gcc/ada/s-taprop-tru64.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) 1992-2009, 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 Tru64 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_Deallocation;
  42
  43 with Interfaces;
  44 with Interfaces.C;
  45
  46 with System.Tasking.Debug;
  47 with System.Interrupt_Management;
  48 with System.OS_Primitives;
  49 with System.Task_Info;
  50
  51 with System.Soft_Links;
  52 --  We use System.Soft_Links instead of System.Tasking.Initialization
  53 --  because the later is a higher level package that we shouldn't depend on.
  54 --  For example when using the restricted run time, it is replaced by
  55 --  System.Tasking.Restricted.Stages.
  56
  57 package body System.Task_Primitives.Operations is
  58
  59    package SSL renames System.Soft_Links;
  60
  61    use System.Tasking.Debug;
  62    use System.Tasking;
  63    use Interfaces.C;
  64    use System.OS_Interface;
  65    use System.Parameters;
  66    use System.OS_Primitives;
  67
  68    ----------------
  69    -- Local Data --
  70    ----------------
  71
  72    --  The followings are logically constants, but need to be initialized
  73    --  at run time.
  74
  75    Single_RTS_Lock : aliased RTS_Lock;
  76    --  This is a lock to allow only one thread of control in the RTS at
  77    --  a time; it is used to execute in mutual exclusion from all other tasks.
  78    --  Used mainly in Single_Lock mode, but also to protect All_Tasks_List
  79
  80    ATCB_Key : aliased pthread_key_t;
  81    --  Key used to find the Ada Task_Id associated with a thread
  82
  83    Environment_Task_Id : Task_Id;
  84    --  A variable to hold Task_Id for the environment task
  85
  86    Unblocked_Signal_Mask : aliased sigset_t;
  87    --  The set of signals that should unblocked in all tasks
  88
  89    Time_Slice_Val : Integer;
  90    pragma Import (C, Time_Slice_Val, "__gl_time_slice_val");
  91
  92    Locking_Policy : Character;
  93    pragma Import (C, Locking_Policy, "__gl_locking_policy");
  94
  95    Dispatching_Policy : Character;
  96    pragma Import (C, Dispatching_Policy, "__gl_task_dispatching_policy");
  97
  98    Curpid : pid_t;
  99
 100    Foreign_Task_Elaborated : aliased Boolean := True;
 101    --  Used to identified fake tasks (i.e., non-Ada Threads)
 102
 103    Abort_Handler_Installed : Boolean := False;
 104    --  True if a handler for the abort signal is installed
 105
 106    --------------------
 107    -- Local Packages --
 108    --------------------
 109
 110    package Specific is
 111
 112       procedure Initialize (Environment_Task : Task_Id);
 113       pragma Inline (Initialize);
 114       --  Initialize various data needed by this package
 115
 116       function Is_Valid_Task return Boolean;
 117       pragma Inline (Is_Valid_Task);
 118       --  Does executing thread have a TCB?
 119
 120       procedure Set (Self_Id : Task_Id);
 121       pragma Inline (Set);
 122       --  Set the self id for the current task
 123
 124       function Self return Task_Id;
 125       pragma Inline (Self);
 126       --  Return a pointer to the Ada Task Control Block of the calling task
 127
 128    end Specific;
 129
 130    package body Specific is separate;
 131    --  The body of this package is target specific
 132
 133    ---------------------------------
 134    -- Support for foreign threads --
 135    ---------------------------------
 136
 137    function Register_Foreign_Thread (Thread : Thread_Id) return Task_Id;
 138    --  Allocate and initialize a new ATCB for the current Thread
 139
 140    function Register_Foreign_Thread
 141      (Thread : Thread_Id) return Task_Id is separate;
 142
 143    -----------------------
 144    -- Local Subprograms --
 145    -----------------------
 146
 147    procedure Abort_Handler (Sig : Signal);
 148    --  Signal handler used to implement asynchronous abort
 149
 150    function Get_Policy (Prio : System.Any_Priority) return Character;
 151    pragma Import (C, Get_Policy, "__gnat_get_specific_dispatching");
 152    --  Get priority specific dispatching policy
 153
 154    -------------------
 155    -- Abort_Handler --
 156    -------------------
 157
 158    procedure Abort_Handler (Sig : Signal) is
 159       pragma Unreferenced (Sig);
 160
 161       T       : constant Task_Id := Self;
 162       Old_Set : aliased sigset_t;
 163
 164       Result : Interfaces.C.int;
 165       pragma Warnings (Off, Result);
 166
 167    begin
 168       --  It's not safe to raise an exception when using GCC ZCX mechanism.
 169       --  Note that we still need to install a signal handler, since in some
 170       --  cases (e.g. shutdown of the Server_Task in System.Interrupts) we
 171       --  need to send the Abort signal to a task.
 172
 173       if ZCX_By_Default and then GCC_ZCX_Support then
 174          return;
 175       end if;
 176
 177       if T.Deferral_Level = 0
 178         and then T.Pending_ATC_Level < T.ATC_Nesting_Level
 179         and then not T.Aborting
 180       then
 181          T.Aborting := True;
 182
 183          --  Make sure signals used for RTS internal purpose are unmasked
 184
 185          Result :=
 186            pthread_sigmask
 187              (SIG_UNBLOCK,
 188               Unblocked_Signal_Mask'Access,
 189               Old_Set'Access);
 190          pragma Assert (Result = 0);
 191
 192          raise Standard'Abort_Signal;
 193       end if;
 194    end Abort_Handler;
 195
 196    ------------------
 197    -- Stack_Guard  --
 198    ------------------
 199
 200    --  The underlying thread system sets a guard page at the bottom of a thread
 201    --  stack, so nothing is needed.
 202
 203    procedure Stack_Guard (T : ST.Task_Id; On : Boolean) is
 204       pragma Unreferenced (T);
 205       pragma Unreferenced (On);
 206    begin
 207       null;
 208    end Stack_Guard;
 209
 210    --------------------
 211    -- Get_Thread_Id  --
 212    --------------------
 213
 214    function Get_Thread_Id (T : ST.Task_Id) return OSI.Thread_Id is
 215    begin
 216       return T.Common.LL.Thread;
 217    end Get_Thread_Id;
 218
 219    ----------
 220    -- Self --
 221    ----------
 222
 223    function Self return Task_Id renames Specific.Self;
 224
 225    ---------------------
 226    -- Initialize_Lock --
 227    ---------------------
 228
 229    --  Note: mutexes and cond_variables needed per-task basis are initialized
 230    --  in Initialize_TCB and the Storage_Error is handled. Other mutexes (such
 231    --  as RTS_Lock, Memory_Lock...) used in RTS is initialized before any
 232    --  status change of RTS. Therefore raising Storage_Error in the following
 233    --  routines should be able to be handled safely.
 234
 235    procedure Initialize_Lock
 236      (Prio : System.Any_Priority;
 237       L    : not null access Lock)
 238    is
 239       Attributes : aliased pthread_mutexattr_t;
 240       Result     : Interfaces.C.int;
 241
 242    begin
 243       Result := pthread_mutexattr_init (Attributes'Access);
 244       pragma Assert (Result = 0 or else Result = ENOMEM);
 245
 246       if Result = ENOMEM then
 247          raise Storage_Error;
 248       end if;
 249
 250       if Locking_Policy = 'C' then
 251          L.Ceiling := Interfaces.C.int (Prio);
 252       end if;
 253
 254       Result := pthread_mutex_init (L.L'Access, Attributes'Access);
 255       pragma Assert (Result = 0 or else Result = ENOMEM);
 256
 257       if Result = ENOMEM then
 258          Result := pthread_mutexattr_destroy (Attributes'Access);
 259          raise Storage_Error;
 260       end if;
 261
 262       Result := pthread_mutexattr_destroy (Attributes'Access);
 263       pragma Assert (Result = 0);
 264    end Initialize_Lock;
 265
 266    procedure Initialize_Lock
 267      (L     : not null access RTS_Lock;
 268       Level : Lock_Level)
 269    is
 270       pragma Unreferenced (Level);
 271
 272       Attributes : aliased pthread_mutexattr_t;
 273       Result     : Interfaces.C.int;
 274
 275    begin
 276       Result := pthread_mutexattr_init (Attributes'Access);
 277       pragma Assert (Result = 0 or else Result = ENOMEM);
 278
 279       if Result = ENOMEM then
 280          raise Storage_Error;
 281       end if;
 282
 283       Result := pthread_mutex_init (L, Attributes'Access);
 284       pragma Assert (Result = 0 or else Result = ENOMEM);
 285
 286       if Result = ENOMEM then
 287          Result := pthread_mutexattr_destroy (Attributes'Access);
 288          raise Storage_Error;
 289       end if;
 290
 291       Result := pthread_mutexattr_destroy (Attributes'Access);
 292       pragma Assert (Result = 0);
 293    end Initialize_Lock;
 294
 295    -------------------
 296    -- Finalize_Lock --
 297    -------------------
 298
 299    procedure Finalize_Lock (L : not null access Lock) is
 300       Result : Interfaces.C.int;
 301    begin
 302       Result := pthread_mutex_destroy (L.L'Access);
 303       pragma Assert (Result = 0);
 304    end Finalize_Lock;
 305
 306    procedure Finalize_Lock (L : not null access RTS_Lock) is
 307       Result : Interfaces.C.int;
 308    begin
 309       Result := pthread_mutex_destroy (L);
 310       pragma Assert (Result = 0);
 311    end Finalize_Lock;
 312
 313    ----------------
 314    -- Write_Lock --
 315    ----------------
 316
 317    procedure Write_Lock
 318      (L                 : not null access Lock;
 319       Ceiling_Violation : out Boolean)
 320    is
 321       Result         : Interfaces.C.int;
 322       Self_ID        : Task_Id;
 323       All_Tasks_Link : Task_Id;
 324       Current_Prio   : System.Any_Priority;
 325
 326    begin
 327       --  Perform ceiling checks only when this is the locking policy in use
 328
 329       if Locking_Policy = 'C' then
 330          Self_ID := Self;
 331          All_Tasks_Link := Self_ID.Common.All_Tasks_Link;
 332          Current_Prio := Get_Priority (Self_ID);
 333
 334          --  If there is no other task, no need to check priorities
 335
 336          if All_Tasks_Link /= Null_Task
 337            and then L.Ceiling < Interfaces.C.int (Current_Prio)
 338          then
 339             Ceiling_Violation := True;
 340             return;
 341          end if;
 342       end if;
 343
 344       Result := pthread_mutex_lock (L.L'Access);
 345       pragma Assert (Result = 0);
 346
 347       Ceiling_Violation := False;
 348    end Write_Lock;
 349
 350    procedure Write_Lock
 351      (L           : not null access RTS_Lock;
 352       Global_Lock : Boolean := False)
 353    is
 354       Result : Interfaces.C.int;
 355    begin
 356       if not Single_Lock or else Global_Lock then
 357          Result := pthread_mutex_lock (L);
 358          pragma Assert (Result = 0);
 359       end if;
 360    end Write_Lock;
 361
 362    procedure Write_Lock (T : Task_Id) is
 363       Result : Interfaces.C.int;
 364    begin
 365       if not Single_Lock then
 366          Result := pthread_mutex_lock (T.Common.LL.L'Access);
 367          pragma Assert (Result = 0);
 368       end if;
 369    end Write_Lock;
 370
 371    ---------------
 372    -- Read_Lock --
 373    ---------------
 374
 375    procedure Read_Lock
 376      (L                 : not null access Lock;
 377       Ceiling_Violation : out Boolean)
 378    is
 379    begin
 380       Write_Lock (L, Ceiling_Violation);
 381    end Read_Lock;
 382
 383    ------------
 384    -- Unlock --
 385    ------------
 386
 387    procedure Unlock (L : not null access Lock) is
 388       Result : Interfaces.C.int;
 389    begin
 390       Result := pthread_mutex_unlock (L.L'Access);
 391       pragma Assert (Result = 0);
 392    end Unlock;
 393
 394    procedure Unlock
 395      (L           : not null access RTS_Lock;
 396       Global_Lock : Boolean := False)
 397    is
 398       Result : Interfaces.C.int;
 399    begin
 400       if not Single_Lock or else Global_Lock then
 401          Result := pthread_mutex_unlock (L);
 402          pragma Assert (Result = 0);
 403       end if;
 404    end Unlock;
 405
 406    procedure Unlock (T : Task_Id) is
 407       Result : Interfaces.C.int;
 408    begin
 409       if not Single_Lock then
 410          Result := pthread_mutex_unlock (T.Common.LL.L'Access);
 411          pragma Assert (Result = 0);
 412       end if;
 413    end Unlock;
 414
 415    -----------------
 416    -- Set_Ceiling --
 417    -----------------
 418
 419    --  Dynamic priority ceilings are not supported by the underlying system
 420
 421    procedure Set_Ceiling
 422      (L    : not null access Lock;
 423       Prio : System.Any_Priority)
 424    is
 425       pragma Unreferenced (L, Prio);
 426    begin
 427       null;
 428    end Set_Ceiling;
 429
 430    -----------
 431    -- Sleep --
 432    -----------
 433
 434    procedure Sleep
 435      (Self_ID : Task_Id;
 436       Reason  : System.Tasking.Task_States)
 437    is
 438       pragma Unreferenced (Reason);
 439
 440       Result : Interfaces.C.int;
 441
 442    begin
 443       Result :=
 444         pthread_cond_wait
 445           (cond  => Self_ID.Common.LL.CV'Access,
 446            mutex => (if Single_Lock
 447                      then Single_RTS_Lock'Access
 448                      else Self_ID.Common.LL.L'Access));
 449
 450       --  EINTR is not considered a failure
 451
 452       pragma Assert (Result = 0 or else Result = EINTR);
 453    end Sleep;
 454
 455    -----------------
 456    -- Timed_Sleep --
 457    -----------------
 458
 459    --  This is for use within the run-time system, so abort is assumed to be
 460    --  already deferred, and the caller should be holding its own ATCB lock.
 461
 462    procedure Timed_Sleep
 463      (Self_ID  : Task_Id;
 464       Time     : Duration;
 465       Mode     : ST.Delay_Modes;
 466       Reason   : System.Tasking.Task_States;
 467       Timedout : out Boolean;
 468       Yielded  : out Boolean)
 469    is
 470       pragma Unreferenced (Reason);
 471
 472       Base_Time  : constant Duration := Monotonic_Clock;
 473       Check_Time : Duration := Base_Time;
 474       Abs_Time   : Duration;
 475       Request    : aliased timespec;
 476       Result     : Interfaces.C.int;
 477
 478    begin
 479       Timedout := True;
 480       Yielded := False;
 481
 482       Abs_Time :=
 483         (if Mode = Relative
 484          then Duration'Min (Time, Max_Sensible_Delay) + Check_Time
 485          else Duration'Min (Check_Time + Max_Sensible_Delay, Time));
 486
 487       if Abs_Time > Check_Time then
 488          Request := To_Timespec (Abs_Time);
 489
 490          loop
 491             exit when Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level;
 492
 493             Result :=
 494               pthread_cond_timedwait
 495                 (cond    => Self_ID.Common.LL.CV'Access,
 496                  mutex   => (if Single_Lock
 497                              then Single_RTS_Lock'Access
 498                              else Self_ID.Common.LL.L'Access),
 499                  abstime => Request'Access);
 500
 501             Check_Time := Monotonic_Clock;
 502             exit when Abs_Time <= Check_Time or else Check_Time < Base_Time;
 503
 504             if Result = 0 or Result = EINTR then
 505
 506                --  Somebody may have called Wakeup for us
 507
 508                Timedout := False;
 509                exit;
 510             end if;
 511
 512             pragma Assert (Result = ETIMEDOUT);
 513          end loop;
 514       end if;
 515    end Timed_Sleep;
 516
 517    -----------------
 518    -- Timed_Delay --
 519    -----------------
 520
 521    --  This is for use in implementing delay statements, so we assume the
 522    --  caller is abort-deferred but is holding no locks.
 523
 524    procedure Timed_Delay
 525      (Self_ID  : Task_Id;
 526       Time     : Duration;
 527       Mode     : ST.Delay_Modes)
 528    is
 529       Base_Time  : constant Duration := Monotonic_Clock;
 530       Check_Time : Duration := Base_Time;
 531       Abs_Time   : Duration;
 532       Request    : aliased timespec;
 533       Result     : Interfaces.C.int;
 534
 535    begin
 536       if Single_Lock then
 537          Lock_RTS;
 538       end if;
 539
 540       Write_Lock (Self_ID);
 541
 542       Abs_Time :=
 543         (if Mode = Relative
 544          then Time + Check_Time
 545          else Duration'Min (Check_Time + Max_Sensible_Delay, Time));
 546
 547       if Abs_Time > Check_Time then
 548          Request := To_Timespec (Abs_Time);
 549          Self_ID.Common.State := Delay_Sleep;
 550
 551          loop
 552             exit when Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level;
 553
 554             Result :=
 555               pthread_cond_timedwait
 556                 (cond    => Self_ID.Common.LL.CV'Access,
 557                  mutex   => (if Single_Lock
 558                              then Single_RTS_Lock'Access
 559                              else Self_ID.Common.LL.L'Access),
 560                  abstime => Request'Access);
 561
 562             Check_Time := Monotonic_Clock;
 563             exit when Abs_Time <= Check_Time or else Check_Time < Base_Time;
 564
 565             pragma Assert (Result = 0         or else
 566                            Result = ETIMEDOUT or else
 567                            Result = EINTR);
 568          end loop;
 569
 570          Self_ID.Common.State := Runnable;
 571       end if;
 572
 573       Unlock (Self_ID);
 574
 575       if Single_Lock then
 576          Unlock_RTS;
 577       end if;
 578
 579       Yield;
 580    end Timed_Delay;
 581
 582    ---------------------
 583    -- Monotonic_Clock --
 584    ---------------------
 585
 586    function Monotonic_Clock return Duration is
 587       TS     : aliased timespec;
 588       Result : Interfaces.C.int;
 589    begin
 590       Result := clock_gettime (CLOCK_REALTIME, TS'Unchecked_Access);
 591       pragma Assert (Result = 0);
 592       return To_Duration (TS);
 593    end Monotonic_Clock;
 594
 595    -------------------
 596    -- RT_Resolution --
 597    -------------------
 598
 599    function RT_Resolution return Duration is
 600    begin
 601       --  Returned value must be an integral multiple of Duration'Small (1 ns)
 602       --  The following is the best approximation of 1/1024. The clock on the
 603       --  DEC Alpha ticks at 1024 Hz.
 604
 605       return 0.000_976_563;
 606    end RT_Resolution;
 607
 608    ------------
 609    -- Wakeup --
 610    ------------
 611
 612    procedure Wakeup (T : Task_Id; Reason : System.Tasking.Task_States) is
 613       pragma Unreferenced (Reason);
 614       Result : Interfaces.C.int;
 615    begin
 616       Result := pthread_cond_signal (T.Common.LL.CV'Access);
 617       pragma Assert (Result = 0);
 618    end Wakeup;
 619
 620    -----------
 621    -- Yield --
 622    -----------
 623
 624    procedure Yield (Do_Yield : Boolean := True) is
 625       Result : Interfaces.C.int;
 626       pragma Unreferenced (Result);
 627    begin
 628       if Do_Yield then
 629          Result := sched_yield;
 630       end if;
 631    end Yield;
 632
 633    ------------------
 634    -- Set_Priority --
 635    ------------------
 636
 637    procedure Set_Priority
 638      (T                   : Task_Id;
 639       Prio                : System.Any_Priority;
 640       Loss_Of_Inheritance : Boolean := False)
 641    is
 642       pragma Unreferenced (Loss_Of_Inheritance);
 643
 644       Result : Interfaces.C.int;
 645       Param  : aliased struct_sched_param;
 646
 647       Priority_Specific_Policy : constant Character := Get_Policy (Prio);
 648       --  Upper case first character of the policy name corresponding to the
 649       --  task as set by a Priority_Specific_Dispatching pragma.
 650
 651    begin
 652       T.Common.Current_Priority := Prio;
 653       Param.sched_priority  := Interfaces.C.int (Underlying_Priorities (Prio));
 654
 655       if Dispatching_Policy = 'R'
 656         or else Priority_Specific_Policy = 'R'
 657         or else Time_Slice_Val > 0
 658       then
 659          Result :=
 660            pthread_setschedparam
 661              (T.Common.LL.Thread, SCHED_RR, Param'Access);
 662
 663       elsif Dispatching_Policy = 'F'
 664         or else Priority_Specific_Policy = 'F'
 665         or else Time_Slice_Val = 0
 666       then
 667          Result :=
 668            pthread_setschedparam
 669              (T.Common.LL.Thread, SCHED_FIFO, Param'Access);
 670
 671       else
 672          Result :=
 673            pthread_setschedparam
 674              (T.Common.LL.Thread, SCHED_OTHER, Param'Access);
 675       end if;
 676
 677       pragma Assert (Result = 0);
 678    end Set_Priority;
 679
 680    ------------------
 681    -- Get_Priority --
 682    ------------------
 683
 684    function Get_Priority (T : Task_Id) return System.Any_Priority is
 685    begin
 686       return T.Common.Current_Priority;
 687    end Get_Priority;
 688
 689    ----------------
 690    -- Enter_Task --
 691    ----------------
 692
 693    procedure Enter_Task (Self_ID : Task_Id) is
 694    begin
 695       Hide_Unhide_Yellow_Zone (Hide => True);
 696       Self_ID.Common.LL.Thread := pthread_self;
 697
 698       Specific.Set (Self_ID);
 699    end Enter_Task;
 700
 701    --------------
 702    -- New_ATCB --
 703    --------------
 704
 705    function New_ATCB (Entry_Num : Task_Entry_Index) return Task_Id is
 706    begin
 707       return new Ada_Task_Control_Block (Entry_Num);
 708    end New_ATCB;
 709
 710    -------------------
 711    -- Is_Valid_Task --
 712    -------------------
 713
 714    function Is_Valid_Task return Boolean renames Specific.Is_Valid_Task;
 715
 716    -----------------------------
 717    -- Register_Foreign_Thread --
 718    -----------------------------
 719
 720    function Register_Foreign_Thread return Task_Id is
 721    begin
 722       if Is_Valid_Task then
 723          return Self;
 724       else
 725          return Register_Foreign_Thread (pthread_self);
 726       end if;
 727    end Register_Foreign_Thread;
 728
 729    --------------------
 730    -- Initialize_TCB --
 731    --------------------
 732
 733    procedure Initialize_TCB (Self_ID : Task_Id; Succeeded : out Boolean) is
 734       Mutex_Attr : aliased pthread_mutexattr_t;
 735       Result     : Interfaces.C.int;
 736       Cond_Attr  : aliased pthread_condattr_t;
 737
 738    begin
 739       if not Single_Lock then
 740          Result := pthread_mutexattr_init (Mutex_Attr'Access);
 741          pragma Assert (Result = 0 or else Result = ENOMEM);
 742
 743          if Result = 0 then
 744             Result :=
 745               pthread_mutex_init
 746                 (Self_ID.Common.LL.L'Access, Mutex_Attr'Access);
 747             pragma Assert (Result = 0 or else Result = ENOMEM);
 748          end if;
 749
 750          if Result /= 0 then
 751             Succeeded := False;
 752             return;
 753          end if;
 754
 755          Result := pthread_mutexattr_destroy (Mutex_Attr'Access);
 756          pragma Assert (Result = 0);
 757       end if;
 758
 759       Result := pthread_condattr_init (Cond_Attr'Access);
 760       pragma Assert (Result = 0 or else Result = ENOMEM);
 761
 762       if Result = 0 then
 763          Result :=
 764            pthread_cond_init
 765              (Self_ID.Common.LL.CV'Access, Cond_Attr'Access);
 766          pragma Assert (Result = 0 or else Result = ENOMEM);
 767       end if;
 768
 769       if Result = 0 then
 770          Succeeded := True;
 771       else
 772          if not Single_Lock then
 773             Result := pthread_mutex_destroy (Self_ID.Common.LL.L'Access);
 774             pragma Assert (Result = 0);
 775          end if;
 776
 777          Succeeded := False;
 778       end if;
 779
 780       Result := pthread_condattr_destroy (Cond_Attr'Access);
 781       pragma Assert (Result = 0);
 782    end Initialize_TCB;
 783
 784    -----------------
 785    -- Create_Task --
 786    -----------------
 787
 788    procedure Create_Task
 789      (T          : Task_Id;
 790       Wrapper    : System.Address;
 791       Stack_Size : System.Parameters.Size_Type;
 792       Priority   : System.Any_Priority;
 793       Succeeded  : out Boolean)
 794    is
 795       Attributes          : aliased pthread_attr_t;
 796       Adjusted_Stack_Size : Interfaces.C.size_t;
 797       Result              : Interfaces.C.int;
 798       Param               : aliased System.OS_Interface.struct_sched_param;
 799
 800       Priority_Specific_Policy : constant Character := Get_Policy (Priority);
 801       --  Upper case first character of the policy name corresponding to the
 802       --  task as set by a Priority_Specific_Dispatching pragma.
 803
 804       use System.Task_Info;
 805
 806    begin
 807       --  Account for the Yellow Zone (2 pages) and the guard page right above.
 808       --  See Hide_Unhide_Yellow_Zone for the rationale.
 809
 810       Adjusted_Stack_Size :=
 811         Interfaces.C.size_t (Stack_Size) + 3 * Get_Page_Size;
 812
 813       Result := pthread_attr_init (Attributes'Access);
 814       pragma Assert (Result = 0 or else Result = ENOMEM);
 815
 816       if Result /= 0 then
 817          Succeeded := False;
 818          return;
 819       end if;
 820
 821       Result :=
 822         pthread_attr_setdetachstate
 823           (Attributes'Access, PTHREAD_CREATE_DETACHED);
 824       pragma Assert (Result = 0);
 825
 826       Result :=
 827         pthread_attr_setstacksize
 828           (Attributes'Access, Adjusted_Stack_Size);
 829       pragma Assert (Result = 0);
 830
 831       Param.sched_priority :=
 832         Interfaces.C.int (Underlying_Priorities (Priority));
 833       Result :=
 834         pthread_attr_setschedparam
 835           (Attributes'Access, Param'Access);
 836       pragma Assert (Result = 0);
 837
 838       if Dispatching_Policy = 'R'
 839         or else Priority_Specific_Policy = 'R'
 840         or else Time_Slice_Val > 0
 841       then
 842          Result :=
 843            pthread_attr_setschedpolicy
 844              (Attributes'Access, System.OS_Interface.SCHED_RR);
 845
 846       elsif Dispatching_Policy = 'F'
 847         or else Priority_Specific_Policy = 'F'
 848         or else Time_Slice_Val = 0
 849       then
 850          Result :=
 851            pthread_attr_setschedpolicy
 852              (Attributes'Access, System.OS_Interface.SCHED_FIFO);
 853
 854       else
 855          Result :=
 856            pthread_attr_setschedpolicy
 857              (Attributes'Access, System.OS_Interface.SCHED_OTHER);
 858       end if;
 859
 860       pragma Assert (Result = 0);
 861
 862       --  Set the scheduling parameters explicitly, since this is the only way
 863       --  to force the OS to take e.g. the sched policy and scope attributes
 864       --  into account.
 865
 866       Result :=
 867         pthread_attr_setinheritsched
 868           (Attributes'Access, PTHREAD_EXPLICIT_SCHED);
 869       pragma Assert (Result = 0);
 870
 871       T.Common.Current_Priority := Priority;
 872
 873       if T.Common.Task_Info /= null then
 874          case T.Common.Task_Info.Contention_Scope is
 875             when System.Task_Info.Process_Scope =>
 876                Result :=
 877                  pthread_attr_setscope
 878                    (Attributes'Access, PTHREAD_SCOPE_PROCESS);
 879
 880             when System.Task_Info.System_Scope =>
 881                Result :=
 882                  pthread_attr_setscope
 883                    (Attributes'Access, PTHREAD_SCOPE_SYSTEM);
 884
 885             when System.Task_Info.Default_Scope =>
 886                Result := 0;
 887          end case;
 888
 889          pragma Assert (Result = 0);
 890       end if;
 891
 892       --  Since the initial signal mask of a thread is inherited from the
 893       --  creator, and the Environment task has all its signals masked, we
 894       --  do not need to manipulate caller's signal mask at this point.
 895       --  All tasks in RTS will have All_Tasks_Mask initially.
 896
 897       Result :=
 898         pthread_create
 899           (T.Common.LL.Thread'Access,
 900            Attributes'Access,
 901            Thread_Body_Access (Wrapper),
 902            To_Address (T));
 903       pragma Assert (Result = 0 or else Result = EAGAIN);
 904
 905       Succeeded := Result = 0;
 906
 907       Result := pthread_attr_destroy (Attributes'Access);
 908       pragma Assert (Result = 0);
 909
 910       if Succeeded and then T.Common.Task_Info /= null then
 911
 912          --  ??? We're using a process-wide function to implement a task
 913          --  specific characteristic.
 914
 915          if T.Common.Task_Info.Bind_To_Cpu_Number = 0 then
 916             Result := bind_to_cpu (Curpid, 0);
 917
 918          elsif T.Common.Task_Info.Bind_To_Cpu_Number > 0 then
 919             Result :=
 920               bind_to_cpu
 921                 (Curpid,
 922                  Interfaces.C.unsigned_long (
 923                    Interfaces.Shift_Left
 924                      (Interfaces.Unsigned_64'(1),
 925                       T.Common.Task_Info.Bind_To_Cpu_Number - 1)));
 926             pragma Assert (Result = 0);
 927          end if;
 928       end if;
 929    end Create_Task;
 930
 931    ------------------
 932    -- Finalize_TCB --
 933    ------------------
 934
 935    procedure Finalize_TCB (T : Task_Id) is
 936       Result  : Interfaces.C.int;
 937       Tmp     : Task_Id := T;
 938       Is_Self : constant Boolean := T = Self;
 939
 940       procedure Free is new
 941         Ada.Unchecked_Deallocation (Ada_Task_Control_Block, Task_Id);
 942
 943    begin
 944       if not Single_Lock then
 945          Result := pthread_mutex_destroy (T.Common.LL.L'Access);
 946          pragma Assert (Result = 0);
 947       end if;
 948
 949       Result := pthread_cond_destroy (T.Common.LL.CV'Access);
 950       pragma Assert (Result = 0);
 951
 952       if T.Known_Tasks_Index /= -1 then
 953          Known_Tasks (T.Known_Tasks_Index) := null;
 954       end if;
 955
 956       Free (Tmp);
 957
 958       if Is_Self then
 959          Specific.Set (null);
 960       end if;
 961    end Finalize_TCB;
 962
 963    ---------------
 964    -- Exit_Task --
 965    ---------------
 966
 967    procedure Exit_Task is
 968    begin
 969       Specific.Set (null);
 970       Hide_Unhide_Yellow_Zone (Hide => False);
 971    end Exit_Task;
 972
 973    ----------------
 974    -- Abort_Task --
 975    ----------------
 976
 977    procedure Abort_Task (T : Task_Id) is
 978       Result : Interfaces.C.int;
 979    begin
 980       if Abort_Handler_Installed then
 981          Result := pthread_kill (T.Common.LL.Thread,
 982            Signal (System.Interrupt_Management.Abort_Task_Interrupt));
 983          pragma Assert (Result = 0);
 984       end if;
 985    end Abort_Task;
 986
 987    ----------------
 988    -- Initialize --
 989    ----------------
 990
 991    procedure Initialize (S : in out Suspension_Object) is
 992       Mutex_Attr : aliased pthread_mutexattr_t;
 993       Cond_Attr  : aliased pthread_condattr_t;
 994       Result     : Interfaces.C.int;
 995
 996    begin
 997       --  Initialize internal state (always to False (RM D.10(6)))
 998
 999       S.State := False;
1000       S.Waiting := False;
1001
1002       --  Initialize internal mutex
1003
1004       Result := pthread_mutexattr_init (Mutex_Attr'Access);
1005       pragma Assert (Result = 0 or else Result = ENOMEM);
1006
1007       if Result = ENOMEM then
1008          raise Storage_Error;
1009       end if;
1010
1011       Result := pthread_mutex_init (S.L'Access, Mutex_Attr'Access);
1012       pragma Assert (Result = 0 or else Result = ENOMEM);
1013
1014       if Result = ENOMEM then
1015          Result := pthread_mutexattr_destroy (Mutex_Attr'Access);
1016          raise Storage_Error;
1017       end if;
1018
1019       Result := pthread_mutexattr_destroy (Mutex_Attr'Access);
1020       pragma Assert (Result = 0);
1021
1022       --  Initialize internal condition variable
1023
1024       Result := pthread_condattr_init (Cond_Attr'Access);
1025       pragma Assert (Result = 0 or else Result = ENOMEM);
1026
1027       Result := pthread_cond_init (S.CV'Access, Cond_Attr'Access);
1028
1029       pragma Assert (Result = 0 or else Result = ENOMEM);
1030
1031       if Result /= 0 then
1032          Result := pthread_mutex_destroy (S.L'Access);
1033          pragma Assert (Result = 0);
1034
1035          if Result = ENOMEM then
1036             raise Storage_Error;
1037          end if;
1038       end if;
1039    end Initialize;
1040
1041    --------------
1042    -- Finalize --
1043    --------------
1044
1045    procedure Finalize (S : in out Suspension_Object) is
1046       Result  : Interfaces.C.int;
1047
1048    begin
1049       --  Destroy internal mutex
1050
1051       Result := pthread_mutex_destroy (S.L'Access);
1052       pragma Assert (Result = 0);
1053
1054       --  Destroy internal condition variable
1055
1056       Result := pthread_cond_destroy (S.CV'Access);
1057       pragma Assert (Result = 0);
1058    end Finalize;
1059
1060    -------------------
1061    -- Current_State --
1062    -------------------
1063
1064    function Current_State (S : Suspension_Object) return Boolean is
1065    begin
1066       --  We do not want to use lock on this read operation. State is marked
1067       --  as Atomic so that we ensure that the value retrieved is correct.
1068
1069       return S.State;
1070    end Current_State;
1071
1072    ---------------
1073    -- Set_False --
1074    ---------------
1075
1076    procedure Set_False (S : in out Suspension_Object) is
1077       Result  : Interfaces.C.int;
1078
1079    begin
1080       SSL.Abort_Defer.all;
1081
1082       Result := pthread_mutex_lock (S.L'Access);
1083       pragma Assert (Result = 0);
1084
1085       S.State := False;
1086
1087       Result := pthread_mutex_unlock (S.L'Access);
1088       pragma Assert (Result = 0);
1089
1090       SSL.Abort_Undefer.all;
1091    end Set_False;
1092
1093    --------------
1094    -- Set_True --
1095    --------------
1096
1097    procedure Set_True (S : in out Suspension_Object) is
1098       Result : Interfaces.C.int;
1099
1100    begin
1101       SSL.Abort_Defer.all;
1102
1103       Result := pthread_mutex_lock (S.L'Access);
1104       pragma Assert (Result = 0);
1105
1106       --  If there is already a task waiting on this suspension object then we
1107       --  resume it, leaving the state of the suspension object to False, as
1108       --  specified in (RM D.10(9)). Otherwise, leave the state set to True.
1109
1110       if S.Waiting then
1111          S.Waiting := False;
1112          S.State := False;
1113
1114          Result := pthread_cond_signal (S.CV'Access);
1115          pragma Assert (Result = 0);
1116
1117       else
1118          S.State := True;
1119       end if;
1120
1121       Result := pthread_mutex_unlock (S.L'Access);
1122       pragma Assert (Result = 0);
1123
1124       SSL.Abort_Undefer.all;
1125    end Set_True;
1126
1127    ------------------------
1128    -- Suspend_Until_True --
1129    ------------------------
1130
1131    procedure Suspend_Until_True (S : in out Suspension_Object) is
1132       Result : Interfaces.C.int;
1133
1134    begin
1135       SSL.Abort_Defer.all;
1136
1137       Result := pthread_mutex_lock (S.L'Access);
1138       pragma Assert (Result = 0);
1139
1140       if S.Waiting then
1141
1142          --  Program_Error must be raised upon calling Suspend_Until_True
1143          --  if another task is already waiting on that suspension object
1144          --  (AM D.10(10)).
1145
1146          Result := pthread_mutex_unlock (S.L'Access);
1147          pragma Assert (Result = 0);
1148
1149          SSL.Abort_Undefer.all;
1150
1151          raise Program_Error;
1152
1153       else
1154          --  Suspend the task if the state is False. Otherwise, the task
1155          --  continues its execution, and the state of the suspension object
1156          --  is set to False (RM D.10(9)).
1157
1158          if S.State then
1159             S.State := False;
1160          else
1161             S.Waiting := True;
1162
1163             loop
1164                --  Loop in case pthread_cond_wait returns earlier than expected
1165                --  (e.g. in case of EINTR caused by a signal).
1166
1167                Result := pthread_cond_wait (S.CV'Access, S.L'Access);
1168                pragma Assert (Result = 0 or else Result = EINTR);
1169
1170                exit when not S.Waiting;
1171             end loop;
1172          end if;
1173
1174          Result := pthread_mutex_unlock (S.L'Access);
1175          pragma Assert (Result = 0);
1176
1177          SSL.Abort_Undefer.all;
1178       end if;
1179    end Suspend_Until_True;
1180
1181    ----------------
1182    -- Check_Exit --
1183    ----------------
1184
1185    --  Dummy version
1186
1187    function Check_Exit (Self_ID : ST.Task_Id) return Boolean is
1188       pragma Unreferenced (Self_ID);
1189    begin
1190       return True;
1191    end Check_Exit;
1192
1193    --------------------
1194    -- Check_No_Locks --
1195    --------------------
1196
1197    function Check_No_Locks (Self_ID : ST.Task_Id) return Boolean is
1198       pragma Unreferenced (Self_ID);
1199    begin
1200       return True;
1201    end Check_No_Locks;
1202
1203    ----------------------
1204    -- Environment_Task --
1205    ----------------------
1206
1207    function Environment_Task return Task_Id is
1208    begin
1209       return Environment_Task_Id;
1210    end Environment_Task;
1211
1212    --------------
1213    -- Lock_RTS --
1214    --------------
1215
1216    procedure Lock_RTS is
1217    begin
1218       Write_Lock (Single_RTS_Lock'Access, Global_Lock => True);
1219    end Lock_RTS;
1220
1221    ----------------
1222    -- Unlock_RTS --
1223    ----------------
1224
1225    procedure Unlock_RTS is
1226    begin
1227       Unlock (Single_RTS_Lock'Access, Global_Lock => True);
1228    end Unlock_RTS;
1229
1230    ------------------
1231    -- Suspend_Task --
1232    ------------------
1233
1234    function Suspend_Task
1235      (T           : ST.Task_Id;
1236       Thread_Self : Thread_Id) return Boolean
1237    is
1238       pragma Unreferenced (T, Thread_Self);
1239    begin
1240       return False;
1241    end Suspend_Task;
1242
1243    -----------------
1244    -- Resume_Task --
1245    -----------------
1246
1247    function Resume_Task
1248      (T           : ST.Task_Id;
1249       Thread_Self : Thread_Id) return Boolean
1250    is
1251       pragma Unreferenced (T, Thread_Self);
1252    begin
1253       return False;
1254    end Resume_Task;
1255
1256    --------------------
1257    -- Stop_All_Tasks --
1258    --------------------
1259
1260    procedure Stop_All_Tasks is
1261    begin
1262       null;
1263    end Stop_All_Tasks;
1264
1265    ---------------
1266    -- Stop_Task --
1267    ---------------
1268
1269    function Stop_Task (T : ST.Task_Id) return Boolean is
1270       pragma Unreferenced (T);
1271    begin
1272       return False;
1273    end Stop_Task;
1274
1275    -------------------
1276    -- Continue_Task --
1277    -------------------
1278
1279    function Continue_Task (T : ST.Task_Id) return Boolean is
1280       pragma Unreferenced (T);
1281    begin
1282       return False;
1283    end Continue_Task;
1284
1285    ----------------
1286    -- Initialize --
1287    ----------------
1288
1289    procedure Initialize (Environment_Task : Task_Id) is
1290       act     : aliased struct_sigaction;
1291       old_act : aliased struct_sigaction;
1292       Tmp_Set : aliased sigset_t;
1293       Result  : Interfaces.C.int;
1294
1295       function State
1296         (Int : System.Interrupt_Management.Interrupt_ID) return Character;
1297       pragma Import (C, State, "__gnat_get_interrupt_state");
1298       --  Get interrupt state. Defined in a-init.c. The input argument is
1299       --  the interrupt number, and the result is one of the following:
1300
1301       Default : constant Character := 's';
1302       --    'n'   this interrupt not set by any Interrupt_State pragma
1303       --    'u'   Interrupt_State pragma set state to User
1304       --    'r'   Interrupt_State pragma set state to Runtime
1305       --    's'   Interrupt_State pragma set state to System (use "default"
1306       --           system handler)
1307
1308    begin
1309       Environment_Task_Id := Environment_Task;
1310
1311       Interrupt_Management.Initialize;
1312
1313       --  Prepare the set of signals that should unblocked in all tasks
1314
1315       Result := sigemptyset (Unblocked_Signal_Mask'Access);
1316       pragma Assert (Result = 0);
1317
1318       for J in Interrupt_Management.Interrupt_ID loop
1319          if System.Interrupt_Management.Keep_Unmasked (J) then
1320             Result := sigaddset (Unblocked_Signal_Mask'Access, Signal (J));
1321             pragma Assert (Result = 0);
1322          end if;
1323       end loop;
1324
1325       Curpid := getpid;
1326
1327       --  Initialize the lock used to synchronize chain of all ATCBs
1328
1329       Initialize_Lock (Single_RTS_Lock'Access, RTS_Lock_Level);
1330
1331       Specific.Initialize (Environment_Task);
1332
1333       --  Make environment task known here because it doesn't go through
1334       --  Activate_Tasks, which does it for all other tasks.
1335
1336       Known_Tasks (Known_Tasks'First) := Environment_Task;
1337       Environment_Task.Known_Tasks_Index := Known_Tasks'First;
1338
1339       Enter_Task (Environment_Task);
1340
1341       if State
1342           (System.Interrupt_Management.Abort_Task_Interrupt) /= Default
1343       then
1344          act.sa_flags := 0;
1345          act.sa_handler := Abort_Handler'Address;
1346
1347          Result := sigemptyset (Tmp_Set'Access);
1348          pragma Assert (Result = 0);
1349          act.sa_mask := Tmp_Set;
1350
1351          Result :=
1352            sigaction
1353              (Signal (System.Interrupt_Management.Abort_Task_Interrupt),
1354               act'Unchecked_Access,
1355               old_act'Unchecked_Access);
1356          pragma Assert (Result = 0);
1357          Abort_Handler_Installed := True;
1358       end if;
1359    end Initialize;
1360
1361 end System.Task_Primitives.Operations;