------------------------------------------------------------------------------ -- -- -- 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) 1999-2006, 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; -- used for Lock_Task, Unlock_Task 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;