Examples: add CustomDistributionStrategy.php

examples/CustomDistributionStrategy.php

@@ -0,0 +1,65 @@
+<?php
+require '../lib/Predis.php';
+
+// Developers can customize the distribution strategy used by the client 
+// to distribute keys among a cluster of servers simply by creating a class 
+// that implements the Predis\Distribution\IDistributionAlgorithm interface.
+
+class NaiveDistributionStrategy
+    implements Predis\Distribution\IDistributionStrategy {
+
+    private $_nodes, $_nodesCount;
+
+    public function __constructor() {
+        $this->_nodes = array();
+        $this->_nodesCount = 0;
+    }
+
+    public function add($node, $weight = null) {
+        $this->_nodes[] = $node;
+        $this->_nodesCount++;
+    }
+
+    public function remove($node) {
+        $this->_nodes = array_filter($this->_nodes, function($n) use($node) {
+            return $n !== $node;
+        });
+        $this->_nodesCount = count($this->_nodes);
+    }
+
+    public function get($key) {
+        $count = $this->_nodesCount;
+        if ($count === 0) {
+            throw new RuntimeException('No connections');
+        }
+        return $this->_nodes[$count > 1 ? abs(crc32($key) % $count) : 0];
+    }
+
+    public function generateKey($value) {
+        return crc32($value);
+    }
+}
+
+$servers = array(
+    'redis://127.0.0.1:6379?alias=first',
+    'redis://127.0.0.1:6380?alias=second',
+);
+
+$options = array(
+    'key_distribution' => new NaiveDistributionStrategy(),
+);
+
+$redis = new Predis\Client($servers, $options);
+
+for ($i = 0; $i < 100; $i++) {
+    $redis->set("key:$i", str_pad($i, 4, '0', 0));
+    $redis->get("key:$i");
+}
+
+$server1 = $redis->getClientFor('first')->info();
+$server2 = $redis->getClientFor('second')->info();
+
+printf("Server '%s' has %d keys while server '%s' has %d keys.\n", 
+    'first', $server1['db0']['keys'], 'second', $server2['db0']['keys']
+);
+?>