From 821fadb67d42b35d2f7889e949ed062fa6605bf9 Mon Sep 17 00:00:00 2001
From: Aaron Schulz <aschulz@wikimedia.org>
Date: Tue, 15 Jul 2014 13:43:35 -0700
Subject: [PATCH] Fixed JobQueueAggregatorRedis to handle empty collections

* Previously it would keep polling if the hash was empty since
  empty and non-existing collections are the same in Redis.
* Also turned off the pointless PHP serialization.
* Bumped the cache version key; this change should be deployed
  in all wikis at once, along with updating the runners.

Change-Id: I33dc55bc579bf678f14a5383e9e2c3c35231d599
---
 .../aggregator/JobQueueAggregatorRedis.php      | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/includes/jobqueue/aggregator/JobQueueAggregatorRedis.php b/includes/jobqueue/aggregator/JobQueueAggregatorRedis.php
index df9ae39e6a..e8e8e30250 100644
--- a/includes/jobqueue/aggregator/JobQueueAggregatorRedis.php
+++ b/includes/jobqueue/aggregator/JobQueueAggregatorRedis.php
@@ -50,6 +50,7 @@ class JobQueueAggregatorRedis extends JobQueueAggregator {
 		$this->servers = isset( $params['redisServers'] )
 			? $params['redisServers']
 			: array( $params['redisServer'] ); // b/c
+		$params['redisConfig']['serializer'] = 'none';
 		$this->redisPool = RedisConnectionPool::singleton( $params['redisConfig'] );
 	}
 
@@ -94,18 +95,16 @@ class JobQueueAggregatorRedis extends JobQueueAggregator {
 			return array();
 		}
 		try {
-			$conn->multi( Redis::PIPELINE );
-			$conn->exists( $this->getReadyQueueKey() );
-			$conn->hGetAll( $this->getReadyQueueKey() );
-			list( $exists, $map ) = $conn->exec();
+			$map = $conn->hGetAll( $this->getReadyQueueKey() );
 
-			if ( $exists ) { // cache hit
+			if ( is_array( $map ) && isset( $map['_epoch'] ) ) {
+				unset( $map['_epoch'] ); // ignore
 				$pendingDBs = array(); // (type => list of wikis)
 				foreach ( $map as $key => $time ) {
 					list( $type, $wiki ) = $this->dencQueueName( $key );
 					$pendingDBs[$type][] = $wiki;
 				}
-			} else { // cache miss
+			} else {
 				// Avoid duplicated effort
 				$rand = wfRandomString( 32 );
 				$conn->multi( Redis::MULTI );
@@ -120,7 +119,7 @@ class JobQueueAggregatorRedis extends JobQueueAggregator {
 
 				$conn->multi( Redis::PIPELINE );
 				$now = time();
-				$map = array();
+				$map = array( '_epoch' => time() ); // dummy key for empty Redis collections
 				foreach ( $pendingDBs as $type => $wikis ) {
 					$conn->hSetNx( $this->getQueueTypesKey(), $type, 'enabled' );
 					foreach ( $wikis as $wiki ) {
@@ -189,14 +188,14 @@ class JobQueueAggregatorRedis extends JobQueueAggregator {
 	 * @return string
 	 */
 	private function getReadyQueueKey() {
-		return "jobqueue:aggregator:h-ready-queues:v1"; // global
+		return "jobqueue:aggregator:h-ready-queues:v2"; // global
 	}
 
 	/**
 	 * @return string
 	 */
 	private function getQueueTypesKey() {
-		return "jobqueue:aggregator:h-queue-types:v1"; // global
+		return "jobqueue:aggregator:h-queue-types:v2"; // global
 	}
 
 	/**
-- 
2.20.1