Include query strings when building cache keys, to avoid corrupting caches...

Include query strings when building cache keys, to avoid corrupting caches with data WP generates based on present query strings.

index-redis-page-cache.php

@@ -29,18 +29,19 @@ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 global $redis_page_cache_config;
 
 $redis_page_cache_config = array(
-	'debug'              => false,
-	'debug_messages'     => '',
-	'stats'              => false,
-	'cached'             => false,
-	'server_ip'          => '127.0.0.1',
-	'redis_server'       => '127.0.0.1',
-	'redis_port'         => 6379,
-	'redis_db'           => 0,
-	'cache_version'      => 0,
-	'cache_headers'      => true,
-	'additional_headers' => array( 'link', 'x-hacker', 'x-pingback' ),
-	'secret_string'      => 'changeme',
+	'debug'                   => true,
+	'debug_messages'          => '',
+	'stats'                   => false,
+	'cached'                  => false,
+	'server_ip'               => '127.0.0.1',
+	'secret_string'           => 'changeme',
+	'redis_server'            => '127.0.0.1',
+	'redis_port'              => 6379,
+	'redis_db'                => 0,
+	'cache_version'           => 0,
+	'cache_headers'           => true,
+	'additional_headers'      => array( 'link', 'x-hacker', 'x-pingback' ),
+	'query_strings_to_ignore' => array(), // common tracking strings are automatically excluded
 );
 
 // Uncomment either option below to fix the values here and disable the admin UI
@@ -135,6 +136,8 @@ function redis_page_cache_get_clean_url() {
 	static $url;
 
 	if ( ! $url ) {
+		global $redis_page_cache_config;
+
 		$proto = 'http';
 		if ( isset( $_SERVER['HTTPS'] ) && ( 'on' === strtolower( $_SERVER['HTTPS'] ) || '1' === $_SERVER['HTTPS'] ) ) {
 			$proto .= 's';
@@ -144,7 +147,30 @@ function redis_page_cache_get_clean_url() {
 
 		$url = parse_url( $proto . '://' . $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'] );
 		if ( $url ) {
-			$url = $url['scheme'] . '://' . $url['host'] . $url['path'];
+			// Query strings create their own caches, so we reduce proliferation by ignoring certain common strings
+			$qs = '';
+			if ( ! empty( $_GET ) ) {
+				$ignore = array( 'c', 'flush', 'secret', 'utm_source', 'utm_medium', 'utm_term', 'utm_content', 'utm_campaign', 'fb_action_ids', 'fb_action_types', 'fb_ref', 'fb_source', 'fb_aggregation_id', );
+				$ignore = array_merge( $ignore, $redis_page_cache_config['query_strings_to_ignore'] );
+				$ignore = array_flip( $ignore );
+
+				$_qs = array_diff_key( $_GET, $ignore );
+
+				if ( ! empty( $_qs ) ) {
+					$qs = '?';
+					foreach ( $_qs as $key => $value ) {
+						if ( strlen( $qs ) > 1 ) {
+							$qs .= '&';
+						}
+
+						$qs .= "{$key}={$value}";
+					}
+
+					$qs = preg_replace( '#[^A-Z0-9=\-\?\&]#i', '', $qs );
+				}
+			}
+
+			$url = $url['scheme'] . '://' . $url['host'] . $url['path'] . $qs;
 		} else {
 			$url = microtime();
 		}