Retwis ported to modern Redis data types.

The example (and related documentation at redis.io) was not updated for
5 years. Redis had no sorted sets and hashes when the original code was
written (!). An update was really needed.

We also use a modern PHP client now: Predis. A copy is shipped within
this repository to make life easier to newcomers trying Redis for the
first time via this example.

Predis/Connection/ComposableStreamConnection.php

@@ -0,0 +1,135 @@
+<?php
+
+/*
+ * This file is part of the Predis package.
+ *
+ * (c) Daniele Alessandri <suppakilla@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Predis\Connection;
+
+use Predis\Command\CommandInterface;
+use Predis\Protocol\ProtocolInterface;
+use Predis\Protocol\Text\TextProtocol;
+
+/**
+ * Connection abstraction to Redis servers based on PHP's stream that uses an
+ * external protocol processor defining the protocol used for the communication.
+ *
+ * @author Daniele Alessandri <suppakilla@gmail.com>
+ */
+class ComposableStreamConnection extends StreamConnection implements ComposableConnectionInterface
+{
+    private $protocol;
+
+    /**
+     * @param ConnectionParametersInterface $parameters Parameters used to initialize the connection.
+     * @param ProtocolInterface             $protocol   A protocol processor.
+     */
+    public function __construct(ConnectionParametersInterface $parameters, ProtocolInterface $protocol = null)
+    {
+        $this->parameters = $this->checkParameters($parameters);
+        $this->protocol = $protocol ?: new TextProtocol();
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function setProtocol(ProtocolInterface $protocol)
+    {
+        if ($protocol === null) {
+            throw new \InvalidArgumentException("The protocol instance cannot be a null value");
+        }
+
+        $this->protocol = $protocol;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getProtocol()
+    {
+        return $this->protocol;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function writeBytes($buffer)
+    {
+        parent::writeBytes($buffer);
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function readBytes($length)
+    {
+        if ($length <= 0) {
+            throw new \InvalidArgumentException('Length parameter must be greater than 0');
+        }
+
+        $value  = '';
+        $socket = $this->getResource();
+
+        do {
+            $chunk = fread($socket, $length);
+
+            if ($chunk === false || $chunk === '') {
+                $this->onConnectionError('Error while reading bytes from the server');
+            }
+
+            $value .= $chunk;
+        } while (($length -= strlen($chunk)) > 0);
+
+        return $value;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function readLine()
+    {
+        $value  = '';
+        $socket = $this->getResource();
+
+        do {
+            $chunk = fgets($socket);
+
+            if ($chunk === false || $chunk === '') {
+                $this->onConnectionError('Error while reading line from the server');
+            }
+
+            $value .= $chunk;
+        } while (substr($value, -2) !== "\r\n");
+
+        return substr($value, 0, -2);
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function writeCommand(CommandInterface $command)
+    {
+        $this->protocol->write($this, $command);
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function read()
+    {
+        return $this->protocol->read($this);
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function __sleep()
+    {
+        return array_diff(array_merge(parent::__sleep(), array('protocol')), array('mbiterable'));
+    }
+}