have flush return the count of successful invalidation requests

src/CacheInvalidator.php

@@ -282,14 +282,14 @@ public function invalidateTags(array $tags)
     /**
      * Send all pending invalidation requests.
      *
-     * @throws ExceptionCollection
+     * @return int The number of cache invalidations performed per caching server.
      *
-     * @return $this
+     * @throws ExceptionCollection If any errors occurred during flush.
      */
     public function flush()
     {
         try {
-            $this->cache->flush();
+            return $this->cache->flush();
         } catch (ExceptionCollection $exceptions) {
             foreach ($exceptions as $exception) {
                 $event = new Event();
@@ -303,7 +303,5 @@ public function flush()
 
             throw $exceptions;
         }
-
-        return $this;
     }
 }

src/Invalidation/AbstractCacheProxy.php

@@ -106,11 +106,13 @@ public function flush()
     {
         $queue = $this->queue;
         if (0 === count($queue)) {
-            return;
+            return 0;
         }
 
         $this->queue = array();
         $this->sendRequests($queue);
+
+        return count($queue);
     }
 
     /**

src/Invalidation/CacheProxyInterface.php

@@ -12,9 +12,9 @@ interface CacheProxyInterface
     /**
      * Send all pending invalidation requests.
      *
-     * @return $this
+     * @return int The number of cache invalidations performed per caching server.
      *
-     * @throws ExceptionCollection If any errors occurred during flush
+     * @throws ExceptionCollection If any errors occurred during flush.
      */
     public function flush();
 }

tests/Functional/Fixtures/varnish/purge.vcl

@@ -10,13 +10,13 @@ sub vcl_recv {
 sub vcl_hit {
     if (req.request == "PURGE") {
         purge;
-        error 200 "Purged";
+        error 204 "Purged";
     }
 }
 
 sub vcl_miss {
     if (req.request == "PURGE") {
         purge;
-        error 404 "Not in cache";
+        error 204 "Purged (Not in cache)";
     }
-}
+}

tests/Unit/Invalidation/VarnishTest.php

@@ -198,6 +198,38 @@ public function testSetServersThrowsInvalidServerException()
         new Varnish(array('http://127.0.0.1:80/some/weird/path'));
     }
 
+    public function testFlushCountSuccess()
+    {
+        $self = $this;
+        $client = \Mockery::mock('\Guzzle\Http\Client[send]', array('', null))
+            ->shouldReceive('send')
+            ->once()
+            ->with(
+                \Mockery::on(
+                    function ($requests) use ($self) {
+                        /** @type Request[] $requests */
+                        $self->assertCount(4, $requests);
+                        foreach ($requests as $request) {
+                            $self->assertEquals('PURGE', $request->getMethod());
+                        }
+
+                        return true;
+                    }
+                )
+            )
+            ->getMock();
+
+        $varnish = new Varnish(array('127.0.0.1', '127.0.0.2'), 'fos.lo', $client);
+
+        $this->assertEquals(
+            2,
+            $varnish
+                ->purge('/c')
+                ->purge('/b')
+                ->flush()
+        );
+    }
+
     protected function setUp()
     {
         $this->mock = new MockPlugin();