150 lines
5.4 KiB
Ada
150 lines
5.4 KiB
Ada
------------------------------------------------------------------------------
|
|
-- --
|
|
-- 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) 1999-2020, 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 3, 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. --
|
|
-- --
|
|
-- As a special exception under Section 7 of GPL version 3, you are granted --
|
|
-- additional permissions described in the GCC Runtime Library Exception, --
|
|
-- version 3.1, as published by the Free Software Foundation. --
|
|
-- --
|
|
-- You should have received a copy of the GNU General Public License and --
|
|
-- a copy of the GCC Runtime Library Exception along with this program; --
|
|
-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
|
|
-- <http://www.gnu.org/licenses/>. --
|
|
-- --
|
|
-- 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;
|