Add BufferBusting echo handler

README.md

@@ -209,6 +209,15 @@ You just pass it to the constructor of the stream:
 $stream = new Stream($handler);
 ```
 
+If you serve PHP via FCGI, you may run into buffering issues, preventing
+individual events from being sent to the browser as they are being issued. 
+For this case the library includes a "BufferBusting" handler which outputs 
+a configurable amount of whitespace before the actual event data.
+
+While this does not interfere with the protocol, it obviously adds some 
+overhead to the network connection. Only choose this option if you are 
+unable to disable the buffers otherwise.
+
 ### PHP time limit
 
 In some setups it may be required to remove the time limit of the script.

src/Igorw/EventSource/BufferBustingEchoHandler.php

@@ -0,0 +1,38 @@
+<?php
+
+/*
+ * This file is part of EventSource.
+ *
+ * (c) Igor Wiedler <igor@wiedler.ch>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Igorw\EventSource;
+
+/**
+ * This handler outputs whitespace ahead of payload to break potential buffer limits from FCGI.
+ */
+class BufferBustingEchoHandler extends EchoHandler
+{
+    /**
+     * @var string
+     */
+    private $buffer;
+
+    /**
+     * @param int $bufferSize
+     */
+    public function __construct($bufferSize = 4096)
+    {
+        $this->buffer = str_repeat(" ", $bufferSize)."\n";
+    }
+
+    public function __invoke($chunk)
+    {
+        echo $this->buffer;
+
+        parent::__invoke($chunk);
+    }
+}

tests/Igorw/Tests/EventSource/BufferBustingEchoHandlerTest.php

@@ -0,0 +1,31 @@
+<?php
+
+/*
+ * This file is part of EventSource.
+ *
+ * (c) Igor Wiedler <igor@wiedler.ch>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Igorw\Tests\EventSource;
+
+use Igorw\EventSource\BufferBustingEchoHandler;
+
+class BufferBustingEchoHandlerTest extends \PHPUnit_Framework_TestCase
+{
+    /**
+     * @covers Igorw\EventSource\BufferBustingEchoHandler
+     */
+    public function testInvoke()
+    {
+        $handler = new BufferBustingEchoHandler(10);
+
+        ob_start();
+        $handler('test string');
+        $output = ob_get_clean();
+
+        $this->expectOutputString("          \ntest string", $output);
+    }
+}