Pragma Thread_Body

Syntax:

     pragma Thread_Body (
       [Entity =>] local_NAME,
      [[Secondary_Stack_Size =>] static_integer_EXPRESSION)];

This pragma specifies that the subprogram whose name is given as the Entity argument is a thread body, which will be activated by being called via its Address from foreign code. The purpose is to allow execution and registration of the foreign thread within the Ada run-time system.

See the library unit System.Threads for details on the expansion of a thread body subprogram, including the calls made to subprograms within System.Threads to register the task. This unit also lists the targets and runtime systems for which this pragma is supported.

A thread body subprogram may not be called directly from Ada code, and it is not permitted to apply the Access (or Unrestricted_Access) attributes to such a subprogram. The only legitimate way of calling such a subprogram is to pass its Address to foreign code and then make the call from the foreign code.

A thread body subprogram may have any parameters, and it may be a function returning a result. The convention of the thread body subprogram may be set in the usual manner using pragma Convention.

The secondary stack size parameter, if given, is used to set the size of secondary stack for the thread. The secondary stack is allocated as a local variable of the expanded thread body subprogram, and thus is allocated out of the main thread stack size. If no secondary stack size parameter is present, the default size (from the declaration in System.Secondary_Stack is used.