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------------------------------------------------------------------------------
-- --
-- GNAT COMPILER COMPONENTS --
-- --
-- G N A T . L O C K _ F I L E S --
-- --
-- S p e c --
-- --
-- Copyright (C) 1995-2008, AdaCore --
-- --
-- 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. --
-- --
------------------------------------------------------------------------------
-- This package contains the necessary routines for using files for the
-- purpose of providing reliable system wide locking capability.
package GNAT.Lock_Files is
pragma Preelaborate;
Lock_Error : exception;
-- Exception raised if file cannot be locked
subtype Path_Name is String;
-- Pathname is used by all services provided in this unit to specified
-- directory name and file name. On DOS based systems both directory
-- separators are handled (i.e. slash and backslash).
procedure Lock_File
(Directory : Path_Name;
Lock_File_Name : Path_Name;
Wait : Duration := 1.0;
Retries : Natural := Natural'Last);
-- Create a lock file Lock_File_Name in directory Directory. 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). The full path of
-- the file is constructed by concatenating Directory and Lock_File_Name.
-- Directory can optionally terminate with a directory separator.
procedure Lock_File
(Lock_File_Name : Path_Name;
Wait : Duration := 1.0;
Retries : Natural := Natural'Last);
-- See above. The full lock file path is given as one string
procedure Unlock_File (Directory : Path_Name; Lock_File_Name : Path_Name);
-- Unlock a file. Directory can optionally terminate with a directory
-- separator.
procedure Unlock_File (Lock_File_Name : Path_Name);
-- Unlock a file whose full path is given in Lock_File_Name
end GNAT.Lock_Files;
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