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    %$self = ();
}

package AnyEvent::Pg::Watcher;

sub _new {
    my ($class, $query) = @_;
    my $self = \$query;
    bless $self, $class;
}

sub DESTROY {
    # cancel query
    my $query = ${shift()};
    delete @{$query}{qw(on_error on_result on_done)};
    $query->{canceled} = 1;
}

1;
__END__

=head1 NAME

AnyEvent::Pg - Query a PostgreSQL database asynchronously

=head1 SYNOPSIS

  use AnyEvent::Pg;
  my $db = AnyEvent::Pg->new("dbname=foo",
                             on_connect => sub { ... });

  $db->push_query(query => 'insert into foo (id, name) values(7, \'seven\')',
                  on_result => sub { ... },
                  on_error => sub { ... } );

  # Note that $1, $2, etc. are Pg placeholders, nothing to do with
  # Perl regexp captures!

  $db->push_query(query => ['insert into foo (id, name) values($1, $2)', 7, 'seven']
                  on_result => sub { ... }, ...);

  $db->push_prepare(name => 'insert_into_foo',
                    query => 'insert into foo (id, name) values($1, $2)',
                    on_result => sub { ... }, ...);

  $db->push_query_prepared(name => 'insert_into_foo',
                           args => [7, 'seven'],
                           on_result => sub { ... }, ...);

=head1 DESCRIPTION

  *******************************************************************
  ***                                                             ***
  *** NOTE: This is a very early release that may contain lots of ***
  *** bugs. The API is not stable and may change between releases ***
  ***                                                             ***
  *******************************************************************

This library allows to query PostgreSQL databases asynchronously. It
is a thin layer on top of L<Pg::PQ> that integrates it inside the
L<AnyEvent> framework.

=head2 API

The following methods are available from the AnyEvent::Pg class:

=over 4

=item $adb = AnyEvent::Pg->new($conninfo, %opts)

Creates and starts the connection to the database. C<$conninfo>
contains the parameters defining how to connect to the database (see
libpq C<PQconnectdbParams> and C<PQconnectdb> documentation for the
details:
L<http://www.postgresql.org/docs/9.0/interactive/libpq-connect.html>).

The following options are accepted:

=over 4

=item on_connect => sub { ... }

The given callback is invoked after the connection has been
successfully established.

=item on_connect_error => sub { ... }

This callback is invoked if a fatal error happens when establishing
the connection to the database server.

=item on_empty_queue => sub { ... }

This callback is called every time the query queue becomes empty.

=item on_notify => sub { ... }

This callback is called when a notification is received.

=item on_error => sub { ... }

This callback is called when some error happens.

=item timeout => $seconds

Sets the default timeout for network activity. When nothing happens on
the network for the given seconds while processing some query, the
connection is marked as dead.

=back

=item $w = $adb->push_query(%opts)

Pushes a query into the object queue that will eventually be
dispatched to the database.

Returns a query watcher object. Destroying the watcher (usually when
it gets unreferenced) cancels the query.

The accepted options are:

=over