Added a getLazyConnectionRef() function to load balancer

* This is useful for injecting dependencies without adding pointless traffic
  in some cases

Change-Id: I755ed008c387a3e4555934c84a5dc013ee8c2392

diff --git a/includes/db/LoadBalancer.php b/includes/db/LoadBalancer.php
index 60c2833..3358488 100644 (file)
--- a/includes/db/LoadBalancer.php
+++ b/includes/db/LoadBalancer.php
@@ -561,6 +561,22 @@ class LoadBalancer {
                return new DBConnRef( $this, $this->getConnection( $db, $groups, $wiki ) );
        }
 
+       /**
+        * Get a database connection handle reference without connecting yet
+        *
+        * The handle's methods wrap simply wrap those of a DatabaseBase handle
+        *
+        * @see LoadBalancer::getConnection() for parameter information
+        *
+        * @param integer $db
+        * @param mixed $groups
+        * @param string $wiki
+        * @return DBConnRef
+        */
+       public function getLazyConnectionRef( $db, $groups = array(), $wiki = false ) {
+               return new DBConnRef( $this, array( $db, $groups, $wiki ) );
+       }
+
        /**
         * Open a connection to the server given by the specified index
         * Index must be an actual index into the array.
@@ -1088,6 +1104,7 @@ class LoadBalancer {
 
 /**
  * Helper class to handle automatically marking connectons as reusable (via RAII pattern)
+ * as well handling deferring the actual network connection until the handle is used
  *
  * @ingroup Database
  * @since 1.22
@@ -1095,23 +1112,35 @@ class LoadBalancer {
 class DBConnRef implements IDatabase {
        /** @var LoadBalancer */
        protected $lb;
-       /** @var DatabaseBase */
+       /** @var DatabaseBase|null */
        protected $conn;
+       /** @var Array|null */
+       protected $params;
 
        /**
         * @param $lb LoadBalancer
-        * @param $conn DatabaseBase
+        * @param $conn DatabaseBase|array Connection or (server index, group, wiki ID) array
         */
-       public function __construct( LoadBalancer $lb, DatabaseBase $conn ) {
+       public function __construct( LoadBalancer $lb, $conn ) {
                $this->lb = $lb;
-               $this->conn = $conn;
+               if ( $conn instanceof DatabaseBase ) {
+                       $this->conn = $conn;
+               } else {
+                       $this->params = $conn;
+               }
        }
 
        public function __call( $name, $arguments ) {
+               if ( $this->conn === null ) {
+                       list( $db, $groups, $wiki ) = $this->params;
+                       $this->conn = $this->lb->getConnection( $db, $groups, $wiki );
+               }
                return call_user_func_array( array( $this->conn, $name ), $arguments );
        }
 
        function __destruct() {
-               $this->lb->reuseConnection( $this->conn );
+               if ( $this->conn !== null ) {
+                       $this->lb->reuseConnection( $this->conn );
+               }
        }
 }