From cd736291de2bc59c36002691276cb40c06b3fed4 Mon Sep 17 00:00:00 2001
From: freakolowsky <freak@drajv.si>
Date: Fri, 24 May 2013 16:05:20 +0200
Subject: [PATCH] Oracle: DRCP and persistent connections support

Adds $wgDBOracleDRCP, when set to true, enables persistent connection
with DRCP on Oracle.

Requires Oracle DB 11gR1 or above. More informations about DRCP can be
found at:
http://www.oracle-base.com/articles/11g/database-resident-connection-pool-11gr1.php

Change-Id: I2be7120a2ebec39d866b79be62ac715bbc3738a9
---
 RELEASE-NOTES-1.22             |  7 +++++++
 includes/DefaultSettings.php   | 29 +++++++++++++++++++++++++++++
 includes/db/DatabaseOracle.php | 10 +++++++++-
 3 files changed, 45 insertions(+), 1 deletion(-)

diff --git a/RELEASE-NOTES-1.22 b/RELEASE-NOTES-1.22
index a26c7d8541..000f6b1709 100644
--- a/RELEASE-NOTES-1.22
+++ b/RELEASE-NOTES-1.22
@@ -26,6 +26,7 @@ production.
 * $wgHandheldStyle was removed.
 * $wgJsMimeType is no longer used by core. Most usage has been removed since
   HTML output is now exclusively HTML5.
+* $wgDBOracleDRCP added. True enables persistent connection with DRCP on Oracle.
 
 === New features in 1.22 ===
 * (bug 44525) mediawiki.jqueryMsg can now parse (whitelisted) HTML elements and attributes.
@@ -86,6 +87,12 @@ production.
   HTTP caches when a page is changed.
 * Changed the patrolling system to always show the link for patrolling in case the
   current revision is patrollable. This also removed the usage of the rcid URI parameters.
+* Oracle DB backend now supports Database Resident Connection Pooling (DRCP).
+  Can be enabled by setting $wgDBOracleDRCP=true.
+  Requires Oracle DB 11gR1 or above, enabled DRCP inside the DB itself and a
+  propper connect string.
+  More about DRCP can be found at:
+  http://www.oracle-base.com/articles/11g/database-resident-connection-pool-11gr1.php
 
 === Bug fixes in 1.22 ===
 * Disable Special:PasswordReset when $wgEnableEmail is false. Previously one
diff --git a/includes/DefaultSettings.php b/includes/DefaultSettings.php
index 173605cceb..29d3127b02 100644
--- a/includes/DefaultSettings.php
+++ b/includes/DefaultSettings.php
@@ -1589,6 +1589,35 @@ $wgDBAvgStatusPoll = 2000;
  */
 $wgDBmysql5 = false;
 
+/**
+ * Set true to enable Oracle DCRP (supported from 11gR1 onward)
+ *
+ * To use this feature set to true and use a datasource defined as
+ * POOLED (i.e. in tnsnames definition set server=pooled in connect_data
+ * block).
+ *
+ * Starting from 11gR1 you can use DCRP (Database Resident Connection
+ * Pool) that maintains established sessions and reuses them on new
+ * connections.
+ *
+ * Not completely tested, but it should fall back on normal connection
+ * in case the pool is full or the datasource is not configured as
+ * pooled.
+ * And the other way around; using oci_pconnect on a non pooled
+ * datasource should produce a normal connection.
+ *
+ * When it comes to frequent shortlived DB connections like with MW
+ * Oracle tends to s***. The problem is the driver connects to the
+ * database reasonably fast, but establishing a session takes time and
+ * resources. MW does not rely on session state (as it does not use
+ * features such as package variables) so establishing a valid session
+ * is in this case an unwanted overhead that just slows things down.
+ *
+ * @warning EXPERIMENTAL!
+ *
+ */
+$wgDBOracleDRCP = false;
+
 /**
  * Other wikis on this site, can be administered from a single developer
  * account.
diff --git a/includes/db/DatabaseOracle.php b/includes/db/DatabaseOracle.php
index 4fa2397c2c..c0d3805d58 100644
--- a/includes/db/DatabaseOracle.php
+++ b/includes/db/DatabaseOracle.php
@@ -249,6 +249,7 @@ class DatabaseOracle extends DatabaseBase {
 	 * @return DatabaseBase|null
 	 */
 	function open( $server, $user, $password, $dbName ) {
+		global $wgDBOracleDRCP;
 		if ( !function_exists( 'oci_connect' ) ) {
 			throw new DBConnectionError( $this, "Oracle functions missing, have you compiled PHP with the --with-oci8 option?\n (Note: if you recently installed PHP, you may need to restart your webserver and database)\n" );
 		}
@@ -276,9 +277,16 @@ class DatabaseOracle extends DatabaseBase {
 			return;
 		}
 
+		if ( $wgDBOracleDRCP ) {
+			$this->setFlag( DBO_PERSISTENT );
+		}
+
 		$session_mode = $this->mFlags & DBO_SYSDBA ? OCI_SYSDBA : OCI_DEFAULT;
+
 		wfSuppressWarnings();
-		if ( $this->mFlags & DBO_DEFAULT ) {
+		if ( $this->mFlags & DBO_PERSISTENT ) {
+			$this->mConn = oci_pconnect( $this->mUser, $this->mPassword, $this->mServer, $this->defaultCharset, $session_mode );
+		} else if ( $this->mFlags & DBO_DEFAULT ) {
 			$this->mConn = oci_new_connect( $this->mUser, $this->mPassword, $this->mServer, $this->defaultCharset, $session_mode );
 		} else {
 			$this->mConn = oci_connect( $this->mUser, $this->mPassword, $this->mServer, $this->defaultCharset, $session_mode );
-- 
2.20.1