gcc/ada/5stasinf.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                     S Y S T E M . T A S K _ I N F O                      --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                                                                          --
   9 --                            $Revision: 1.1 $
  10 --                                                                          --
  11 --          Copyright (C) 1992-2000 Free Software Foundation, Inc.          --
  12 --                                                                          --
  13 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  14 -- terms of the  GNU General Public License as published  by the Free Soft- --
  15 -- ware  Foundation;  either version 2,  or (at your option) any later ver- --
  16 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  17 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  18 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  19 -- for  more details.  You should have  received  a copy of the GNU General --
  20 -- Public License  distributed with GNAT;  see file COPYING.  If not, write --
  21 -- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
  22 -- MA 02111-1307, USA.                                                      --
  23 --                                                                          --
  24 -- As a special exception,  if other files  instantiate  generics from this --
  25 -- unit, or you link  this unit with other files  to produce an executable, --
  26 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  27 -- covered  by the  GNU  General  Public  License.  This exception does not --
  28 -- however invalidate  any other reasons why  the executable file  might be --
  29 -- covered by the  GNU Public License.                                      --
  30 --                                                                          --
  31 -- GNAT was originally developed  by the GNAT team at  New York University. --
  32 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  33 --                                                                          --
  34 ------------------------------------------------------------------------------
  35
  36 --  This package contains the definitions and routines associated with the
  37 --  implementation of the Task_Info pragma.
  38
  39 --  This is the Solaris (native) version of this module.
  40
  41 with System.OS_Interface;
  42 with Unchecked_Deallocation;
  43 package System.Task_Info is
  44 pragma Elaborate_Body;
  45 --  To ensure that a body is allowed
  46
  47    -----------------------------------------------------
  48    -- Binding of Tasks to LWPs and LWPs to processors --
  49    -----------------------------------------------------
  50
  51    --  The Solaris implementation of the GNU Low-Level Interface (GNULLI)
  52    --  implements each Ada task as a Solaris thread.  The Solaris thread
  53    --  library distributes threads across one or more LWPs (Light Weight
  54    --  Process) that are members of the same process. Solaris distributes
  55    --  processes and LWPs across the available CPUs on a given machine. The
  56    --  pragma Task_Info provides the mechanism to control the distribution
  57    --  of tasks to LWPs, and LWPs to processors.
  58
  59    --  Each thread has a number of attributes that dictate it's scheduling.
  60    --  These attributes are:
  61    --
  62    --      New_LWP:       whether a new LWP is created for this thread.
  63    --
  64    --      Bound_To_LWP:  whether the thread is bound to a specific LWP
  65    --                     for its entire lifetime.
  66    --
  67    --      CPU:           the CPU number associated to the LWP
  68    --
  69
  70    --  The Task_Info pragma:
  71
  72    --    pragma Task_Info (EXPRESSION);
  73
  74    --  allows the specification on a task by task basis of a value of type
  75    --  System.Task_Info.Task_Info_Type to be passed to a task when it is
  76    --  created. The specification of this type, and the effect on the task
  77    --  that is created is target dependent.
  78
  79    --  The Task_Info pragma appears within a task definition (compare the
  80    --  definition and implementation of pragma Priority). If no such pragma
  81    --  appears, then the value Task_Info_Unspecified is passed. If a pragma
  82    --  is present, then it supplies an alternative value. If the argument of
  83    --  the pragma is a discriminant reference, then the value can be set on
  84    --  a task by task basis by supplying the appropriate discriminant value.
  85
  86    --  Note that this means that the type used for Task_Info_Type must be
  87    --  suitable for use as a discriminant (i.e. a scalar or access type).
  88
  89    -----------------------
  90    -- Thread Attributes --
  91    -----------------------
  92
  93    subtype CPU_Number is System.OS_Interface.processorid_t;
  94
  95    CPU_UNCHANGED : constant CPU_Number := System.OS_Interface.PBIND_QUERY;
  96    --  Do not bind the LWP to a specific processor
  97
  98    ANY_CPU       : constant CPU_Number := System.OS_Interface.PBIND_NONE;
  99    --  Bind the LWP to any processor
 100
 101    Invalid_CPU_Number : exception;
 102
 103    type Thread_Attributes (New_LWP : Boolean) is record
 104       Bound_To_LWP     : Boolean    := True;
 105       case New_LWP is
 106          when False =>
 107             null;
 108          when True =>
 109             CPU        : CPU_Number := CPU_UNCHANGED;
 110       end case;
 111    end record;
 112
 113    Default_Thread_Attributes : constant Thread_Attributes := (False, True);
 114
 115    function Unbound_Thread_Attributes
 116       return Thread_Attributes;
 117
 118    function Bound_Thread_Attributes
 119       return Thread_Attributes;
 120
 121    function Bound_Thread_Attributes (CPU : CPU_Number)
 122       return Thread_Attributes;
 123
 124    type Task_Info_Type is access all Thread_Attributes;
 125
 126    function New_Unbound_Thread_Attributes
 127       return Task_Info_Type;
 128
 129    function New_Bound_Thread_Attributes
 130       return Task_Info_Type;
 131
 132    function New_Bound_Thread_Attributes (CPU : CPU_Number)
 133       return Task_Info_Type;
 134
 135    type Task_Image_Type is access String;
 136    --  Used to generate a meaningful identifier for tasks that are variables
 137    --  and components of variables.
 138
 139    procedure Free_Task_Image is new
 140      Unchecked_Deallocation (String, Task_Image_Type);
 141
 142    Unspecified_Task_Info : constant Task_Info_Type := null;
 143
 144 end System.Task_Info;