------------------------------------------------------------------------------ -- -- -- GNAT LIBRARY COMPONENTS -- -- -- -- 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) 2003-2005, AdaCore -- -- -- -- 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, 51 Franklin Street, Fifth Floor, -- -- Boston, MA 02110-1301, 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 (http://www.gnat.com). -- -- -- ------------------------------------------------------------------------------ -- 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; generic 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;