DBD::Gofer::Transport::corostream

Section: User Contributed Perl Documentation (3)
Updated: 2021-01-27
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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

   $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

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

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.