---
name: "File::Flock::Retry"
section: "3pm"
platform: "linux"
package: "libfile-flock-retry-perl"
version: "0.632-2"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/File::Flock::Retry"
---

# File::Flock::Retry(3pm)

Yet another flock module

## 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.