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```{index} single: DBD::Gofer::Transport::corostream
```

# DBD::Gofer::Transport::corostream

Async DBD::Gofer stream transport using Coro and AnyEvent

## SYNOPSIS

```text
DBI_AUTOPROXY="dbi:Gofer:transport=corostream" perl some-perl-script-using-dbi.pl
```

or

```perl
$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](../../../Coro.md) is that it enables the use of existing
DBI frameworks like [DBIx::Class](https://metacpan.org/pod/DBIx::Class).

## KNOWN ISSUES AND LIMITATIONS

```text
- 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](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](https://perldoc.perl.org/perlartistic).

## SEE ALSO

[DBD::Gofer::Transport::stream](stream.md)

[DBD::Gofer](../../Gofer.md)

## APPENDIX

Example code:

```perl
#!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:

```text
$ 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.