snabb at epipe
Oct 7, 2011, 11:17 AM
Views: 549
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Re: Session duplicate key constraints on concurrent requests
[In reply to]
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On Fri, 7 Oct 2011, Janne Snabb wrote:
> I think the proper way to solve it is to drop the constraint on the
> cookie and just insert the cookie and have an auto_increment ID in
> the table. And when reading, select the cookie with the highest ID
> (because there might be several).
Something like this perhaps? Untested code.
--
Janne Snabb / EPIPE Communications
snabb [at] epipe - http://epipe.com/
diff -U5 -r Catalyst-Plugin-Session-Store-DBI-0.16/lib/Catalyst/Plugin/Session/Store/DBI.pm Catalyst-Plugin-Session-Store-DBI-0.16+sessionpatch//lib/Catalyst/Plugin/Session/Store/DBI.pm
--- Catalyst-Plugin-Session-Store-DBI-0.16/lib/Catalyst/Plugin/Session/Store/DBI.pm 2010-03-24 04:47:13.000000000 +0700
+++ Catalyst-Plugin-Session-Store-DBI-0.16+sessionpatch//lib/Catalyst/Plugin/Session/Store/DBI.pm 2011-10-08 01:13:30.183410460 +0700
@@ -120,10 +120,14 @@
sub session_store_dbi_id_field {
return shift->_session_plugin_config->{'dbi_id_field'} || 'id';
}
+sub session_store_dbi_selector_field {
+ return shift->_session_plugin_config->{'dbi_selector_field'} || 'selector';
+}
+
sub session_store_dbi_data_field {
return shift->_session_plugin_config->{'dbi_data_field'} || 'session_data';
}
sub session_store_dbi_expires_field {
@@ -148,11 +152,11 @@
my ( $table, $id_field, $data_field, $expires_field ) =
map { $c->${\"session_store_$_"} }
qw/dbi_table dbi_id_field dbi_data_field dbi_expires_field/;
$c->_session_sql( {
get_session_data =>
- "SELECT $data_field FROM $table WHERE $id_field = ?",
+ "SELECT $data_field FROM $table WHERE $id_field = ? ORDER BY selector ASC LIMIT 1",
get_expires =>
"SELECT $expires_field FROM $table WHERE $id_field = ?",
check_existing =>
"SELECT 1 FROM $table WHERE $id_field = ?",
update_session =>
@@ -338,11 +342,12 @@
=head1 SYNOPSIS
# Create a table in your database for sessions
CREATE TABLE sessions (
- id char(72) primary key,
+ id char(72) key,
+ selector int auto_increment primary key,
session_data text,
expires int(10)
);
# In your app
@@ -354,20 +359,22 @@
dbi_dsn => 'dbi:mysql:database',
dbi_user => 'foo',
dbi_pass => 'bar',
dbi_table => 'sessions',
dbi_id_field => 'id',
+ dbi_selector_field => 'selector',
dbi_data_field => 'session_data',
dbi_expires_field => 'expires',
});
# Or use an existing database handle from a DBIC/CDBI class
MyApp->config('Plugin::Session' => {
expires => 3600,
dbi_dbh => 'DBIC', # which means MyApp::Model::DBIC
dbi_table => 'sessions',
dbi_id_field => 'id',
+ dbi_selector_field => 'selector',
dbi_data_field => 'session_data',
dbi_expires_field => 'expires',
});
# ... in an action:
@@ -423,10 +430,17 @@
=head2 dbi_id_field
The name of the field on your sessions table which stores the session ID.
Defaults to C<id>.
+=head2 dbi_selector_field
+
+The name of the field on your sessions table which is used to differentiate
+amongst multiple instances of the id field (which happens when multiple
+instances try to store the same session at the same time).
+Defaults to C<selector>.
+
=head2 dbi_data_field
The name of the field on your sessions table which stores session data.
Defaults to C<session_data>.
@@ -435,13 +449,14 @@
The name of the field on your sessions table which stores the expiration
time of the session. Defaults to C<expires>.
=head1 SCHEMA
-Your 'sessions' table must contain at minimum the following 3 columns:
+Your 'sessions' table must contain at minimum the following 4 columns:
- id char(72) primary key
+ id char(72) key
+ selector int auto_increment primary key
session_data text
expires int(10)
The 'id' column should probably be 72 characters. It needs to handle the
longest string that can be returned by
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