| ------------------------------------------------------------------------------ |
| -- -- |
| -- 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) 1999-2023, 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; |
