File : g-boumai.ads
1 ------------------------------------------------------------------------------
2 -- --
3 -- GNAT LIBRARY COMPONENTS --
4 -- --
5 -- G N A T . B O U N D E D _ M A I L B O X E S --
6 -- --
7 -- S p e c --
8 -- --
9 -- Copyright (C) 2003-2010, AdaCore --
10 -- --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 3, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. --
17 -- --
18 -- --
19 -- --
20 -- --
21 -- --
22 -- You should have received a copy of the GNU General Public License and --
23 -- a copy of the GCC Runtime Library Exception along with this program; --
24 -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
25 -- <http://www.gnu.org/licenses/>. --
26 -- --
27 -- GNAT was originally developed by the GNAT team at New York University. --
28 -- It is now maintained by Ada Core Technologies Inc (http://www.gnat.com). --
29 -- --
30 ------------------------------------------------------------------------------
31
32 -- This package provides a thread-safe asynchronous communication facility
33 -- in the form of mailboxes. Individual mailbox objects are bounded in size
34 -- to a value specified by their Capacity discriminants.
35
36 -- Mailboxes actually hold references to messages, not the message values
37 -- themselves.
38
39 -- Type Mailbox is defined explicitly as a protected type (via derivation
40 -- from a protected type) so that clients may treat them accordingly (for
41 -- example, by making conditional/timed entry calls).
42
43 with System;
44 with GNAT.Bounded_Buffers;
45
46 generic
47 type Message (<>) is limited private;
48 type Message_Reference is access all Message;
49 -- Mailboxes hold references to Message values, of this type
50
51 package GNAT.Bounded_Mailboxes is
52 pragma Preelaborate;
53
54 package Message_Refs is
55 new GNAT.Bounded_Buffers (Message_Reference);
56
57 type Mailbox is new Message_Refs.Bounded_Buffer;
58
59 -- Type Mailbox has two inherited discriminants:
60
61 -- Capacity : Positive;
62 -- Capacity is the maximum number of Message references
63 -- possibly contained at any given instant.
64
65 -- Ceiling : System.Priority;
66 -- Users must specify the ceiling priority for the object.
67 -- If the Real-Time Systems Annex is not in use this value
68 -- is not important.
69
70 -- Protected type Mailbox has the following inherited interface:
71
72 -- entry Insert (Item : Message_Reference);
73 -- Insert Item into the Mailbox. Blocks caller
74 -- until space is available.
75
76 -- entry Remove (Item : out Message_Reference);
77 -- Remove next available Message_Reference from Mailbox.
78 -- Blocks caller until a Message_Reference is available.
79
80 -- function Empty return Boolean;
81 -- Returns whether the Mailbox contains any Message_References.
82 -- Note: State may change immediately after call returns.
83
84 -- function Full return Boolean;
85 -- Returns whether any space remains within the Mailbox.
86 -- Note: State may change immediately after call returns.
87
88 -- function Extent return Natural;
89 -- Returns the number of Message_Reference values currently held
90 -- within the Mailbox.
91 -- Note: State may change immediately after call returns.
92
93 Default_Ceiling : constant System.Priority := Message_Refs.Default_Ceiling;
94 -- A convenience value for the Ceiling discriminant
95
96 end GNAT.Bounded_Mailboxes;