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------------------------------------------------------------------------------
-- --
-- GNAT COMPILER COMPONENTS --
-- --
-- S Y S T E M . G L O B A L _ L O C K S --
-- --
-- B o d y --
-- --
-- Copyright (C) 1999-2008, Free Software Foundation, Inc. --
-- --
-- GNAT is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
-- ware Foundation; either version 2, or (at your option) any later ver- --
-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
-- for more details. You should have received a copy of the GNU General --
-- Public License distributed with GNAT; see file COPYING. If not, write --
-- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, --
-- Boston, MA 02110-1301, USA. --
-- --
-- As a special exception, if other files instantiate generics from this --
-- unit, or you link this unit with other files to produce an executable, --
-- this unit does not by itself cause the resulting executable to be --
-- covered by the GNU General Public License. This exception does not --
-- however invalidate any other reasons why the executable file might be --
-- covered by the GNU Public License. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
------------------------------------------------------------------------------
with System.Soft_Links;
package body System.Global_Locks is
type String_Access is access String;
Dir_Separator : Character;
pragma Import (C, Dir_Separator, "__gnat_dir_separator");
type Lock_File_Entry is record
Dir : String_Access;
File : String_Access;
end record;
Last_Lock : Lock_Type := Null_Lock;
Lock_Table : array (Lock_Type range 1 .. 15) of Lock_File_Entry;
procedure Lock_File
(Dir : String;
File : String;
Wait : Duration := 0.1;
Retries : Natural := Natural'Last);
-- Create a lock file File in directory Dir. If the file cannot be
-- locked because someone already owns the lock, this procedure
-- waits Wait seconds and retries at most Retries times. If the file
-- still cannot be locked, Lock_Error is raised. The default is to try
-- every second, almost forever (Natural'Last times).
------------------
-- Acquire_Lock --
------------------
procedure Acquire_Lock (Lock : in out Lock_Type) is
begin
Lock_File
(Lock_Table (Lock).Dir.all,
Lock_Table (Lock).File.all);
end Acquire_Lock;
-----------------
-- Create_Lock --
-----------------
procedure Create_Lock (Lock : out Lock_Type; Name : String) is
L : Lock_Type;
begin
System.Soft_Links.Lock_Task.all;
Last_Lock := Last_Lock + 1;
L := Last_Lock;
System.Soft_Links.Unlock_Task.all;
if L > Lock_Table'Last then
raise Lock_Error;
end if;
for J in reverse Name'Range loop
if Name (J) = Dir_Separator then
Lock_Table (L).Dir := new String'(Name (Name'First .. J - 1));
Lock_Table (L).File := new String'(Name (J + 1 .. Name'Last));
exit;
end if;
end loop;
if Lock_Table (L).Dir = null then
Lock_Table (L).Dir := new String'(".");
Lock_Table (L).File := new String'(Name);
end if;
Lock := L;
end Create_Lock;
---------------
-- Lock_File --
---------------
procedure Lock_File
(Dir : String;
File : String;
Wait : Duration := 0.1;
Retries : Natural := Natural'Last)
is
C_Dir : aliased String := Dir & ASCII.NUL;
C_File : aliased String := File & ASCII.NUL;
function Try_Lock (Dir, File : System.Address) return Integer;
pragma Import (C, Try_Lock, "__gnat_try_lock");
begin
for I in 0 .. Retries loop
if Try_Lock (C_Dir'Address, C_File'Address) = 1 then
return;
end if;
exit when I = Retries;
delay Wait;
end loop;
raise Lock_Error;
end Lock_File;
------------------
-- Release_Lock --
------------------
procedure Release_Lock (Lock : in out Lock_Type) is
S : aliased String :=
Lock_Table (Lock).Dir.all & Dir_Separator &
Lock_Table (Lock).File.all & ASCII.NUL;
procedure unlink (A : System.Address);
pragma Import (C, unlink, "unlink");
begin
unlink (S'Address);
end Release_Lock;
end System.Global_Locks;
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