File : s-tasinf.ads


------------------------------------------------------------------------------
--                                                                          --
--                         GNAT COMPILER COMPONENTS                         --
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------------------------------------------------------------------------------

--  This package contains the definitions and routines associated with the
--  implementation of the Task_Info pragma. It is specialized appropriately
--  for targets that make use of this pragma.

--  Note: the compiler generates direct calls to this interface, via Rtsfind.
--  Any changes to this interface may require corresponding compiler changes.

with Unchecked_Deallocation;
package System.Task_Info is
pragma Elaborate_Body;
--  To ensure that a body is allowed

   -----------------------------------------
   -- Implementation of Task_Info Feature --
   -----------------------------------------

   --  The Task_Info pragma:

   --    pragma Task_Info (EXPRESSION);

   --  allows the specification on a task by task basis of a value of type
   --  System.Task_Info.Task_Info_Type to be passed to a task when it is
   --  created. The specification of this type, and the effect on the task
   --  that is created is target dependent.

   --  The Task_Info pragma appears within a task definition (compare the
   --  definition and implementation of pragma Priority). If no such pragma
   --  appears, then the value Task_Info_Unspecified is passed. If a pragma
   --  is present, then it supplies an alternative value. If the argument of
   --  the pragma is a discriminant reference, then the value can be set on
   --  a task by task basis by supplying the appropriate discriminant value.

   --  Note that this means that the type used for Task_Info_Type must be
   --  suitable for use as a discriminant (i.e. a scalar or access type).

   ------------------
   -- Declarations --
   ------------------

   type Scope_Type is 
     (Process_Scope,
      --  Contend only with threads in same process

      System_Scope,
      --  Contend with all threads on same CPU

      Default_Scope);

   type Task_Info_Type is new Scope_Type; 
   --  Type used for passing information to task create call, using the
   --  Task_Info pragma. This type may be specialized for individual
   --  implementations, but it must be a type that can be used as a
   --  discriminant (i.e. a scalar or access type).

   type Task_Image_Type is access String; 
   --  Used to generate a meaningful identifier for tasks that are variables
   --  and components of variables.

   procedure Free_Task_Image is new 
     Unchecked_Deallocation (String, Task_Image_Type);

   Unspecified_Task_Info : constant Task_Info_Type := Default_Scope; 
   --  Value passed to task in the absence of a Task_Info pragma

end System.Task_Info;