NAME

Queue::Q4Pg::Lite - Simple message queue using PostgreSQL

SYNOPSIS

  use Queue::Q4Pg::Lite;

  my $q = Queue::Q4Pg::Lite->connect(
    connect_info => [
      'dbi:Pg:dbname=mydb',
      $username,
      $password
    ],
  );

  for (1..10) {
    $q->insert($table, \%fieldvals);
  }

  while ($q->next($table)) {
    my $cols = $q->fetch_hashref()
    print "col1 = $cols->{col1}, col2 = $cols->{col2}, col3 = $cols->{col3}\n";
    $q->ack;
  }

  $q->disconnect;

  # Table schema requires id column.
  CREATE TABLE mq ( id SERIAL PRIMARY KEY, message TEXT );

DESCRIPTION

Queue::Q4Pg::Lite is a simple message queue using PostgreSQL which supports pg_advisory_lock (version 8.2 or later).

This algorithms was invented by http://d.hatena.ne.jp/n_shuyo/20090415/mq .

Many codes copied from Queue::Q4M.

METHODS

new

Creates a new Queue::Q4Pg::Lite instance. Normally you should use connect() instead.

connect

Connects to the target database.

  my $q = Queue::Q4Pg::Lite->connect(
    connect_info => [
      'dbi:Pg:dbname=q4pg',
    ]
  );

next($table, [$where]);

Blocks until the next item is available.

$where is same of arguments for SQL::Abstract->select($table, $col, $where)

  # SELECT * FROM mq WHERE priority < 10;
  $q->next("mq", { priority => { "<", 10 } });

fetch_hashref

Fetches the next available row as hashref.

  my $hashref = $q->fetch_hashref();

ack

Delete the fetched row from table.

If You don't call ack(), the fetched row is not deleted from table.

insert($table, \%field)

Inserts into the queue. The first argument should be a scalar specifying a table name. The second argument is a hashref that specifies the mapping between column names and their respective values.

  $q->insert($table, { col1 => $val1, col2 => $val2, col3 => $val3 });

clear($table);

Deletes everything the specified queue.

dbh

Returns the database handle after making sure that it's connected.

disconnect

Disconnects.

AUTHOR

FUJIWARA Shunichiro <fujiwara@cpan.org>

SEE ALSO

Queue::Q4M, SQL::Abstract, http://d.hatena.ne.jp/n_shuyo/20090415/mq

LICENSE

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

cpanm Queue::Q4Pg::Lite

perl -MCPAN -e shell
install Queue::Q4Pg::Lite