gcc/ada/s-taprop-hpux-dce.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 --         Copyright (C) 1992-2004, 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 2,  or (at your option) any later ver- --
  14 -- sion. GNARL is distributed in the hope that it will be useful, but WITH- --
  15 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  16 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  17 -- for  more details.  You should have  received  a copy of the GNU General --
  18 -- Public License  distributed with GNARL; see file COPYING.  If not, write --
  19 -- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
  20 -- MA 02111-1307, USA.                                                      --
  21 --                                                                          --
  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.                                      --
  28 --                                                                          --
  29 -- GNARL was developed by the GNARL team at Florida State University.       --
  30 -- Extensive contributions were provided by Ada Core Technologies, Inc.     --
  31 --                                                                          --
  32 ------------------------------------------------------------------------------
  33
  34 --  This is a HP-UX DCE threads (HPUX 10) version of this package
  35
  36 --  This package contains all the GNULL primitives that interface directly
  37 --  with the underlying OS.
  38
  39 pragma Polling (Off);
  40 --  Turn off polling, we do not want ATC polling to take place during
  41 --  tasking operations. It causes infinite loops and other problems.
  42
  43 with System.Tasking.Debug;
  44 --  used for Known_Tasks
  45
  46 with Interfaces.C;
  47 --  used for int
  48 --           size_t
  49
  50 with System.Interrupt_Management;
  51 --  used for Keep_Unmasked
  52 --           Abort_Task_Interrupt
  53 --           Interrupt_ID
  54
  55 with System.Interrupt_Management.Operations;
  56 --  used for Set_Interrupt_Mask
  57 --           All_Tasks_Mask
  58 pragma Elaborate_All (System.Interrupt_Management.Operations);
  59
  60 with System.Parameters;
  61 --  used for Size_Type
  62
  63 with System.Task_Primitives.Interrupt_Operations;
  64 --  used for Get_Interrupt_ID
  65
  66 with System.Tasking;
  67 --  used for Ada_Task_Control_Block
  68 --           Task_Id
  69
  70 with System.Soft_Links;
  71 --  used for Defer/Undefer_Abort
  72
  73 --  Note that we do not use System.Tasking.Initialization directly since
  74 --  this is a higher level package that we shouldn't depend on. For example
  75 --  when using the restricted run time, it is replaced by
  76 --  System.Tasking.Restricted.Stages.
  77
  78 with System.OS_Primitives;
  79 --  used for Delay_Modes
  80
  81 with Unchecked_Conversion;
  82 with Unchecked_Deallocation;
  83
  84 package body System.Task_Primitives.Operations is
  85
  86    use System.Tasking.Debug;
  87    use System.Tasking;
  88    use Interfaces.C;
  89    use System.OS_Interface;
  90    use System.Parameters;
  91    use System.OS_Primitives;
  92
  93    package PIO renames System.Task_Primitives.Interrupt_Operations;
  94    package SSL renames System.Soft_Links;
  95
  96    ----------------
  97    -- Local Data --
  98    ----------------
  99
 100    --  The followings are logically constants, but need to be initialized
 101    --  at run time.
 102
 103    Single_RTS_Lock : aliased RTS_Lock;
 104    --  This is a lock to allow only one thread of control in the RTS at
 105    --  a time; it is used to execute in mutual exclusion from all other tasks.
 106    --  Used mainly in Single_Lock mode, but also to protect All_Tasks_List
 107
 108    ATCB_Key : aliased pthread_key_t;
 109    --  Key used to find the Ada Task_Id associated with a thread
 110
 111    Environment_Task_Id : Task_Id;
 112    --  A variable to hold Task_Id for the environment task
 113
 114    Unblocked_Signal_Mask : aliased sigset_t;
 115    --  The set of signals that should unblocked in all tasks
 116
 117    Time_Slice_Val : Integer;
 118    pragma Import (C, Time_Slice_Val, "__gl_time_slice_val");
 119
 120    Dispatching_Policy : Character;
 121    pragma Import (C, Dispatching_Policy, "__gl_task_dispatching_policy");
 122
 123    --  Note: the reason that Locking_Policy is not needed is that this
 124    --  is not implemented for DCE threads. The HPUX 10 port is at this
 125    --  stage considered dead, and no further work is planned on it.
 126
 127    FIFO_Within_Priorities : constant Boolean := Dispatching_Policy = 'F';
 128    --  Indicates whether FIFO_Within_Priorities is set
 129
 130    Foreign_Task_Elaborated : aliased Boolean := True;
 131    --  Used to identified fake tasks (i.e., non-Ada Threads)
 132
 133    --------------------
 134    -- Local Packages --
 135    --------------------
 136
 137    package Specific is
 138
 139       procedure Initialize (Environment_Task : Task_Id);
 140       pragma Inline (Initialize);
 141       --  Initialize various data needed by this package
 142
 143       function Is_Valid_Task return Boolean;
 144       pragma Inline (Is_Valid_Task);
 145       --  Does the executing thread have a TCB?
 146
 147       procedure Set (Self_Id : Task_Id);
 148       pragma Inline (Set);
 149       --  Set the self id for the current task
 150
 151       function Self return Task_Id;
 152       pragma Inline (Self);
 153       --  Return a pointer to the Ada Task Control Block of the calling task
 154
 155    end Specific;
 156
 157    package body Specific is separate;
 158    --  The body of this package is target specific
 159
 160    ---------------------------------
 161    -- Support for foreign threads --
 162    ---------------------------------
 163
 164    function Register_Foreign_Thread (Thread : Thread_Id) return Task_Id;
 165    --  Allocate and Initialize a new ATCB for the current Thread
 166
 167    function Register_Foreign_Thread
 168      (Thread : Thread_Id) return Task_Id is separate;
 169
 170    -----------------------
 171    -- Local Subprograms --
 172    -----------------------
 173
 174    procedure Abort_Handler (Sig : Signal);
 175
 176    function To_Address is new Unchecked_Conversion (Task_Id, System.Address);
 177
 178    -------------------
 179    -- Abort_Handler --
 180    -------------------
 181
 182    procedure Abort_Handler (Sig : Signal) is
 183       pragma Unreferenced (Sig);
 184
 185       Self_Id : constant Task_Id := Self;
 186       Result  : Interfaces.C.int;
 187       Old_Set : aliased sigset_t;
 188
 189    begin
 190       if Self_Id.Deferral_Level = 0
 191         and then Self_Id.Pending_ATC_Level < Self_Id.ATC_Nesting_Level and then
 192         not Self_Id.Aborting
 193       then
 194          Self_Id.Aborting := True;
 195
 196          --  Make sure signals used for RTS internal purpose are unmasked
 197
 198          Result := pthread_sigmask (SIG_UNBLOCK,
 199            Unblocked_Signal_Mask'Unchecked_Access, Old_Set'Unchecked_Access);
 200          pragma Assert (Result = 0);
 201
 202          raise Standard'Abort_Signal;
 203       end if;
 204    end Abort_Handler;
 205
 206    -----------------
 207    -- Stack_Guard --
 208    -----------------
 209
 210    --  The underlying thread system sets a guard page at the
 211    --  bottom of a thread stack, so nothing is needed.
 212    --  ??? Check the comment above
 213
 214    procedure Stack_Guard (T : ST.Task_Id; On : Boolean) is
 215       pragma Unreferenced (T, On);
 216    begin
 217       null;
 218    end Stack_Guard;
 219
 220    -------------------
 221    -- Get_Thread_Id --
 222    -------------------
 223
 224    function Get_Thread_Id (T : ST.Task_Id) return OSI.Thread_Id is
 225    begin
 226       return T.Common.LL.Thread;
 227    end Get_Thread_Id;
 228
 229    ----------
 230    -- Self --
 231    ----------
 232
 233    function Self return Task_Id renames Specific.Self;
 234
 235    ---------------------
 236    -- Initialize_Lock --
 237    ---------------------
 238
 239    --  Note: mutexes and cond_variables needed per-task basis are
 240    --        initialized in Initialize_TCB and the Storage_Error is
 241    --        handled. Other mutexes (such as RTS_Lock, Memory_Lock...)
 242    --        used in RTS is initialized before any status change of RTS.
 243    --        Therefore rasing Storage_Error in the following routines
 244    --        should be able to be handled safely.
 245
 246    procedure Initialize_Lock
 247      (Prio : System.Any_Priority;
 248       L    : access Lock)
 249    is
 250       Attributes : aliased pthread_mutexattr_t;
 251       Result     : Interfaces.C.int;
 252
 253    begin
 254       Result := pthread_mutexattr_init (Attributes'Access);
 255       pragma Assert (Result = 0 or else Result = ENOMEM);
 256
 257       if Result = ENOMEM then
 258          raise Storage_Error;
 259       end if;
 260
 261       L.Priority := Prio;
 262
 263       Result := pthread_mutex_init (L.L'Access, Attributes'Access);
 264       pragma Assert (Result = 0 or else Result = ENOMEM);
 265
 266       if Result = ENOMEM then
 267          raise Storage_Error;
 268       end if;
 269
 270       Result := pthread_mutexattr_destroy (Attributes'Access);
 271       pragma Assert (Result = 0);
 272    end Initialize_Lock;
 273
 274    procedure Initialize_Lock (L : access RTS_Lock; Level : Lock_Level) is
 275       pragma Unreferenced (Level);
 276
 277       Attributes : aliased pthread_mutexattr_t;
 278       Result     : Interfaces.C.int;
 279
 280    begin
 281       Result := pthread_mutexattr_init (Attributes'Access);
 282       pragma Assert (Result = 0 or else Result = ENOMEM);
 283
 284       if Result = ENOMEM then
 285          raise Storage_Error;
 286       end if;
 287
 288       Result := pthread_mutex_init (L, Attributes'Access);
 289
 290       pragma Assert (Result = 0 or else Result = ENOMEM);
 291
 292       if Result = ENOMEM then
 293          raise Storage_Error;
 294       end if;
 295
 296       Result := pthread_mutexattr_destroy (Attributes'Access);
 297       pragma Assert (Result = 0);
 298    end Initialize_Lock;
 299
 300    -------------------
 301    -- Finalize_Lock --
 302    -------------------
 303
 304    procedure Finalize_Lock (L : access Lock) is
 305       Result : Interfaces.C.int;
 306    begin
 307       Result := pthread_mutex_destroy (L.L'Access);
 308       pragma Assert (Result = 0);
 309    end Finalize_Lock;
 310
 311    procedure Finalize_Lock (L : access RTS_Lock) is
 312       Result : Interfaces.C.int;
 313    begin
 314       Result := pthread_mutex_destroy (L);
 315       pragma Assert (Result = 0);
 316    end Finalize_Lock;
 317
 318    ----------------
 319    -- Write_Lock --
 320    ----------------
 321
 322    procedure Write_Lock (L : access Lock; Ceiling_Violation : out Boolean) is
 323       Result : Interfaces.C.int;
 324
 325    begin
 326       L.Owner_Priority := Get_Priority (Self);
 327
 328       if L.Priority < L.Owner_Priority then
 329          Ceiling_Violation := True;
 330          return;
 331       end if;
 332
 333       Result := pthread_mutex_lock (L.L'Access);
 334       pragma Assert (Result = 0);
 335       Ceiling_Violation := False;
 336    end Write_Lock;
 337
 338    procedure Write_Lock
 339      (L : access RTS_Lock; Global_Lock : Boolean := False)
 340    is
 341       Result : Interfaces.C.int;
 342    begin
 343       if not Single_Lock or else Global_Lock then
 344          Result := pthread_mutex_lock (L);
 345          pragma Assert (Result = 0);
 346       end if;
 347    end Write_Lock;
 348
 349    procedure Write_Lock (T : Task_Id) is
 350       Result : Interfaces.C.int;
 351    begin
 352       if not Single_Lock then
 353          Result := pthread_mutex_lock (T.Common.LL.L'Access);
 354          pragma Assert (Result = 0);
 355       end if;
 356    end Write_Lock;
 357
 358    ---------------
 359    -- Read_Lock --
 360    ---------------
 361
 362    procedure Read_Lock (L : access Lock; Ceiling_Violation : out Boolean) is
 363    begin
 364       Write_Lock (L, Ceiling_Violation);
 365    end Read_Lock;
 366
 367    ------------
 368    -- Unlock --
 369    ------------
 370
 371    procedure Unlock (L : access Lock) is
 372       Result : Interfaces.C.int;
 373    begin
 374       Result := pthread_mutex_unlock (L.L'Access);
 375       pragma Assert (Result = 0);
 376    end Unlock;
 377
 378    procedure Unlock (L : access RTS_Lock; Global_Lock : Boolean := False) is
 379       Result : Interfaces.C.int;
 380    begin
 381       if not Single_Lock or else Global_Lock then
 382          Result := pthread_mutex_unlock (L);
 383          pragma Assert (Result = 0);
 384       end if;
 385    end Unlock;
 386
 387    procedure Unlock (T : Task_Id) is
 388       Result : Interfaces.C.int;
 389    begin
 390       if not Single_Lock then
 391          Result := pthread_mutex_unlock (T.Common.LL.L'Access);
 392          pragma Assert (Result = 0);
 393       end if;
 394    end Unlock;
 395
 396    -----------
 397    -- Sleep --
 398    -----------
 399
 400    procedure Sleep
 401      (Self_ID : Task_Id;
 402       Reason  : System.Tasking.Task_States)
 403    is
 404       pragma Unreferenced (Reason);
 405
 406       Result : Interfaces.C.int;
 407    begin
 408       if Single_Lock then
 409          Result := pthread_cond_wait
 410            (Self_ID.Common.LL.CV'Access, Single_RTS_Lock'Access);
 411       else
 412          Result := pthread_cond_wait
 413            (Self_ID.Common.LL.CV'Access, Self_ID.Common.LL.L'Access);
 414       end if;
 415
 416       --  EINTR is not considered a failure
 417
 418       pragma Assert (Result = 0 or else Result = EINTR);
 419    end Sleep;
 420
 421    -----------------
 422    -- Timed_Sleep --
 423    -----------------
 424
 425    procedure Timed_Sleep
 426      (Self_ID  : Task_Id;
 427       Time     : Duration;
 428       Mode     : ST.Delay_Modes;
 429       Reason   : System.Tasking.Task_States;
 430       Timedout : out Boolean;
 431       Yielded  : out Boolean)
 432    is
 433       pragma Unreferenced (Reason);
 434
 435       Check_Time : constant Duration := Monotonic_Clock;
 436       Abs_Time   : Duration;
 437       Request    : aliased timespec;
 438       Result     : Interfaces.C.int;
 439
 440    begin
 441       Timedout := True;
 442       Yielded := False;
 443
 444       if Mode = Relative then
 445          Abs_Time := Duration'Min (Time, Max_Sensible_Delay) + Check_Time;
 446       else
 447          Abs_Time := Duration'Min (Check_Time + Max_Sensible_Delay, Time);
 448       end if;
 449
 450       if Abs_Time > Check_Time then
 451          Request := To_Timespec (Abs_Time);
 452
 453          loop
 454             exit when Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level
 455               or else Self_ID.Pending_Priority_Change;
 456
 457             if Single_Lock then
 458                Result := pthread_cond_timedwait
 459                  (Self_ID.Common.LL.CV'Access, Single_RTS_Lock'Access,
 460                   Request'Access);
 461
 462             else
 463                Result := pthread_cond_timedwait
 464                  (Self_ID.Common.LL.CV'Access, Self_ID.Common.LL.L'Access,
 465                   Request'Access);
 466             end if;
 467
 468             exit when Abs_Time <= Monotonic_Clock;
 469
 470             if Result = 0 or Result = EINTR then
 471
 472                --  Somebody may have called Wakeup for us
 473
 474                Timedout := False;
 475                exit;
 476             end if;
 477
 478             pragma Assert (Result = ETIMEDOUT);
 479          end loop;
 480       end if;
 481    end Timed_Sleep;
 482
 483    -----------------
 484    -- Timed_Delay --
 485    -----------------
 486
 487    procedure Timed_Delay
 488      (Self_ID  : Task_Id;
 489       Time     : Duration;
 490       Mode     : ST.Delay_Modes)
 491    is
 492       Check_Time : constant Duration := Monotonic_Clock;
 493       Abs_Time   : Duration;
 494       Request    : aliased timespec;
 495       Result     : Interfaces.C.int;
 496
 497    begin
 498       --  The little window between deferring abort and locking Self_ID is the
 499       --  only reason to check for pending abort and priority change below!
 500
 501       SSL.Abort_Defer.all;
 502
 503       if Single_Lock then
 504          Lock_RTS;
 505       end if;
 506
 507       Write_Lock (Self_ID);
 508
 509       if Mode = Relative then
 510          Abs_Time := Time + Check_Time;
 511       else
 512          Abs_Time := Duration'Min (Check_Time + Max_Sensible_Delay, Time);
 513       end if;
 514
 515       if Abs_Time > Check_Time then
 516          Request := To_Timespec (Abs_Time);
 517          Self_ID.Common.State := Delay_Sleep;
 518
 519          loop
 520             if Self_ID.Pending_Priority_Change then
 521                Self_ID.Pending_Priority_Change := False;
 522                Self_ID.Common.Base_Priority := Self_ID.New_Base_Priority;
 523                Set_Priority (Self_ID, Self_ID.Common.Base_Priority);
 524             end if;
 525
 526             exit when Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level;
 527
 528             if Single_Lock then
 529                Result := pthread_cond_timedwait (Self_ID.Common.LL.CV'Access,
 530                  Single_RTS_Lock'Access, Request'Access);
 531             else
 532                Result := pthread_cond_timedwait (Self_ID.Common.LL.CV'Access,
 533                  Self_ID.Common.LL.L'Access, Request'Access);
 534             end if;
 535
 536             exit when Abs_Time <= Monotonic_Clock;
 537
 538             pragma Assert (Result = 0 or else
 539               Result = ETIMEDOUT or else
 540               Result = EINTR);
 541          end loop;
 542
 543          Self_ID.Common.State := Runnable;
 544       end if;
 545
 546       Unlock (Self_ID);
 547
 548       if Single_Lock then
 549          Unlock_RTS;
 550       end if;
 551
 552       Result := sched_yield;
 553       SSL.Abort_Undefer.all;
 554    end Timed_Delay;
 555
 556    ---------------------
 557    -- Monotonic_Clock --
 558    ---------------------
 559
 560    function Monotonic_Clock return Duration is
 561       TS     : aliased timespec;
 562       Result : Interfaces.C.int;
 563    begin
 564       Result := Clock_Gettime (CLOCK_REALTIME, TS'Unchecked_Access);
 565       pragma Assert (Result = 0);
 566       return To_Duration (TS);
 567    end Monotonic_Clock;
 568
 569    -------------------
 570    -- RT_Resolution --
 571    -------------------
 572
 573    function RT_Resolution return Duration is
 574    begin
 575       return 10#1.0#E-6;
 576    end RT_Resolution;
 577
 578    ------------
 579    -- Wakeup --
 580    ------------
 581
 582    procedure Wakeup (T : Task_Id; Reason : System.Tasking.Task_States) is
 583       pragma Unreferenced (Reason);
 584
 585       Result : Interfaces.C.int;
 586
 587    begin
 588       Result := pthread_cond_signal (T.Common.LL.CV'Access);
 589       pragma Assert (Result = 0);
 590    end Wakeup;
 591
 592    -----------
 593    -- Yield --
 594    -----------
 595
 596    procedure Yield (Do_Yield : Boolean := True) is
 597       Result : Interfaces.C.int;
 598       pragma Unreferenced (Result);
 599    begin
 600       if Do_Yield then
 601          Result := sched_yield;
 602       end if;
 603    end Yield;
 604
 605    ------------------
 606    -- Set_Priority --
 607    ------------------
 608
 609    type Prio_Array_Type is array (System.Any_Priority) of Integer;
 610    pragma Atomic_Components (Prio_Array_Type);
 611
 612    Prio_Array : Prio_Array_Type;
 613    --  Global array containing the id of the currently running task for
 614    --  each priority.
 615    --
 616    --  Note: we assume that we are on a single processor with run-til-blocked
 617    --  scheduling.
 618
 619    procedure Set_Priority
 620      (T                   : Task_Id;
 621       Prio                : System.Any_Priority;
 622       Loss_Of_Inheritance : Boolean := False)
 623    is
 624       Result     : Interfaces.C.int;
 625       Array_Item : Integer;
 626       Param      : aliased struct_sched_param;
 627
 628    begin
 629       Param.sched_priority  := Interfaces.C.int (Underlying_Priorities (Prio));
 630
 631       if Time_Slice_Val > 0 then
 632          Result := pthread_setschedparam
 633            (T.Common.LL.Thread, SCHED_RR, Param'Access);
 634
 635       elsif FIFO_Within_Priorities or else Time_Slice_Val = 0 then
 636          Result := pthread_setschedparam
 637            (T.Common.LL.Thread, SCHED_FIFO, Param'Access);
 638
 639       else
 640          Result := pthread_setschedparam
 641            (T.Common.LL.Thread, SCHED_OTHER, Param'Access);
 642       end if;
 643
 644       pragma Assert (Result = 0);
 645
 646       if FIFO_Within_Priorities then
 647
 648          --  Annex D requirement [RM D.2.2 par. 9]:
 649          --    If the task drops its priority due to the loss of inherited
 650          --    priority, it is added at the head of the ready queue for its
 651          --    new active priority.
 652
 653          if Loss_Of_Inheritance
 654            and then Prio < T.Common.Current_Priority
 655          then
 656             Array_Item := Prio_Array (T.Common.Base_Priority) + 1;
 657             Prio_Array (T.Common.Base_Priority) := Array_Item;
 658
 659             loop
 660                --  Let some processes a chance to arrive
 661
 662                Yield;
 663
 664                --  Then wait for our turn to proceed
 665
 666                exit when Array_Item = Prio_Array (T.Common.Base_Priority)
 667                  or else Prio_Array (T.Common.Base_Priority) = 1;
 668             end loop;
 669
 670             Prio_Array (T.Common.Base_Priority) :=
 671               Prio_Array (T.Common.Base_Priority) - 1;
 672          end if;
 673       end if;
 674
 675       T.Common.Current_Priority := Prio;
 676    end Set_Priority;
 677
 678    ------------------
 679    -- Get_Priority --
 680    ------------------
 681
 682    function Get_Priority (T : Task_Id) return System.Any_Priority is
 683    begin
 684       return T.Common.Current_Priority;
 685    end Get_Priority;
 686
 687    ----------------
 688    -- Enter_Task --
 689    ----------------
 690
 691    procedure Enter_Task (Self_ID : Task_Id) is
 692    begin
 693       Self_ID.Common.LL.Thread := pthread_self;
 694       Specific.Set (Self_ID);
 695
 696       Lock_RTS;
 697
 698       for J in Known_Tasks'Range loop
 699          if Known_Tasks (J) = null then
 700             Known_Tasks (J) := Self_ID;
 701             Self_ID.Known_Tasks_Index := J;
 702             exit;
 703          end if;
 704       end loop;
 705
 706       Unlock_RTS;
 707    end Enter_Task;
 708
 709    --------------
 710    -- New_ATCB --
 711    --------------
 712
 713    function New_ATCB (Entry_Num : Task_Entry_Index) return Task_Id is
 714    begin
 715       return new Ada_Task_Control_Block (Entry_Num);
 716    end New_ATCB;
 717
 718    -------------------
 719    -- Is_Valid_Task --
 720    -------------------
 721
 722    function Is_Valid_Task return Boolean renames Specific.Is_Valid_Task;
 723
 724    -----------------------------
 725    -- Register_Foreign_Thread --
 726    -----------------------------
 727
 728    function Register_Foreign_Thread return Task_Id is
 729    begin
 730       if Is_Valid_Task then
 731          return Self;
 732       else
 733          return Register_Foreign_Thread (pthread_self);
 734       end if;
 735    end Register_Foreign_Thread;
 736
 737    --------------------
 738    -- Initialize_TCB --
 739    --------------------
 740
 741    procedure Initialize_TCB (Self_ID : Task_Id; Succeeded : out Boolean) is
 742       Mutex_Attr : aliased pthread_mutexattr_t;
 743       Result     : Interfaces.C.int;
 744       Cond_Attr  : aliased pthread_condattr_t;
 745
 746    begin
 747       if not Single_Lock then
 748          Result := pthread_mutexattr_init (Mutex_Attr'Access);
 749          pragma Assert (Result = 0 or else Result = ENOMEM);
 750
 751          if Result = 0 then
 752             Result := pthread_mutex_init (Self_ID.Common.LL.L'Access,
 753               Mutex_Attr'Access);
 754             pragma Assert (Result = 0 or else Result = ENOMEM);
 755          end if;
 756
 757          if Result /= 0 then
 758             Succeeded := False;
 759             return;
 760          end if;
 761
 762          Result := pthread_mutexattr_destroy (Mutex_Attr'Access);
 763          pragma Assert (Result = 0);
 764       end if;
 765
 766       Result := pthread_condattr_init (Cond_Attr'Access);
 767       pragma Assert (Result = 0 or else Result = ENOMEM);
 768
 769       if Result = 0 then
 770          Result := pthread_cond_init (Self_ID.Common.LL.CV'Access,
 771            Cond_Attr'Access);
 772          pragma Assert (Result = 0 or else Result = ENOMEM);
 773       end if;
 774
 775       if Result = 0 then
 776          Succeeded := True;
 777       else
 778          if not Single_Lock then
 779             Result := pthread_mutex_destroy (Self_ID.Common.LL.L'Access);
 780             pragma Assert (Result = 0);
 781          end if;
 782
 783          Succeeded := False;
 784       end if;
 785
 786       Result := pthread_condattr_destroy (Cond_Attr'Access);
 787       pragma Assert (Result = 0);
 788    end Initialize_TCB;
 789
 790    -----------------
 791    -- Create_Task --
 792    -----------------
 793
 794    procedure Create_Task
 795      (T          : Task_Id;
 796       Wrapper    : System.Address;
 797       Stack_Size : System.Parameters.Size_Type;
 798       Priority   : System.Any_Priority;
 799       Succeeded  : out Boolean)
 800    is
 801       Attributes          : aliased pthread_attr_t;
 802       Adjusted_Stack_Size : Interfaces.C.size_t;
 803       Result              : Interfaces.C.int;
 804
 805       function Thread_Body_Access is new
 806         Unchecked_Conversion (System.Address, Thread_Body);
 807
 808    begin
 809       if Stack_Size = Unspecified_Size then
 810          Adjusted_Stack_Size := Interfaces.C.size_t (Default_Stack_Size);
 811
 812       elsif Stack_Size < Minimum_Stack_Size then
 813          Adjusted_Stack_Size := Interfaces.C.size_t (Minimum_Stack_Size);
 814
 815       else
 816          Adjusted_Stack_Size := Interfaces.C.size_t (Stack_Size);
 817       end if;
 818
 819       Result := pthread_attr_init (Attributes'Access);
 820       pragma Assert (Result = 0 or else Result = ENOMEM);
 821
 822       if Result /= 0 then
 823          Succeeded := False;
 824          return;
 825       end if;
 826
 827       Result := pthread_attr_setstacksize
 828         (Attributes'Access, Adjusted_Stack_Size);
 829       pragma Assert (Result = 0);
 830
 831       --  Since the initial signal mask of a thread is inherited from the
 832       --  creator, and the Environment task has all its signals masked, we
 833       --  do not need to manipulate caller's signal mask at this point.
 834       --  All tasks in RTS will have All_Tasks_Mask initially.
 835
 836       Result := pthread_create
 837         (T.Common.LL.Thread'Access,
 838          Attributes'Access,
 839          Thread_Body_Access (Wrapper),
 840          To_Address (T));
 841       pragma Assert (Result = 0 or else Result = EAGAIN);
 842
 843       Succeeded := Result = 0;
 844
 845       pthread_detach (T.Common.LL.Thread'Access);
 846       --  Detach the thread using pthread_detach, sinc DCE threads do not have
 847       --  pthread_attr_set_detachstate.
 848
 849       Result := pthread_attr_destroy (Attributes'Access);
 850       pragma Assert (Result = 0);
 851
 852       Set_Priority (T, Priority);
 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       Tmp     : Task_Id := T;
 862       Is_Self : constant Boolean := T = Self;
 863
 864       procedure Free is new
 865         Unchecked_Deallocation (Ada_Task_Control_Block, Task_Id);
 866
 867    begin
 868       if not Single_Lock then
 869          Result := pthread_mutex_destroy (T.Common.LL.L'Access);
 870          pragma Assert (Result = 0);
 871       end if;
 872
 873       Result := pthread_cond_destroy (T.Common.LL.CV'Access);
 874       pragma Assert (Result = 0);
 875
 876       if T.Known_Tasks_Index /= -1 then
 877          Known_Tasks (T.Known_Tasks_Index) := null;
 878       end if;
 879
 880       Free (Tmp);
 881
 882       if Is_Self then
 883          Specific.Set (null);
 884       end if;
 885    end Finalize_TCB;
 886
 887    ---------------
 888    -- Exit_Task --
 889    ---------------
 890
 891    procedure Exit_Task is
 892    begin
 893       Specific.Set (null);
 894    end Exit_Task;
 895
 896    ----------------
 897    -- Abort_Task --
 898    ----------------
 899
 900    procedure Abort_Task (T : Task_Id) is
 901    begin
 902       --
 903       --  Interrupt Server_Tasks may be waiting on an "event" flag (signal)
 904       --
 905       if T.Common.State = Interrupt_Server_Blocked_On_Event_Flag then
 906          System.Interrupt_Management.Operations.Interrupt_Self_Process
 907            (System.Interrupt_Management.Interrupt_ID
 908              (PIO.Get_Interrupt_ID (T)));
 909       end if;
 910    end Abort_Task;
 911
 912    ----------------
 913    -- Check_Exit --
 914    ----------------
 915
 916    --  Dummy version
 917
 918    function Check_Exit (Self_ID : ST.Task_Id) return Boolean is
 919       pragma Unreferenced (Self_ID);
 920    begin
 921       return True;
 922    end Check_Exit;
 923
 924    --------------------
 925    -- Check_No_Locks --
 926    --------------------
 927
 928    function Check_No_Locks (Self_ID : ST.Task_Id) return Boolean is
 929       pragma Unreferenced (Self_ID);
 930    begin
 931       return True;
 932    end Check_No_Locks;
 933
 934    ----------------------
 935    -- Environment_Task --
 936    ----------------------
 937
 938    function Environment_Task return Task_Id is
 939    begin
 940       return Environment_Task_Id;
 941    end Environment_Task;
 942
 943    --------------
 944    -- Lock_RTS --
 945    --------------
 946
 947    procedure Lock_RTS is
 948    begin
 949       Write_Lock (Single_RTS_Lock'Access, Global_Lock => True);
 950    end Lock_RTS;
 951
 952    ----------------
 953    -- Unlock_RTS --
 954    ----------------
 955
 956    procedure Unlock_RTS is
 957    begin
 958       Unlock (Single_RTS_Lock'Access, Global_Lock => True);
 959    end Unlock_RTS;
 960
 961    ------------------
 962    -- Suspend_Task --
 963    ------------------
 964
 965    function Suspend_Task
 966      (T           : ST.Task_Id;
 967       Thread_Self : Thread_Id) return Boolean
 968    is
 969       pragma Unreferenced (T);
 970       pragma Unreferenced (Thread_Self);
 971    begin
 972       return False;
 973    end Suspend_Task;
 974
 975    -----------------
 976    -- Resume_Task --
 977    -----------------
 978
 979    function Resume_Task
 980      (T           : ST.Task_Id;
 981       Thread_Self : Thread_Id) return Boolean
 982    is
 983       pragma Unreferenced (T);
 984       pragma Unreferenced (Thread_Self);
 985    begin
 986       return False;
 987    end Resume_Task;
 988
 989    ----------------
 990    -- Initialize --
 991    ----------------
 992
 993    procedure Initialize (Environment_Task : Task_Id) is
 994       act       : aliased struct_sigaction;
 995       old_act   : aliased struct_sigaction;
 996       Tmp_Set   : aliased sigset_t;
 997       Result    : Interfaces.C.int;
 998
 999       function State
1000         (Int : System.Interrupt_Management.Interrupt_ID) return Character;
1001       pragma Import (C, State, "__gnat_get_interrupt_state");
1002       --  Get interrupt state. Defined in a-init.c. The input argument is
1003       --  the interrupt number, and the result is one of the following:
1004
1005       Default : constant Character := 's';
1006       --    'n'   this interrupt not set by any Interrupt_State pragma
1007       --    'u'   Interrupt_State pragma set state to User
1008       --    'r'   Interrupt_State pragma set state to Runtime
1009       --    's'   Interrupt_State pragma set state to System (use "default"
1010       --           system handler)
1011
1012    begin
1013       Environment_Task_Id := Environment_Task;
1014
1015       --  Initialize the lock used to synchronize chain of all ATCBs
1016
1017       Initialize_Lock (Single_RTS_Lock'Access, RTS_Lock_Level);
1018
1019       Specific.Initialize (Environment_Task);
1020
1021       Enter_Task (Environment_Task);
1022
1023       --  Install the abort-signal handler
1024
1025       if State (System.Interrupt_Management.Abort_Task_Interrupt)
1026                                                      /= Default
1027       then
1028          act.sa_flags := 0;
1029          act.sa_handler := Abort_Handler'Address;
1030
1031          Result := sigemptyset (Tmp_Set'Access);
1032          pragma Assert (Result = 0);
1033          act.sa_mask := Tmp_Set;
1034
1035          Result :=
1036            sigaction (
1037              Signal (System.Interrupt_Management.Abort_Task_Interrupt),
1038              act'Unchecked_Access,
1039              old_act'Unchecked_Access);
1040          pragma Assert (Result = 0);
1041       end if;
1042    end Initialize;
1043
1044    --  NOTE: Unlike other pthread implementations, we do *not* mask all
1045    --  signals here since we handle signals using the process-wide primitive
1046    --  signal, rather than using sigthreadmask and sigwait. The reason of
1047    --  this difference is that sigwait doesn't work when some critical
1048    --  signals (SIGABRT, SIGPIPE) are masked.
1049
1050 end System.Task_Primitives.Operations;