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 ------------------------------------------------------------------------------
37 package body System.Global_Locks is
39 type String_Access is access String;
41 package TSL renames GNAT.Task_Lock;
43 Dir_Separator : Character;
44 pragma Import (C, Dir_Separator, "__gnat_dir_separator");
46 type Lock_File_Entry is
52 Last_Lock : Lock_Type := Null_Lock;
53 Lock_Table : array (Lock_Type range 1 .. 15) of Lock_File_Entry;
58 Wait : Duration := 0.1;
59 Retries : Natural := Natural'Last);
60 -- Create a lock file File in directory Dir. If the file cannot be
61 -- locked because someone already owns the lock, this procedure
62 -- waits Wait seconds and retries at most Retries times. If the file
63 -- still cannot be locked, Lock_Error is raised. The default is to try
64 -- every second, almost forever (Natural'Last times).
70 procedure Acquire_Lock
71 (Lock : in out Lock_Type)
75 (Lock_Table (Lock).Dir.all,
76 Lock_Table (Lock).File.all);
84 (Lock : out Lock_Type;
91 Last_Lock := Last_Lock + 1;
95 if L > Lock_Table'Last then
99 for J in reverse Name'Range loop
100 if Name (J) = Dir_Separator then
102 := new String'(Name (Name'First .. J - 1));
104 := new String'(Name (J + 1 .. Name'Last));
109 if Lock_Table (L).Dir = null then
110 Lock_Table (L).Dir := new String'(".");
111 Lock_Table (L).File := new String'(Name);
124 Wait : Duration := 0.1;
125 Retries : Natural := Natural'Last)
127 C_Dir : aliased String := Dir & ASCII.NUL;
128 C_File : aliased String := File & ASCII.NUL;
130 function Try_Lock (Dir, File : System.Address) return Integer;
131 pragma Import (C, Try_Lock, "__gnat_try_lock");
134 for I in 0 .. Retries loop
135 if Try_Lock (C_Dir'Address, C_File'Address) = 1 then
138 exit when I = Retries;
148 procedure Release_Lock
149 (Lock : in out Lock_Type)
151 S : aliased String :=
152 Lock_Table (Lock).Dir.all & Dir_Separator &
153 Lock_Table (Lock).File.all & ASCII.NUL;
155 procedure unlink (A : System.Address);
156 pragma Import (C, unlink, "unlink");
162 end System.Global_Locks;