Change Compressor to use more efficient deflate_init() context

Author: clue

src/Compressor.php

@@ -31,18 +31,43 @@
  * For more details, see ReactPHP's
  * [`DuplexStreamInterface`](https://github.com/reactphp/stream#duplexstreaminterface).
  */
-final class Compressor extends ZlibFilterStream
+final class Compressor extends TransformStream
 {
+    /** @var ?resource */
+    private $context;
+
     /**
      * @param int $encoding ZLIB_ENCODING_GZIP, ZLIB_ENCODING_RAW or ZLIB_ENCODING_DEFLATE
      * @param int $level    optional compression level
      */
     public function __construct($encoding, $level = -1)
     {
-        parent::__construct(
-            Filter\fun('zlib.deflate', array('window' => $encoding, 'level' => $level))
-        );
+        $context = @deflate_init($encoding, ['level' => $level]);
+        if ($context === false) {
+            throw new \InvalidArgumentException('Unable to initialize compressor' . strstr(error_get_last()['message'], ':'));
+        }
+
+        $this->context = $context;
+    }
+
+    protected function transformData($chunk)
+    {
+        $ret = deflate_add($this->context, $chunk, ZLIB_NO_FLUSH);
+
+        if ($ret !== '') {
+            $this->forwardData($ret);
+        }
+    }
+
+    protected function transformEnd($chunk)
+    {
+        $ret = deflate_add($this->context, $chunk, ZLIB_FINISH);
+        $this->context = null;
+
+        if ($ret !== '') {
+            $this->forwardData($ret);
+        }
 
-        $this->emptyWrite = $encoding;
+        $this->forwardEnd();
     }
 }

src/ZlibFilterStream.php

@@ -20,13 +20,6 @@ class ZlibFilterStream extends TransformStream
 {
     private $filter;
 
-    /**
-     * @var int|null
-     * @see Compressor
-     * @internal
-     */
-    protected $emptyWrite;
-
     public function __construct($filter)
     {
         $this->filter = $filter;
@@ -38,7 +31,6 @@ protected function transformData($chunk)
         $ret = $filter($chunk);
 
         if ($ret !== '') {
-            $this->emptyWrite = null;
             $this->forwardData($ret);
         }
     }
@@ -48,13 +40,6 @@ protected function transformEnd($chunk)
         $filter = $this->filter;
         $ret = $filter($chunk) . $filter();
 
-        // Stream ends successfully and did not emit any data whatsoever?
-        // This happens when compressing an empty stream with PHP 7 only.
-        // Bypass filter and manually compress/encode empty string.
-        if ($this->emptyWrite !== null && $ret === '') {
-            $ret = \zlib_encode('', $this->emptyWrite);
-        }
-
         if ($ret !== '') {
             $this->forwardData($ret);
         }

tests/CompressorTest.php

@@ -0,0 +1,14 @@
+<?php
+
+use Clue\React\Zlib\Compressor;
+
+class CompressorTest extends TestCase
+{
+    /**
+     * @expectedException InvalidArgumentException
+     */
+    public function testCtorThrowsForInvalidEncoding()
+    {
+        new Compressor(0);
+    }
+}