode = Relative then
 695          Rel_Time := Time;
 696          Abs_Time := Time + Check_Time;
 697       else
 698          Rel_Time := Time - Check_Time;
 699          Abs_Time := Time;
 700       end if;
 701
 702       if Rel_Time > 0.0 then
 703          Self_ID.Common.State := Delay_Sleep;
 704
 705          loop
 706             if Self_ID.Pending_Priority_Change then
 707                Self_ID.Pending_Priority_Change := False;
 708                Self_ID.Common.Base_Priority := Self_ID.New_Base_Priority;
 709                Set_Priority (Self_ID, Self_ID.Common.Base_Priority);
 710             end if;
 711
 712             exit when Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level;
 713
 714             if Single_Lock then
 715                Cond_Timed_Wait (Self_ID.Common.LL.CV'Access,
 716                  Single_RTS_Lock'Access, Rel_Time, Timedout, Result);
 717             else
 718                Cond_Timed_Wait (Self_ID.Common.LL.CV'Access,
 719                  Self_ID.Common.LL.L'Access, Rel_Time, Timedout, Result);
 720             end if;
 721
 722             exit when Abs_Time <= Monotonic_Clock;
 723
 724             Rel_Time := Abs_Time - Monotonic_Clock;
 725          end loop;
 726
 727          Self_ID.Common.State := Runnable;
 728       end if;
 729
 730       Unlock (Self_ID);
 731
 732       if Single_Lock then
 733          Unlock_RTS;
 734       end if;
 735
 736       Yield;
 737       SSL.Abort_Undefer.all;
 738    end Timed_Delay;
 739
 740    ------------
 741    -- Wakeup --
 742    ------------
 743
 744    procedure Wakeup (T : Task_ID; Reason : System.Tasking.Task_States) is
 745    begin
 746       Cond_Signal (T.Common.LL.CV'Access);
 747    end Wakeup;
 748
 749    -----------
 750    -- Yield --
 751    -----------
 752
 753    procedure Yield (Do_Yield : Boolean := True) is
 754    begin
 755       if Do_Yield then
 756          Sleep (0);
 757       end if;
 758    end Yield;
 759
 760    ------------------
 761    -- Set_Priority --
 762    ------------------
 763
 764    type Prio_Array_Type is array (System.Any_Priority) of Integer;
 765    pragma Atomic_Components (Prio_Array_Type);
 766
 767    Prio_Array : Prio_Array_Type;
 768    --  Global array containing the id of the currently running task for
 769    --  each priority.
 770    --
 771    --  Note: we assume that we are on a single processor with run-til-blocked
 772    --  scheduling.
 773
 774    procedure Set_Priority
 775      (T : Task_ID;
 776       Prio : System.Any_Priority;
 777       Loss_Of_Inheritance : Boolean := False)
 778    is
 779       Res        : BOOL;
 780       Array_Item : Integer;
 781
 782    begin
 783       Res := SetThreadPriority
 784         (T.Common.LL.Thread, Interfaces.C.int (Underlying_Priorities (Prio)));
 785       pragma Assert (Res = True);
 786
 787       --  ??? Work around a bug in NT 4.0 SP3 scheduler
 788       --  It looks like when a task with Thread_Priority_Idle (using RT class)
 789       --  never reaches its time slice (e.g by doing multiple and simple RV,
 790       --  see CXD8002), the scheduler never gives higher priority task a
 791       --  chance to run.
 792       --  Note that this works fine on NT 4.0 SP1
 793
 794       if Time_Slice_Val = 0
 795         and then Underlying_Priorities (Prio) = Thread_Priority_Idle
 796         and then Loss_Of_Inheritance
 797       then
 798          Sleep (20);
 799       end if;
 800
 801       if FIFO_Within_Priorities then
 802
 803          --  Annex D requirement [RM D.2.2 par. 9]:
 804          --    If the task drops its priority due to the loss of inherited
 805          --    priority, it is added at the head of the ready queue for its
 806          --    new active priority.
 807
 808          if Loss_Of_Inheritance
 809            and then Prio < T.Common.Current_Priority
 810          then
 811             Array_Item := Prio_Array (T.Common.Base_Priority) + 1;
 812             Prio_Array (T.Common.Base_Priority) := Array_Item;
 813
 814             loop
 815                --  Let some processes a chance to arrive
 816
 817                Yield;
 818
 819                --  Then wait for our turn to proceed
 820
 821                exit when Array_Item = Prio_Array (T.Common.Base_Priority)
 822                  or else Prio_Array (T.Common.Base_Priority) = 1;
 823             end loop;
 824
 825             Prio_Array (T.Common.Base_Priority) :=
 826               Prio_Array (T.Common.Base_Priority) - 1;
 827          end if;
 828       end if;
 829
 830       T.Common.Current_Priority := Prio;
 831    end Set_Priority;
 832
 833    ------------------
 834    -- Get_Priority --
 835    ------------------
 836
 837    function Get_Priority (T : Task_ID) return System.Any_Priority is
 838    begin
 839       return T.Common.Current_Priority;
 840    end Get_Priority;
 841
 842    ----------------
 843    -- Enter_Task --
 844    ----------------
 845
 846    --  There were two paths were we needed to call Enter_Task :
 847    --  1) from System.Task_Primitives.Operations.Initialize
 848    --  2) from System.Tasking.Stages.Task_Wrapper
 849    --
 850    --  The thread initialisation has to be done only for the first case.
 851    --
 852    --  This is because the GetCurrentThread NT call does not return the
 853    --  real thread handler but only a "pseudo" one. It is not possible to
 854    --  release the thread handle and free the system ressources from this
 855    --  "pseudo" handle. So we really want to keep the real thread handle
 856    --  set in System.Task_Primitives.Operations.Create_Task during the
 857    --  thread creation.
 858
 859    procedure Enter_Task (Self_ID : Task_ID) is
 860       procedure Init_Float;
 861       pragma Import (C, Init_Float, "__gnat_init_float");
 862       --  Properly initializes the FPU for x86 systems.
 863
 864       Succeeded : BOOL;
 865
 866    begin
 867       Succeeded := TlsSetValue (TlsIndex, To_Address (Self_ID));
 868       pragma Assert (Succeeded = True);
 869       Init_Float;
 870
 871       Self_ID.Common.LL.Thread_Id := GetCurrentThreadId;
 872
 873       Lock_RTS;
 874
 875       for J in Known_Tasks'Range loop
 876          if Known_Tasks (J) = null then
 877             Known_Tasks (J) := Self_ID;
 878             Self_ID.Known_Tasks_Index := J;
 879             exit;
 880          end if;
 881       end loop;
 882
 883       Unlock_RTS;
 884    end Enter_Task;
 885
 886    --------------
 887    -- New_ATCB --
 888    --------------
 889
 890    function New_ATCB (Entry_Num : Task_Entry_Index) return Task_ID is
 891    begin
 892       return new Ada_Task_Control_Block (Entry_Num);
 893    end New_ATCB;
 894
 895    --------------------
 896    -- Initialize_TCB --
 897    --------------------
 898
 899    procedure Initialize_TCB (Self_ID : Task_ID; Succeeded : out Boolean) is
 900    begin
 901       Initialize_Cond (Self_ID.Common.LL.CV'Access);
 902
 903       if not Single_Lock then
 904          Initialize_Lock (Self_ID.Common.LL.L'Access, ATCB_Level);
 905       end if;
 906
 907       Succeeded := True;
 908    end Initialize_TCB;
 909
 910    -----------------
 911    -- Create_Task --
 912    -----------------
 913
 914    procedure Create_Task
 915      (T          : Task_ID;
 916       Wrapper    : System.Address;
 917       Stack_Size : System.Parameters.Size_Type;
 918       Priority   : System.Any_Priority;
 919       Succeeded  : out Boolean)
 920    is
 921       hTask          : HANDLE;
 922       TaskId         : aliased DWORD;
 923       pTaskParameter : System.OS_Interface.PVOID;
 924       dwStackSize    : DWORD;
 925       Result         : DWORD;
 926       Entry_Point    : PTHREAD_START_ROUTINE;
 927
 928       function To_PTHREAD_START_ROUTINE is new
 929         Unchecked_Conversion (System.Address, PTHREAD_START_ROUTINE);
 930
 931    begin
 932       pTaskParameter := To_Address (T);
 933
 934       if Stack_Size = Unspecified_Size then
 935          dwStackSize := DWORD (Default_Stack_Size);
 936
 937       elsif Stack_Size < Minimum_Stack_Size then
 938          dwStackSize := DWORD (Minimum_Stack_Size);
 939
 940       else
 941          dwStackSize := DWORD (Stack_Size);
 942       end if;
 943
 944       Entry_Point := To_PTHREAD_START_ROUTINE (Wrapper);
 945
 946       hTask := CreateThread
 947          (null,
 948           dwStackSize,
 949           Entry_Point,
 950           pTaskParameter,
 951           DWORD (Create_Suspended),
 952           TaskId'Unchecked_Access);
 953
 954       --  Step 1: Create the thread in blocked mode
 955
 956       if hTask = 0 then
 957          raise Storage_Error;
 958       end if;
 959
 960       --  Step 2: set its TCB
 961
 962       T.Common.LL.Thread := hTask;
 963
 964       --  Step 3: set its priority (child has inherited priority from parent)
 965
 966       Set_Priority (T, Priority);
 967
 968       --  Step 4: Now, start it for good:
 969
 970       Result := ResumeThread (hTask);
 971       pragma Assert (Result = 1);
 972
 973       Succeeded := Result = 1;
 974    end Create_Task;
 975
 976    ------------------
 977    -- Finalize_TCB --
 978    ------------------
 979
 980    procedure Finalize_TCB (T : Task_ID) is
 981       Self_ID   : Task_ID := T;
 982       Result    : DWORD;
 983       Succeeded : BOOL;
 984
 985       procedure Free is new
 986         Unchecked_Deallocation (Ada_Task_Control_Block, Task_ID);
 987
 988    begin
 989       if not Single_Lock then
 990          Finalize_Lock (T.Common.LL.L'Access);
 991       end if;
 992
 993       Finalize_Cond (T.Common.LL.CV'Access);
 994
 995       if T.Known_Tasks_Index /= -1 then
 996          Known_Tasks (T.Known_Tasks_Index) := null;
 997       end if;
 998
 999       --  Wait for the thread to terminate then close it. this is needed
1000       --  to release system ressources.
1001
1002       Result := WaitForSingleObject (T.Common.LL.Thread, Wait_Infinite);
1003       pragma Assert (Result /= WAIT_FAILED);
1004       Succeeded := CloseHandle (T.Common.LL.Thread);
1005       pragma Assert (Succeeded = True);
1006
1007       Free (Self_ID);
1008    end Finalize_TCB;
1009
1010    ---------------
1011    -- Exit_Task --
1012    ---------------
1013
1014    procedure Exit_Task is
1015    begin
1016       ExitThread (0);
1017    end Exit_Task;
1018
1019    ----------------
1020    -- Abort_Task --
1021    ----------------
1022
1023    procedure Abort_Task (T : Task_ID) is
1024    begin
1025       null;
1026    end Abort_Task;
1027
1028    ----------------------
1029    -- Environment_Task --
1030    ----------------------
1031
1032    function Environment_Task return Task_ID is
1033    begin
1034       return Environment_Task_ID;
1035    end Environment_Task;
1036
1037    --------------
1038    -- Lock_RTS --
1039    --------------
1040
1041    procedure Lock_RTS is
1042    begin
1043       Write_Lock (Single_RTS_Lock'Access, Global_Lock => True);
1044    end Lock_RTS;
1045
1046    ----------------
1047    -- Unlock_RTS --
1048    ----------------
1049
1050    procedure Unlock_RTS is
1051    begin
1052       Unlock (Single_RTS_Lock'Access, Global_Lock => True);
1053    end Unlock_RTS;
1054
1055    ----------------
1056    -- Initialize --
1057    ----------------
1058
1059    procedure Initialize (Environment_Task : Task_ID) is
1060       Res : BOOL;
1061    begin
1062       Environment_Task_ID := Environment_Task;
1063
1064       if Time_Slice_Val = 0 or else FIFO_Within_Priorities then
1065          Res := OS_Interface.SetPriorityClass
1066            (GetCurrentProcess, Realtime_Priority_Class);
1067       end if;
1068
1069       TlsIndex := TlsAlloc;
1070
1071       --  Initialize the lock used to synchronize chain of all ATCBs.
1072
1073       Initialize_Lock (Single_RTS_Lock'Access, RTS_Lock_Level);
1074
1075       Environment_Task.Common.LL.Thread := GetCurrentThread;
1076       Enter_Task (Environment_Task);
1077
1078       --  Create a free ATCB for use on the Fake_ATCB_List
1079
1080       Next_Fake_ATCB := new Fake_ATCB;
1081    end Initialize;
1082
1083    ---------------------
1084    -- Monotonic_Clock --
1085    ---------------------
1086
1087    function Monotonic_Clock return Duration
1088      renames System.OS_Primitives.Monotonic_Clock;
1089
1090    -------------------
1091    -- RT_Resolution --
1092    -------------------
1093
1094    function RT_Resolution return Duration is
1095    begin
1096       return 0.000_001; --  1 micro-second
1097    end RT_Resolution;
1098
1099    ----------------
1100    -- Check_Exit --
1101    ----------------
1102
1103    --  Dummy versions.  The only currently working versions is for solaris
1104    --  (native).
1105
1106    function Check_Exit (Self_ID : ST.Task_ID) return Boolean is
1107    begin
1108       return True;
1109    end Check_Exit;
1110
1111    --------------------
1112    -- Check_No_Locks --
1113    --------------------
1114
1115    function Check_No_Locks (Self_ID : ST.Task_ID) return Boolean is
1116    begin
1117       return True;
1118    end Check_No_Locks;
1119
1120    ------------------
1121    -- Suspend_Task --
1122    ------------------
1123
1124    function Suspend_Task
1125      (T           : ST.Task_ID;
1126       Thread_Self : Thread_Id) return Boolean is
1127    begin
1128       if T.Common.LL.Thread /= Thread_Self then
1129          return SuspendThread (T.Common.LL.Thread) = NO_ERROR;
1130       else
1131          return True;
1132       end if;
1133    end Suspend_Task;
1134
1135    -----------------
1136    -- Resume_Task --
1137    -----------------
1138
1139    function Resume_Task
1140      (T           : ST.Task_ID;
1141       Thread_Self : Thread_Id) return Boolean is
1142    begin
1143       if T.Common.LL.Thread /= Thread_Self then
1144          return ResumeThread (T.Common.LL.Thread) = NO_ERROR;
1145       else
1146          return True;
1147       end if;
1148    end Resume_Task;
1149
1150 end System.Task_Primitives.Operations;