Use parallel gunzip process for faster gzip decompression

Author: clue

composer.json

@@ -18,8 +18,8 @@
         "react/stream": "^1.0 || ^0.7 || ^0.6"
     },
     "require-dev": {
-        "clue/zlib-react": "^1.0 || ^0.2.2",
         "phpunit/phpunit": "^7.0 || ^6.0 || ^5.7 || ^4.8.35",
+        "react/child-process": "^0.6",
         "react/event-loop": "^1.0 || ^0.5 || ^0.4 || ^0.3"
     }
 }

examples/92-benchmark-count-gzip.php

@@ -11,9 +11,8 @@
 // $ php examples/92-benchmark-count-gzip.php < IRAhandle_tweets_1.csv.gz
 
 use Clue\React\Csv\AssocDecoder;
-use Clue\React\Zlib\Decompressor;
+use React\ChildProcess\Process;
 use React\EventLoop\Factory;
-use React\Stream\ReadableResourceStream;
 
 require __DIR__ . '/../vendor/autoload.php';
 
@@ -22,14 +21,19 @@
 }
 
 $loop = Factory::create();
-$input = new ReadableResourceStream(STDIN, $loop);
-$decompressor = new Decompressor(ZLIB_ENCODING_GZIP);
-$input->pipe($decompressor);
-$decoder = new AssocDecoder($decompressor);
 
-$decompressor->on('error', function (Exception $e) {
-    printf("\nDecompression error: " . $e->getMessage() . "\n");
-});
+// This benchmark example spawns the decompressor in a child `gunzip` process
+// because parsing CSV files is already mostly CPU-bound and multi-processing
+// is preferred here. If the input source is slower (such as an HTTP download)
+// or if `gunzip` is not available (Windows), using a built-in decompressor
+// such as https://github.com/clue/reactphp-zlib would be preferable.
+$process = new Process('exec gunzip', null, null, array(
+    0 => STDIN,
+    1 => array('pipe', 'w'),
+    STDERR
+));
+$process->start($loop);
+$decoder = new AssocDecoder($process->stdout);
 
 $count = 0;
 $decoder->on('data', function () use (&$count) {