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 --          Copyright (C) 1992-2001 Free Software Foundation, Inc.          --
  10 --                                                                          --
  11 -- GNAT 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.  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.  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 GNAT;  see file COPYING.  If not, write --
  19 -- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
  20 -- MA 02111-1307, 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 -- GNAT was originally developed  by the GNAT team at  New York University. --
  30 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  31 --                                                                          --
  32 ------------------------------------------------------------------------------
  33
  34 --  This package contains the definitions and routines associated with the
  35 --  implementation of the Task_Info pragma.
  36
  37 --  This is the SGI (libathread) specific version of this module.
  38
  39 with System.OS_Interface;
  40 with Unchecked_Deallocation;
  41
  42 package System.Task_Info is
  43 pragma Elaborate_Body;
  44 --  To ensure that a body is allowed
  45
  46    ---------------------------------------------------------
  47    -- Binding of Tasks to sprocs and sprocs to processors --
  48    ---------------------------------------------------------
  49
  50    --  The SGI implementation of the GNU Low-Level Interface (GNULLI)
  51    --  implements each Ada task as a Posix thread (Pthread). The SGI
  52    --  Pthread library distributes threads across one or more processes
  53    --  that are members of a common share group. Irix distributes
  54    --  processes across the available CPUs on a given machine. The
  55    --  pragma Task_Info provides the mechanism to control the distribution
  56    --  of tasks to sprocs, and sprocs to processors.
  57
  58    --  Each thread has a number of attributes that dictate it's scheduling.
  59    --  These attributes are:
  60    --
  61    --      Bound_To_Sproc:  whether the thread is bound to a specific sproc
  62    --                       for its entire lifetime.
  63    --
  64    --      Timeslice:       Amount of time that a thread is allowed to execute
  65    --                       before the system yeilds control to another thread
  66    --                       of equal priority.
  67    --
  68    --      Resource_Vector: A bitmask used to control the binding of threads
  69    --                       to sprocs.
  70    --
  71
  72    --  Each share group process (sproc)
  73
  74    --  The Task_Info pragma:
  75
  76    --    pragma Task_Info (EXPRESSION);
  77
  78    --  allows the specification on a task by task basis of a value of type
  79    --  System.Task_Info.Task_Info_Type to be passed to a task when it is
  80    --  created. The specification of this type, and the effect on the task
  81    --  that is created is target dependent.
  82
  83    --  The Task_Info pragma appears within a task definition (compare the
  84    --  definition and implementation of pragma Priority). If no such pragma
  85    --  appears, then the value Task_Info_Unspecified is passed. If a pragma
  86    --  is present, then it supplies an alternative value. If the argument of
  87    --  the pragma is a discriminant reference, then the value can be set on
  88    --  a task by task basis by supplying the appropriate discriminant value.
  89
  90    --  Note that this means that the type used for Task_Info_Type must be
  91    --  suitable for use as a discriminant (i.e. a scalar or access type).
  92
  93    ----------------------
  94    -- Resource Vectors --
  95    ----------------------
  96
  97    --  <discussion>
  98
  99    type Resource_Vector_T is array (0 .. 31) of Boolean;
 100    pragma Pack (Resource_Vector_T);
 101
 102    NO_RESOURCES : constant Resource_Vector_T := (others => False);
 103
 104    generic
 105       type Resource_T is (<>);
 106       --  Discrete type up to 32 entries
 107
 108    package Resource_Vector_Functions is
 109       function "+"
 110         (R    : Resource_T)
 111          return Resource_Vector_T;
 112
 113       function "+"
 114         (R1   : Resource_T;
 115          R2   : Resource_T)
 116          return Resource_Vector_T;
 117
 118       function "+"
 119         (R    : Resource_T;
 120          S    : Resource_Vector_T)
 121          return Resource_Vector_T;
 122
 123       function "+"
 124         (S    : Resource_Vector_T;
 125          R    : Resource_T)
 126          return Resource_Vector_T;
 127
 128       function "+"
 129         (S1   : Resource_Vector_T;
 130          S2   : Resource_Vector_T)
 131          return Resource_Vector_T;
 132
 133       function "-"
 134         (S    : Resource_Vector_T;
 135          R    : Resource_T)
 136          return Resource_Vector_T;
 137    end Resource_Vector_Functions;
 138
 139    ----------------------
 140    -- Sproc Attributes --
 141    ----------------------
 142
 143    subtype sproc_t is System.OS_Interface.sproc_t;
 144
 145    subtype CPU_Number is Integer range -1 .. Integer'Last;
 146
 147    ANY_CPU : constant CPU_Number := CPU_Number'First;
 148
 149    type Non_Degrading_Priority is range 0 .. 255;
 150    --  Specification of IRIX Non Degrading Priorities.
 151    --
 152    --  WARNING: IRIX priorities have the reverse meaning of Ada priorities.
 153    --           The lower the priority value, the greater the greater the
 154    --           scheduling preference.
 155    --
 156    --  See the schedctl(2) man page for a complete discussion of non-degrading
 157    --  priorities.
 158
 159    NDPHIMAX : constant Non_Degrading_Priority := 30;
 160    NDPHIMIN : constant Non_Degrading_Priority := 39;
 161    --  These priorities are higher than ALL normal user process priorities
 162
 163    subtype NDP_High is Non_Degrading_Priority range NDPHIMAX .. NDPHIMIN;
 164
 165    NDPNORMMAX : constant Non_Degrading_Priority := 40;
 166    NDPNORMMIN : constant Non_Degrading_Priority := 127;
 167    --  These priorities overlap normal user process priorities
 168
 169    subtype NDP_Norm is Non_Degrading_Priority range NDPNORMMAX .. NDPNORMMIN;
 170
 171    NDPLOMAX : constant Non_Degrading_Priority := 128;
 172    NDPLOMIN : constant Non_Degrading_Priority := 254;
 173    --  These priorities are below ALL normal user process priorities
 174
 175    NDP_NONE   : constant Non_Degrading_Priority := 255;
 176
 177    subtype NDP_LOW is Non_Degrading_Priority range NDPLOMAX .. NDPLOMIN;
 178
 179    type Page_Locking is
 180       (NOLOCK,     --  Do not lock pages in memory
 181        PROCLOCK,   --  Lock text and data segments into memory (process lock)
 182        TXTLOCK,    --  Lock text segment into memory (text lock)
 183        DATLOCK     --  Lock data segment into memory (data lock)
 184       );
 185
 186    type Sproc_Attributes is record
 187       Sproc_Resources : Resource_Vector_T      := NO_RESOURCES;
 188       CPU             : CPU_Number             := ANY_CPU;
 189       Resident        : Page_Locking           := NOLOCK;
 190       NDPRI           : Non_Degrading_Priority := NDP_NONE;
 191 --  ??? why is that commented out, should it be removed ?
 192 --       Sproc_Slice     : Duration               := 0.0;
 193 --       Deadline_Period : Duration               := 0.0;
 194 --       Deadline_Alloc  : Duration               := 0.0;
 195    end record;
 196
 197    Default_Sproc_Attributes : constant Sproc_Attributes :=
 198       (NO_RESOURCES, ANY_CPU, NOLOCK, NDP_NONE);
 199
 200    function New_Sproc (Attr : Sproc_Attributes) return sproc_t;
 201    function New_Sproc
 202      (Sproc_Resources : Resource_Vector_T      := NO_RESOURCES;
 203       CPU             : CPU_Number             := ANY_CPU;
 204       Resident        : Page_Locking           := NOLOCK;
 205       NDPRI           : Non_Degrading_Priority := NDP_NONE)
 206       return            sproc_t;
 207    --  Allocates a sproc_t control structure and creates the
 208    --  corresponding sproc.
 209
 210    Invalid_CPU_Number : exception;
 211    Permission_Error   : exception;
 212    Sproc_Create_Error : exception;
 213
 214    -----------------------
 215    -- Thread Attributes --
 216    -----------------------
 217
 218    type Thread_Attributes (Bound_To_Sproc : Boolean) is record
 219       Thread_Resources : Resource_Vector_T := NO_RESOURCES;
 220
 221       Thread_Timeslice : Duration          := 0.0;
 222
 223       case Bound_To_Sproc is
 224          when False =>
 225             null;
 226          when True   =>
 227             Sproc : sproc_t;
 228       end case;
 229    end record;
 230
 231    Default_Thread_Attributes : constant Thread_Attributes :=
 232      (False, NO_RESOURCES, 0.0);
 233
 234    function Unbound_Thread_Attributes
 235      (Thread_Resources : Resource_Vector_T := NO_RESOURCES;
 236       Thread_Timeslice : Duration          := 0.0)
 237       return             Thread_Attributes;
 238
 239    function Bound_Thread_Attributes
 240      (Thread_Resources : Resource_Vector_T := NO_RESOURCES;
 241       Thread_Timeslice : Duration          := 0.0;
 242       Sproc            : sproc_t)
 243       return             Thread_Attributes;
 244
 245    function Bound_Thread_Attributes
 246      (Thread_Resources : Resource_Vector_T      := NO_RESOURCES;
 247       Thread_Timeslice : Duration               := 0.0;
 248       Sproc_Resources  : Resource_Vector_T      := NO_RESOURCES;
 249       CPU              : CPU_Number             := ANY_CPU;
 250       Resident         : Page_Locking           := NOLOCK;
 251       NDPRI            : Non_Degrading_Priority := NDP_NONE)
 252       return             Thread_Attributes;
 253
 254    type Task_Info_Type is access all Thread_Attributes;
 255
 256    function New_Unbound_Thread_Attributes
 257      (Thread_Resources : Resource_Vector_T := NO_RESOURCES;
 258       Thread_Timeslice : Duration          := 0.0)
 259       return             Task_Info_Type;
 260
 261    function New_Bound_Thread_Attributes
 262      (Thread_Resources : Resource_Vector_T := NO_RESOURCES;
 263       Thread_Timeslice : Duration          := 0.0;
 264       Sproc            : sproc_t)
 265       return             Task_Info_Type;
 266
 267    function New_Bound_Thread_Attributes
 268      (Thread_Resources : Resource_Vector_T      := NO_RESOURCES;
 269       Thread_Timeslice : Duration               := 0.0;
 270       Sproc_Resources  : Resource_Vector_T      := NO_RESOURCES;
 271       CPU              : CPU_Number             := ANY_CPU;
 272       Resident         : Page_Locking           := NOLOCK;
 273       NDPRI            : Non_Degrading_Priority := NDP_NONE)
 274       return             Task_Info_Type;
 275
 276    type Task_Image_Type is access String;
 277    --  Used to generate a meaningful identifier for tasks that are variables
 278    --  and components of variables.
 279
 280    procedure Free_Task_Image is new
 281      Unchecked_Deallocation (String, Task_Image_Type);
 282
 283    Unspecified_Task_Info : constant Task_Info_Type := null;
 284
 285 end System.Task_Info;