| ------------------------------------------------------------------------------ |
| -- -- |
| -- 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; |
