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) 1992-2005, 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,  51  Franklin  Street,  Fifth  Floor, --
  20 -- Boston, MA 02110-1301, 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 OpenVMS/Alpha 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.Parameters;
  51 --  used for Size_Type
  52
  53 with System.Tasking;
  54 --  used for Ada_Task_Control_Block
  55 --           Task_Id
  56
  57 with System.Soft_Links;
  58 --  used for Defer/Undefer_Abort
  59 --           Set_Exc_Stack_Addr
  60
  61 --  Note that we do not use System.Tasking.Initialization directly since
  62 --  this is a higher level package that we shouldn't depend on. For example
  63 --  when using the restricted run time, it is replaced by
  64 --  System.Tasking.Restricted.Stages.
  65
  66 with System.OS_Primitives;
  67 --  used for Delay_Modes
  68
  69 with Unchecked_Conversion;
  70 with Unchecked_Deallocation;
  71
  72 package body System.Task_Primitives.Operations is
  73
  74    use System.Tasking.Debug;
  75    use System.Tasking;
  76    use Interfaces.C;
  77    use System.OS_Interface;
  78    use System.Parameters;
  79    use System.OS_Primitives;
  80    use type System.OS_Primitives.OS_Time;
  81
  82    package SSL renames System.Soft_Links;
  83
  84    ----------------
  85    -- Local Data --
  86    ----------------
  87
  88    --  The followings are logically constants, but need to be initialized
  89    --  at run time.
  90
  91    Single_RTS_Lock : aliased RTS_Lock;
  92    --  This is a lock to allow only one thread of control in the RTS at
  93    --  a time; it is used to execute in mutual exclusion from all other tasks.
  94    --  Used mainly in Single_Lock mode, but also to protect All_Tasks_List
  95
  96    ATCB_Key : aliased pthread_key_t;
  97    --  Key used to find the Ada Task_Id associated with a thread
  98
  99    Environment_Task_Id : Task_Id;
 100    --  A variable to hold Task_Id for the environment task.
 101
 102    Time_Slice_Val : Integer;
 103    pragma Import (C, Time_Slice_Val, "__gl_time_slice_val");
 104
 105    Dispatching_Policy : Character;
 106    pragma Import (C, Dispatching_Policy, "__gl_task_dispatching_policy");
 107
 108    FIFO_Within_Priorities : constant Boolean := Dispatching_Policy = 'F';
 109    --  Indicates whether FIFO_Within_Priorities is set.
 110
 111    Foreign_Task_Elaborated : aliased Boolean := True;
 112    --  Used to identified fake tasks (i.e., non-Ada Threads).
 113
 114    --------------------
 115    -- Local Packages --
 116    --------------------
 117
 118    package Specific is
 119
 120       procedure Initialize (Environment_Task : Task_Id);
 121       pragma Inline (Initialize);
 122       --  Initialize various data needed by this package.
 123
 124       function Is_Valid_Task return Boolean;
 125       pragma Inline (Is_Valid_Task);
 126       --  Does executing thread have a TCB?
 127
 128       procedure Set (Self_Id : Task_Id);
 129       pragma Inline (Set);
 130       --  Set the self id for the current task
 131
 132       function Self return Task_Id;
 133       pragma Inline (Self);
 134       --  Return a pointer to the Ada Task Control Block of the calling task
 135
 136    end Specific;
 137
 138    package body Specific is separate;
 139    --  The body of this package is target specific.
 140
 141    ---------------------------------
 142    -- Support for foreign threads --
 143    ---------------------------------
 144
 145    function Register_Foreign_Thread (Thread : Thread_Id) return Task_Id;
 146    --  Allocate and Initialize a new ATCB for the current Thread
 147
 148    function Register_Foreign_Thread
 149      (Thread : Thread_Id) return Task_Id is separate;
 150
 151    -----------------------
 152    -- Local Subprograms --
 153    -----------------------
 154
 155    function To_Task_Id is new Unchecked_Conversion (System.Address, Task_Id);
 156
 157    function To_Address is new Unchecked_Conversion (Task_Id, System.Address);
 158
 159    procedure Timer_Sleep_AST (ID : Address);
 160    --  Signal the condition variable when AST fires.
 161
 162    procedure Timer_Sleep_AST (ID : Address) is
 163       Result  : Interfaces.C.int;
 164       Self_ID : constant Task_Id := To_Task_Id (ID);
 165    begin
 166       Self_ID.Common.LL.AST_Pending := False;
 167       Result := pthread_cond_signal_int_np (Self_ID.Common.LL.CV'Access);
 168       pragma Assert (Result = 0);
 169    end Timer_Sleep_AST;
 170
 171    -----------------
 172    -- Stack_Guard --
 173    -----------------
 174
 175    --  The underlying thread system sets a guard page at the
 176    --  bottom of a thread stack, so nothing is needed.
 177    --  ??? Check the comment above
 178
 179    procedure Stack_Guard (T : ST.Task_Id; On : Boolean) is
 180       pragma Unreferenced (T);
 181       pragma Unreferenced (On);
 182    begin
 183       null;
 184    end Stack_Guard;
 185
 186    --------------------
 187    -- Get_Thread_Id  --
 188    --------------------
 189
 190    function Get_Thread_Id (T : ST.Task_Id) return OSI.Thread_Id is
 191    begin
 192       return T.Common.LL.Thread;
 193    end Get_Thread_Id;
 194
 195    ----------
 196    -- Self --
 197    ----------
 198
 199    function Self return Task_Id renames Specific.Self;
 200
 201    ---------------------
 202    -- Initialize_Lock --
 203    ---------------------
 204
 205    --  Note: mutexes and cond_variables needed per-task basis are
 206    --  initialized in Initialize_TCB and the Storage_Error is
 207    --  handled. Other mutexes (such as RTS_Lock, Memory_Lock...)
 208    --  used in RTS is initialized before any status change of RTS.
 209    --  Therefore rasing Storage_Error in the following routines
 210    --  should be able to be handled safely.
 211
 212    procedure Initialize_Lock (Prio : System.Any_Priority; L : access Lock) is
 213       Attributes : aliased pthread_mutexattr_t;
 214       Result     : Interfaces.C.int;
 215
 216    begin
 217       Result := pthread_mutexattr_init (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       L.Prio_Save := 0;
 225       L.Prio := Interfaces.C.int (Prio);
 226
 227       Result := pthread_mutex_init (L.L'Access, Attributes'Access);
 228       pragma Assert (Result = 0 or else Result = ENOMEM);
 229
 230       if Result = ENOMEM then
 231          raise Storage_Error;
 232       end if;
 233
 234       Result := pthread_mutexattr_destroy (Attributes'Access);
 235       pragma Assert (Result = 0);
 236    end Initialize_Lock;
 237
 238    procedure Initialize_Lock (L : access RTS_Lock; Level : Lock_Level) is
 239       pragma Unreferenced (Level);
 240
 241       Attributes : aliased pthread_mutexattr_t;
 242       Result : Interfaces.C.int;
 243
 244    begin
 245       Result := pthread_mutexattr_init (Attributes'Access);
 246       pragma Assert (Result = 0 or else Result = ENOMEM);
 247
 248       if Result = ENOMEM then
 249          raise Storage_Error;
 250       end if;
 251
 252 --      Don't use, see comment in s-osinte.ads about ERRORCHECK mutexes???
 253 --      Result := pthread_mutexattr_settype_np
 254 --        (Attributes'Access, PTHREAD_MUTEX_ERRORCHECK_NP);
 255 --      pragma Assert (Result = 0);
 256
 257 --      Result := pthread_mutexattr_setprotocol
 258 --        (Attributes'Access, PTHREAD_PRIO_PROTECT);
 259 --      pragma Assert (Result = 0);
 260
 261 --      Result := pthread_mutexattr_setprioceiling
 262 --         (Attributes'Access, Interfaces.C.int (System.Any_Priority'Last));
 263 --      pragma Assert (Result = 0);
 264
 265       Result := pthread_mutex_init (L, Attributes'Access);
 266
 267       pragma Assert (Result = 0 or else Result = ENOMEM);
 268
 269       if Result = ENOMEM then
 270          raise Storage_Error;
 271       end if;
 272
 273       Result := pthread_mutexattr_destroy (Attributes'Access);
 274       pragma Assert (Result = 0);
 275    end Initialize_Lock;
 276
 277    -------------------
 278    -- Finalize_Lock --
 279    -------------------
 280
 281    procedure Finalize_Lock (L : access Lock) is
 282       Result : Interfaces.C.int;
 283    begin
 284       Result := pthread_mutex_destroy (L.L'Access);
 285       pragma Assert (Result = 0);
 286    end Finalize_Lock;
 287
 288    procedure Finalize_Lock (L : access RTS_Lock) is
 289       Result : Interfaces.C.int;
 290    begin
 291       Result := pthread_mutex_destroy (L);
 292       pragma Assert (Result = 0);
 293    end Finalize_Lock;
 294
 295    ----------------
 296    -- Write_Lock --
 297    ----------------
 298
 299    procedure Write_Lock (L : access Lock; Ceiling_Violation : out Boolean) is
 300       Self_ID        : constant Task_Id := Self;
 301       All_Tasks_Link : constant Task_Id := Self.Common.All_Tasks_Link;
 302       Current_Prio   : System.Any_Priority;
 303       Result         : Interfaces.C.int;
 304
 305    begin
 306       Current_Prio := Get_Priority (Self_ID);
 307
 308       --  If there is no other tasks, no need to check priorities
 309
 310       if All_Tasks_Link /= Null_Task
 311         and then L.Prio < Interfaces.C.int (Current_Prio)
 312       then
 313          Ceiling_Violation := True;
 314          return;
 315       end if;
 316
 317       Result := pthread_mutex_lock (L.L'Access);
 318       pragma Assert (Result = 0);
 319
 320       Ceiling_Violation := False;
 321 --  Why is this commented out ???
 322 --      L.Prio_Save := Interfaces.C.int (Current_Prio);
 323 --      Set_Priority (Self_ID, System.Any_Priority (L.Prio));
 324    end Write_Lock;
 325
 326    procedure Write_Lock
 327      (L           : access RTS_Lock;
 328       Global_Lock : Boolean := False)
 329    is
 330       Result : Interfaces.C.int;
 331    begin
 332       if not Single_Lock or else Global_Lock then
 333          Result := pthread_mutex_lock (L);
 334          pragma Assert (Result = 0);
 335       end if;
 336    end Write_Lock;
 337
 338    procedure Write_Lock (T : Task_Id) is
 339       Result : Interfaces.C.int;
 340    begin
 341       if not Single_Lock then
 342          Result := pthread_mutex_lock (T.Common.LL.L'Access);
 343          pragma Assert (Result = 0);
 344       end if;
 345    end Write_Lock;
 346
 347    ---------------
 348    -- Read_Lock --
 349    ---------------
 350
 351    procedure Read_Lock (L : access Lock; Ceiling_Violation : out Boolean) is
 352    begin
 353       Write_Lock (L, Ceiling_Violation);
 354    end Read_Lock;
 355
 356    ------------
 357    -- Unlock --
 358    ------------
 359
 360    procedure Unlock (L : access Lock) is
 361       Result : Interfaces.C.int;
 362    begin
 363       Result := pthread_mutex_unlock (L.L'Access);
 364       pragma Assert (Result = 0);
 365    end Unlock;
 366
 367    procedure Unlock (L : access RTS_Lock; Global_Lock : Boolean := False) is
 368       Result : Interfaces.C.int;
 369    begin
 370       if not Single_Lock or else Global_Lock then
 371          Result := pthread_mutex_unlock (L);
 372          pragma Assert (Result = 0);
 373       end if;
 374    end Unlock;
 375
 376    procedure Unlock (T : Task_Id) is
 377       Result : Interfaces.C.int;
 378    begin
 379       if not Single_Lock then
 380          Result := pthread_mutex_unlock (T.Common.LL.L'Access);
 381          pragma Assert (Result = 0);
 382       end if;
 383    end Unlock;
 384
 385    -----------
 386    -- Sleep --
 387    -----------
 388
 389    procedure Sleep
 390      (Self_ID : Task_Id;
 391       Reason  : System.Tasking.Task_States)
 392    is
 393       pragma Unreferenced (Reason);
 394       Result : Interfaces.C.int;
 395
 396    begin
 397       if Single_Lock then
 398          Result := pthread_cond_wait
 399            (Self_ID.Common.LL.CV'Access, Single_RTS_Lock'Access);
 400       else
 401          Result := pthread_cond_wait
 402            (Self_ID.Common.LL.CV'Access, Self_ID.Common.LL.L'Access);
 403       end if;
 404
 405       --  EINTR is not considered a failure
 406
 407       pragma Assert (Result = 0 or else Result = EINTR);
 408
 409       if Self_ID.Deferral_Level = 0
 410         and then Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level
 411       then
 412          Unlock (Self_ID);
 413          raise Standard'Abort_Signal;
 414       end if;
 415    end Sleep;
 416
 417    -----------------
 418    -- Timed_Sleep --
 419    -----------------
 420
 421    procedure Timed_Sleep
 422      (Self_ID  : Task_Id;
 423       Time     : Duration;
 424       Mode     : ST.Delay_Modes;
 425       Reason   : System.Tasking.Task_States;
 426       Timedout : out Boolean;
 427       Yielded  : out Boolean)
 428    is
 429       pragma Unreferenced (Reason);
 430
 431       Sleep_Time : OS_Time;
 432       Result     : Interfaces.C.int;
 433       Status     : Cond_Value_Type;
 434
 435       --  The body below requires more comments ???
 436
 437    begin
 438       Timedout := False;
 439       Yielded := False;
 440
 441       Sleep_Time := To_OS_Time (Time, Mode);
 442
 443       if Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level
 444         or else Self_ID.Pending_Priority_Change
 445       then
 446          return;
 447       end if;
 448
 449       Self_ID.Common.LL.AST_Pending := True;
 450
 451       Sys_Setimr
 452        (Status, 0, Sleep_Time,
 453         Timer_Sleep_AST'Access, To_Address (Self_ID), 0);
 454
 455       if (Status and 1) /= 1 then
 456          raise Storage_Error;
 457       end if;
 458
 459       if Single_Lock then
 460          Result := pthread_cond_wait
 461            (Self_ID.Common.LL.CV'Access, Single_RTS_Lock'Access);
 462          pragma Assert (Result = 0);
 463
 464       else
 465          Result := pthread_cond_wait
 466            (Self_ID.Common.LL.CV'Access, Self_ID.Common.LL.L'Access);
 467          pragma Assert (Result = 0);
 468       end if;
 469
 470       Yielded := True;
 471
 472       if not Self_ID.Common.LL.AST_Pending then
 473          Timedout := True;
 474       else
 475          Sys_Cantim (Status, To_Address (Self_ID), 0);
 476          pragma Assert ((Status and 1) = 1);
 477       end if;
 478    end Timed_Sleep;
 479
 480    -----------------
 481    -- Timed_Delay --
 482    -----------------
 483
 484    procedure Timed_Delay
 485      (Self_ID : Task_Id;
 486       Time    : Duration;
 487       Mode    : ST.Delay_Modes)
 488    is
 489       Sleep_Time : OS_Time;
 490       Result     : Interfaces.C.int;
 491       Status     : Cond_Value_Type;
 492       Yielded    : Boolean := False;
 493
 494    begin
 495       --  Only the little window between deferring abort and
 496       --  locking Self_ID is the reason we need to
 497       --  check for pending abort and priority change below!
 498
 499       if Single_Lock then
 500          Lock_RTS;
 501       end if;
 502
 503       --  More comments required in body below ???
 504
 505       SSL.Abort_Defer.all;
 506       Write_Lock (Self_ID);
 507
 508       if Time /= 0.0 or else Mode /= Relative then
 509          Sleep_Time := To_OS_Time (Time, Mode);
 510
 511          if Mode = Relative or else OS_Clock < Sleep_Time then
 512             Self_ID.Common.State := Delay_Sleep;
 513             Self_ID.Common.LL.AST_Pending := True;
 514
 515             Sys_Setimr
 516              (Status, 0, Sleep_Time,
 517               Timer_Sleep_AST'Access, To_Address (Self_ID), 0);
 518
 519             if (Status and 1) /= 1 then
 520                raise Storage_Error;
 521             end if;
 522
 523             loop
 524                if Self_ID.Pending_Priority_Change then
 525                   Self_ID.Pending_Priority_Change := False;
 526                   Self_ID.Common.Base_Priority := Self_ID.New_Base_Priority;
 527                   Set_Priority (Self_ID, Self_ID.Common.Base_Priority);
 528                end if;
 529
 530                if Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level then
 531                   Sys_Cantim (Status, To_Address (Self_ID), 0);
 532                   pragma Assert ((Status and 1) = 1);
 533                   exit;
 534                end if;
 535
 536                if Single_Lock then
 537                   Result := pthread_cond_wait
 538                     (Self_ID.Common.LL.CV'Access, Single_RTS_Lock'Access);
 539                   pragma Assert (Result = 0);
 540                else
 541                   Result := pthread_cond_wait
 542                     (Self_ID.Common.LL.CV'Access, Self_ID.Common.LL.L'Access);
 543                   pragma Assert (Result = 0);
 544                end if;
 545
 546                Yielded := True;
 547
 548                exit when not Self_ID.Common.LL.AST_Pending;
 549             end loop;
 550
 551             Self_ID.Common.State := Runnable;
 552          end if;
 553       end if;
 554
 555       Unlock (Self_ID);
 556
 557       if Single_Lock then
 558          Unlock_RTS;
 559       end if;
 560
 561       if not Yielded then
 562          Result := sched_yield;
 563          pragma Assert (Result = 0);
 564       end if;
 565
 566       SSL.Abort_Undefer.all;
 567    end Timed_Delay;
 568
 569    ---------------------
 570    -- Monotonic_Clock --
 571    ---------------------
 572
 573    function Monotonic_Clock return Duration
 574      renames System.OS_Primitives.Monotonic_Clock;
 575
 576    -------------------
 577    -- RT_Resolution --
 578    -------------------
 579
 580    function RT_Resolution return Duration is
 581    begin
 582       return 10#1.0#E-3;
 583    end RT_Resolution;
 584
 585    ------------
 586    -- Wakeup --
 587    ------------
 588
 589    procedure Wakeup (T : Task_Id; Reason : System.Tasking.Task_States) is
 590       pragma Unreferenced (Reason);
 591       Result : Interfaces.C.int;
 592    begin
 593       Result := pthread_cond_signal (T.Common.LL.CV'Access);
 594       pragma Assert (Result = 0);
 595    end Wakeup;
 596
 597    -----------
 598    -- Yield --
 599    -----------
 600
 601    procedure Yield (Do_Yield : Boolean := True) is
 602       Result : Interfaces.C.int;
 603       pragma Unreferenced (Result);
 604    begin
 605       if Do_Yield then
 606          Result := sched_yield;
 607       end if;
 608    end Yield;
 609
 610    ------------------
 611    -- Set_Priority --
 612    ------------------
 613
 614    procedure Set_Priority
 615      (T                   : Task_Id;
 616       Prio                : System.Any_Priority;
 617       Loss_Of_Inheritance : Boolean := False)
 618    is
 619       pragma Unreferenced (Loss_Of_Inheritance);
 620
 621       Result : Interfaces.C.int;
 622       Param  : aliased struct_sched_param;
 623
 624    begin
 625       T.Common.Current_Priority := Prio;
 626       Param.sched_priority := Interfaces.C.int (Underlying_Priorities (Prio));
 627
 628       if Time_Slice_Val > 0 then
 629          Result := pthread_setschedparam
 630            (T.Common.LL.Thread, SCHED_RR, Param'Access);
 631
 632       elsif FIFO_Within_Priorities or else Time_Slice_Val = 0 then
 633          Result := pthread_setschedparam
 634            (T.Common.LL.Thread, SCHED_FIFO, Param'Access);
 635
 636       else
 637          --  SCHED_OTHER priorities are restricted to the range 8 - 15.
 638          --  Since the translation from Underlying priorities results
 639          --  in a range of 16 - 31, dividing by 2 gives the correct result.
 640
 641          Param.sched_priority := Param.sched_priority / 2;
 642          Result := pthread_setschedparam
 643            (T.Common.LL.Thread, SCHED_OTHER, Param'Access);
 644       end if;
 645
 646       pragma Assert (Result = 0);
 647    end Set_Priority;
 648
 649    ------------------
 650    -- Get_Priority --
 651    ------------------
 652
 653    function Get_Priority (T : Task_Id) return System.Any_Priority is
 654    begin
 655       return T.Common.Current_Priority;
 656    end Get_Priority;
 657
 658    ----------------
 659    -- Enter_Task --
 660    ----------------
 661
 662    procedure Enter_Task (Self_ID : Task_Id) is
 663    begin
 664       Self_ID.Common.LL.Thread := pthread_self;
 665
 666       Specific.Set (Self_ID);
 667
 668       Lock_RTS;
 669
 670       for J in Known_Tasks'Range loop
 671          if Known_Tasks (J) = null then
 672             Known_Tasks (J) := Self_ID;
 673             Self_ID.Known_Tasks_Index := J;
 674             exit;
 675          end if;
 676       end loop;
 677
 678       Unlock_RTS;
 679    end Enter_Task;
 680
 681    --------------
 682    -- New_ATCB --
 683    --------------
 684
 685    function New_ATCB (Entry_Num : Task_Entry_Index) return Task_Id is
 686    begin
 687       return new Ada_Task_Control_Block (Entry_Num);
 688    end New_ATCB;
 689
 690    -------------------
 691    -- Is_Valid_Task --
 692    -------------------
 693
 694    function Is_Valid_Task return Boolean renames Specific.Is_Valid_Task;
 695
 696    -----------------------------
 697    -- Register_Foreign_Thread --
 698    -----------------------------
 699
 700    function Register_Foreign_Thread return Task_Id is
 701    begin
 702       if Is_Valid_Task then
 703          return Self;
 704       else
 705          return Register_Foreign_Thread (pthread_self);
 706       end if;
 707    end Register_Foreign_Thread;
 708
 709    --------------------
 710    -- Initialize_TCB --
 711    --------------------
 712
 713    procedure Initialize_TCB (Self_ID : Task_Id; Succeeded : out Boolean) is
 714       Mutex_Attr : aliased pthread_mutexattr_t;
 715       Result     : Interfaces.C.int;
 716       Cond_Attr  : aliased pthread_condattr_t;
 717
 718    begin
 719       --  More comments required in body below ???
 720
 721       if not Single_Lock then
 722          Result := pthread_mutexattr_init (Mutex_Attr'Access);
 723          pragma Assert (Result = 0 or else Result = ENOMEM);
 724
 725          if Result = 0 then
 726             Result := pthread_mutex_init (Self_ID.Common.LL.L'Access,
 727               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 := pthread_cond_init (Self_ID.Common.LL.CV'Access,
 745            Cond_Attr'Access);
 746          pragma Assert (Result = 0 or else Result = ENOMEM);
 747       end if;
 748
 749       if Result = 0 then
 750          Succeeded := True;
 751          Self_ID.Common.LL.Exc_Stack_Ptr := new Exc_Stack_T;
 752          SSL.Set_Exc_Stack_Addr
 753            (To_Address (Self_ID),
 754             Self_ID.Common.LL.Exc_Stack_Ptr (Exc_Stack_T'Last)'Address);
 755
 756       else
 757          if not Single_Lock then
 758             Result := pthread_mutex_destroy (Self_ID.Common.LL.L'Access);
 759             pragma Assert (Result = 0);
 760          end if;
 761
 762          Succeeded := False;
 763       end if;
 764
 765       Result := pthread_condattr_destroy (Cond_Attr'Access);
 766       pragma Assert (Result = 0);
 767    end Initialize_TCB;
 768
 769    -----------------
 770    -- Create_Task --
 771    -----------------
 772
 773    procedure Create_Task
 774      (T          : Task_Id;
 775       Wrapper    : System.Address;
 776       Stack_Size : System.Parameters.Size_Type;
 777       Priority   : System.Any_Priority;
 778       Succeeded  : out Boolean)
 779    is
 780       Attributes          : aliased pthread_attr_t;
 781       Adjusted_Stack_Size : Interfaces.C.size_t;
 782       Result              : Interfaces.C.int;
 783
 784       function Thread_Body_Access is new
 785         Unchecked_Conversion (System.Address, Thread_Body);
 786
 787    begin
 788       if Stack_Size = Unspecified_Size then
 789          Adjusted_Stack_Size := Interfaces.C.size_t (Default_Stack_Size);
 790
 791       elsif Stack_Size < Minimum_Stack_Size then
 792          Adjusted_Stack_Size := Interfaces.C.size_t (Minimum_Stack_Size);
 793
 794       else
 795          Adjusted_Stack_Size := Interfaces.C.size_t (Stack_Size);
 796       end if;
 797
 798       --  Since the initial signal mask of a thread is inherited from the
 799       --  creator, we need to set our local signal mask mask all signals
 800       --  during the creation operation, to make sure the new thread is
 801       --  not disturbed by signals before it has set its own Task_Id.
 802
 803       Result := pthread_attr_init (Attributes'Access);
 804       pragma Assert (Result = 0 or else Result = ENOMEM);
 805
 806       if Result /= 0 then
 807          Succeeded := False;
 808          return;
 809       end if;
 810
 811       Result := pthread_attr_setdetachstate
 812         (Attributes'Access, PTHREAD_CREATE_DETACHED);
 813       pragma Assert (Result = 0);
 814
 815       Result := pthread_attr_setstacksize
 816         (Attributes'Access, Adjusted_Stack_Size);
 817       pragma Assert (Result = 0);
 818
 819       --  This call may be unnecessary, not sure. ???
 820
 821       Result :=
 822         pthread_attr_setinheritsched
 823           (Attributes'Access, PTHREAD_EXPLICIT_SCHED);
 824       pragma Assert (Result = 0);
 825
 826       Result := pthread_create
 827         (T.Common.LL.Thread'Access,
 828          Attributes'Access,
 829          Thread_Body_Access (Wrapper),
 830          To_Address (T));
 831
 832       --  ENOMEM is a valid run-time error.  Don't shut down.
 833
 834       pragma Assert (Result = 0
 835         or else Result = EAGAIN or else Result = ENOMEM);
 836
 837       Succeeded := Result = 0;
 838
 839       Result := pthread_attr_destroy (Attributes'Access);
 840       pragma Assert (Result = 0);
 841
 842       if Succeeded then
 843          Set_Priority (T, Priority);
 844       end if;
 845    end Create_Task;
 846
 847    ------------------
 848    -- Finalize_TCB --
 849    ------------------
 850
 851    procedure Finalize_TCB (T : Task_Id) is
 852       Result  : Interfaces.C.int;
 853       Tmp     : Task_Id := T;
 854       Is_Self : constant Boolean := T = Self;
 855
 856       procedure Free is new
 857         Unchecked_Deallocation (Ada_Task_Control_Block, Task_Id);
 858
 859       procedure Free is new Unchecked_Deallocation
 860        (Exc_Stack_T, Exc_Stack_Ptr_T);
 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       Free (T.Common.LL.Exc_Stack_Ptr);
 876
 877       Free (Tmp);
 878
 879       if Is_Self then
 880          Specific.Set (null);
 881       end if;
 882    end Finalize_TCB;
 883
 884    ---------------
 885    -- Exit_Task --
 886    ---------------
 887
 888    procedure Exit_Task is
 889    begin
 890       null;
 891    end Exit_Task;
 892
 893    ----------------
 894    -- Abort_Task --
 895    ----------------
 896
 897    procedure Abort_Task (T : Task_Id) is
 898    begin
 899       --  Interrupt Server_Tasks may be waiting on an event flag
 900
 901       if T.Common.State = Interrupt_Server_Blocked_On_Event_Flag then
 902          Wakeup (T, Interrupt_Server_Blocked_On_Event_Flag);
 903       end if;
 904    end Abort_Task;
 905
 906    ----------------
 907    -- Initialize --
 908    ----------------
 909
 910    procedure Initialize (S : in out Suspension_Object) is
 911       Mutex_Attr : aliased pthread_mutexattr_t;
 912       Cond_Attr  : aliased pthread_condattr_t;
 913       Result     : Interfaces.C.int;
 914    begin
 915       --  Initialize internal state. It is always initialized to False (ARM
 916       --  D.10 par. 6).
 917
 918       S.State := False;
 919       S.Waiting := False;
 920
 921       --  Initialize internal mutex
 922
 923       Result := pthread_mutexattr_init (Mutex_Attr'Access);
 924       pragma Assert (Result = 0 or else Result = ENOMEM);
 925
 926       if Result = ENOMEM then
 927          raise Storage_Error;
 928       end if;
 929
 930       Result := pthread_mutex_init (S.L'Access, Mutex_Attr'Access);
 931       pragma Assert (Result = 0 or else Result = ENOMEM);
 932
 933       if Result = ENOMEM then
 934          Result := pthread_mutexattr_destroy (Mutex_Attr'Access);
 935          pragma Assert (Result = 0);
 936
 937          raise Storage_Error;
 938       end if;
 939
 940       Result := pthread_mutexattr_destroy (Mutex_Attr'Access);
 941       pragma Assert (Result = 0);
 942
 943       --  Initialize internal condition variable
 944
 945       Result := pthread_condattr_init (Cond_Attr'Access);
 946       pragma Assert (Result = 0 or else Result = ENOMEM);
 947
 948       if Result /= 0 then
 949          Result := pthread_mutex_destroy (S.L'Access);
 950          pragma Assert (Result = 0);
 951
 952          if Result = ENOMEM then
 953             raise Storage_Error;
 954          end if;
 955       end if;
 956
 957       Result := pthread_cond_init (S.CV'Access, Cond_Attr'Access);
 958       pragma Assert (Result = 0 or else Result = ENOMEM);
 959
 960       if Result /= 0 then
 961          Result := pthread_mutex_destroy (S.L'Access);
 962          pragma Assert (Result = 0);
 963
 964          if Result = ENOMEM then
 965             Result := pthread_condattr_destroy (Cond_Attr'Access);
 966             pragma Assert (Result = 0);
 967
 968             raise Storage_Error;
 969          end if;
 970       end if;
 971
 972       Result := pthread_condattr_destroy (Cond_Attr'Access);
 973       pragma Assert (Result = 0);
 974    end Initialize;
 975
 976    --------------
 977    -- Finalize --
 978    --------------
 979
 980    procedure Finalize (S : in out Suspension_Object) is
 981       Result  : Interfaces.C.int;
 982    begin
 983       --  Destroy internal mutex
 984
 985       Result := pthread_mutex_destroy (S.L'Access);
 986       pragma Assert (Result = 0);
 987
 988       --  Destroy internal condition variable
 989
 990       Result := pthread_cond_destroy (S.CV'Access);
 991       pragma Assert (Result = 0);
 992    end Finalize;
 993
 994    -------------------
 995    -- Current_State --
 996    -------------------
 997
 998    function Current_State (S : Suspension_Object) return Boolean is
 999    begin
1000       --  We do not want to use lock on this read operation. State is marked
1001       --  as Atomic so that we ensure that the value retrieved is correct.
1002
1003       return S.State;
1004    end Current_State;
1005
1006    ---------------
1007    -- Set_False --
1008    ---------------
1009
1010    procedure Set_False (S : in out Suspension_Object) is
1011       Result  : Interfaces.C.int;
1012    begin
1013       Result := pthread_mutex_lock (S.L'Access);
1014       pragma Assert (Result = 0);
1015
1016       S.State := False;
1017
1018       Result := pthread_mutex_unlock (S.L'Access);
1019       pragma Assert (Result = 0);
1020    end Set_False;
1021
1022    --------------
1023    -- Set_True --
1024    --------------
1025
1026    procedure Set_True (S : in out Suspension_Object) is
1027       Result : Interfaces.C.int;
1028    begin
1029       Result := pthread_mutex_lock (S.L'Access);
1030       pragma Assert (Result = 0);
1031
1032       --  If there is already a task waiting on this suspension object then
1033       --  we resume it, leaving the state of the suspension object to False,
1034       --  as it is specified in ARM D.10 par. 9. Otherwise, it just leaves
1035       --  the state to True.
1036
1037       if S.Waiting then
1038          S.Waiting := False;
1039          S.State := False;
1040
1041          Result := pthread_cond_signal (S.CV'Access);
1042          pragma Assert (Result = 0);
1043       else
1044          S.State := True;
1045       end if;
1046
1047       Result := pthread_mutex_unlock (S.L'Access);
1048       pragma Assert (Result = 0);
1049    end Set_True;
1050
1051    ------------------------
1052    -- Suspend_Until_True --
1053    ------------------------
1054
1055    procedure Suspend_Until_True (S : in out Suspension_Object) is
1056       Result : Interfaces.C.int;
1057    begin
1058       Result := pthread_mutex_lock (S.L'Access);
1059       pragma Assert (Result = 0);
1060
1061       if S.Waiting then
1062          --  Program_Error must be raised upon calling Suspend_Until_True
1063          --  if another task is already waiting on that suspension object
1064          --  (ARM D.10 par. 10).
1065
1066          Result := pthread_mutex_unlock (S.L'Access);
1067          pragma Assert (Result = 0);
1068
1069          raise Program_Error;
1070       else
1071          --  Suspend the task if the state is False. Otherwise, the task
1072          --  continues its execution, and the state of the suspension object
1073          --  is set to False (ARM D.10 par. 9).
1074
1075          if S.State then
1076             S.State := False;
1077          else
1078             S.Waiting := True;
1079             Result := pthread_cond_wait (S.CV'Access, S.L'Access);
1080          end if;
1081       end if;
1082
1083       Result := pthread_mutex_unlock (S.L'Access);
1084       pragma Assert (Result = 0);
1085    end Suspend_Until_True;
1086
1087    ----------------
1088    -- Check_Exit --
1089    ----------------
1090
1091    --  Dummy version
1092
1093    function Check_Exit (Self_ID : ST.Task_Id) return Boolean is
1094       pragma Unreferenced (Self_ID);
1095    begin
1096       return True;
1097    end Check_Exit;
1098
1099    --------------------
1100    -- Check_No_Locks --
1101    --------------------
1102
1103    function Check_No_Locks (Self_ID : ST.Task_Id) return Boolean is
1104       pragma Unreferenced (Self_ID);
1105    begin
1106       return True;
1107    end Check_No_Locks;
1108
1109    ----------------------
1110    -- Environment_Task --
1111    ----------------------
1112
1113    function Environment_Task return Task_Id is
1114    begin
1115       return Environment_Task_Id;
1116    end Environment_Task;
1117
1118    --------------
1119    -- Lock_RTS --
1120    --------------
1121
1122    procedure Lock_RTS is
1123    begin
1124       Write_Lock (Single_RTS_Lock'Access, Global_Lock => True);
1125    end Lock_RTS;
1126
1127    ----------------
1128    -- Unlock_RTS --
1129    ----------------
1130
1131    procedure Unlock_RTS is
1132    begin
1133       Unlock (Single_RTS_Lock'Access, Global_Lock => True);
1134    end Unlock_RTS;
1135
1136    ------------------
1137    -- Suspend_Task --
1138    ------------------
1139
1140    function Suspend_Task
1141      (T           : ST.Task_Id;
1142       Thread_Self : Thread_Id) return Boolean
1143    is
1144       pragma Unreferenced (T);
1145       pragma Unreferenced (Thread_Self);
1146    begin
1147       return False;
1148    end Suspend_Task;
1149
1150    -----------------
1151    -- Resume_Task --
1152    -----------------
1153
1154    function Resume_Task
1155      (T           : ST.Task_Id;
1156       Thread_Self : Thread_Id) return Boolean
1157    is
1158       pragma Unreferenced (T);
1159       pragma Unreferenced (Thread_Self);
1160    begin
1161       return False;
1162    end Resume_Task;
1163
1164    ----------------
1165    -- Initialize --
1166    ----------------
1167
1168    procedure Initialize (Environment_Task : Task_Id) is
1169    begin
1170       Environment_Task_Id := Environment_Task;
1171
1172       --  Initialize the lock used to synchronize chain of all ATCBs
1173
1174       Initialize_Lock (Single_RTS_Lock'Access, RTS_Lock_Level);
1175
1176       Specific.Initialize (Environment_Task);
1177
1178       Enter_Task (Environment_Task);
1179    end Initialize;
1180
1181 end System.Task_Primitives.Operations;