gcc/ada/s-taprop-posix.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) 1992-2011, 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 POSIX-like version of this package
  33
  34 --  This package contains all the GNULL primitives that interface directly with
  35 --  the underlying OS.
  36
  37 --  Note: this file can only be used for POSIX compliant systems that implement
  38 --  SCHED_FIFO and Ceiling Locking correctly.
  39
  40 --  For configurations where SCHED_FIFO and priority ceiling are not a
  41 --  requirement, this file can also be used (e.g AiX threads)
  42
  43 pragma Polling (Off);
  44 --  Turn off polling, we do not want ATC polling to take place during tasking
  45 --  operations. It causes infinite loops and other problems.
  46
  47 with Ada.Unchecked_Conversion;
  48
  49 with Interfaces.C;
  50
  51 with System.Tasking.Debug;
  52 with System.Interrupt_Management;
  53 with System.OS_Primitives;
  54 with System.Task_Info;
  55
  56 with System.Soft_Links;
  57 --  We use System.Soft_Links instead of System.Tasking.Initialization
  58 --  because the later is a higher level package that we shouldn't depend on.
  59 --  For example when using the restricted run time, it is replaced by
  60 --  System.Tasking.Restricted.Stages.
  61
  62 package body System.Task_Primitives.Operations is
  63
  64    package SSL renames System.Soft_Links;
  65
  66    use System.Tasking.Debug;
  67    use System.Tasking;
  68    use Interfaces.C;
  69    use System.OS_Interface;
  70    use System.Parameters;
  71    use System.OS_Primitives;
  72
  73    ----------------
  74    -- Local Data --
  75    ----------------
  76
  77    --  The followings are logically constants, but need to be initialized
  78    --  at run time.
  79
  80    Single_RTS_Lock : aliased RTS_Lock;
  81    --  This is a lock to allow only one thread of control in the RTS at
  82    --  a time; it is used to execute in mutual exclusion from all other tasks.
  83    --  Used mainly in Single_Lock mode, but also to protect All_Tasks_List
  84
  85    Environment_Task_Id : Task_Id;
  86    --  A variable to hold Task_Id for the environment task
  87
  88    Locking_Policy : Character;
  89    pragma Import (C, Locking_Policy, "__gl_locking_policy");
  90    --  Value of the pragma Locking_Policy:
  91    --    'C' for Ceiling_Locking
  92    --    'I' for Inherit_Locking
  93    --    ' ' for none.
  94
  95    Unblocked_Signal_Mask : aliased sigset_t;
  96    --  The set of signals that should unblocked in all tasks
  97
  98    --  The followings are internal configuration constants needed
  99
 100    Next_Serial_Number : Task_Serial_Number := 100;
 101    --  We start at 100, to reserve some special values for
 102    --  using in error checking.
 103
 104    Time_Slice_Val : Integer;
 105    pragma Import (C, Time_Slice_Val, "__gl_time_slice_val");
 106
 107    Dispatching_Policy : Character;
 108    pragma Import (C, Dispatching_Policy, "__gl_task_dispatching_policy");
 109
 110    Foreign_Task_Elaborated : aliased Boolean := True;
 111    --  Used to identified fake tasks (i.e., non-Ada Threads)
 112
 113    Use_Alternate_Stack : constant Boolean := Alternate_Stack_Size /= 0;
 114    --  Whether to use an alternate signal stack for stack overflows
 115
 116    Abort_Handler_Installed : Boolean := False;
 117    --  True if a handler for the abort signal is installed
 118
 119    --------------------
 120    -- Local Packages --
 121    --------------------
 122
 123    package Specific is
 124
 125       procedure Initialize (Environment_Task : Task_Id);
 126       pragma Inline (Initialize);
 127       --  Initialize various data needed by this package
 128
 129       function Is_Valid_Task return Boolean;
 130       pragma Inline (Is_Valid_Task);
 131       --  Does executing thread have a TCB?
 132
 133       procedure Set (Self_Id : Task_Id);
 134       pragma Inline (Set);
 135       --  Set the self id for the current task
 136
 137       function Self return Task_Id;
 138       pragma Inline (Self);
 139       --  Return a pointer to the Ada Task Control Block of the calling task
 140
 141    end Specific;
 142
 143    package body Specific is separate;
 144    --  The body of this package is target specific
 145
 146    ----------------------------------
 147    -- ATCB allocation/deallocation --
 148    ----------------------------------
 149
 150    package body ATCB_Allocation is separate;
 151    --  The body of this package is shared across several targets
 152
 153    ---------------------------------
 154    -- Support for foreign threads --
 155    ---------------------------------
 156
 157    function Register_Foreign_Thread (Thread : Thread_Id) return Task_Id;
 158    --  Allocate and Initialize a new ATCB for the current Thread
 159
 160    function Register_Foreign_Thread
 161      (Thread : Thread_Id) return Task_Id is separate;
 162
 163    -----------------------
 164    -- Local Subprograms --
 165    -----------------------
 166
 167    procedure Abort_Handler (Sig : Signal);
 168    --  Signal handler used to implement asynchronous abort.
 169    --  See also comment before body, below.
 170
 171    function To_Address is
 172      new Ada.Unchecked_Conversion (Task_Id, System.Address);
 173
 174    -------------------
 175    -- Abort_Handler --
 176    -------------------
 177
 178    --  Target-dependent binding of inter-thread Abort signal to the raising of
 179    --  the Abort_Signal exception.
 180
 181    --  The technical issues and alternatives here are essentially the
 182    --  same as for raising exceptions in response to other signals
 183    --  (e.g. Storage_Error). See code and comments in the package body
 184    --  System.Interrupt_Management.
 185
 186    --  Some implementations may not allow an exception to be propagated out of
 187    --  a handler, and others might leave the signal or interrupt that invoked
 188    --  this handler masked after the exceptional return to the application
 189    --  code.
 190
 191    --  GNAT exceptions are originally implemented using setjmp()/longjmp(). On
 192    --  most UNIX systems, this will allow transfer out of a signal handler,
 193    --  which is usually the only mechanism available for implementing
 194    --  asynchronous handlers of this kind. However, some systems do not
 195    --  restore the signal mask on longjmp(), leaving the abort signal masked.
 196
 197    procedure Abort_Handler (Sig : Signal) is
 198       pragma Unreferenced (Sig);
 199
 200       T       : constant Task_Id := Self;
 201       Old_Set : aliased sigset_t;
 202
 203       Result : Interfaces.C.int;
 204       pragma Warnings (Off, Result);
 205
 206    begin
 207       --  It's not safe to raise an exception when using GCC ZCX mechanism.
 208       --  Note that we still need to install a signal handler, since in some
 209       --  cases (e.g. shutdown of the Server_Task in System.Interrupts) we
 210       --  need to send the Abort signal to a task.
 211
 212       if ZCX_By_Default then
 213          return;
 214       end if;
 215
 216       if T.Deferral_Level = 0
 217         and then T.Pending_ATC_Level < T.ATC_Nesting_Level and then
 218         not T.Aborting
 219       then
 220          T.Aborting := True;
 221
 222          --  Make sure signals used for RTS internal purpose are unmasked
 223
 224          Result := pthread_sigmask (SIG_UNBLOCK,
 225            Unblocked_Signal_Mask'Access, Old_Set'Access);
 226          pragma Assert (Result = 0);
 227
 228          raise Standard'Abort_Signal;
 229       end if;
 230    end Abort_Handler;
 231
 232    -----------------
 233    -- Stack_Guard --
 234    -----------------
 235
 236    procedure Stack_Guard (T : ST.Task_Id; On : Boolean) is
 237       Stack_Base : constant Address := Get_Stack_Base (T.Common.LL.Thread);
 238       Guard_Page_Address : Address;
 239
 240       Res : Interfaces.C.int;
 241
 242    begin
 243       if Stack_Base_Available then
 244
 245          --  Compute the guard page address
 246
 247          Guard_Page_Address :=
 248            Stack_Base - (Stack_Base mod Get_Page_Size) + Get_Page_Size;
 249
 250          Res :=
 251            mprotect (Guard_Page_Address, Get_Page_Size,
 252                      prot => (if On then PROT_ON else PROT_OFF));
 253          pragma Assert (Res = 0);
 254       end if;
 255    end Stack_Guard;
 256
 257    --------------------
 258    -- Get_Thread_Id  --
 259    --------------------
 260
 261    function Get_Thread_Id (T : ST.Task_Id) return OSI.Thread_Id is
 262    begin
 263       return T.Common.LL.Thread;
 264    end Get_Thread_Id;
 265
 266    ----------
 267    -- Self --
 268    ----------
 269
 270    function Self return Task_Id renames Specific.Self;
 271
 272    ---------------------
 273    -- Initialize_Lock --
 274    ---------------------
 275
 276    --  Note: mutexes and cond_variables needed per-task basis are
 277    --        initialized in Initialize_TCB and the Storage_Error is
 278    --        handled. Other mutexes (such as RTS_Lock, Memory_Lock...)
 279    --        used in RTS is initialized before any status change of RTS.
 280    --        Therefore raising Storage_Error in the following routines
 281    --        should be able to be handled safely.
 282
 283    procedure Initialize_Lock
 284      (Prio : System.Any_Priority;
 285       L    : not null access Lock)
 286    is
 287       Attributes : aliased pthread_mutexattr_t;
 288       Result : Interfaces.C.int;
 289
 290    begin
 291       Result := pthread_mutexattr_init (Attributes'Access);
 292       pragma Assert (Result = 0 or else Result = ENOMEM);
 293
 294       if Result = ENOMEM then
 295          raise Storage_Error;
 296       end if;
 297
 298       if Locking_Policy = 'C' then
 299          Result := pthread_mutexattr_setprotocol
 300            (Attributes'Access, PTHREAD_PRIO_PROTECT);
 301          pragma Assert (Result = 0);
 302
 303          Result := pthread_mutexattr_setprioceiling
 304             (Attributes'Access, Interfaces.C.int (Prio));
 305          pragma Assert (Result = 0);
 306
 307       elsif Locking_Policy = 'I' then
 308          Result := pthread_mutexattr_setprotocol
 309            (Attributes'Access, PTHREAD_PRIO_INHERIT);
 310          pragma Assert (Result = 0);
 311       end if;
 312
 313       Result := pthread_mutex_init (L, Attributes'Access);
 314       pragma Assert (Result = 0 or else Result = ENOMEM);
 315
 316       if Result = ENOMEM then
 317          Result := pthread_mutexattr_destroy (Attributes'Access);
 318          raise Storage_Error;
 319       end if;
 320
 321       Result := pthread_mutexattr_destroy (Attributes'Access);
 322       pragma Assert (Result = 0);
 323    end Initialize_Lock;
 324
 325    procedure Initialize_Lock
 326      (L : not null access RTS_Lock; Level : Lock_Level)
 327    is
 328       pragma Unreferenced (Level);
 329
 330       Attributes : aliased pthread_mutexattr_t;
 331       Result     : Interfaces.C.int;
 332
 333    begin
 334       Result := pthread_mutexattr_init (Attributes'Access);
 335       pragma Assert (Result = 0 or else Result = ENOMEM);
 336
 337       if Result = ENOMEM then
 338          raise Storage_Error;
 339       end if;
 340
 341       if Locking_Policy = 'C' then
 342          Result := pthread_mutexattr_setprotocol
 343            (Attributes'Access, PTHREAD_PRIO_PROTECT);
 344          pragma Assert (Result = 0);
 345
 346          Result := pthread_mutexattr_setprioceiling
 347             (Attributes'Access, Interfaces.C.int (System.Any_Priority'Last));
 348          pragma Assert (Result = 0);
 349
 350       elsif Locking_Policy = 'I' then
 351          Result := pthread_mutexattr_setprotocol
 352            (Attributes'Access, PTHREAD_PRIO_INHERIT);
 353          pragma Assert (Result = 0);
 354       end if;
 355
 356       Result := pthread_mutex_init (L, Attributes'Access);
 357       pragma Assert (Result = 0 or else Result = ENOMEM);
 358
 359       if Result = ENOMEM then
 360          Result := pthread_mutexattr_destroy (Attributes'Access);
 361          raise Storage_Error;
 362       end if;
 363
 364       Result := pthread_mutexattr_destroy (Attributes'Access);
 365       pragma Assert (Result = 0);
 366    end Initialize_Lock;
 367
 368    -------------------
 369    -- Finalize_Lock --
 370    -------------------
 371
 372    procedure Finalize_Lock (L : not null access Lock) is
 373       Result : Interfaces.C.int;
 374    begin
 375       Result := pthread_mutex_destroy (L);
 376       pragma Assert (Result = 0);
 377    end Finalize_Lock;
 378
 379    procedure Finalize_Lock (L : not null access RTS_Lock) is
 380       Result : Interfaces.C.int;
 381    begin
 382       Result := pthread_mutex_destroy (L);
 383       pragma Assert (Result = 0);
 384    end Finalize_Lock;
 385
 386    ----------------
 387    -- Write_Lock --
 388    ----------------
 389
 390    procedure Write_Lock
 391      (L : not null access Lock; Ceiling_Violation : out Boolean)
 392    is
 393       Result : Interfaces.C.int;
 394
 395    begin
 396       Result := pthread_mutex_lock (L);
 397
 398       --  Assume that the cause of EINVAL is a priority ceiling violation
 399
 400       Ceiling_Violation := (Result = EINVAL);
 401       pragma Assert (Result = 0 or else Result = EINVAL);
 402    end Write_Lock;
 403
 404    procedure Write_Lock
 405      (L           : not null access RTS_Lock;
 406       Global_Lock : Boolean := False)
 407    is
 408       Result : Interfaces.C.int;
 409    begin
 410       if not Single_Lock or else Global_Lock then
 411          Result := pthread_mutex_lock (L);
 412          pragma Assert (Result = 0);
 413       end if;
 414    end Write_Lock;
 415
 416    procedure Write_Lock (T : Task_Id) is
 417       Result : Interfaces.C.int;
 418    begin
 419       if not Single_Lock then
 420          Result := pthread_mutex_lock (T.Common.LL.L'Access);
 421          pragma Assert (Result = 0);
 422       end if;
 423    end Write_Lock;
 424
 425    ---------------
 426    -- Read_Lock --
 427    ---------------
 428
 429    procedure Read_Lock
 430      (L : not null access Lock; Ceiling_Violation : out Boolean) is
 431    begin
 432       Write_Lock (L, Ceiling_Violation);
 433    end Read_Lock;
 434
 435    ------------
 436    -- Unlock --
 437    ------------
 438
 439    procedure Unlock (L : not null access Lock) is
 440       Result : Interfaces.C.int;
 441    begin
 442       Result := pthread_mutex_unlock (L);
 443       pragma Assert (Result = 0);
 444    end Unlock;
 445
 446    procedure Unlock
 447      (L : not null access RTS_Lock; Global_Lock : Boolean := False)
 448    is
 449       Result : Interfaces.C.int;
 450    begin
 451       if not Single_Lock or else Global_Lock then
 452          Result := pthread_mutex_unlock (L);
 453          pragma Assert (Result = 0);
 454       end if;
 455    end Unlock;
 456
 457    procedure Unlock (T : Task_Id) is
 458       Result : Interfaces.C.int;
 459    begin
 460       if not Single_Lock then
 461          Result := pthread_mutex_unlock (T.Common.LL.L'Access);
 462          pragma Assert (Result = 0);
 463       end if;
 464    end Unlock;
 465
 466    -----------------
 467    -- Set_Ceiling --
 468    -----------------
 469
 470    --  Dynamic priority ceilings are not supported by the underlying system
 471
 472    procedure Set_Ceiling
 473      (L    : not null access Lock;
 474       Prio : System.Any_Priority)
 475    is
 476       pragma Unreferenced (L, Prio);
 477    begin
 478       null;
 479    end Set_Ceiling;
 480
 481    -----------
 482    -- Sleep --
 483    -----------
 484
 485    procedure Sleep
 486      (Self_ID : Task_Id;
 487       Reason  : System.Tasking.Task_States)
 488    is
 489       pragma Unreferenced (Reason);
 490
 491       Result : Interfaces.C.int;
 492
 493    begin
 494       Result :=
 495         pthread_cond_wait
 496           (cond  => Self_ID.Common.LL.CV'Access,
 497            mutex => (if Single_Lock
 498                      then Single_RTS_Lock'Access
 499                      else Self_ID.Common.LL.L'Access));
 500
 501       --  EINTR is not considered a failure
 502
 503       pragma Assert (Result = 0 or else Result = EINTR);
 504    end Sleep;
 505
 506    -----------------
 507    -- Timed_Sleep --
 508    -----------------
 509
 510    --  This is for use within the run-time system, so abort is
 511    --  assumed to be already deferred, and the caller should be
 512    --  holding its own ATCB lock.
 513
 514    procedure Timed_Sleep
 515      (Self_ID  : Task_Id;
 516       Time     : Duration;
 517       Mode     : ST.Delay_Modes;
 518       Reason   : Task_States;
 519       Timedout : out Boolean;
 520       Yielded  : out Boolean)
 521    is
 522       pragma Unreferenced (Reason);
 523
 524       Base_Time  : constant Duration := Monotonic_Clock;
 525       Check_Time : Duration := Base_Time;
 526       Rel_Time   : Duration;
 527       Abs_Time   : Duration;
 528       Request    : aliased timespec;
 529       Result     : Interfaces.C.int;
 530
 531    begin
 532       Timedout := True;
 533       Yielded := False;
 534
 535       if Mode = Relative then
 536          Abs_Time := Duration'Min (Time, Max_Sensible_Delay) + Check_Time;
 537
 538          if Relative_Timed_Wait then
 539             Rel_Time := Duration'Min (Max_Sensible_Delay, Time);
 540          end if;
 541
 542       else
 543          Abs_Time := Duration'Min (Check_Time + Max_Sensible_Delay, Time);
 544
 545          if Relative_Timed_Wait then
 546             Rel_Time := Duration'Min (Max_Sensible_Delay, Time - Check_Time);
 547          end if;
 548       end if;
 549
 550       if Abs_Time > Check_Time then
 551          Request :=
 552            To_Timespec (if Relative_Timed_Wait then Rel_Time else Abs_Time);
 553
 554          loop
 555             exit when Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level;
 556
 557             Result :=
 558               pthread_cond_timedwait
 559                 (cond    => Self_ID.Common.LL.CV'Access,
 560                  mutex   => (if Single_Lock
 561                              then Single_RTS_Lock'Access
 562                              else Self_ID.Common.LL.L'Access),
 563                  abstime => Request'Access);
 564
 565             Check_Time := Monotonic_Clock;
 566             exit when Abs_Time <= Check_Time or else Check_Time < Base_Time;
 567
 568             if Result = 0 or Result = EINTR then
 569
 570                --  Somebody may have called Wakeup for us
 571
 572                Timedout := False;
 573                exit;
 574             end if;
 575
 576             pragma Assert (Result = ETIMEDOUT);
 577          end loop;
 578       end if;
 579    end Timed_Sleep;
 580
 581    -----------------
 582    -- Timed_Delay --
 583    -----------------
 584
 585    --  This is for use in implementing delay statements, so we assume the
 586    --  caller is abort-deferred but is holding no locks.
 587
 588    procedure Timed_Delay
 589      (Self_ID : Task_Id;
 590       Time    : Duration;
 591       Mode    : ST.Delay_Modes)
 592    is
 593       Base_Time  : constant Duration := Monotonic_Clock;
 594       Check_Time : Duration := Base_Time;
 595       Abs_Time   : Duration;
 596       Rel_Time   : Duration;
 597       Request    : aliased timespec;
 598
 599       Result : Interfaces.C.int;
 600       pragma Warnings (Off, Result);
 601
 602    begin
 603       if Single_Lock then
 604          Lock_RTS;
 605       end if;
 606
 607       Write_Lock (Self_ID);
 608
 609       if Mode = Relative then
 610          Abs_Time := Duration'Min (Time, Max_Sensible_Delay) + Check_Time;
 611
 612          if Relative_Timed_Wait then
 613             Rel_Time := Duration'Min (Max_Sensible_Delay, Time);
 614          end if;
 615
 616       else
 617          Abs_Time := Duration'Min (Check_Time + Max_Sensible_Delay, Time);
 618
 619          if Relative_Timed_Wait then
 620             Rel_Time := Duration'Min (Max_Sensible_Delay, Time - Check_Time);
 621          end if;
 622       end if;
 623
 624       if Abs_Time > Check_Time then
 625          Request :=
 626            To_Timespec (if Relative_Timed_Wait then Rel_Time else Abs_Time);
 627          Self_ID.Common.State := Delay_Sleep;
 628
 629          loop
 630             exit when Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level;
 631
 632             Result :=
 633               pthread_cond_timedwait
 634                 (cond    => Self_ID.Common.LL.CV'Access,
 635                  mutex   => (if Single_Lock
 636                              then Single_RTS_Lock'Access
 637                              else Self_ID.Common.LL.L'Access),
 638                  abstime => Request'Access);
 639
 640             Check_Time := Monotonic_Clock;
 641             exit when Abs_Time <= Check_Time or else Check_Time < Base_Time;
 642
 643             pragma Assert (Result = 0
 644                              or else Result = ETIMEDOUT
 645                              or else Result = EINTR);
 646          end loop;
 647
 648          Self_ID.Common.State := Runnable;
 649       end if;
 650
 651       Unlock (Self_ID);
 652
 653       if Single_Lock then
 654          Unlock_RTS;
 655       end if;
 656
 657       Result := sched_yield;
 658    end Timed_Delay;
 659
 660    ---------------------
 661    -- Monotonic_Clock --
 662    ---------------------
 663
 664    function Monotonic_Clock return Duration is
 665       TS     : aliased timespec;
 666       Result : Interfaces.C.int;
 667    begin
 668       Result := clock_gettime
 669         (clock_id => CLOCK_MONOTONIC, tp => TS'Unchecked_Access);
 670       pragma Assert (Result = 0);
 671       return To_Duration (TS);
 672    end Monotonic_Clock;
 673
 674    -------------------
 675    -- RT_Resolution --
 676    -------------------
 677
 678    function RT_Resolution return Duration is
 679    begin
 680       return 10#1.0#E-6;
 681    end RT_Resolution;
 682
 683    ------------
 684    -- Wakeup --
 685    ------------
 686
 687    procedure Wakeup (T : Task_Id; Reason : System.Tasking.Task_States) is
 688       pragma Unreferenced (Reason);
 689       Result : Interfaces.C.int;
 690    begin
 691       Result := pthread_cond_signal (T.Common.LL.CV'Access);
 692       pragma Assert (Result = 0);
 693    end Wakeup;
 694
 695    -----------
 696    -- Yield --
 697    -----------
 698
 699    procedure Yield (Do_Yield : Boolean := True) is
 700       Result : Interfaces.C.int;
 701       pragma Unreferenced (Result);
 702    begin
 703       if Do_Yield then
 704          Result := sched_yield;
 705       end if;
 706    end Yield;
 707
 708    ------------------
 709    -- Set_Priority --
 710    ------------------
 711
 712    procedure Set_Priority
 713      (T                   : Task_Id;
 714       Prio                : System.Any_Priority;
 715       Loss_Of_Inheritance : Boolean := False)
 716    is
 717       pragma Unreferenced (Loss_Of_Inheritance);
 718
 719       Result : Interfaces.C.int;
 720       Param  : aliased struct_sched_param;
 721
 722       function Get_Policy (Prio : System.Any_Priority) return Character;
 723       pragma Import (C, Get_Policy, "__gnat_get_specific_dispatching");
 724       --  Get priority specific dispatching policy
 725
 726       Priority_Specific_Policy : constant Character := Get_Policy (Prio);
 727       --  Upper case first character of the policy name corresponding to the
 728       --  task as set by a Priority_Specific_Dispatching pragma.
 729
 730    begin
 731       T.Common.Current_Priority := Prio;
 732       Param.sched_priority := To_Target_Priority (Prio);
 733
 734       if Time_Slice_Supported
 735         and then (Dispatching_Policy = 'R'
 736                   or else Priority_Specific_Policy = 'R'
 737                   or else Time_Slice_Val > 0)
 738       then
 739          Result := pthread_setschedparam
 740            (T.Common.LL.Thread, SCHED_RR, Param'Access);
 741
 742       elsif Dispatching_Policy = 'F'
 743         or else Priority_Specific_Policy = 'F'
 744         or else Time_Slice_Val = 0
 745       then
 746          Result := pthread_setschedparam
 747            (T.Common.LL.Thread, SCHED_FIFO, Param'Access);
 748
 749       else
 750          Result := pthread_setschedparam
 751            (T.Common.LL.Thread, SCHED_OTHER, Param'Access);
 752       end if;
 753
 754       pragma Assert (Result = 0);
 755    end Set_Priority;
 756
 757    ------------------
 758    -- Get_Priority --
 759    ------------------
 760
 761    function Get_Priority (T : Task_Id) return System.Any_Priority is
 762    begin
 763       return T.Common.Current_Priority;
 764    end Get_Priority;
 765
 766    ----------------
 767    -- Enter_Task --
 768    ----------------
 769
 770    procedure Enter_Task (Self_ID : Task_Id) is
 771    begin
 772       Self_ID.Common.LL.Thread := pthread_self;
 773       Self_ID.Common.LL.LWP := lwp_self;
 774
 775       Specific.Set (Self_ID);
 776
 777       if Use_Alternate_Stack then
 778          declare
 779             Stack  : aliased stack_t;
 780             Result : Interfaces.C.int;
 781          begin
 782             Stack.ss_sp    := Self_ID.Common.Task_Alternate_Stack;
 783             Stack.ss_size  := Alternate_Stack_Size;
 784             Stack.ss_flags := 0;
 785             Result := sigaltstack (Stack'Access, null);
 786             pragma Assert (Result = 0);
 787          end;
 788       end if;
 789    end Enter_Task;
 790
 791    -------------------
 792    -- Is_Valid_Task --
 793    -------------------
 794
 795    function Is_Valid_Task return Boolean renames Specific.Is_Valid_Task;
 796
 797    -----------------------------
 798    -- Register_Foreign_Thread --
 799    -----------------------------
 800
 801    function Register_Foreign_Thread return Task_Id is
 802    begin
 803       if Is_Valid_Task then
 804          return Self;
 805       else
 806          return Register_Foreign_Thread (pthread_self);
 807       end if;
 808    end Register_Foreign_Thread;
 809
 810    --------------------
 811    -- Initialize_TCB --
 812    --------------------
 813
 814    procedure Initialize_TCB (Self_ID : Task_Id; Succeeded : out Boolean) is
 815       Mutex_Attr : aliased pthread_mutexattr_t;
 816       Result     : Interfaces.C.int;
 817       Cond_Attr  : aliased pthread_condattr_t;
 818
 819    begin
 820       --  Give the task a unique serial number
 821
 822       Self_ID.Serial_Number := Next_Serial_Number;
 823       Next_Serial_Number := Next_Serial_Number + 1;
 824       pragma Assert (Next_Serial_Number /= 0);
 825
 826       if not Single_Lock then
 827          Result := pthread_mutexattr_init (Mutex_Attr'Access);
 828          pragma Assert (Result = 0 or else Result = ENOMEM);
 829
 830          if Result = 0 then
 831             if Locking_Policy = 'C' then
 832                Result :=
 833                  pthread_mutexattr_setprotocol
 834                    (Mutex_Attr'Access,
 835                     PTHREAD_PRIO_PROTECT);
 836                pragma Assert (Result = 0);
 837
 838                Result :=
 839                  pthread_mutexattr_setprioceiling
 840                    (Mutex_Attr'Access,
 841                     Interfaces.C.int (System.Any_Priority'Last));
 842                pragma Assert (Result = 0);
 843
 844             elsif Locking_Policy = 'I' then
 845                Result :=
 846                  pthread_mutexattr_setprotocol
 847                    (Mutex_Attr'Access,
 848                     PTHREAD_PRIO_INHERIT);
 849                pragma Assert (Result = 0);
 850             end if;
 851
 852             Result :=
 853               pthread_mutex_init
 854                 (Self_ID.Common.LL.L'Access,
 855                  Mutex_Attr'Access);
 856             pragma Assert (Result = 0 or else Result = ENOMEM);
 857          end if;
 858
 859          if Result /= 0 then
 860             Succeeded := False;
 861             return;
 862          end if;
 863
 864          Result := pthread_mutexattr_destroy (Mutex_Attr'Access);
 865          pragma Assert (Result = 0);
 866       end if;
 867
 868       Result := pthread_condattr_init (Cond_Attr'Access);
 869       pragma Assert (Result = 0 or else Result = ENOMEM);
 870
 871       if Result = 0 then
 872          Result :=
 873            pthread_cond_init
 874              (Self_ID.Common.LL.CV'Access, Cond_Attr'Access);
 875          pragma Assert (Result = 0 or else Result = ENOMEM);
 876       end if;
 877
 878       if Result = 0 then
 879          Succeeded := True;
 880       else
 881          if not Single_Lock then
 882             Result := pthread_mutex_destroy (Self_ID.Common.LL.L'Access);
 883             pragma Assert (Result = 0);
 884          end if;
 885
 886          Succeeded := False;
 887       end if;
 888
 889       Result := pthread_condattr_destroy (Cond_Attr'Access);
 890       pragma Assert (Result = 0);
 891    end Initialize_TCB;
 892
 893    -----------------
 894    -- Create_Task --
 895    -----------------
 896
 897    procedure Create_Task
 898      (T          : Task_Id;
 899       Wrapper    : System.Address;
 900       Stack_Size : System.Parameters.Size_Type;
 901       Priority   : System.Any_Priority;
 902       Succeeded  : out Boolean)
 903    is
 904       Attributes          : aliased pthread_attr_t;
 905       Adjusted_Stack_Size : Interfaces.C.size_t;
 906       Page_Size           : constant Interfaces.C.size_t := Get_Page_Size;
 907       Result              : Interfaces.C.int;
 908
 909       function Thread_Body_Access is new
 910         Ada.Unchecked_Conversion (System.Address, Thread_Body);
 911
 912       use System.Task_Info;
 913
 914    begin
 915       Adjusted_Stack_Size :=
 916          Interfaces.C.size_t (Stack_Size + Alternate_Stack_Size);
 917
 918       if Stack_Base_Available then
 919
 920          --  If Stack Checking is supported then allocate 2 additional pages:
 921
 922          --  In the worst case, stack is allocated at something like
 923          --  N * Get_Page_Size - epsilon, we need to add the size for 2 pages
 924          --  to be sure the effective stack size is greater than what
 925          --  has been asked.
 926
 927          Adjusted_Stack_Size := Adjusted_Stack_Size + 2 * Page_Size;
 928       end if;
 929
 930       --  Round stack size as this is required by some OSes (Darwin)
 931
 932       Adjusted_Stack_Size := Adjusted_Stack_Size + Page_Size - 1;
 933       Adjusted_Stack_Size :=
 934         Adjusted_Stack_Size - Adjusted_Stack_Size mod Page_Size;
 935
 936       Result := pthread_attr_init (Attributes'Access);
 937       pragma Assert (Result = 0 or else Result = ENOMEM);
 938
 939       if Result /= 0 then
 940          Succeeded := False;
 941          return;
 942       end if;
 943
 944       Result :=
 945         pthread_attr_setdetachstate
 946           (Attributes'Access, PTHREAD_CREATE_DETACHED);
 947       pragma Assert (Result = 0);
 948
 949       Result :=
 950         pthread_attr_setstacksize
 951           (Attributes'Access, Adjusted_Stack_Size);
 952       pragma Assert (Result = 0);
 953
 954       if T.Common.Task_Info /= Default_Scope then
 955          case T.Common.Task_Info is
 956             when System.Task_Info.Process_Scope =>
 957                Result :=
 958                  pthread_attr_setscope
 959                    (Attributes'Access, PTHREAD_SCOPE_PROCESS);
 960
 961             when System.Task_Info.System_Scope =>
 962                Result :=
 963                  pthread_attr_setscope
 964                    (Attributes'Access, PTHREAD_SCOPE_SYSTEM);
 965
 966             when System.Task_Info.Default_Scope =>
 967                Result := 0;
 968          end case;
 969
 970          pragma Assert (Result = 0);
 971       end if;
 972
 973       --  Since the initial signal mask of a thread is inherited from the
 974       --  creator, and the Environment task has all its signals masked, we
 975       --  do not need to manipulate caller's signal mask at this point.
 976       --  All tasks in RTS will have All_Tasks_Mask initially.
 977
 978       Result := pthread_create
 979         (T.Common.LL.Thread'Access,
 980          Attributes'Access,
 981          Thread_Body_Access (Wrapper),
 982          To_Address (T));
 983       pragma Assert (Result = 0 or else Result = EAGAIN);
 984
 985       Succeeded := Result = 0;
 986
 987       Result := pthread_attr_destroy (Attributes'Access);
 988       pragma Assert (Result = 0);
 989
 990       if Succeeded then
 991          Set_Priority (T, Priority);
 992       end if;
 993    end Create_Task;
 994
 995    ------------------
 996    -- Finalize_TCB --
 997    ------------------
 998
 999    procedure Finalize_TCB (T : Task_Id) is
1000       Result : Interfaces.C.int;
1001
1002    begin
1003       if not Single_Lock then
1004          Result := pthread_mutex_destroy (T.Common.LL.L'Access);
1005          pragma Assert (Result = 0);
1006       end if;
1007
1008       Result := pthread_cond_destroy (T.Common.LL.CV'Access);
1009       pragma Assert (Result = 0);
1010
1011       if T.Known_Tasks_Index /= -1 then
1012          Known_Tasks (T.Known_Tasks_Index) := null;
1013       end if;
1014
1015       ATCB_Allocation.Free_ATCB (T);
1016    end Finalize_TCB;
1017
1018    ---------------
1019    -- Exit_Task --
1020    ---------------
1021
1022    procedure Exit_Task is
1023    begin
1024       --  Mark this task as unknown, so that if Self is called, it won't
1025       --  return a dangling pointer.
1026
1027       Specific.Set (null);
1028    end Exit_Task;
1029
1030    ----------------
1031    -- Abort_Task --
1032    ----------------
1033
1034    procedure Abort_Task (T : Task_Id) is
1035       Result : Interfaces.C.int;
1036    begin
1037       if Abort_Handler_Installed then
1038          Result :=
1039            pthread_kill
1040              (T.Common.LL.Thread,
1041               Signal (System.Interrupt_Management.Abort_Task_Interrupt));
1042          pragma Assert (Result = 0);
1043       end if;
1044    end Abort_Task;
1045
1046    ----------------
1047    -- Initialize --
1048    ----------------
1049
1050    procedure Initialize (S : in out Suspension_Object) is
1051       Mutex_Attr : aliased pthread_mutexattr_t;
1052       Cond_Attr  : aliased pthread_condattr_t;
1053       Result     : Interfaces.C.int;
1054
1055    begin
1056       --  Initialize internal state (always to False (RM D.10 (6)))
1057
1058       S.State := False;
1059       S.Waiting := False;
1060
1061       --  Initialize internal mutex
1062
1063       Result := pthread_mutexattr_init (Mutex_Attr'Access);
1064       pragma Assert (Result = 0 or else Result = ENOMEM);
1065
1066       if Result = ENOMEM then
1067          raise Storage_Error;
1068       end if;
1069
1070       Result := pthread_mutex_init (S.L'Access, Mutex_Attr'Access);
1071       pragma Assert (Result = 0 or else Result = ENOMEM);
1072
1073       if Result = ENOMEM then
1074          Result := pthread_mutexattr_destroy (Mutex_Attr'Access);
1075          pragma Assert (Result = 0);
1076
1077          raise Storage_Error;
1078       end if;
1079
1080       Result := pthread_mutexattr_destroy (Mutex_Attr'Access);
1081       pragma Assert (Result = 0);
1082
1083       --  Initialize internal condition variable
1084
1085       Result := pthread_condattr_init (Cond_Attr'Access);
1086       pragma Assert (Result = 0 or else Result = ENOMEM);
1087
1088       if Result /= 0 then
1089          Result := pthread_mutex_destroy (S.L'Access);
1090          pragma Assert (Result = 0);
1091
1092          if Result = ENOMEM then
1093             raise Storage_Error;
1094          end if;
1095       end if;
1096
1097       Result := pthread_cond_init (S.CV'Access, Cond_Attr'Access);
1098       pragma Assert (Result = 0 or else Result = ENOMEM);
1099
1100       if Result /= 0 then
1101          Result := pthread_mutex_destroy (S.L'Access);
1102          pragma Assert (Result = 0);
1103
1104          if Result = ENOMEM then
1105             Result := pthread_condattr_destroy (Cond_Attr'Access);
1106             pragma Assert (Result = 0);
1107             raise Storage_Error;
1108          end if;
1109       end if;
1110
1111       Result := pthread_condattr_destroy (Cond_Attr'Access);
1112       pragma Assert (Result = 0);
1113    end Initialize;
1114
1115    --------------
1116    -- Finalize --
1117    --------------
1118
1119    procedure Finalize (S : in out Suspension_Object) is
1120       Result : Interfaces.C.int;
1121
1122    begin
1123       --  Destroy internal mutex
1124
1125       Result := pthread_mutex_destroy (S.L'Access);
1126       pragma Assert (Result = 0);
1127
1128       --  Destroy internal condition variable
1129
1130       Result := pthread_cond_destroy (S.CV'Access);
1131       pragma Assert (Result = 0);
1132    end Finalize;
1133
1134    -------------------
1135    -- Current_State --
1136    -------------------
1137
1138    function Current_State (S : Suspension_Object) return Boolean is
1139    begin
1140       --  We do not want to use lock on this read operation. State is marked
1141       --  as Atomic so that we ensure that the value retrieved is correct.
1142
1143       return S.State;
1144    end Current_State;
1145
1146    ---------------
1147    -- Set_False --
1148    ---------------
1149
1150    procedure Set_False (S : in out Suspension_Object) is
1151       Result : Interfaces.C.int;
1152
1153    begin
1154       SSL.Abort_Defer.all;
1155
1156       Result := pthread_mutex_lock (S.L'Access);
1157       pragma Assert (Result = 0);
1158
1159       S.State := False;
1160
1161       Result := pthread_mutex_unlock (S.L'Access);
1162       pragma Assert (Result = 0);
1163
1164       SSL.Abort_Undefer.all;
1165    end Set_False;
1166
1167    --------------
1168    -- Set_True --
1169    --------------
1170
1171    procedure Set_True (S : in out Suspension_Object) is
1172       Result : Interfaces.C.int;
1173
1174    begin
1175       SSL.Abort_Defer.all;
1176
1177       Result := pthread_mutex_lock (S.L'Access);
1178       pragma Assert (Result = 0);
1179
1180       --  If there is already a task waiting on this suspension object then
1181       --  we resume it, leaving the state of the suspension object to False,
1182       --  as it is specified in (RM D.10(9)). Otherwise, it just leaves
1183       --  the state to True.
1184
1185       if S.Waiting then
1186          S.Waiting := False;
1187          S.State := False;
1188
1189          Result := pthread_cond_signal (S.CV'Access);
1190          pragma Assert (Result = 0);
1191
1192       else
1193          S.State := True;
1194       end if;
1195
1196       Result := pthread_mutex_unlock (S.L'Access);
1197       pragma Assert (Result = 0);
1198
1199       SSL.Abort_Undefer.all;
1200    end Set_True;
1201
1202    ------------------------
1203    -- Suspend_Until_True --
1204    ------------------------
1205
1206    procedure Suspend_Until_True (S : in out Suspension_Object) is
1207       Result : Interfaces.C.int;
1208
1209    begin
1210       SSL.Abort_Defer.all;
1211
1212       Result := pthread_mutex_lock (S.L'Access);
1213       pragma Assert (Result = 0);
1214
1215       if S.Waiting then
1216
1217          --  Program_Error must be raised upon calling Suspend_Until_True
1218          --  if another task is already waiting on that suspension object
1219          --  (RM D.10(10)).
1220
1221          Result := pthread_mutex_unlock (S.L'Access);
1222          pragma Assert (Result = 0);
1223
1224          SSL.Abort_Undefer.all;
1225
1226          raise Program_Error;
1227
1228       else
1229          --  Suspend the task if the state is False. Otherwise, the task
1230          --  continues its execution, and the state of the suspension object
1231          --  is set to False (ARM D.10 par. 9).
1232
1233          if S.State then
1234             S.State := False;
1235          else
1236             S.Waiting := True;
1237
1238             loop
1239                --  Loop in case pthread_cond_wait returns earlier than expected
1240                --  (e.g. in case of EINTR caused by a signal).
1241
1242                Result := pthread_cond_wait (S.CV'Access, S.L'Access);
1243                pragma Assert (Result = 0 or else Result = EINTR);
1244
1245                exit when not S.Waiting;
1246             end loop;
1247          end if;
1248
1249          Result := pthread_mutex_unlock (S.L'Access);
1250          pragma Assert (Result = 0);
1251
1252          SSL.Abort_Undefer.all;
1253       end if;
1254    end Suspend_Until_True;
1255
1256    ----------------
1257    -- Check_Exit --
1258    ----------------
1259
1260    --  Dummy version
1261
1262    function Check_Exit (Self_ID : ST.Task_Id) return Boolean is
1263       pragma Unreferenced (Self_ID);
1264    begin
1265       return True;
1266    end Check_Exit;
1267
1268    --------------------
1269    -- Check_No_Locks --
1270    --------------------
1271
1272    function Check_No_Locks (Self_ID : ST.Task_Id) return Boolean is
1273       pragma Unreferenced (Self_ID);
1274    begin
1275       return True;
1276    end Check_No_Locks;
1277
1278    ----------------------
1279    -- Environment_Task --
1280    ----------------------
1281
1282    function Environment_Task return Task_Id is
1283    begin
1284       return Environment_Task_Id;
1285    end Environment_Task;
1286
1287    --------------
1288    -- Lock_RTS --
1289    --------------
1290
1291    procedure Lock_RTS is
1292    begin
1293       Write_Lock (Single_RTS_Lock'Access, Global_Lock => True);
1294    end Lock_RTS;
1295
1296    ----------------
1297    -- Unlock_RTS --
1298    ----------------
1299
1300    procedure Unlock_RTS is
1301    begin
1302       Unlock (Single_RTS_Lock'Access, Global_Lock => True);
1303    end Unlock_RTS;
1304
1305    ------------------
1306    -- Suspend_Task --
1307    ------------------
1308
1309    function Suspend_Task
1310      (T           : ST.Task_Id;
1311       Thread_Self : Thread_Id) return Boolean
1312    is
1313       pragma Unreferenced (T, Thread_Self);
1314    begin
1315       return False;
1316    end Suspend_Task;
1317
1318    -----------------
1319    -- Resume_Task --
1320    -----------------
1321
1322    function Resume_Task
1323      (T           : ST.Task_Id;
1324       Thread_Self : Thread_Id) return Boolean
1325    is
1326       pragma Unreferenced (T, Thread_Self);
1327    begin
1328       return False;
1329    end Resume_Task;
1330
1331    --------------------
1332    -- Stop_All_Tasks --
1333    --------------------
1334
1335    procedure Stop_All_Tasks is
1336    begin
1337       null;
1338    end Stop_All_Tasks;
1339
1340    ---------------
1341    -- Stop_Task --
1342    ---------------
1343
1344    function Stop_Task (T : ST.Task_Id) return Boolean is
1345       pragma Unreferenced (T);
1346    begin
1347       return False;
1348    end Stop_Task;
1349
1350    -------------------
1351    -- Continue_Task --
1352    -------------------
1353
1354    function Continue_Task (T : ST.Task_Id) return Boolean is
1355       pragma Unreferenced (T);
1356    begin
1357       return False;
1358    end Continue_Task;
1359
1360    ----------------
1361    -- Initialize --
1362    ----------------
1363
1364    procedure Initialize (Environment_Task : Task_Id) is
1365       act     : aliased struct_sigaction;
1366       old_act : aliased struct_sigaction;
1367       Tmp_Set : aliased sigset_t;
1368       Result  : Interfaces.C.int;
1369
1370       function State
1371         (Int : System.Interrupt_Management.Interrupt_ID) return Character;
1372       pragma Import (C, State, "__gnat_get_interrupt_state");
1373       --  Get interrupt state.  Defined in a-init.c
1374       --  The input argument is the interrupt number,
1375       --  and the result is one of the following:
1376
1377       Default : constant Character := 's';
1378       --    'n'   this interrupt not set by any Interrupt_State pragma
1379       --    'u'   Interrupt_State pragma set state to User
1380       --    'r'   Interrupt_State pragma set state to Runtime
1381       --    's'   Interrupt_State pragma set state to System (use "default"
1382       --           system handler)
1383
1384    begin
1385       Environment_Task_Id := Environment_Task;
1386
1387       Interrupt_Management.Initialize;
1388
1389       --  Prepare the set of signals that should unblocked in all tasks
1390
1391       Result := sigemptyset (Unblocked_Signal_Mask'Access);
1392       pragma Assert (Result = 0);
1393
1394       for J in Interrupt_Management.Interrupt_ID loop
1395          if System.Interrupt_Management.Keep_Unmasked (J) then
1396             Result := sigaddset (Unblocked_Signal_Mask'Access, Signal (J));
1397             pragma Assert (Result = 0);
1398          end if;
1399       end loop;
1400
1401       --  Initialize the lock used to synchronize chain of all ATCBs
1402
1403       Initialize_Lock (Single_RTS_Lock'Access, RTS_Lock_Level);
1404
1405       Specific.Initialize (Environment_Task);
1406
1407       if Use_Alternate_Stack then
1408          Environment_Task.Common.Task_Alternate_Stack :=
1409            Alternate_Stack'Address;
1410       end if;
1411
1412       --  Make environment task known here because it doesn't go through
1413       --  Activate_Tasks, which does it for all other tasks.
1414
1415       Known_Tasks (Known_Tasks'First) := Environment_Task;
1416       Environment_Task.Known_Tasks_Index := Known_Tasks'First;
1417
1418       Enter_Task (Environment_Task);
1419
1420       if State
1421           (System.Interrupt_Management.Abort_Task_Interrupt) /= Default
1422       then
1423          act.sa_flags := 0;
1424          act.sa_handler := Abort_Handler'Address;
1425
1426          Result := sigemptyset (Tmp_Set'Access);
1427          pragma Assert (Result = 0);
1428          act.sa_mask := Tmp_Set;
1429
1430          Result :=
1431            sigaction
1432              (Signal (System.Interrupt_Management.Abort_Task_Interrupt),
1433               act'Unchecked_Access,
1434               old_act'Unchecked_Access);
1435          pragma Assert (Result = 0);
1436          Abort_Handler_Installed := True;
1437       end if;
1438    end Initialize;
1439
1440    -----------------------
1441    -- Set_Task_Affinity --
1442    -----------------------
1443
1444    procedure Set_Task_Affinity (T : ST.Task_Id) is
1445       pragma Unreferenced (T);
1446
1447    begin
1448       --  Setting task affinity is not supported by the underlying system
1449
1450       null;
1451    end Set_Task_Affinity;
1452
1453 end System.Task_Primitives.Operations;