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) 1992-2009, 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 3,  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.                                     --
17--                                                                          --
18-- As a special exception under Section 7 of GPL version 3, you are granted --
19-- additional permissions described in the GCC Runtime Library Exception,   --
20-- version 3.1, as published by the Free Software Foundation.               --
21--                                                                          --
22-- You should have received a copy of the GNU General Public License and    --
23-- a copy of the GCC Runtime Library Exception along with this program;     --
24-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
25-- <http://www.gnu.org/licenses/>.                                          --
26--                                                                          --
27-- GNAT was originally developed  by the GNAT team at  New York University. --
28-- Extensive contributions were provided by Ada Core Technologies Inc.      --
29--                                                                          --
30------------------------------------------------------------------------------
31
32--  This package contains the definitions and routines associated with the
33--  implementation and use of the Task_Info pragma. It is specialized
34--  appropriately for targets that make use of this pragma.
35
36--  Note: the compiler generates direct calls to this interface, via Rtsfind.
37--  Any changes to this interface may require corresponding compiler changes.
38
39--  This unit may be used directly from an application program by providing
40--  an appropriate WITH, and the interface can be expected to remain stable.
41
42--  This is the Solaris (native) version of this module
43
44with System.OS_Interface;
45
46package System.Task_Info is
47   pragma Preelaborate;
48   pragma Elaborate_Body;
49   --  To ensure that a body is allowed
50
51   -----------------------------------------------------
52   -- Binding of Tasks to LWPs and LWPs to processors --
53   -----------------------------------------------------
54
55   --  The Solaris implementation of the GNU Low-Level Interface (GNULLI)
56   --  implements each Ada task as a Solaris thread.  The Solaris thread
57   --  library distributes threads across one or more LWPs (Light Weight
58   --  Process) that are members of the same process. Solaris distributes
59   --  processes and LWPs across the available CPUs on a given machine. The
60   --  pragma Task_Info provides the mechanism to control the distribution
61   --  of tasks to LWPs, and LWPs to processors.
62
63   --  Each thread has a number of attributes that dictate it's scheduling.
64   --  These attributes are:
65   --
66   --      New_LWP:       whether a new LWP is created for this thread.
67   --
68   --      Bound_To_LWP:  whether the thread is bound to a specific LWP
69   --                     for its entire lifetime.
70   --
71   --      CPU:           the CPU number associated to the LWP
72   --
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 Unspecified_Task_Info 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   -- Thread Attributes --
95   -----------------------
96
97   subtype CPU_Number is System.OS_Interface.processorid_t;
98
99   CPU_UNCHANGED : constant CPU_Number := System.OS_Interface.PBIND_QUERY;
100   --  Do not bind the LWP to a specific processor
101
102   ANY_CPU       : constant CPU_Number := System.OS_Interface.PBIND_NONE;
103   --  Bind the LWP to any processor
104
105   Invalid_CPU_Number : exception;
106
107   type Thread_Attributes (New_LWP : Boolean) is record
108      Bound_To_LWP     : Boolean    := True;
109      case New_LWP is
110         when False =>
111            null;
112         when True =>
113            CPU        : CPU_Number := CPU_UNCHANGED;
114      end case;
115   end record;
116
117   Default_Thread_Attributes : constant Thread_Attributes := (False, True);
118
119   function Unbound_Thread_Attributes
120      return Thread_Attributes;
121
122   function Bound_Thread_Attributes
123      return Thread_Attributes;
124
125   function Bound_Thread_Attributes (CPU : CPU_Number)
126      return Thread_Attributes;
127
128   type Task_Info_Type is access all Thread_Attributes;
129
130   function New_Unbound_Thread_Attributes
131      return Task_Info_Type;
132
133   function New_Bound_Thread_Attributes
134      return Task_Info_Type;
135
136   function New_Bound_Thread_Attributes (CPU : CPU_Number)
137      return Task_Info_Type;
138
139   Unspecified_Task_Info : constant Task_Info_Type := null;
140
141end System.Task_Info;
142