Author: timbo
Date: Wed Dec 29 06:15:07 2010
New Revision: 14610
Added:
dbi/trunk/ex/corogofer.pl
dbi/trunk/lib/DBD/Gofer/Transport/corostream.pm
Modified:
dbi/trunk/Changes
Log:
Add DBD::Gofer::Transport::corostream
Modified: dbi/trunk/Changes
==============================================================================
--- dbi/trunk/Changes (original)
+++ dbi/trunk/Changes Wed Dec 29 06:15:07 2010
@@ -21,6 +21,10 @@
Optimized connect() to remove redundant FETCH of \%attrib values.
Improved initialization phases in DBI::DBD::SqlEngine (Jens Rehsack)
+ Added DBD::Gofer::Transport::corostream. A experimental proof-of-concept
+ transport that enables asynchronous database calls with few code changes.
+ Including asynchronous use of DBI frameworks like DBIx::Class.
+
Added additional notes on DBDs which avoid creating a statement in
the do() method and the effects on error handlers (Martin J. Evans)
Adding new attribute "sql_dialect" to DBI::DBD::SqlEngine to allow
Added: dbi/trunk/ex/corogofer.pl
==============================================================================
--- (empty file)
+++ dbi/trunk/ex/corogofer.pl Wed Dec 29 06:15:07 2010
@@ -0,0 +1,32 @@
+#!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_PUREPERL} = 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..5) {
+ warn "entering DBI...\n";
+ $dbh->do("sleep 0.3"); # pseudo-sql understood by the DBD::NullP driver
+ warn "...returned\n";
+}
+
+warn "done.";
+
Added: dbi/trunk/lib/DBD/Gofer/Transport/corostream.pm
==============================================================================
--- (empty file)
+++ dbi/trunk/lib/DBD/Gofer/Transport/corostream.pm Wed Dec 29 06:15:07 2010
@@ -0,0 +1,144 @@
+package DBD::Gofer::Transport::corostream;
+
+use strict;
+use warnings;
+
+use Carp;
+
+use Coro::Select; # a slow but coro-aware replacement for CORE::select
(global effect!)
+
+use Coro;
+use Coro::Handle;
+
+use base qw(DBD::Gofer::Transport::stream);
+
+# XXX ensure DBI_PUREPERL for parent doesn't pass to child
+sub start_pipe_command {
+ local $ENV{DBI_PUREPERL} = $ENV{DBI_PUREPERL_COROCHILD}; # typically undef
+ my $connection = shift->SUPER::start_pipe_command(@_);
+ return $connection;
+}
+
+
+
+1;
+
+__END__
+
+=head1 NAME
+
+DBD::Gofer::Transport::corostream - Async DBD::Gofer stream transport using
Coro and AnyEvent
+
+=head1 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", ...);
+
+=head1 DESCRIPTION
+
+The I<BIG WIN> from using L<Coro> is that it enables the use of existing
+DBI frameworks like L<DBIx::Class>.
+
+=head1 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.
+
+=head1 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!
+
+=head1 AUTHOR
+
+Tim Bunce, L<http://www.tim.bunce.name>
+
+=head1 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 L<perlartistic>.
+
+=head1 SEE ALSO
+
+L<DBD::Gofer::Transport::stream>
+
+L<DBD::Gofer>
+
+=head1 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.
+
+=cut
