1------------------------------------------------------------------------------
2--                                                                          --
3--                         GNAT COMPILER COMPONENTS                         --
4--                                                                          --
5--                  S Y S T E M . G L O B A L _ L O C K S                   --
6--                                                                          --
7--                                 S p e c                                  --
8--                                                                          --
9--          Copyright (C) 1999-2021, Free Software Foundation, Inc.         --
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-- As a special exception under Section 7 of GPL version 3, you are granted --
19-- additional permissions described in the GCC Runtime Library Exception,   --
20-- version 3.1, as published by the Free Software Foundation.               --
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-- Extensive contributions were provided by Ada Core Technologies Inc.      --
29--                                                                          --
30------------------------------------------------------------------------------
31
32   --  This package contains the necessary routines to provide
33   --  reliable system wide locking capability.
34
35package System.Global_Locks is
36
37   Lock_Error : exception;
38   --  Exception raised if a request cannot be executed on a lock
39
40   type Lock_Type is private;
41   --  Such a lock is a global lock between partitions. This lock is
42   --  uniquely defined between the partitions because of its name.
43
44   Null_Lock : constant Lock_Type;
45   --  This needs comments ???
46
47   procedure Create_Lock (Lock : out Lock_Type; Name : String);
48   --  Create or retrieve a global lock for the current partition using
49   --  its Name.
50
51   procedure Acquire_Lock (Lock : in out Lock_Type);
52   --  If the lock cannot be acquired because someone already owns it, this
53   --  procedure is supposed to wait and retry forever.
54
55   procedure Release_Lock (Lock : in out Lock_Type);
56
57private
58
59   type Lock_Type is new Natural;
60
61   Null_Lock : constant Lock_Type := 0;
62
63end System.Global_Locks;
64