gcc/ada/s-taprop-vms.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                 GNAT 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 --         Copyright (C) 1992-2012, 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 ------------------------------------------------------------------------------
  31
  32 --  This is a OpenVMS/Alpha version of this package
  33
  34 --  This package contains all the GNULL primitives that interface directly with
  35 --  the underlying OS.
  36
  37 pragma Polling (Off);
  38 --  Turn off polling, we do not want ATC polling to take place during tasking
  39 --  operations. It causes infinite loops and other problems.
  40
  41 with Ada.Unchecked_Conversion;
  42
  43 with Interfaces.C;
  44
  45 with System.Tasking.Debug;
  46 with System.OS_Primitives;
  47 with System.Soft_Links;
  48 with System.Aux_DEC;
  49
  50 package body System.Task_Primitives.Operations is
  51
  52    use System.Tasking.Debug;
  53    use System.Tasking;
  54    use Interfaces.C;
  55    use System.OS_Interface;
  56    use System.Parameters;
  57    use System.OS_Primitives;
  58    use type System.OS_Primitives.OS_Time;
  59
  60    package SSL renames System.Soft_Links;
  61
  62    ----------------
  63    -- Local Data --
  64    ----------------
  65
  66    --  The followings are logically constants, but need to be initialized
  67    --  at run time.
  68
  69    Single_RTS_Lock : aliased RTS_Lock;
  70    --  This is a lock to allow only one thread of control in the RTS at
  71    --  a time; it is used to execute in mutual exclusion from all other tasks.
  72    --  Used mainly in Single_Lock mode, but also to protect All_Tasks_List
  73
  74    ATCB_Key : aliased pthread_key_t;
  75    --  Key used to find the Ada Task_Id associated with a thread
  76
  77    Environment_Task_Id : Task_Id;
  78    --  A variable to hold Task_Id for the environment task
  79
  80    Time_Slice_Val : Integer;
  81    pragma Import (C, Time_Slice_Val, "__gl_time_slice_val");
  82
  83    Dispatching_Policy : Character;
  84    pragma Import (C, Dispatching_Policy, "__gl_task_dispatching_policy");
  85
  86    Foreign_Task_Elaborated : aliased Boolean := True;
  87    --  Used to identified fake tasks (i.e., non-Ada Threads)
  88
  89    --------------------
  90    -- Local Packages --
  91    --------------------
  92
  93    package Specific is
  94
  95       procedure Initialize (Environment_Task : Task_Id);
  96       pragma Inline (Initialize);
  97       --  Initialize various data needed by this package
  98
  99       function Is_Valid_Task return Boolean;
 100       pragma Inline (Is_Valid_Task);
 101       --  Does executing thread have a TCB?
 102
 103       procedure Set (Self_Id : Task_Id);
 104       pragma Inline (Set);
 105       --  Set the self id for the current task
 106
 107       function Self return Task_Id;
 108       pragma Inline (Self);
 109       --  Return a pointer to the Ada Task Control Block of the calling task
 110
 111    end Specific;
 112
 113    package body Specific is separate;
 114    --  The body of this package is target specific
 115
 116    ----------------------------------
 117    -- ATCB allocation/deallocation --
 118    ----------------------------------
 119
 120    package body ATCB_Allocation is separate;
 121    --  The body of this package is shared across several targets
 122
 123    ---------------------------------
 124    -- Support for foreign threads --
 125    ---------------------------------
 126
 127    function Register_Foreign_Thread (Thread : Thread_Id) return Task_Id;
 128    --  Allocate and Initialize a new ATCB for the current Thread
 129
 130    function Register_Foreign_Thread
 131      (Thread : Thread_Id) return Task_Id is separate;
 132
 133    -----------------------
 134    -- Local Subprograms --
 135    -----------------------
 136
 137    function To_Task_Id is
 138      new Ada.Unchecked_Conversion
 139        (System.Task_Primitives.Task_Address, Task_Id);
 140
 141    function To_Address is
 142      new Ada.Unchecked_Conversion
 143        (Task_Id, System.Task_Primitives.Task_Address);
 144
 145    procedure Timer_Sleep_AST (ID : Address);
 146    pragma Convention (C, Timer_Sleep_AST);
 147    --  Signal the condition variable when AST fires
 148
 149    procedure Timer_Sleep_AST (ID : Address) is
 150       Result : Interfaces.C.int;
 151       pragma Warnings (Off, Result);
 152       Self_ID : constant Task_Id := To_Task_Id (ID);
 153    begin
 154       Self_ID.Common.LL.AST_Pending := False;
 155       Result := pthread_cond_signal_int_np (Self_ID.Common.LL.CV'Access);
 156       pragma Assert (Result = 0);
 157    end Timer_Sleep_AST;
 158
 159    -----------------
 160    -- Stack_Guard --
 161    -----------------
 162
 163    --  The underlying thread system sets a guard page at the bottom of a thread
 164    --  stack, so nothing is needed.
 165    --  ??? Check the comment above
 166
 167    procedure Stack_Guard (T : ST.Task_Id; On : Boolean) is
 168       pragma Unreferenced (T);
 169       pragma Unreferenced (On);
 170    begin
 171       null;
 172    end Stack_Guard;
 173
 174    --------------------
 175    -- Get_Thread_Id  --
 176    --------------------
 177
 178    function Get_Thread_Id (T : ST.Task_Id) return OSI.Thread_Id is
 179    begin
 180       return T.Common.LL.Thread;
 181    end Get_Thread_Id;
 182
 183    ----------
 184    -- Self --
 185    ----------
 186
 187    function Self return Task_Id renames Specific.Self;
 188
 189    ---------------------
 190    -- Initialize_Lock --
 191    ---------------------
 192
 193    --  Note: mutexes and cond_variables needed per-task basis are initialized
 194    --  in Initialize_TCB and the Storage_Error is handled. Other mutexes (such
 195    --  as RTS_Lock, Memory_Lock...) used in RTS is initialized before any
 196    --  status change of RTS. Therefore raising Storage_Error in the following
 197    --  routines should be able to be handled safely.
 198
 199    procedure Initialize_Lock
 200      (Prio : System.Any_Priority;
 201       L    : not null access Lock)
 202    is
 203       Attributes : aliased pthread_mutexattr_t;
 204       Result     : Interfaces.C.int;
 205
 206    begin
 207       Result := pthread_mutexattr_init (Attributes'Access);
 208       pragma Assert (Result = 0 or else Result = ENOMEM);
 209
 210       if Result = ENOMEM then
 211          raise Storage_Error;
 212       end if;
 213
 214       L.Prio_Save := 0;
 215       L.Prio := Interfaces.C.int (Prio);
 216
 217       Result := pthread_mutex_init (L.L'Access, Attributes'Access);
 218       pragma Assert (Result = 0 or else Result = ENOMEM);
 219
 220       if Result = ENOMEM then
 221          raise Storage_Error;
 222       end if;
 223
 224       Result := pthread_mutexattr_destroy (Attributes'Access);
 225       pragma Assert (Result = 0);
 226    end Initialize_Lock;
 227
 228    procedure Initialize_Lock
 229      (L     : not null access RTS_Lock;
 230       Level : Lock_Level)
 231    is
 232       pragma Unreferenced (Level);
 233
 234       Attributes : aliased pthread_mutexattr_t;
 235       Result : Interfaces.C.int;
 236
 237    begin
 238       Result := pthread_mutexattr_init (Attributes'Access);
 239       pragma Assert (Result = 0 or else Result = ENOMEM);
 240
 241       if Result = ENOMEM then
 242          raise Storage_Error;
 243       end if;
 244
 245 --      Don't use, see comment in s-osinte.ads about ERRORCHECK mutexes???
 246 --      Result := pthread_mutexattr_settype_np
 247 --        (Attributes'Access, PTHREAD_MUTEX_ERRORCHECK_NP);
 248 --      pragma Assert (Result = 0);
 249
 250 --      Result := pthread_mutexattr_setprotocol
 251 --        (Attributes'Access, PTHREAD_PRIO_PROTECT);
 252 --      pragma Assert (Result = 0);
 253
 254 --      Result := pthread_mutexattr_setprioceiling
 255 --         (Attributes'Access, Interfaces.C.int (System.Any_Priority'Last));
 256 --      pragma Assert (Result = 0);
 257
 258       Result := pthread_mutex_init (L, Attributes'Access);
 259
 260       pragma Assert (Result = 0 or else Result = ENOMEM);
 261
 262       if Result = ENOMEM then
 263          raise Storage_Error;
 264       end if;
 265
 266       Result := pthread_mutexattr_destroy (Attributes'Access);
 267       pragma Assert (Result = 0);
 268    end Initialize_Lock;
 269
 270    -------------------
 271    -- Finalize_Lock --
 272    -------------------
 273
 274    procedure Finalize_Lock (L : not null access Lock) is
 275       Result : Interfaces.C.int;
 276    begin
 277       Result := pthread_mutex_destroy (L.L'Access);
 278       pragma Assert (Result = 0);
 279    end Finalize_Lock;
 280
 281    procedure Finalize_Lock (L : not null access RTS_Lock) is
 282       Result : Interfaces.C.int;
 283    begin
 284       Result := pthread_mutex_destroy (L);
 285       pragma Assert (Result = 0);
 286    end Finalize_Lock;
 287
 288    ----------------
 289    -- Write_Lock --
 290    ----------------
 291
 292    procedure Write_Lock
 293      (L                 : not null access Lock;
 294       Ceiling_Violation : out Boolean)
 295    is
 296       Self_ID        : constant Task_Id := Self;
 297       All_Tasks_Link : constant Task_Id := Self.Common.All_Tasks_Link;
 298       Current_Prio   : System.Any_Priority;
 299       Result         : Interfaces.C.int;
 300
 301    begin
 302       Current_Prio := Get_Priority (Self_ID);
 303
 304       --  If there is no other tasks, no need to check priorities
 305
 306       if All_Tasks_Link /= Null_Task
 307         and then L.Prio < Interfaces.C.int (Current_Prio)
 308       then
 309          Ceiling_Violation := True;
 310          return;
 311       end if;
 312
 313       Result := pthread_mutex_lock (L.L'Access);
 314       pragma Assert (Result = 0);
 315
 316       Ceiling_Violation := False;
 317 --  Why is this commented out ???
 318 --      L.Prio_Save := Interfaces.C.int (Current_Prio);
 319 --      Set_Priority (Self_ID, System.Any_Priority (L.Prio));
 320    end Write_Lock;
 321
 322    procedure Write_Lock
 323      (L           : not null access RTS_Lock;
 324       Global_Lock : Boolean := False)
 325    is
 326       Result : Interfaces.C.int;
 327    begin
 328       if not Single_Lock or else Global_Lock then
 329          Result := pthread_mutex_lock (L);
 330          pragma Assert (Result = 0);
 331       end if;
 332    end Write_Lock;
 333
 334    procedure Write_Lock (T : Task_Id) is
 335       Result : Interfaces.C.int;
 336    begin
 337       if not Single_Lock then
 338          Result := pthread_mutex_lock (T.Common.LL.L'Access);
 339          pragma Assert (Result = 0);
 340       end if;
 341    end Write_Lock;
 342
 343    ---------------
 344    -- Read_Lock --
 345    ---------------
 346
 347    procedure Read_Lock
 348      (L                 : not null access Lock;
 349       Ceiling_Violation : out Boolean)
 350    is
 351    begin
 352       Write_Lock (L, Ceiling_Violation);
 353    end Read_Lock;
 354
 355    ------------
 356    -- Unlock --
 357    ------------
 358
 359    procedure Unlock (L : not null access Lock) is
 360       Result : Interfaces.C.int;
 361    begin
 362       Result := pthread_mutex_unlock (L.L'Access);
 363       pragma Assert (Result = 0);
 364    end Unlock;
 365
 366    procedure Unlock
 367      (L           : not null access RTS_Lock;
 368       Global_Lock : Boolean := False)
 369    is
 370       Result : Interfaces.C.int;
 371    begin
 372       if not Single_Lock or else Global_Lock then
 373          Result := pthread_mutex_unlock (L);
 374          pragma Assert (Result = 0);
 375       end if;
 376    end Unlock;
 377
 378    procedure Unlock (T : Task_Id) is
 379       Result : Interfaces.C.int;
 380    begin
 381       if not Single_Lock then
 382          Result := pthread_mutex_unlock (T.Common.LL.L'Access);
 383          pragma Assert (Result = 0);
 384       end if;
 385    end Unlock;
 386
 387    -----------------
 388    -- Set_Ceiling --
 389    -----------------
 390
 391    --  Dynamic priority ceilings are not supported by the underlying system
 392
 393    procedure Set_Ceiling
 394      (L    : not null access Lock;
 395       Prio : System.Any_Priority)
 396    is
 397       pragma Unreferenced (L, Prio);
 398    begin
 399       null;
 400    end Set_Ceiling;
 401
 402    -----------
 403    -- Sleep --
 404    -----------
 405
 406    procedure Sleep
 407      (Self_ID : Task_Id;
 408       Reason  : System.Tasking.Task_States)
 409    is
 410       pragma Unreferenced (Reason);
 411       Result : Interfaces.C.int;
 412
 413    begin
 414       Result :=
 415         pthread_cond_wait
 416           (cond  => Self_ID.Common.LL.CV'Access,
 417            mutex => (if Single_Lock
 418                      then Single_RTS_Lock'Access
 419                      else Self_ID.Common.LL.L'Access));
 420
 421       --  EINTR is not considered a failure
 422
 423       pragma Assert (Result = 0 or else Result = EINTR);
 424
 425       if Self_ID.Deferral_Level = 0
 426         and then Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level
 427       then
 428          Unlock (Self_ID);
 429          raise Standard'Abort_Signal;
 430       end if;
 431    end Sleep;
 432
 433    -----------------
 434    -- Timed_Sleep --
 435    -----------------
 436
 437    procedure Timed_Sleep
 438      (Self_ID  : Task_Id;
 439       Time     : Duration;
 440       Mode     : ST.Delay_Modes;
 441       Reason   : System.Tasking.Task_States;
 442       Timedout : out Boolean;
 443       Yielded  : out Boolean)
 444    is
 445       pragma Unreferenced (Reason);
 446
 447       Sleep_Time : OS_Time;
 448       Result     : Interfaces.C.int;
 449       Status     : Cond_Value_Type;
 450
 451       --  The body below requires more comments ???
 452
 453    begin
 454       Timedout := False;
 455       Yielded := False;
 456
 457       Sleep_Time := To_OS_Time (Time, Mode);
 458
 459       if Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level then
 460          return;
 461       end if;
 462
 463       Self_ID.Common.LL.AST_Pending := True;
 464
 465       Sys_Setimr
 466        (Status, 0, Sleep_Time,
 467         Timer_Sleep_AST'Access, To_Address (Self_ID), 0);
 468
 469       if (Status and 1) /= 1 then
 470          raise Storage_Error;
 471       end if;
 472
 473       if Single_Lock then
 474          Result :=
 475            pthread_cond_wait
 476              (Self_ID.Common.LL.CV'Access, Single_RTS_Lock'Access);
 477          pragma Assert (Result = 0);
 478
 479       else
 480          Result :=
 481            pthread_cond_wait
 482              (Self_ID.Common.LL.CV'Access, Self_ID.Common.LL.L'Access);
 483          pragma Assert (Result = 0);
 484       end if;
 485
 486       Yielded := True;
 487
 488       if not Self_ID.Common.LL.AST_Pending then
 489          Timedout := True;
 490       else
 491          Sys_Cantim (Status, To_Address (Self_ID), 0);
 492          pragma Assert ((Status and 1) = 1);
 493       end if;
 494    end Timed_Sleep;
 495
 496    -----------------
 497    -- Timed_Delay --
 498    -----------------
 499
 500    procedure Timed_Delay
 501      (Self_ID : Task_Id;
 502       Time    : Duration;
 503       Mode    : ST.Delay_Modes)
 504    is
 505       Sleep_Time : OS_Time;
 506       Result     : Interfaces.C.int;
 507       Status     : Cond_Value_Type;
 508       Yielded    : Boolean := False;
 509
 510    begin
 511       if Single_Lock then
 512          Lock_RTS;
 513       end if;
 514
 515       --  More comments required in body below ???
 516
 517       Write_Lock (Self_ID);
 518
 519       if Time /= 0.0 or else Mode /= Relative then
 520          Sleep_Time := To_OS_Time (Time, Mode);
 521
 522          if Mode = Relative or else OS_Clock <= Sleep_Time then
 523             Self_ID.Common.State := Delay_Sleep;
 524             Self_ID.Common.LL.AST_Pending := True;
 525
 526             Sys_Setimr
 527              (Status, 0, Sleep_Time,
 528               Timer_Sleep_AST'Access, To_Address (Self_ID), 0);
 529
 530             --  Comment following test
 531
 532             if (Status and 1) /= 1 then
 533                raise Storage_Error;
 534             end if;
 535
 536             loop
 537                if Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level then
 538                   Sys_Cantim (Status, To_Address (Self_ID), 0);
 539                   pragma Assert ((Status and 1) = 1);
 540                   exit;
 541                end if;
 542
 543                Result :=
 544                  pthread_cond_wait
 545                    (cond  => Self_ID.Common.LL.CV'Access,
 546                     mutex => (if Single_Lock
 547                               then Single_RTS_Lock'Access
 548                               else Self_ID.Common.LL.L'Access));
 549                pragma Assert (Result = 0);
 550
 551                Yielded := True;
 552
 553                exit when not Self_ID.Common.LL.AST_Pending;
 554             end loop;
 555
 556             Self_ID.Common.State := Runnable;
 557          end if;
 558       end if;
 559
 560       Unlock (Self_ID);
 561
 562       if Single_Lock then
 563          Unlock_RTS;
 564       end if;
 565
 566       if not Yielded then
 567          Result := sched_yield;
 568          pragma Assert (Result = 0);
 569       end if;
 570    end Timed_Delay;
 571
 572    ---------------------
 573    -- Monotonic_Clock --
 574    ---------------------
 575
 576    function Monotonic_Clock return Duration
 577      renames System.OS_Primitives.Monotonic_Clock;
 578
 579    -------------------
 580    -- RT_Resolution --
 581    -------------------
 582
 583    function RT_Resolution return Duration is
 584    begin
 585       --  Document origin of this magic constant ???
 586       return 10#1.0#E-3;
 587    end RT_Resolution;
 588
 589    ------------
 590    -- Wakeup --
 591    ------------
 592
 593    procedure Wakeup (T : Task_Id; Reason : System.Tasking.Task_States) is
 594       pragma Unreferenced (Reason);
 595       Result : Interfaces.C.int;
 596    begin
 597       Result := pthread_cond_signal (T.Common.LL.CV'Access);
 598       pragma Assert (Result = 0);
 599    end Wakeup;
 600
 601    -----------
 602    -- Yield --
 603    -----------
 604
 605    procedure Yield (Do_Yield : Boolean := True) is
 606       Result : Interfaces.C.int;
 607       pragma Unreferenced (Result);
 608    begin
 609       if Do_Yield then
 610          Result := sched_yield;
 611       end if;
 612    end Yield;
 613
 614    ------------------
 615    -- Set_Priority --
 616    ------------------
 617
 618    procedure Set_Priority
 619      (T                   : Task_Id;
 620       Prio                : System.Any_Priority;
 621       Loss_Of_Inheritance : Boolean := False)
 622    is
 623       pragma Unreferenced (Loss_Of_Inheritance);
 624
 625       Result : Interfaces.C.int;
 626       Param  : aliased struct_sched_param;
 627
 628       function Get_Policy (Prio : System.Any_Priority) return Character;
 629       pragma Import (C, Get_Policy, "__gnat_get_specific_dispatching");
 630       --  Get priority specific dispatching policy
 631
 632       Priority_Specific_Policy : constant Character := Get_Policy (Prio);
 633       --  Upper case first character of the policy name corresponding to the
 634       --  task as set by a Priority_Specific_Dispatching pragma.
 635
 636    begin
 637       T.Common.Current_Priority := Prio;
 638       Param.sched_priority := Interfaces.C.int (Underlying_Priorities (Prio));
 639
 640       if Dispatching_Policy = 'R'
 641         or else Priority_Specific_Policy = 'R'
 642         or else Time_Slice_Val > 0
 643       then
 644          Result :=
 645            pthread_setschedparam
 646              (T.Common.LL.Thread, SCHED_RR, Param'Access);
 647
 648       elsif Dispatching_Policy = 'F'
 649         or else Priority_Specific_Policy = 'F'
 650         or else Time_Slice_Val = 0
 651       then
 652          Result :=
 653            pthread_setschedparam
 654              (T.Common.LL.Thread, SCHED_FIFO, Param'Access);
 655
 656       else
 657          --  SCHED_OTHER priorities are restricted to the range 8 - 15.
 658          --  Since the translation from Underlying priorities results
 659          --  in a range of 16 - 31, dividing by 2 gives the correct result.
 660
 661          Param.sched_priority := Param.sched_priority / 2;
 662          Result :=
 663            pthread_setschedparam
 664              (T.Common.LL.Thread, SCHED_OTHER, Param'Access);
 665       end if;
 666
 667       pragma Assert (Result = 0);
 668    end Set_Priority;
 669
 670    ------------------
 671    -- Get_Priority --
 672    ------------------
 673
 674    function Get_Priority (T : Task_Id) return System.Any_Priority is
 675    begin
 676       return T.Common.Current_Priority;
 677    end Get_Priority;
 678
 679    ----------------
 680    -- Enter_Task --
 681    ----------------
 682
 683    procedure Enter_Task (Self_ID : Task_Id) is
 684    begin
 685       Self_ID.Common.LL.Thread := pthread_self;
 686       Specific.Set (Self_ID);
 687    end Enter_Task;
 688
 689    -------------------
 690    -- Is_Valid_Task --
 691    -------------------
 692
 693    function Is_Valid_Task return Boolean renames Specific.Is_Valid_Task;
 694
 695    -----------------------------
 696    -- Register_Foreign_Thread --
 697    -----------------------------
 698
 699    function Register_Foreign_Thread return Task_Id is
 700    begin
 701       if Is_Valid_Task then
 702          return Self;
 703       else
 704          return Register_Foreign_Thread (pthread_self);
 705       end if;
 706    end Register_Foreign_Thread;
 707
 708    --------------------
 709    -- Initialize_TCB --
 710    --------------------
 711
 712    procedure Initialize_TCB (Self_ID : Task_Id; Succeeded : out Boolean) is
 713       Mutex_Attr : aliased pthread_mutexattr_t;
 714       Result     : Interfaces.C.int;
 715       Cond_Attr  : aliased pthread_condattr_t;
 716
 717    begin
 718       --  More comments required in body below ???
 719
 720       if not Single_Lock then
 721          Result := pthread_mutexattr_init (Mutex_Attr'Access);
 722          pragma Assert (Result = 0 or else Result = ENOMEM);
 723
 724          if Result = 0 then
 725             Result :=
 726               pthread_mutex_init
 727                 (Self_ID.Common.LL.L'Access, Mutex_Attr'Access);
 728             pragma Assert (Result = 0 or else Result = ENOMEM);
 729          end if;
 730
 731          if Result /= 0 then
 732             Succeeded := False;
 733             return;
 734          end if;
 735
 736          Result := pthread_mutexattr_destroy (Mutex_Attr'Access);
 737          pragma Assert (Result = 0);
 738       end if;
 739
 740       Result := pthread_condattr_init (Cond_Attr'Access);
 741       pragma Assert (Result = 0 or else Result = ENOMEM);
 742
 743       if Result = 0 then
 744          Result :=
 745            pthread_cond_init
 746              (Self_ID.Common.LL.CV'Access, Cond_Attr'Access);
 747          pragma Assert (Result = 0 or else Result = ENOMEM);
 748       end if;
 749
 750       if Result = 0 then
 751          Succeeded := True;
 752
 753       else
 754          if not Single_Lock then
 755             Result := pthread_mutex_destroy (Self_ID.Common.LL.L'Access);
 756             pragma Assert (Result = 0);
 757          end if;
 758
 759          Succeeded := False;
 760       end if;
 761
 762       Result := pthread_condattr_destroy (Cond_Attr'Access);
 763       pragma Assert (Result = 0);
 764    end Initialize_TCB;
 765
 766    -----------------
 767    -- Create_Task --
 768    -----------------
 769
 770    procedure Create_Task
 771      (T          : Task_Id;
 772       Wrapper    : System.Address;
 773       Stack_Size : System.Parameters.Size_Type;
 774       Priority   : System.Any_Priority;
 775       Succeeded  : out Boolean)
 776    is
 777       Attributes : aliased pthread_attr_t;
 778       Result     : Interfaces.C.int;
 779
 780       function Thread_Body_Access is new
 781         Ada.Unchecked_Conversion (System.Aux_DEC.Short_Address, Thread_Body);
 782
 783       Task_Name : String (1 .. System.Parameters.Max_Task_Image_Length + 1);
 784
 785    begin
 786       --  Since the initial signal mask of a thread is inherited from the
 787       --  creator, we need to set our local signal mask to mask all signals
 788       --  during the creation operation, to make sure the new thread is
 789       --  not disturbed by signals before it has set its own Task_Id.
 790
 791       Result := pthread_attr_init (Attributes'Access);
 792       pragma Assert (Result = 0 or else Result = ENOMEM);
 793
 794       if Result /= 0 then
 795          Succeeded := False;
 796          return;
 797       end if;
 798
 799       Result := pthread_attr_setdetachstate
 800         (Attributes'Access, PTHREAD_CREATE_DETACHED);
 801       pragma Assert (Result = 0);
 802
 803       Result := pthread_attr_setstacksize
 804         (Attributes'Access, Interfaces.C.size_t (Stack_Size));
 805       pragma Assert (Result = 0);
 806
 807       --  This call may be unnecessary, not sure. ???
 808
 809       Result :=
 810         pthread_attr_setinheritsched
 811           (Attributes'Access, PTHREAD_EXPLICIT_SCHED);
 812       pragma Assert (Result = 0);
 813
 814       if T.Common.Task_Image_Len > 0 then
 815
 816          --  Set thread name to ease debugging
 817
 818          Task_Name (1 .. T.Common.Task_Image_Len) :=
 819            T.Common.Task_Image (1 .. T.Common.Task_Image_Len);
 820          Task_Name (T.Common.Task_Image_Len + 1) := ASCII.NUL;
 821
 822          Result := pthread_attr_setname_np
 823            (Attributes'Access, Task_Name'Address, Null_Address);
 824          pragma Assert (Result = 0);
 825       end if;
 826
 827       --  Note: the use of Unrestricted_Access in the following call is needed
 828       --  because otherwise we have an error of getting a access-to-volatile
 829       --  value which points to a non-volatile object. But in this case it is
 830       --  safe to do this, since we know we have no problems with aliasing and
 831       --  Unrestricted_Access bypasses this check.
 832
 833       Result :=
 834         pthread_create
 835           (T.Common.LL.Thread'Unrestricted_Access,
 836            Attributes'Access,
 837            Thread_Body_Access (Wrapper),
 838            To_Address (T));
 839
 840       --  ENOMEM is a valid run-time error -- do not shut down
 841
 842       pragma Assert (Result = 0
 843         or else Result = EAGAIN or else Result = ENOMEM);
 844
 845       Succeeded := Result = 0;
 846
 847       Result := pthread_attr_destroy (Attributes'Access);
 848       pragma Assert (Result = 0);
 849
 850       if Succeeded then
 851          Set_Priority (T, Priority);
 852       end if;
 853    end Create_Task;
 854
 855    ------------------
 856    -- Finalize_TCB --
 857    ------------------
 858
 859    procedure Finalize_TCB (T : Task_Id) is
 860       Result : Interfaces.C.int;
 861
 862    begin
 863       if not Single_Lock then
 864          Result := pthread_mutex_destroy (T.Common.LL.L'Access);
 865          pragma Assert (Result = 0);
 866       end if;
 867
 868       Result := pthread_cond_destroy (T.Common.LL.CV'Access);
 869       pragma Assert (Result = 0);
 870
 871       if T.Known_Tasks_Index /= -1 then
 872          Known_Tasks (T.Known_Tasks_Index) := null;
 873       end if;
 874
 875       ATCB_Allocation.Free_ATCB (T);
 876    end Finalize_TCB;
 877
 878    ---------------
 879    -- Exit_Task --
 880    ---------------
 881
 882    procedure Exit_Task is
 883    begin
 884       null;
 885    end Exit_Task;
 886
 887    ----------------
 888    -- Abort_Task --
 889    ----------------
 890
 891    procedure Abort_Task (T : Task_Id) is
 892    begin
 893       --  Interrupt Server_Tasks may be waiting on an event flag
 894
 895       if T.Common.State = Interrupt_Server_Blocked_On_Event_Flag then
 896          Wakeup (T, Interrupt_Server_Blocked_On_Event_Flag);
 897       end if;
 898    end Abort_Task;
 899
 900    ----------------
 901    -- Initialize --
 902    ----------------
 903
 904    procedure Initialize (S : in out Suspension_Object) is
 905       Mutex_Attr : aliased pthread_mutexattr_t;
 906       Cond_Attr  : aliased pthread_condattr_t;
 907       Result     : Interfaces.C.int;
 908    begin
 909       --  Initialize internal state (always to False (D.10 (6)))
 910
 911       S.State := False;
 912       S.Waiting := False;
 913
 914       --  Initialize internal mutex
 915
 916       Result := pthread_mutexattr_init (Mutex_Attr'Access);
 917       pragma Assert (Result = 0 or else Result = ENOMEM);
 918
 919       if Result = ENOMEM then
 920          raise Storage_Error;
 921       end if;
 922
 923       Result := pthread_mutex_init (S.L'Access, Mutex_Attr'Access);
 924       pragma Assert (Result = 0 or else Result = ENOMEM);
 925
 926       if Result = ENOMEM then
 927          Result := pthread_mutexattr_destroy (Mutex_Attr'Access);
 928          pragma Assert (Result = 0);
 929
 930          raise Storage_Error;
 931       end if;
 932
 933       Result := pthread_mutexattr_destroy (Mutex_Attr'Access);
 934       pragma Assert (Result = 0);
 935
 936       --  Initialize internal condition variable
 937
 938       Result := pthread_condattr_init (Cond_Attr'Access);
 939       pragma Assert (Result = 0 or else Result = ENOMEM);
 940
 941       if Result /= 0 then
 942          Result := pthread_mutex_destroy (S.L'Access);
 943          pragma Assert (Result = 0);
 944
 945          if Result = ENOMEM then
 946             raise Storage_Error;
 947          end if;
 948       end if;
 949
 950       Result := pthread_cond_init (S.CV'Access, Cond_Attr'Access);
 951       pragma Assert (Result = 0 or else Result = ENOMEM);
 952
 953       if Result /= 0 then
 954          Result := pthread_mutex_destroy (S.L'Access);
 955          pragma Assert (Result = 0);
 956
 957          if Result = ENOMEM then
 958             Result := pthread_condattr_destroy (Cond_Attr'Access);
 959             pragma Assert (Result = 0);
 960
 961             raise Storage_Error;
 962          end if;
 963       end if;
 964
 965       Result := pthread_condattr_destroy (Cond_Attr'Access);
 966       pragma Assert (Result = 0);
 967    end Initialize;
 968
 969    --------------
 970    -- Finalize --
 971    --------------
 972
 973    procedure Finalize (S : in out Suspension_Object) is
 974       Result : Interfaces.C.int;
 975
 976    begin
 977       --  Destroy internal mutex
 978
 979       Result := pthread_mutex_destroy (S.L'Access);
 980       pragma Assert (Result = 0);
 981
 982       --  Destroy internal condition variable
 983
 984       Result := pthread_cond_destroy (S.CV'Access);
 985       pragma Assert (Result = 0);
 986    end Finalize;
 987
 988    -------------------
 989    -- Current_State --
 990    -------------------
 991
 992    function Current_State (S : Suspension_Object) return Boolean is
 993    begin
 994       --  We do not want to use lock on this read operation. State is marked
 995       --  as Atomic so that we ensure that the value retrieved is correct.
 996
 997       return S.State;
 998    end Current_State;
 999
1000    ---------------
1001    -- Set_False --
1002    ---------------
1003
1004    procedure Set_False (S : in out Suspension_Object) is
1005       Result : Interfaces.C.int;
1006
1007    begin
1008       SSL.Abort_Defer.all;
1009
1010       Result := pthread_mutex_lock (S.L'Access);
1011       pragma Assert (Result = 0);
1012
1013       S.State := False;
1014
1015       Result := pthread_mutex_unlock (S.L'Access);
1016       pragma Assert (Result = 0);
1017
1018       SSL.Abort_Undefer.all;
1019    end Set_False;
1020
1021    --------------
1022    -- Set_True --
1023    --------------
1024
1025    procedure Set_True (S : in out Suspension_Object) is
1026       Result : Interfaces.C.int;
1027
1028    begin
1029       SSL.Abort_Defer.all;
1030
1031       Result := pthread_mutex_lock (S.L'Access);
1032       pragma Assert (Result = 0);
1033
1034       --  If there is already a task waiting on this suspension object then
1035       --  we resume it, leaving the state of the suspension object to False,
1036       --  as specified in (RM D.10(9)), otherwise leave state set to True.
1037
1038       if S.Waiting then
1039          S.Waiting := False;
1040          S.State := False;
1041
1042          Result := pthread_cond_signal (S.CV'Access);
1043          pragma Assert (Result = 0);
1044
1045       else
1046          S.State := True;
1047       end if;
1048
1049       Result := pthread_mutex_unlock (S.L'Access);
1050       pragma Assert (Result = 0);
1051
1052       SSL.Abort_Undefer.all;
1053    end Set_True;
1054
1055    ------------------------
1056    -- Suspend_Until_True --
1057    ------------------------
1058
1059    procedure Suspend_Until_True (S : in out Suspension_Object) is
1060       Result : Interfaces.C.int;
1061
1062    begin
1063       SSL.Abort_Defer.all;
1064
1065       Result := pthread_mutex_lock (S.L'Access);
1066       pragma Assert (Result = 0);
1067
1068       if S.Waiting then
1069
1070          --  Program_Error must be raised upon calling Suspend_Until_True
1071          --  if another task is already waiting on that suspension object
1072          --  (RM D.10(10)).
1073
1074          Result := pthread_mutex_unlock (S.L'Access);
1075          pragma Assert (Result = 0);
1076
1077          SSL.Abort_Undefer.all;
1078
1079          raise Program_Error;
1080
1081       else
1082          --  Suspend the task if the state is False. Otherwise, the task
1083          --  continues its execution, and the state of the suspension object
1084          --  is set to False (ARM D.10 par. 9).
1085
1086          if S.State then
1087             S.State := False;
1088          else
1089             S.Waiting := True;
1090
1091             loop
1092                --  Loop in case pthread_cond_wait returns earlier than expected
1093                --  (e.g. in case of EINTR caused by a signal).
1094
1095                Result := pthread_cond_wait (S.CV'Access, S.L'Access);
1096                pragma Assert (Result = 0 or else Result = EINTR);
1097
1098                exit when not S.Waiting;
1099             end loop;
1100          end if;
1101
1102          Result := pthread_mutex_unlock (S.L'Access);
1103          pragma Assert (Result = 0);
1104
1105          SSL.Abort_Undefer.all;
1106       end if;
1107    end Suspend_Until_True;
1108
1109    ----------------
1110    -- Check_Exit --
1111    ----------------
1112
1113    --  Dummy version
1114
1115    function Check_Exit (Self_ID : ST.Task_Id) return Boolean is
1116       pragma Unreferenced (Self_ID);
1117    begin
1118       return True;
1119    end Check_Exit;
1120
1121    --------------------
1122    -- Check_No_Locks --
1123    --------------------
1124
1125    function Check_No_Locks (Self_ID : ST.Task_Id) return Boolean is
1126       pragma Unreferenced (Self_ID);
1127    begin
1128       return True;
1129    end Check_No_Locks;
1130
1131    ----------------------
1132    -- Environment_Task --
1133    ----------------------
1134
1135    function Environment_Task return Task_Id is
1136    begin
1137       return Environment_Task_Id;
1138    end Environment_Task;
1139
1140    --------------
1141    -- Lock_RTS --
1142    --------------
1143
1144    procedure Lock_RTS is
1145    begin
1146       Write_Lock (Single_RTS_Lock'Access, Global_Lock => True);
1147    end Lock_RTS;
1148
1149    ----------------
1150    -- Unlock_RTS --
1151    ----------------
1152
1153    procedure Unlock_RTS is
1154    begin
1155       Unlock (Single_RTS_Lock'Access, Global_Lock => True);
1156    end Unlock_RTS;
1157
1158    ------------------
1159    -- Suspend_Task --
1160    ------------------
1161
1162    function Suspend_Task
1163      (T           : ST.Task_Id;
1164       Thread_Self : Thread_Id) return Boolean
1165    is
1166       pragma Unreferenced (T);
1167       pragma Unreferenced (Thread_Self);
1168    begin
1169       return False;
1170    end Suspend_Task;
1171
1172    -----------------
1173    -- Resume_Task --
1174    -----------------
1175
1176    function Resume_Task
1177      (T           : ST.Task_Id;
1178       Thread_Self : Thread_Id) return Boolean
1179    is
1180       pragma Unreferenced (T);
1181       pragma Unreferenced (Thread_Self);
1182    begin
1183       return False;
1184    end Resume_Task;
1185
1186    --------------------
1187    -- Stop_All_Tasks --
1188    --------------------
1189
1190    procedure Stop_All_Tasks is
1191    begin
1192       null;
1193    end Stop_All_Tasks;
1194
1195    ---------------
1196    -- Stop_Task --
1197    ---------------
1198
1199    function Stop_Task (T : ST.Task_Id) return Boolean is
1200       pragma Unreferenced (T);
1201    begin
1202       return False;
1203    end Stop_Task;
1204
1205    -------------------
1206    -- Continue_Task --
1207    -------------------
1208
1209    function Continue_Task (T : ST.Task_Id) return Boolean is
1210       pragma Unreferenced (T);
1211    begin
1212       return False;
1213    end Continue_Task;
1214
1215    ----------------
1216    -- Initialize --
1217    ----------------
1218
1219    procedure Initialize (Environment_Task : Task_Id) is
1220
1221       --  The DEC Ada facility code defined in Starlet
1222       Ada_Facility : constant := 49;
1223
1224       function DBGEXT (Control_Block : System.Address)
1225         return System.Aux_DEC.Unsigned_Word;
1226       --  DBGEXT is imported  from s-tasdeb.adb and its parameter re-typed
1227       --  as Address to avoid having a VMS specific s-tasdeb.ads.
1228       pragma Import (C, DBGEXT);
1229       pragma Import_Function (DBGEXT, "GNAT$DBGEXT");
1230
1231       type Facility_Type is range 0 .. 65535;
1232
1233       procedure Debug_Register
1234         (ADBGEXT    : System.Address;
1235          ATCB_Key   : pthread_key_t;
1236          Facility   : Facility_Type;
1237          Std_Prolog : Integer);
1238       pragma Import (C, Debug_Register, "CMA$DEBUG_REGISTER");
1239    begin
1240       Environment_Task_Id := Environment_Task;
1241
1242       --  Initialize the lock used to synchronize chain of all ATCBs
1243
1244       Initialize_Lock (Single_RTS_Lock'Access, RTS_Lock_Level);
1245
1246       Specific.Initialize (Environment_Task);
1247
1248       --  Pass the context key on to CMA along with the other parameters
1249       Debug_Register
1250        (
1251         DBGEXT'Address,    --  Our DEBUG handling entry point
1252         ATCB_Key,          --  CMA context key for our Ada TCB's
1253         Ada_Facility,      --  Out facility code
1254         0                  --  False, we don't have the std TCB prolog
1255        );
1256
1257       --  Make environment task known here because it doesn't go through
1258       --  Activate_Tasks, which does it for all other tasks.
1259
1260       Known_Tasks (Known_Tasks'First) := Environment_Task;
1261       Environment_Task.Known_Tasks_Index := Known_Tasks'First;
1262
1263       Enter_Task (Environment_Task);
1264    end Initialize;
1265
1266    -----------------------
1267    -- Set_Task_Affinity --
1268    -----------------------
1269
1270    procedure Set_Task_Affinity (T : ST.Task_Id) is
1271       pragma Unreferenced (T);
1272
1273    begin
1274       --  Setting task affinity is not supported by the underlying system
1275
1276       null;
1277    end Set_Task_Affinity;
1278 end System.Task_Primitives.Operations;