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POE::Component::DBIAgent::Helper.3pm
Langue: en
Version: 2008-01-18 (ubuntu - 24/10/10)
Section: 3 (Bibliothèques de fonctions)
NAME
POE::Component::DBIAgent::Helper - DBI Query Helper for DBIAgentSYNOPSYS
use Socket qw/:crlf/; use POE qw/Filter::Line Wheel::Run Component::DBIAgent::Helper/; sub _start { my $helper = POE::Wheel::Run ->new( Program => sub { POE::Component::DBIAgent::Helper->run($self->{dsn}, $self->{queries} ); }, StdoutEvent => 'db_reply', StderrEvent => 'remote_stderr', ErrorEvent => 'error', StdinFilter => POE::Filter::Line->new(), StdoutFilter => POE::Filter::Line->new( Literal => CRLF), StderrFilter => POE::Filter::Line->new(), ) or carp "Can't create new DBIAgent::Helper: $!\n"; } sub query { my ($self, $query, $package, $state, @rest) = @_; $self->{helper}->put(join '|', $query, $package, $state, @rest); } sub db_reply { my ($kernel, $self, $heap, $input) = @_[KERNEL, OBJECT, HEAP, ARG0]; # $input is either the string 'EOF' or a Storable object. }
DESCRIPTION
This is our helper routine for DBIAgent. It accepts queries on STDIN, and returns the results on STDOUT. Queries are returned on a row-by-row basis, followed by a row consisting of the string 'EOF'.Each row is the return value of $sth->fetch, which is an arrayref. This row is then passed to Storable for transport, and printed to STDOUT. HOWEVER, Storable uses newlines (``\n'') in its serialized strings, so the Helper is designed to use the ``network newline'' pair CR LF as the line terminator for STDOUT.
When fetch() returns undef, one final row is returned to the calling state: the string 'EOF'. Sessions should test for this value FIRST when being invoked with input from a query.
Initialization
The Helper has one public subroutine, called "run()", and is invoked with two parameters:- The DSN
- An arrayref of parameters to pass to DBI->connect (usually a dsn, username, and password).
- The Queries.
- A hashref of the form Query_Name => ``$SQL''. See POE::Component::DBIAgent for details.
BUGS
I have NO idea what to do about handling signals intelligently. Specifically, under some circumstances, Oracle will refuse to acknowledge SIGTERM (presumably since its libraries are non-reentrant) so sometimes SIGKILL is required to terminate a Helper process.AUTHOR
This module has been fine-tuned and packaged by Rob Bloodgood <robb@empire2.com>. However, most of the code came directly from Fletch <fletch@phydeaux.org>, either directly (Po:Co:DBIAgent:Queue) or via his ideas. Thank you, Fletch!However, I own all of the bugs.
This module is free software; you may redistribute it and/or modify it under the same terms as Perl itself.
Contenus ©2006-2024 Benjamin Poulain
Design ©2006-2024 Maxime Vantorre