File::Flock::Subprocess3pm

Usage

 use File::Flock::Subprocess;
 lock($filename);
 lock($filename, 'shared');
 lock($filename, undef, 'nonblocking');
 lock($filename, 'shared', 'nonblocking');
 unlock($filename);
 lock_rename($oldfilename, $newfilename)
 my $lock = new File::Flock '/somefile';
 $lock->unlock();
 $lock->lock_rename('/new/file');
 forget_locks();

Overview

This is a wrapper around File::Flock that starts a subprocess and does the locking in the subprocess with File::Flock. The purpose of this is to handle operating systems (eg: Solaris) that do not retain locks across a call to fork().

The sub-process for this is created with fork() when File::Flock::Subprocess is compiled. I've tried to minimize the side-effects calling fork() by doing calling it early and by using POSIX::_exit() to quit but it is still worth being aware of. I suggest loading File::Flock::Subprocess early.

Use File::Flock::Forking to automatically detect when this is needed.

Read the docs for File::Flock for details of the API.

Errata

Any errors reported by the locking proxy File::Flock::Subprocess starts will be reported as "Compilation Failed" errors because the proxy is started in a BEGIN{} block.