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-- --
-- --
-- G N A T . B O U N D E D _ M A I L B O X E S --
-- --
-- S p e c --
-- --
-- Copyright (C) 2003 Ada Core Technologies, Inc. --
-- --
-- GNAT is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
-- ware Foundation; either version 2, or (at your option) any later ver- --
-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
-- for more details. You should have received a copy of the GNU General --
-- Public License distributed with GNAT; see file COPYING. If not, write --
-- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
-- MA 02111-1307, USA. --
-- --
-- As a special exception, if other files instantiate generics from this --
-- unit, or you link this unit with other files to produce an executable, --
-- this unit does not by itself cause the resulting executable to be --
-- covered by the GNU General Public License. This exception does not --
-- however invalidate any other reasons why the executable file might be --
-- covered by the GNU Public License. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- It is now maintained by Ada Core Technologies Inc ( --
-- --
-- This package provides a thread-safe asynchronous communication facility
-- in the form of mailboxes. Individual mailbox objects are bounded in size
-- to a value specified by their Capacity discriminants.
-- Mailboxes actually hold references to messages, not the message values
-- themselves.
-- Type Mailbox is defined explicitly as a protected type (via derivation
-- from a protected type) so that clients may treat them accordingly (for
-- example, by making conditional/timed entry calls).
with System;
with GNAT.Bounded_Buffers;
type Message (<>) is limited private;
type Message_Reference is access all Message;
-- Mailboxes hold references to Message values, of this type
package GNAT.Bounded_Mailboxes is
pragma Preelaborate;
package Message_Refs is
new GNAT.Bounded_Buffers (Message_Reference);
type Mailbox is new Message_Refs.Bounded_Buffer;
-- Type Mailbox has two inherited discriminants:
-- Capacity : Positive;
-- Capacity is the maximum number of Message references
-- possibly contained at any given instant.
-- Ceiling : System.Priority;
-- Users must specify the ceiling priority for the object.
-- If the Real-Time Systems Annex is not in use this value
-- is not important.
-- Protected type Mailbox has the following inherited interface:
-- entry Insert (Item : in Message_Reference);
-- Insert Item into the Mailbox. Blocks caller
-- until space is available.
-- entry Remove (Item : out Message_Reference);
-- Remove next available Message_Reference from Mailbox.
-- Blocks caller until a Message_Reference is available.
-- function Empty return Boolean;
-- Returns whether the Mailbox contains any Message_References.
-- Note: State may change immediately after call returns.
-- function Full return Boolean;
-- Returns whether any space remains within the Mailbox.
-- Note: State may change immediately after call returns.
-- function Extent return Natural;
-- Returns the number of Message_Reference values currently held
-- within the Mailbox.
-- Note: State may change immediately after call returns.
Default_Ceiling : constant System.Priority := Message_Refs.Default_Ceiling;
-- A convenience value for the Ceiling discriminant
end GNAT.Bounded_Mailboxes;