# DBD::Gofer::Transport::corostream - phpMan

## NAME
    [DBD::Gofer::Transport::corostream] - Async [DBD::Gofer] stream transport
    using Coro and AnyEvent

## SYNOPSIS
       DBI_AUTOPROXY="dbi:Gofer:transport=corostream" perl some-perl-script-using-dbi.pl

    or

       $dsn = ...; # the DSN for the driver and database you want to use
       $dbh = DBI->connect("dbi:Gofer:transport=corostream;dsn=$dsn", ...);

## DESCRIPTION
    The *BIG WIN* from using Coro is that it enables the use of existing DBI
    frameworks like [DBIx::Class].

## KNOWN ISSUES AND LIMITATIONS
      - Uses [Coro::Select] so alters [CORE::select] globally
        Parent class probably needs refactoring to enable a more encapsulated approach.

      - Doesn't prevent multiple concurrent requests
        Probably just needs a per-connection semaphore

      - Coro has many caveats. Caveat emptor.

## STATUS
    THIS IS CURRENTLY JUST A PROOF-OF-CONCEPT IMPLEMENTATION FOR
    EXPERIMENTATION.

    Please note that I have no plans to develop this code further myself.
    I'd very much welcome contributions. Interested? Let me know!

## AUTHOR
    Tim Bunce, <<http://www.tim.bunce.name>>

## LICENCE AND COPYRIGHT
    Copyright (c) 2010, Tim Bunce, Ireland. All rights reserved.

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

## SEE ALSO
    [DBD::Gofer::Transport::stream]

    [DBD::Gofer]

## APPENDIX
    Example code:

        #!perl

        use strict;
        use warnings;
        use [Time::HiRes] qw(time);

        BEGIN { $ENV{PERL_ANYEVENT_STRICT} = 1; $ENV{PERL_ANYEVENT_VERBOSE} = 1; }

        use AnyEvent;

        BEGIN { $ENV{DBI_TRACE} = 0; $ENV{DBI_GOFER_TRACE} = 0; $ENV{DBD_GOFER_TRACE} = 0; };

        use DBI;

        $ENV{DBI_AUTOPROXY} = 'dbi:Gofer:transport=corostream';

        my $ticker = AnyEvent->timer( after => 0, interval => 0.1, cb => sub {
            warn sprintf "-tick- %.2f\n", time
        } );

        warn "connecting...\n";
        my $dbh = DBI->connect("dbi:NullP:");
        warn "...connected\n";

        for (1..3) {
            warn "entering DBI...\n";
            $dbh->do("sleep 0.3"); # pseudo-sql understood by the [DBD::NullP] driver
            warn "...returned\n";
        }

        warn "done.";

    Example output:

        $ perl corogofer.pl
        connecting...
        -tick- 1293631437.14
        -tick- 1293631437.14
        ...connected
        entering DBI...
        -tick- 1293631437.25
        -tick- 1293631437.35
        -tick- 1293631437.45
        -tick- 1293631437.55
        ...returned
        entering DBI...
        -tick- 1293631437.66
        -tick- 1293631437.76
        -tick- 1293631437.86
        ...returned
        entering DBI...
        -tick- 1293631437.96
        -tick- 1293631438.06
        -tick- 1293631438.16
        ...returned
        done. at corogofer.pl line 39.

    You can see that the timer callback is firing while the code 'waits'
    inside the do() method for the response from the database. Normally that
    would block.