From 5a1ea0b9b28138bc4e06d96e2910b0cf3be1eab2 Mon Sep 17 00:00:00 2001
From: Evan Prodromou <evan@status.net>
Date: Mon, 4 Jan 2010 08:59:19 -1000
Subject: [PATCH] Stop caching unfindable keys

There were some problems with the automated cache/uncache system
for data objects that made us cache unfindable keys (with null
attributes and sometimes null names). Fixed those problems and
refactored the encache() and decache() methods so they use a helper
to find the cache keys to use.
---
 classes/Memcached_DataObject.php | 87 +++++++++++++++++++-------------
 1 file changed, 52 insertions(+), 35 deletions(-)

diff --git a/classes/Memcached_DataObject.php b/classes/Memcached_DataObject.php
index 1608720d14..020d813b2c 100644
--- a/classes/Memcached_DataObject.php
+++ b/classes/Memcached_DataObject.php
@@ -152,52 +152,69 @@ class Memcached_DataObject extends DB_DataObject
     function encache()
     {
         $c = $this->memcache();
+
         if (!$c) {
             return false;
-        } else {
-            $pkey = array();
-            $pval = array();
-            $types = $this->keyTypes();
-            ksort($types);
-            foreach ($types as $key => $type) {
-                if ($type == 'K') {
-                    $pkey[] = $key;
-                    $pval[] = $this->$key;
-                } else {
-                    $c->set($this->cacheKey($this->tableName(), $key, $this->$key), $this);
-                }
-            }
-            # XXX: should work for both compound and scalar pkeys
-            $pvals = implode(',', $pval);
-            $pkeys = implode(',', $pkey);
-            $c->set($this->cacheKey($this->tableName(), $pkeys, $pvals), $this);
+        }
+
+        $keys = $this->_allCacheKeys();
+
+        foreach ($keys as $key) {
+            $c->set($key, $this);
         }
     }
 
     function decache()
     {
         $c = $this->memcache();
+
         if (!$c) {
             return false;
-        } else {
-            $pkey = array();
-            $pval = array();
-            $types = $this->keyTypes();
-            ksort($types);
-            foreach ($types as $key => $type) {
-                if ($type == 'K') {
-                    $pkey[] = $key;
-                    $pval[] = $this->$key;
-                } else {
-                    $c->delete($this->cacheKey($this->tableName(), $key, $this->$key));
-                }
-            }
-            # should work for both compound and scalar pkeys
-            # XXX: comma works for now but may not be safe separator for future keys
-            $pvals = implode(',', $pval);
-            $pkeys = implode(',', $pkey);
-            $c->delete($this->cacheKey($this->tableName(), $pkeys, $pvals));
         }
+
+        $keys = $this->_allCacheKeys();
+
+        foreach ($keys as $key) {
+            $c->delete($key, $this);
+        }
+    }
+
+    function _allCacheKeys()
+    {
+        $ckeys = array();
+
+        $types = $this->keyTypes();
+        ksort($types);
+
+        $pkey = array();
+        $pval = array();
+
+        foreach ($types as $key => $type) {
+
+            assert(!empty($key));
+
+            if ($type == 'U') {
+                if (empty($this->$key)) {
+                    continue;
+                }
+                $ckeys[] = $this->cacheKey($this->tableName(), $key, $this->$key);
+            } else if ($type == 'K' || $type == 'N') {
+                $pkey[] = $key;
+                $pval[] = $this->$key;
+            } else {
+                throw new Exception("Unknown key type $key => $type for " . $this->tableName());
+            }
+        }
+
+        assert(count($pkey) > 0);
+
+        // XXX: should work for both compound and scalar pkeys
+        $pvals = implode(',', $pval);
+        $pkeys = implode(',', $pkey);
+
+        $ckeys[] = $this->cacheKey($this->tableName(), $pkeys, $pvals);
+
+        return $ckeys;
     }
 
     function multicache($cls, $kv)