Specify a timeout for the connect() operation to sentinel servers.

This value should be reasonably low so that the client can fallback to the next
sentinel if the connect() operation is taking too much and slowing things down.

When the connection parameters of sentinels contain a "timeout" parameter, its
value takes the precedence over the default sentinels timeout.

src/Connection/Aggregate/SentinelReplication.php

@@ -16,6 +16,7 @@ use Predis\Connection\ConnectionException;
 use Predis\Connection\Factory as ConnectionFactory;
 use Predis\Connection\FactoryInterface as ConnectionFactoryInterface;
 use Predis\Connection\NodeConnectionInterface;
+use Predis\Connection\Parameters;
 use Predis\Replication\ReplicationStrategy;
 use Predis\Response\ErrorInterface as ErrorResponseInterface;
 use Predis\Response\ServerException;
@@ -48,6 +49,11 @@ class SentinelReplication extends MasterSlaveReplication
      */
     protected $sentinelConnection;
 
+    /**
+     * Timeout for the connection to a sentinel.
+     */
+    protected $sentinelTimeout = 0.100;
+
     /**
      * @param array                      $sentinels         Sentinel servers connection parameters.
      * @param string                     $service           Name of the service for autodiscovery.
@@ -67,6 +73,19 @@ class SentinelReplication extends MasterSlaveReplication
         parent::__construct($strategy);
     }
 
+    /**
+     * Sets a default timeout for connections to sentinels.
+     *
+     * When "timeout" is present in the connection parameters of sentinels, its
+     * value overrides the default sentinel timeout.
+     *
+     * @param float $timeout Timeout value.
+     */
+    public function setDefaultSentinelTimeout($timeout)
+    {
+        $this->sentinelTimeout = (float) $timeout;
+    }
+
     /**
      * {@inheritdoc}
      */
@@ -88,6 +107,32 @@ class SentinelReplication extends MasterSlaveReplication
         $this->slaves = null;
     }
 
+    /**
+     * Creates the connection to a sentinel server.
+     *
+     * @return NodeConnectionInterface
+     */
+    protected function createSentinelConnection($parameters)
+    {
+        if ($parameters instanceof NodeConnectionInterface) {
+            return $parameters;
+        }
+
+        if (is_string($parameters)) {
+            $parameters = Parameters::parse($parameters);
+        }
+
+        if (is_array($parameters)) {
+            $parameters += array(
+                'timeout' => $this->sentinelTimeout,
+            );
+        }
+
+        $connection = $this->connectionFactory->create($parameters);
+
+        return $connection;
+    }
+
     /**
      * Returns the current sentinel connection.
      *
@@ -103,7 +148,7 @@ class SentinelReplication extends MasterSlaveReplication
             }
 
             $sentinel = array_shift($this->sentinels);
-            $this->sentinelConnection = $this->connectionFactory->create($sentinel);
+            $this->sentinelConnection = $this->createSentinelConnection($sentinel);
         }
 
         return $this->sentinelConnection;