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 ------------------------------------------------------------------------------
36 package body System
.Global_Locks
is
38 type String_Access
is access String;
40 package TSL
renames GNAT
.Task_Lock
;
42 Dir_Separator
: Character;
43 pragma Import
(C
, Dir_Separator
, "__gnat_dir_separator");
45 type Lock_File_Entry
is record
50 Last_Lock
: Lock_Type
:= Null_Lock
;
51 Lock_Table
: array (Lock_Type
range 1 .. 15) of Lock_File_Entry
;
56 Wait
: Duration := 0.1;
57 Retries
: Natural := Natural'Last);
58 -- Create a lock file File in directory Dir. If the file cannot be
59 -- locked because someone already owns the lock, this procedure
60 -- waits Wait seconds and retries at most Retries times. If the file
61 -- still cannot be locked, Lock_Error is raised. The default is to try
62 -- every second, almost forever (Natural'Last times).
68 procedure Acquire_Lock
69 (Lock
: in out Lock_Type
) is
72 (Lock_Table
(Lock
).Dir
.all,
73 Lock_Table
(Lock
).File
.all);
81 (Lock
: out Lock_Type
;
88 Last_Lock
:= Last_Lock
+ 1;
92 if L
> Lock_Table
'Last then
96 for J
in reverse Name
'Range loop
97 if Name
(J
) = Dir_Separator
then
99 := new String'(Name (Name'First .. J - 1));
101 := new String'(Name
(J
+ 1 .. Name
'Last));
106 if Lock_Table
(L
).Dir
= null then
107 Lock_Table
(L
).Dir
:= new String'(".");
108 Lock_Table (L).File := new String'(Name
);
121 Wait
: Duration := 0.1;
122 Retries
: Natural := Natural'Last)
124 C_Dir
: aliased String := Dir
& ASCII
.NUL
;
125 C_File
: aliased String := File
& ASCII
.NUL
;
127 function Try_Lock
(Dir
, File
: System
.Address
) return Integer;
128 pragma Import
(C
, Try_Lock
, "__gnat_try_lock");
131 for I
in 0 .. Retries
loop
132 if Try_Lock
(C_Dir
'Address, C_File
'Address) = 1 then
135 exit when I
= Retries
;
145 procedure Release_Lock
146 (Lock
: in out Lock_Type
)
148 S
: aliased String :=
149 Lock_Table
(Lock
).Dir
.all & Dir_Separator
&
150 Lock_Table
(Lock
).File
.all & ASCII
.NUL
;
152 procedure unlink
(A
: System
.Address
);
153 pragma Import
(C
, unlink
, "unlink");
159 end System
.Global_Locks
;