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/Iterator/MultiBulkResponse.php

@@ -0,0 +1,100 @@
+<?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\Iterator;
+
+use Predis\ResponseObjectInterface;
+
+/**
+ * Iterator that abstracts the access to multibulk replies and allows
+ * them to be consumed by user's code in a streaming fashion.
+ *
+ * @author Daniele Alessandri <suppakilla@gmail.com>
+ */
+abstract class MultiBulkResponse implements \Iterator, \Countable, ResponseObjectInterface
+{
+    protected $position;
+    protected $current;
+    protected $replySize;
+
+    /**
+     * {@inheritdoc}
+     */
+    public function rewind()
+    {
+        // NOOP
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function current()
+    {
+        return $this->current;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function key()
+    {
+        return $this->position;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function next()
+    {
+        if (++$this->position < $this->replySize) {
+            $this->current = $this->getValue();
+        }
+
+        return $this->position;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function valid()
+    {
+        return $this->position < $this->replySize;
+    }
+
+    /**
+     * Returns the number of items of the whole multibulk reply.
+     *
+     * This method should be used to get the size of the current multibulk
+     * reply without using iterator_count, which actually consumes the
+     * iterator to calculate the size (rewinding is not supported).
+     *
+     * @return int
+     */
+    public function count()
+    {
+        return $this->replySize;
+    }
+
+    /**
+     * Returns the current position of the iterator.
+     *
+     * @return int
+     */
+    public function getPosition()
+    {
+        return $this->position;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    abstract protected function getValue();
+}

Predis/Iterator/MultiBulkResponseSimple.php

@@ -0,0 +1,89 @@
+<?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\Iterator;
+
+use Predis\Connection\SingleConnectionInterface;
+
+/**
+ * Streams a multibulk reply.
+ *
+ * @author Daniele Alessandri <suppakilla@gmail.com>
+ */
+class MultiBulkResponseSimple extends MultiBulkResponse
+{
+    private $connection;
+
+    /**
+     * @param SingleConnectionInterface $connection Connection to Redis.
+     * @param int                       $size       Number of elements of the multibulk reply.
+     */
+    public function __construct(SingleConnectionInterface $connection, $size)
+    {
+        $this->connection = $connection;
+        $this->position = 0;
+        $this->current = $size > 0 ? $this->getValue() : null;
+        $this->replySize = $size;
+    }
+
+    /**
+     * Handles the synchronization of the client with the Redis protocol
+     * then PHP's garbage collector kicks in (e.g. then the iterator goes
+     * out of the scope of a foreach).
+     */
+    public function __destruct()
+    {
+        $this->sync(true);
+    }
+
+    /**
+     * Synchronizes the client with the queued elements that have not been
+     * read from the connection by consuming the rest of the multibulk reply,
+     * or simply by dropping the connection.
+     *
+     * @param bool $drop True to synchronize the client by dropping the connection.
+     *                   False to synchronize the client by consuming the multibulk reply.
+     */
+    public function sync($drop = false)
+    {
+        if ($drop == true) {
+            if ($this->valid()) {
+                $this->position = $this->replySize;
+                $this->connection->disconnect();
+            }
+        } else {
+            while ($this->valid()) {
+                $this->next();
+            }
+        }
+    }
+
+    /**
+     * Reads the next item of the multibulk reply from the server.
+     *
+     * @return mixed
+     */
+    protected function getValue()
+    {
+        return $this->connection->read();
+    }
+
+    /**
+     * Returns an iterator that reads the multi-bulk response as
+     * list of tuples.
+     *
+     * @return MultiBulkResponseTuple
+     */
+    public function asTuple()
+    {
+        return new MultiBulkResponseTuple($this);
+    }
+}

Predis/Iterator/MultiBulkResponseTuple.php

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+<?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\Iterator;
+
+/**
+ * Abstracts the access to a streamable list of tuples represented
+ * as a multibulk reply that alternates keys and values.
+ *
+ * @author Daniele Alessandri <suppakilla@gmail.com>
+ */
+class MultiBulkResponseTuple extends MultiBulkResponse implements \OuterIterator
+{
+    private $iterator;
+
+    /**
+     * @param MultiBulkResponseSimple $iterator Multibulk reply iterator.
+     */
+    public function __construct(MultiBulkResponseSimple $iterator)
+    {
+        $this->checkPreconditions($iterator);
+
+        $virtualSize = count($iterator) / 2;
+        $this->iterator = $iterator;
+        $this->position = $iterator->getPosition();
+        $this->current = $virtualSize > 0 ? $this->getValue() : null;
+        $this->replySize = $virtualSize;
+    }
+
+    /**
+     * Checks for valid preconditions.
+     *
+     * @param MultiBulkResponseSimple $iterator Multibulk reply iterator.
+     */
+    protected function checkPreconditions(MultiBulkResponseSimple $iterator)
+    {
+        if ($iterator->getPosition() !== 0) {
+            throw new \RuntimeException('Cannot initialize a tuple iterator with an already initiated iterator');
+        }
+
+        if (($size = count($iterator)) % 2 !== 0) {
+            throw new \UnexpectedValueException("Invalid reply size for a tuple iterator [$size]");
+        }
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getInnerIterator()
+    {
+        return $this->iterator;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function __destruct()
+    {
+        $this->iterator->sync(true);
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    protected function getValue()
+    {
+        $k = $this->iterator->current();
+        $this->iterator->next();
+
+        $v = $this->iterator->current();
+        $this->iterator->next();
+
+        return array($k, $v);
+    }
+}