caching layer for DB/DataObject

I added a new class, Memcached_DataObject, that will (optionally)
fetch data out of a memcached server if it's available. This only
works on 'staticGet'.

Methods that write to the database (insert, update, delete) will clear
and set the cache correctly, too.

darcs-hash:20080926160941-5ed1f-922de078b4c1941853ad014edf9a17fae486f8cf.gz

1 files changed, 144 insertions, 0 deletions

diff --git a/classes/Memcached_Object.php b/classes/Memcached_Object.php
new file mode 100644
index 000000000..a11c9883f
--- /dev/null
+++ b/classes/Memcached_Object.php
@@ -0,0 +1,144 @@
+<?php
+/*
+ * Laconica - a distributed open-source microblogging tool
+ * Copyright (C) 2008, Controlez-Vous, Inc.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+if (!defined('LACONICA')) { exit(1); }
+
+require_once 'classes/Memcached_DataObject.php';
+
+class Memcached_DataObject extends DB_DataObject 
+{
+    static function &staticGet($cls, $k, $v=NULL) {
+		$i = $this->getcached($cls, $k, $v);
+		if (!is_null($i)) {
+			return $i;
+		} else {
+			$i = parent::staticGet($k, $v);
+			if (!is_null($i)) {
+				$i->encache();
+			}
+			return $i;
+		}
+	}
+	
+	function insert() {
+		$result = parent::insert();
+		if ($result) {
+			$this->encache();
+		}
+		return $result;
+	}
+	
+	function update($orig=NULL) {
+		if (!is_null($orig)) {
+			$orig->decache(); # might be different keys
+		}
+		$result = parent::update($orig);
+		if ($result) {
+			$this->encache();
+		}
+	}
+	
+	function delete() {
+		$this->decache(); # while we still have the values!
+		return parent::delete();
+	}
+	
+	static function memcache() {
+		if (!common_config('memcached', 'enabled')) {
+			return NULL;
+		} else {
+			$cache = new Memcache();
+			$res = $cache->connect(common_config('memcached', 'server'), 
+								   common_config('memcached', 'port'));
+			return ($res) ? $cache : NULL;
+		}
+	}
+	
+	static function cacheKey($cls, $k, $v) {
+		return common_cache_key(strtolower($cls) . ':' .
+								$k . ':' .
+								$v);
+	}
+	
+	static function getcached($cls, $k, $v) {
+		$c = Memcached_DataObject::memcache();
+		if (!$c) {
+			return false;
+		} else {
+			return $c->get(Memcached_DataObject::cacheKey($cls, $k, $v));
+		}
+	}
+
+	function keyTypes() {
+		global $_DB_DATAOBJECT;
+        if (!isset($_DB_DATAOBJECT['INI'][$this->_database][$this->__table."__keys"])) {
+			$this->databaseStructure();
+
+        }
+		return $_DB_DATAOBJECT['INI'][$this->_database][$this->__table."__keys"];
+	}
+	
+	function encache() {
+		$c = $this->memcache();
+		if (!$c) {
+			return false;
+		} else {
+			$primary = array();
+			$types = ksort($this->keyTypes());
+			foreach ($types as $key => $type) {
+				if ($type == 'K') {
+					$primary[] = $key;
+				} else {
+					$c->set($this->cacheKey($this->tableName(), $key, $this->$key),
+							$this);
+				}
+			}
+			# XXX: figure out what to do with compound pkeys
+			if (count($primary) == 1) {
+				$key = $primary[0];
+				$c->set($this->cacheKey($this->tableName(), $key, $this->$key),
+						$this);
+			}
+		}
+	}
+	
+	function decache() {
+		$c = $this->memcache();
+		if (!$c) {
+			return false;
+		} else {
+			$primary = array();
+			$types = ksort($this->keyTypes());
+			foreach ($types as $key => $type) {
+				if ($type == 'K') {
+					$primary[] = $this->$key;
+				} else {
+					$c->delete($this->cacheKey($this->tableName(), $key, $this->$key),
+							   $this);
+				}
+			}
+			# XXX: figure out what to do with compound pkeys
+			if (count($primary) == 1) {
+				$key = $primary[0];
+				$c->delete($this->cacheKey($this->tableName(), $key, $this->$key),
+						   $this);
+			}
+		}
+	}
+}