1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
5 -- S Y S T E M . G L O B A L _ L O C K S --
11 -- Copyright (C) 1999-2001 Ada Core Technologies, Inc. --
13 -- GNAT is free software; you can redistribute it and/or modify it under --
14 -- terms of the GNU General Public License as published by the Free Soft- --
15 -- ware Foundation; either version 2, or (at your option) any later ver- --
16 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
17 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
18 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
19 -- for more details. You should have received a copy of the GNU General --
20 -- Public License distributed with GNAT; see file COPYING. If not, write --
21 -- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
22 -- MA 02111-1307, USA. --
24 -- As a special exception, if other files instantiate generics from this --
25 -- unit, or you link this unit with other files to produce an executable, --
26 -- this unit does not by itself cause the resulting executable to be --
27 -- covered by the GNU General Public License. This exception does not --
28 -- however invalidate any other reasons why the executable file might be --
29 -- covered by the GNU Public License. --
31 -- GNAT is maintained by Ada Core Technologies Inc (http://www.gnat.com). --
33 ------------------------------------------------------------------------------
35 -- This package contains the necessary routines to provide
36 -- reliable system wide locking capability.
38 package System.Global_Locks is
40 Lock_Error : exception;
41 -- Exception raised if a request cannot be executed on a lock.
43 type Lock_Type is private;
44 -- Such a lock is a global lock between partitions. This lock is
45 -- uniquely defined between the partitions because of its name.
47 Null_Lock : constant Lock_Type;
50 (Lock : out Lock_Type;
52 -- Create or retrieve a global lock for the current partition using
55 procedure Acquire_Lock
56 (Lock : in out Lock_Type);
57 -- If the lock cannot be acquired because someone already owns it, this
58 -- procedure is supposed to wait and retry forever.
60 procedure Release_Lock
61 (Lock : in out Lock_Type);
65 type Lock_Type is new Natural;
67 Null_Lock : constant Lock_Type := 0;
69 end System.Global_Locks;