NAME

Mojolicious::Plugin::PgLock - postgres advisory locks for Mojolicious application

SYNOPSIS

my $pg = Mojo::Pg->new('postgresql://...');
$app->plugin( PgLock => { pg => $pg } );

if ( my $lock = $app->get_lock ) {
  # make something exclusively
}

DESCRIPTION

Mojolicious::Plugin::PgLock implements get_lock helper. It is a shugar for postgres advisory lock functions.

HELPERS

Mojolicious::Plugin::PgLock implements the following helper.

get_lock

my $lock = $app->get_lock
    or die "another process is running";

# use a name and try to get a shared lock
my $shared_lock = $app->get_lock( name => 'mySharedLock', shared => 1 );

# use explicit id and wait until a lock is granted
my $lock = $app->get_lock( id => 9874738, wait => 1 );

get_lock helper uses one of postgres advisory lock function pg_try_advisory_lock, pg_advisory_lock, pg_advisory_lock_shared, pg_advisory_lock_shared to get an exclusive or shared lock depending on parameters.

get_lock helper returns a Mojolicious::Plugin::PgLock::Sentinel object which holds the lock while it is alive.

• id

  id parameter is used as integer key argument in postgres advisory lock function call. Default value for id is CRC32 hash of name parameter.

• name

  name is used for id calculation only if id is not set. Default value for name is (caller(2))[0]. It allows to use get_helper without parameters in Mojolicious::Commands modules

• shared

  shared parameter chose shared or exclusive lock. Default is false.

• wait

  If wait is true then function will wait until a lock is granted.

LICENSE

Copyright (C) Alexander Onokhov onokhov@cpan.org.

This library is free software; you can redistribute it and/or modify it under the MIT license terms.

AUTHOR

Copyright (C) Alexander Onokhov onokhov@cpan.org.