gcc/ada/5gtasinf.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: 1.4 $
  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 -- It is now maintained by Ada Core Technologies Inc (http://www.gnat.com). --
  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 SGI (libathread) specific 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 sprocs and sprocs to processors --
  49    ---------------------------------------------------------
  50
  51    --  The SGI implementation of the GNU Low-Level Interface (GNULLI)
  52    --  implements each Ada task as a Posix thread (Pthread).  The SGI
  53    --  Pthread library distributes threads across one or more processes
  54    --  that are members of a common share group.  Irix distributes
  55    --  processes across the available CPUs on a given machine.  The
  56    --  pragma Task_Info provides the mechanism to control the distribution
  57    --  of tasks to sprocs, and sprocs to processors.
  58
  59    --  Each thread has a number of attributes that dictate it's scheduling.
  60    --  These attributes are:
  61    --
  62    --      Bound_To_Sproc:  whether the thread is bound to a specific sproc
  63    --                       for its entire lifetime.
  64    --
  65    --      Timeslice:       Amount of time that a thread is allowed to execute
  66    --                       before the system yeilds control to another thread
  67    --                       of equal priority.
  68    --
  69    --      Resource_Vector: A bitmask used to control the binding of threads
  70    --                       to sprocs.
  71    --
  72
  73    --  Each share group process (sproc)
  74
  75    --  The Task_Info pragma:
  76
  77    --    pragma Task_Info (EXPRESSION);
  78
  79    --  allows the specification on a task by task basis of a value of type
  80    --  System.Task_Info.Task_Info_Type to be passed to a task when it is
  81    --  created. The specification of this type, and the effect on the task
  82    --  that is created is target dependent.
  83
  84    --  The Task_Info pragma appears within a task definition (compare the
  85    --  definition and implementation of pragma Priority). If no such pragma
  86    --  appears, then the value Task_Info_Unspecified is passed. If a pragma
  87    --  is present, then it supplies an alternative value. If the argument of
  88    --  the pragma is a discriminant reference, then the value can be set on
  89    --  a task by task basis by supplying the appropriate discriminant value.
  90
  91    --  Note that this means that the type used for Task_Info_Type must be
  92    --  suitable for use as a discriminant (i.e. a scalar or access type).
  93
  94    ----------------------
  95    -- Resource Vectors --
  96    ----------------------
  97
  98    --  <discussion>
  99
 100    type Resource_Vector_T is array (0 .. 31) of Boolean;
 101    pragma Pack (Resource_Vector_T);
 102
 103    NO_RESOURCES : constant Resource_Vector_T := (others => False);
 104
 105    generic
 106       type Resource_T is (<>); -- Discrete type up to 32 entries
 107    package Resource_Vector_Functions is
 108       function "+"(R : Resource_T)
 109          return Resource_Vector_T;
 110       function "+"(R1, R2 : Resource_T)
 111          return Resource_Vector_T;
 112       function "+"(R : Resource_T; S : Resource_Vector_T)
 113          return Resource_Vector_T;
 114       function "+"(S : Resource_Vector_T; R : Resource_T)
 115          return Resource_Vector_T;
 116       function "+"(S1, S2 : Resource_Vector_T)
 117          return Resource_Vector_T;
 118       function "-"(S : Resource_Vector_T; R : Resource_T)
 119          return Resource_Vector_T;
 120    end Resource_Vector_Functions;
 121
 122    ----------------------
 123    -- Sproc Attributes --
 124    ----------------------
 125
 126    subtype sproc_t is System.OS_Interface.sproc_t;
 127
 128    subtype CPU_Number is Integer range -1 .. Integer'Last;
 129
 130    ANY_CPU : constant CPU_Number := CPU_Number'First;
 131
 132    --
 133    --  Specification of IRIX Non Degrading Priorities.
 134    --
 135    --  WARNING: IRIX priorities have the reverse meaning of Ada priorities.
 136    --           The lower the priority value, the greater the greater the
 137    --           scheduling preference.
 138    --
 139    --  See the schedctl(2) man page for a complete discussion of non-degrading
 140    --  priorities.
 141    --
 142    type Non_Degrading_Priority is range 0 .. 255;
 143
 144    --  these priorities are higher than ALL normal user process priorities
 145    NDPHIMAX   : constant Non_Degrading_Priority := 30;
 146    NDPHIMIN   : constant Non_Degrading_Priority := 39;
 147
 148    subtype NDP_High is Non_Degrading_Priority range NDPHIMAX .. NDPHIMIN;
 149
 150    --  these priorities overlap normal user process priorities
 151    NDPNORMMAX : constant Non_Degrading_Priority := 40;
 152    NDPNORMMIN : constant Non_Degrading_Priority := 127;
 153
 154    subtype NDP_Norm is Non_Degrading_Priority range NDPNORMMAX .. NDPNORMMIN;
 155
 156    --  these priorities are below ALL normal user process priorities
 157    NDPLOMAX   : constant Non_Degrading_Priority := 128;
 158    NDPLOMIN   : constant Non_Degrading_Priority := 254;
 159
 160    NDP_NONE   : constant Non_Degrading_Priority := 255;
 161
 162    subtype NDP_LOW is Non_Degrading_Priority range NDPLOMAX .. NDPLOMIN;
 163
 164    type Page_Locking is
 165       (NOLOCK,     --  Do not lock pages in memory
 166        PROCLOCK,   --  Lock text and data segments into memory (process lock)
 167        TXTLOCK,    --  Lock text segment into memory (text lock)
 168        DATLOCK     --  Lock data segment into memory (data lock)
 169       );
 170
 171    type Sproc_Attributes is
 172       record
 173          Sproc_Resources : Resource_Vector_T      := NO_RESOURCES;
 174          CPU             : CPU_Number             := ANY_CPU;
 175          Resident        : Page_Locking           := NOLOCK;
 176          NDPRI           : Non_Degrading_Priority := NDP_NONE;
 177 --       Sproc_Slice     : Duration               := 0.0;
 178 --       Deadline_Period : Duration               := 0.0;
 179 --       Deadline_Alloc  : Duration               := 0.0;
 180
 181       end record;
 182
 183    Default_Sproc_Attributes : constant Sproc_Attributes :=
 184       (NO_RESOURCES, ANY_CPU, NOLOCK, NDP_NONE);
 185
 186    function New_Sproc (Attr : Sproc_Attributes) return sproc_t;
 187    function New_Sproc
 188      (Sproc_Resources : Resource_Vector_T      := NO_RESOURCES;
 189       CPU             : CPU_Number             := ANY_CPU;
 190       Resident        : Page_Locking           := NOLOCK;
 191       NDPRI           : Non_Degrading_Priority := NDP_NONE)
 192       return            sproc_t;
 193    --
 194    --  Allocates a sproc_t controll structure and creates the
 195    --  corresponding sproc.
 196    --
 197
 198    Invalid_CPU_Number : exception;
 199    Permission_Error   : exception;
 200    Sproc_Create_Error : exception;
 201
 202    -----------------------
 203    -- Thread Attributes --
 204    -----------------------
 205
 206    type Thread_Attributes (Bound_To_Sproc : Boolean) is
 207       record
 208          Thread_Resources : Resource_Vector_T := NO_RESOURCES;
 209          Thread_Timeslice : Duration          := 0.0;
 210          case Bound_To_Sproc is
 211             when False =>
 212                null;
 213             when True   =>
 214                Sproc : sproc_t;
 215          end case;
 216       end record;
 217
 218    Default_Thread_Attributes : constant Thread_Attributes :=
 219      (False, NO_RESOURCES, 0.0);
 220
 221    function Unbound_Thread_Attributes
 222      (Thread_Resources : Resource_Vector_T := NO_RESOURCES;
 223       Thread_Timeslice : Duration          := 0.0)
 224       return             Thread_Attributes;
 225
 226    function Bound_Thread_Attributes
 227      (Thread_Resources : Resource_Vector_T := NO_RESOURCES;
 228       Thread_Timeslice : Duration          := 0.0;
 229       Sproc            : sproc_t)
 230       return             Thread_Attributes;
 231
 232    function Bound_Thread_Attributes
 233      (Thread_Resources : Resource_Vector_T      := NO_RESOURCES;
 234       Thread_Timeslice : Duration               := 0.0;
 235       Sproc_Resources  : Resource_Vector_T      := NO_RESOURCES;
 236       CPU              : CPU_Number             := ANY_CPU;
 237       Resident         : Page_Locking           := NOLOCK;
 238       NDPRI            : Non_Degrading_Priority := NDP_NONE)
 239       return             Thread_Attributes;
 240
 241    type Task_Info_Type is access all Thread_Attributes;
 242
 243    function New_Unbound_Thread_Attributes
 244      (Thread_Resources : Resource_Vector_T := NO_RESOURCES;
 245       Thread_Timeslice : Duration          := 0.0)
 246       return             Task_Info_Type;
 247
 248    function New_Bound_Thread_Attributes
 249      (Thread_Resources : Resource_Vector_T := NO_RESOURCES;
 250       Thread_Timeslice : Duration          := 0.0;
 251       Sproc            : sproc_t)
 252       return             Task_Info_Type;
 253
 254    function New_Bound_Thread_Attributes
 255      (Thread_Resources : Resource_Vector_T      := NO_RESOURCES;
 256       Thread_Timeslice : Duration               := 0.0;
 257       Sproc_Resources  : Resource_Vector_T      := NO_RESOURCES;
 258       CPU              : CPU_Number             := ANY_CPU;
 259       Resident         : Page_Locking           := NOLOCK;
 260       NDPRI            : Non_Degrading_Priority := NDP_NONE)
 261       return             Task_Info_Type;
 262
 263    type Task_Image_Type is access String;
 264    --  Used to generate a meaningful identifier for tasks that are variables
 265    --  and components of variables.
 266
 267    procedure Free_Task_Image is new
 268      Unchecked_Deallocation (String, Task_Image_Type);
 269
 270    Unspecified_Task_Info : constant Task_Info_Type := null;
 271
 272 end System.Task_Info;