gcc/ada/s-taspri-posix.ads

   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              --
   6 --                                                                          --
   7 --                                  S p e c                                 --
   8 --                                                                          --
   9 --             Copyright (C) 1991-1994, Florida State University            --
  10 --                     Copyright (C) 1995-2005, AdaCore                     --
  11 --                                                                          --
  12 -- GNARL is free software; you can  redistribute it  and/or modify it under --
  13 -- terms of the  GNU General Public License as published  by the Free Soft- --
  14 -- ware  Foundation;  either version 2,  or (at your option) any later ver- --
  15 -- sion. GNARL is distributed in the hope that it will be useful, but WITH- --
  16 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  17 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  18 -- for  more details.  You should have  received  a copy of the GNU General --
  19 -- Public License  distributed with GNARL; see file COPYING.  If not, write --
  20 -- to  the  Free Software Foundation,  51  Franklin  Street,  Fifth  Floor, --
  21 -- Boston, MA 02110-1301, USA.                                              --
  22 --                                                                          --
  23 -- As a special exception,  if other files  instantiate  generics from this --
  24 -- unit, or you link  this unit with other files  to produce an executable, --
  25 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  26 -- covered  by the  GNU  General  Public  License.  This exception does not --
  27 -- however invalidate  any other reasons why  the executable file  might be --
  28 -- covered by the  GNU Public License.                                      --
  29 --                                                                          --
  30 -- GNARL was developed by the GNARL team at Florida State University.       --
  31 -- Extensive contributions were provided by Ada Core Technologies, Inc.     --
  32 --                                                                          --
  33 ------------------------------------------------------------------------------
  34
  35 --  This is a POSIX-like version of this package
  36
  37 --  Note: this file can only be used for POSIX compliant systems
  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.OS_Interface;
  44 --  used for pthread_mutex_t
  45 --           pthread_cond_t
  46 --           pthread_t
  47
  48 package System.Task_Primitives is
  49    pragma Preelaborate;
  50
  51    type Lock is limited private;
  52    --  Should be used for implementation of protected objects
  53
  54    type RTS_Lock is limited private;
  55    --  Should be used inside the runtime system. The difference between Lock
  56    --  and the RTS_Lock is that the later one serves only as a semaphore so
  57    --  that do not check for ceiling violations.
  58
  59    type Suspension_Object is limited private;
  60    --  Should be used for the implementation of Ada.Synchronous_Task_Control
  61
  62    type Task_Body_Access is access procedure;
  63    --  Pointer to the task body's entry point (or possibly a wrapper declared
  64    --  local to the GNARL).
  65
  66    type Private_Data is limited private;
  67    --  Any information that the GNULLI needs maintained on a per-task basis.
  68    --  A component of this type is guaranteed to be included in the
  69    --  Ada_Task_Control_Block.
  70
  71 private
  72
  73    type Lock is new System.OS_Interface.pthread_mutex_t;
  74    type RTS_Lock is new System.OS_Interface.pthread_mutex_t;
  75
  76    type Suspension_Object is record
  77       State : Boolean;
  78       pragma Atomic (State);
  79       --  Boolean that indicates whether the object is open. This field is
  80       --  marked Atomic to ensure that we can read its value without locking
  81       --  the access to the Suspension_Object.
  82
  83       Waiting : Boolean;
  84       --  Flag showing if there is a task already suspended on this object
  85
  86       L : aliased System.OS_Interface.pthread_mutex_t;
  87       --  Protection for ensuring mutual exclusion on the Suspension_Object
  88
  89       CV : aliased System.OS_Interface.pthread_cond_t;
  90       --  Condition variable used to queue threads until condition is signaled
  91    end record;
  92
  93    type Private_Data is record
  94       Thread : aliased System.OS_Interface.pthread_t;
  95       pragma Atomic (Thread);
  96       --  Thread field may be updated by two different threads of control.
  97       --  (See, Enter_Task and Create_Task in s-taprop.adb). They put the same
  98       --  value (thr_self value). We do not want to use lock on those
  99       --  operations and the only thing we have to make sure is that they are
 100       --  updated in atomic fashion.
 101
 102       LWP : aliased System.Address;
 103       --  The purpose of this field is to provide a better tasking support on
 104       --  gdb. The order of the two first fields (Thread and LWP) is important.
 105       --  On targets where lwp is not relevant, this is equivalent to Thread.
 106
 107       CV : aliased System.OS_Interface.pthread_cond_t;
 108       --  Should be commented ??? (in all versions of taspri)
 109
 110       L : aliased RTS_Lock;
 111       --  Protection for all components is lock L
 112    end record;
 113
 114 end System.Task_Primitives;