1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
5 -- S Y S T E M . G L O B A L _ L O C K S --
10 -- Copyright (C) 1999-2001 Free Software Foundation, Inc. --
12 -- GNAT is free software; you can redistribute it and/or modify it under --
13 -- terms of the GNU General Public License as published by the Free Soft- --
14 -- ware Foundation; either version 2, or (at your option) any later ver- --
15 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
16 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
17 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
18 -- for more details. You should have received a copy of the GNU General --
19 -- Public License distributed with GNAT; see file COPYING. If not, write --
20 -- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
21 -- MA 02111-1307, USA. --
23 -- As a special exception, if other files instantiate generics from this --
24 -- unit, or you link this unit with other files to produce an executable, --
25 -- this unit does not by itself cause the resulting executable to be --
26 -- covered by the GNU General Public License. This exception does not --
27 -- however invalidate any other reasons why the executable file might be --
28 -- covered by the GNU Public License. --
30 -- GNAT is maintained by Ada Core Technologies Inc (http://www.gnat.com). --
32 ------------------------------------------------------------------------------
34 -- This package contains the necessary routines to provide
35 -- reliable system wide locking capability.
37 package System.Global_Locks is
39 Lock_Error : exception;
40 -- Exception raised if a request cannot be executed on a lock.
42 type Lock_Type is private;
43 -- Such a lock is a global lock between partitions. This lock is
44 -- uniquely defined between the partitions because of its name.
46 Null_Lock : constant Lock_Type;
49 (Lock : out Lock_Type;
51 -- Create or retrieve a global lock for the current partition using
54 procedure Acquire_Lock
55 (Lock : in out Lock_Type);
56 -- If the lock cannot be acquired because someone already owns it, this
57 -- procedure is supposed to wait and retry forever.
59 procedure Release_Lock
60 (Lock : in out Lock_Type);
64 type Lock_Type is new Natural;
66 Null_Lock : constant Lock_Type := 0;
68 end System.Global_Locks;