NAME File::Flock::Retry - Yet another flock module VERSION This document describes version 0.632 of File::Flock::Retry (from Perl distribution File-Flock-Retry), released on 2021-08-10. SYNOPSIS use File::Flock::Retry; # try to acquire exclusive lock. if fail to acquire lock within 60s, die. my $lock = File::Flock::Retry->lock($file); # explicitly unlock $lock->release; # automatically unlock if object is DESTROY-ed. undef $lock; DESCRIPTION This is yet another flock module. It is a more lightweight alternative to File::Flock with some other differences: * OO interface only * Autoretry (by default for 60s) when trying to acquire lock I prefer this approach to blocking/waiting indefinitely or failing immediately. METHODS lock Usage: $lock = File::Flock::Retry->lock($path, \%opts) Attempt to acquire an exclusive lock on $path. By default, $path will be created if not already exists (see "mode"). If $path is already locked by another process, will retry every second for a number of seconds (by default 60). Will die if failed to acquire lock after all retries. Will automatically unlock if $lock goes out of scope. Upon unlock, will remove $path if it is still empty (zero-sized). Available options: * mode Integer. Default: O_CREAT | O_RDWR. File open mode, to be passed to Perl's "sysopen()". For example, if you want to avoid race condition between creating and locking the file, you might want to use "O_CREAT | O_EXCL | O_RDWR" to fail when the file already exists. Note that the constants are available after you do a "use Fcntl ':DEFAULT';". * retries Integer. Default: 60. Number of retries (equals number of seconds, since retry is done every second). * shared Boolean. Default: 0. By default, an exclusive lock (LOCK_EX) is attempted. However, if this option is set to true, a shared lock (LOCK_SH) is attempted. unlock Usage: $lock->unlock Unlock. will remove lock file if it is still empty. release Usage: $lock->release Synonym for "unlock". handle Usage: my $fh = $lock->handle; Return the file handle. HOMEPAGE Please visit the project's homepage at <https://metacpan.org/release/File-Flock-Retry>. SOURCE Source repository is at <https://github.com/perlancar/perl-File-Flock-Retry>. BUGS Please report any bugs or feature requests on the bugtracker website <https://rt.cpan.org/Public/Dist/Display.html?Name=File-Flock-Retry> When submitting a bug or request, please include a test-file or a patch to an existing test-file that illustrates the bug or desired feature. CAVEATS Not yet tested on Windows. Some filesystems do not support inode? SEE ALSO File::Flock, a bit too heavy in terms of dependencies and startup overhead, for my taste. It depends on things like File::Slurp and Data::Structure::Util (which loads Digest::MD5, Storable, among others). File::Flock::Tiny which is also tiny, but does not have the autoremove and autoretry capability which I want. See also: <https://github.com/trinitum/perl-File-Flock-Tiny/issues/1> flock() Perl function. An alternative to flock() is just using sysopen() with O_CREAT|O_EXCL mode to create lock files. This is supported on more filesystems (particularly network filesystems which lack flock()). AUTHOR perlancar <perlancar@cpan.org> COPYRIGHT AND LICENSE This software is copyright (c) 2021, 2019, 2017, 2015, 2014 by perlancar <perlancar@cpan.org>. This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.