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/AbstractConnection.php

@@ -0,0 +1,227 @@
+<?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\ClientException;
+use Predis\CommunicationException;
+use Predis\NotSupportedException;
+use Predis\Command\CommandInterface;
+use Predis\Protocol\ProtocolException;
+
+/**
+ * Base class with the common logic used by connection classes to communicate with Redis.
+ *
+ * @author Daniele Alessandri <suppakilla@gmail.com>
+ */
+abstract class AbstractConnection implements SingleConnectionInterface
+{
+    private $resource;
+    private $cachedId;
+
+    protected $parameters;
+    protected $initCmds = array();
+
+    /**
+     * @param ConnectionParametersInterface $parameters Parameters used to initialize the connection.
+     */
+    public function __construct(ConnectionParametersInterface $parameters)
+    {
+        $this->parameters = $this->checkParameters($parameters);
+    }
+
+    /**
+     * Disconnects from the server and destroys the underlying resource when
+     * PHP's garbage collector kicks in.
+     */
+    public function __destruct()
+    {
+        $this->disconnect();
+    }
+
+    /**
+     * Checks some of the parameters used to initialize the connection.
+     *
+     * @param  ConnectionParametersInterface $parameters Initialization parameters for the connection.
+     * @return ConnectionParametersInterface
+     */
+    protected function checkParameters(ConnectionParametersInterface $parameters)
+    {
+        switch ($parameters->scheme) {
+            case 'unix':
+                if (!isset($parameters->path)) {
+                    throw new \InvalidArgumentException('Missing UNIX domain socket path');
+                }
+
+            case 'tcp':
+                return $parameters;
+
+            default:
+                throw new \InvalidArgumentException("Invalid scheme: {$parameters->scheme}");
+        }
+    }
+
+    /**
+     * Creates the underlying resource used to communicate with Redis.
+     *
+     * @return mixed
+     */
+    abstract protected function createResource();
+
+    /**
+     * {@inheritdoc}
+     */
+    public function isConnected()
+    {
+        return isset($this->resource);
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function connect()
+    {
+        if ($this->isConnected()) {
+            throw new ClientException('Connection already estabilished');
+        }
+
+        $this->resource = $this->createResource();
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function disconnect()
+    {
+        unset($this->resource);
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function pushInitCommand(CommandInterface $command)
+    {
+        $this->initCmds[] = $command;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function executeCommand(CommandInterface $command)
+    {
+        $this->writeCommand($command);
+
+        return $this->readResponse($command);
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function readResponse(CommandInterface $command)
+    {
+        return $this->read();
+    }
+
+    /**
+     * Helper method to handle connection errors.
+     *
+     * @param string $message Error message.
+     * @param int    $code    Error code.
+     */
+    protected function onConnectionError($message, $code = null)
+    {
+        CommunicationException::handle(new ConnectionException($this, "$message [{$this->parameters->scheme}://{$this->getIdentifier()}]", $code));
+    }
+
+    /**
+     * Helper method to handle protocol errors.
+     *
+     * @param string $message Error message.
+     */
+    protected function onProtocolError($message)
+    {
+        CommunicationException::handle(new ProtocolException($this, "$message [{$this->parameters->scheme}://{$this->getIdentifier()}]"));
+    }
+
+    /**
+     * Helper method to handle not supported connection parameters.
+     *
+     * @param string $option     Name of the option.
+     * @param mixed  $parameters Parameters used to initialize the connection.
+     */
+    protected function onInvalidOption($option, $parameters = null)
+    {
+        $class = get_called_class();
+        $message = "Invalid option for connection $class: $option";
+
+        if (isset($parameters)) {
+            $message .= sprintf(' [%s => %s]', $option, $parameters->{$option});
+        }
+
+        throw new NotSupportedException($message);
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getResource()
+    {
+        if (isset($this->resource)) {
+            return $this->resource;
+        }
+
+        $this->connect();
+
+        return $this->resource;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getParameters()
+    {
+        return $this->parameters;
+    }
+
+    /**
+     * Gets an identifier for the connection.
+     *
+     * @return string
+     */
+    protected function getIdentifier()
+    {
+        if ($this->parameters->scheme === 'unix') {
+            return $this->parameters->path;
+        }
+
+        return "{$this->parameters->host}:{$this->parameters->port}";
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function __toString()
+    {
+        if (!isset($this->cachedId)) {
+            $this->cachedId = $this->getIdentifier();
+        }
+
+        return $this->cachedId;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function __sleep()
+    {
+        return array('parameters', 'initCmds');
+    }
+}