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) 1992-2003 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 and use of the Task_Info pragma. It is specialized
  36 --  appropriately for targets that make use of this pragma.
  37
  38 --  Note: the compiler generates direct calls to this interface, via Rtsfind.
  39 --  Any changes to this interface may require corresponding compiler changes.
  40
  41 --  This unit may be used directly from an application program by providing
  42 --  an appropriate WITH, and the interface can be expected to remain stable.
  43
  44 --  This is the SGI (libathread) specific version of this module.
  45
  46 with System.OS_Interface;
  47
  48 package System.Task_Info is
  49    pragma Elaborate_Body;
  50    --  To ensure that a body is allowed
  51
  52    ---------------------------------------------------------
  53    -- Binding of Tasks to sprocs and sprocs to processors --
  54    ---------------------------------------------------------
  55
  56    --  The SGI implementation of the GNU Low-Level Interface (GNULLI)
  57    --  implements each Ada task as a Posix thread (Pthread). The SGI
  58    --  Pthread library distributes threads across one or more processes
  59    --  that are members of a common share group. Irix distributes
  60    --  processes across the available CPUs on a given machine. The
  61    --  pragma Task_Info provides the mechanism to control the distribution
  62    --  of tasks to sprocs, and sprocs to processors.
  63
  64    --  Each thread has a number of attributes that dictate it's scheduling.
  65    --  These attributes are:
  66    --
  67    --      Bound_To_Sproc:  whether the thread is bound to a specific sproc
  68    --                       for its entire lifetime.
  69    --
  70    --      Timeslice:       Amount of time that a thread is allowed to execute
  71    --                       before the system yeilds control to another thread
  72    --                       of equal priority.
  73    --
  74    --      Resource_Vector: A bitmask used to control the binding of threads
  75    --                       to sprocs.
  76    --
  77
  78    --  Each share group process (sproc)
  79
  80    --  The Task_Info pragma:
  81
  82    --    pragma Task_Info (EXPRESSION);
  83
  84    --  allows the specification on a task by task basis of a value of type
  85    --  System.Task_Info.Task_Info_Type to be passed to a task when it is
  86    --  created. The specification of this type, and the effect on the task
  87    --  that is created is target dependent.
  88
  89    --  The Task_Info pragma appears within a task definition (compare the
  90    --  definition and implementation of pragma Priority). If no such pragma
  91    --  appears, then the value Task_Info_Unspecified is passed. If a pragma
  92    --  is present, then it supplies an alternative value. If the argument of
  93    --  the pragma is a discriminant reference, then the value can be set on
  94    --  a task by task basis by supplying the appropriate discriminant value.
  95
  96    --  Note that this means that the type used for Task_Info_Type must be
  97    --  suitable for use as a discriminant (i.e. a scalar or access type).
  98
  99    ----------------------
 100    -- Resource Vectors --
 101    ----------------------
 102
 103    --  <discussion>
 104
 105    type Resource_Vector_T is array (0 .. 31) of Boolean;
 106    pragma Pack (Resource_Vector_T);
 107
 108    NO_RESOURCES : constant Resource_Vector_T := (others => False);
 109
 110    generic
 111       type Resource_T is (<>);
 112       --  Discrete type up to 32 entries
 113
 114    package Resource_Vector_Functions is
 115       function "+"
 116         (R    : Resource_T)
 117          return Resource_Vector_T;
 118
 119       function "+"
 120         (R1   : Resource_T;
 121          R2   : Resource_T)
 122          return Resource_Vector_T;
 123
 124       function "+"
 125         (R    : Resource_T;
 126          S    : Resource_Vector_T)
 127          return Resource_Vector_T;
 128
 129       function "+"
 130         (S    : Resource_Vector_T;
 131          R    : Resource_T)
 132          return Resource_Vector_T;
 133
 134       function "+"
 135         (S1   : Resource_Vector_T;
 136          S2   : Resource_Vector_T)
 137          return Resource_Vector_T;
 138
 139       function "-"
 140         (S    : Resource_Vector_T;
 141          R    : Resource_T)
 142          return Resource_Vector_T;
 143    end Resource_Vector_Functions;
 144
 145    ----------------------
 146    -- Sproc Attributes --
 147    ----------------------
 148
 149    subtype sproc_t is System.OS_Interface.sproc_t;
 150
 151    subtype CPU_Number is Integer range -1 .. Integer'Last;
 152
 153    ANY_CPU : constant CPU_Number := CPU_Number'First;
 154
 155    type Non_Degrading_Priority is range 0 .. 255;
 156    --  Specification of IRIX Non Degrading Priorities.
 157    --
 158    --  WARNING: IRIX priorities have the reverse meaning of Ada priorities.
 159    --           The lower the priority value, the greater the greater the
 160    --           scheduling preference.
 161    --
 162    --  See the schedctl(2) man page for a complete discussion of non-degrading
 163    --  priorities.
 164
 165    NDPHIMAX : constant Non_Degrading_Priority := 30;
 166    NDPHIMIN : constant Non_Degrading_Priority := 39;
 167    --  These priorities are higher than ALL normal user process priorities
 168
 169    subtype NDP_High is Non_Degrading_Priority range NDPHIMAX .. NDPHIMIN;
 170
 171    NDPNORMMAX : constant Non_Degrading_Priority := 40;
 172    NDPNORMMIN : constant Non_Degrading_Priority := 127;
 173    --  These priorities overlap normal user process priorities
 174
 175    subtype NDP_Norm is Non_Degrading_Priority range NDPNORMMAX .. NDPNORMMIN;
 176
 177    NDPLOMAX : constant Non_Degrading_Priority := 128;
 178    NDPLOMIN : constant Non_Degrading_Priority := 254;
 179    --  These priorities are below ALL normal user process priorities
 180
 181    NDP_NONE   : constant Non_Degrading_Priority := 255;
 182
 183    subtype NDP_LOW is Non_Degrading_Priority range NDPLOMAX .. NDPLOMIN;
 184
 185    type Page_Locking is
 186       (NOLOCK,     --  Do not lock pages in memory
 187        PROCLOCK,   --  Lock text and data segments into memory (process lock)
 188        TXTLOCK,    --  Lock text segment into memory (text lock)
 189        DATLOCK     --  Lock data segment into memory (data lock)
 190       );
 191
 192    type Sproc_Attributes is record
 193       Sproc_Resources : Resource_Vector_T      := NO_RESOURCES;
 194       CPU             : CPU_Number             := ANY_CPU;
 195       Resident        : Page_Locking           := NOLOCK;
 196       NDPRI           : Non_Degrading_Priority := NDP_NONE;
 197 --  ??? why is that commented out, should it be removed ?
 198 --       Sproc_Slice     : Duration               := 0.0;
 199 --       Deadline_Period : Duration               := 0.0;
 200 --       Deadline_Alloc  : Duration               := 0.0;
 201    end record;
 202
 203    Default_Sproc_Attributes : constant Sproc_Attributes :=
 204       (NO_RESOURCES, ANY_CPU, NOLOCK, NDP_NONE);
 205
 206    function New_Sproc (Attr : Sproc_Attributes) return sproc_t;
 207    function New_Sproc
 208      (Sproc_Resources : Resource_Vector_T      := NO_RESOURCES;
 209       CPU             : CPU_Number             := ANY_CPU;
 210       Resident        : Page_Locking           := NOLOCK;
 211       NDPRI           : Non_Degrading_Priority := NDP_NONE)
 212       return            sproc_t;
 213    --  Allocates a sproc_t control structure and creates the
 214    --  corresponding sproc.
 215
 216    Invalid_CPU_Number : exception;
 217    Permission_Error   : exception;
 218    Sproc_Create_Error : exception;
 219
 220    -----------------------
 221    -- Thread Attributes --
 222    -----------------------
 223
 224    type Thread_Attributes (Bound_To_Sproc : Boolean) is record
 225       Thread_Resources : Resource_Vector_T := NO_RESOURCES;
 226
 227       Thread_Timeslice : Duration          := 0.0;
 228
 229       case Bound_To_Sproc is
 230          when False =>
 231             null;
 232          when True   =>
 233             Sproc : sproc_t;
 234       end case;
 235    end record;
 236
 237    Default_Thread_Attributes : constant Thread_Attributes :=
 238      (False, NO_RESOURCES, 0.0);
 239
 240    function Unbound_Thread_Attributes
 241      (Thread_Resources : Resource_Vector_T := NO_RESOURCES;
 242       Thread_Timeslice : Duration          := 0.0)
 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            : sproc_t)
 249       return             Thread_Attributes;
 250
 251    function Bound_Thread_Attributes
 252      (Thread_Resources : Resource_Vector_T      := NO_RESOURCES;
 253       Thread_Timeslice : Duration               := 0.0;
 254       Sproc_Resources  : Resource_Vector_T      := NO_RESOURCES;
 255       CPU              : CPU_Number             := ANY_CPU;
 256       Resident         : Page_Locking           := NOLOCK;
 257       NDPRI            : Non_Degrading_Priority := NDP_NONE)
 258       return             Thread_Attributes;
 259
 260    type Task_Info_Type is access all Thread_Attributes;
 261
 262    function New_Unbound_Thread_Attributes
 263      (Thread_Resources : Resource_Vector_T := NO_RESOURCES;
 264       Thread_Timeslice : Duration          := 0.0)
 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            : sproc_t)
 271       return             Task_Info_Type;
 272
 273    function New_Bound_Thread_Attributes
 274      (Thread_Resources : Resource_Vector_T      := NO_RESOURCES;
 275       Thread_Timeslice : Duration               := 0.0;
 276       Sproc_Resources  : Resource_Vector_T      := NO_RESOURCES;
 277       CPU              : CPU_Number             := ANY_CPU;
 278       Resident         : Page_Locking           := NOLOCK;
 279       NDPRI            : Non_Degrading_Priority := NDP_NONE)
 280       return             Task_Info_Type;
 281
 282    Unspecified_Task_Info : constant Task_Info_Type := null;
 283
 284 end System.Task_Info;