feat(Core): add retryFunction in GrpcRequestWrapper::send

Core/src/GrpcRequestWrapper.php

@@ -111,20 +111,23 @@ public function __construct(array $config = [])
      *           request. **Defaults to** `60`.
      *     @type int $retries Number of retries for a failed request.
      *           **Defaults to** `3`.
+     *     @type callable $retryFunction Returns bool for whether or not to retry.
      *     @type array $grpcOptions gRPC specific configuration options.
      * }
      * @return array
      */
     public function send(callable $request, array $args, array $options = [])
     {
         $retries = isset($options['retries']) ? $options['retries'] : $this->retries;
+        $retryFunction = isset($options['retryFunction'])
+            ? $options['retryFunction']
+            : function (\Exception $ex) {
+                $statusCode = $ex->getCode();
+                return in_array($statusCode, $this->grpcRetryCodes);
+            };
         $grpcOptions = isset($options['grpcOptions']) ? $options['grpcOptions'] : $this->grpcOptions;
         $timeout = isset($options['requestTimeout']) ? $options['requestTimeout'] : $this->requestTimeout;
-        $backoff = new ExponentialBackoff($retries, function (\Exception $ex) {
-            $statusCode = $ex->getCode();
-
-            return in_array($statusCode, $this->grpcRetryCodes);
-        });
+        $backoff = new ExponentialBackoff($retries, $retryFunction);
 
         if (!isset($grpcOptions['retrySettings'])) {
             $retrySettings = [

Core/tests/Unit/GrpcRequestWrapperTest.php

@@ -109,6 +109,34 @@ public function responseProvider()
         ];
     }
 
+    public function testRetryFunction()
+    {
+        $requestWrapper = new GrpcRequestWrapper();
+        $timesCalled = 0;
+        $requestWrapper->send(
+            function () use (&$timesCalled) {
+                if (1 === $timesCalled++) {
+                    // succeed on second try
+                    return;
+                }
+                throw new ApiException(
+                    'Retryable exception',
+                    \Google\Rpc\Code::NOT_FOUND,
+                    \Google\ApiCore\ApiStatus::NOT_FOUND
+                );
+            },
+            [[]],
+            [
+                'retries' => 1,
+                'retryFunction' => function (\Exception $ex) {
+                    return $ex->getMessage() === 'Retryable exception';
+                }
+            ]
+        );
+
+        $this->assertEquals(2, $timesCalled);
+    }
+
     public function testThrowsExceptionWhenRequestFails()
     {
         $this->expectException('Google\Cloud\Core\Exception\GoogleException');