- Patch #29274 by Jeremy: the "fuzzy cache" mechanism is supposed to enforce a minimum time before the cache table is flushed. Logical errors in the fuzzy cache implementation are leading to the cache table being flushed more frequently. Configuration is simplified by removing all references to "strict" and "loose" caches. Instead, the cache is either "disabled" or "enabled". Additionally, the site administrator can now configure the "minimum cache lifetime", the minimum amount of time cached data will remain cached.

1 files changed, 34 insertions, 30 deletions

diff --git a/includes/bootstrap.inc b/includes/bootstrap.inc
index 07aa5c226..1ce0ea3f8 100644
--- a/includes/bootstrap.inc
+++ b/includes/bootstrap.inc
@@ -10,8 +10,7 @@ define('CACHE_PERMANENT', 0);
 define('CACHE_TEMPORARY', -1);
 
 define('CACHE_DISABLED', 0);
-define('CACHE_ENABLED_STRICT', 1);
-define('CACHE_ENABLED_LOOSE', 2);
+define('CACHE_ENABLED', 1);
 
 define('WATCHDOG_NOTICE', 0);
 define('WATCHDOG_WARNING', 1);
@@ -267,9 +266,9 @@ function variable_del($name) {
 function cache_get($key) {
   global $user;
 
-  // CACHE_ENABLED_LOOSE garbage collection
+  // Garbage collection necessary when enforcing a minimum cache lifetime
   $cache_flush = variable_get('cache_flush', 0);
-  if ($cache_flush && ($cache_flush + variable_get('cache_flush_delay', 300) <= time())) {
+  if ($cache_flush && ($cache_flush + variable_get('cache_lifetime', 0) <= time())) {
     // Time to flush old cache data
     db_query("DELETE FROM {cache} WHERE expire != %d AND expire <= %d", CACHE_PERMANENT, $cache_flush);
     variable_set('cache_flush', 0);
@@ -277,14 +276,16 @@ function cache_get($key) {
 
   $cache = db_fetch_object(db_query("SELECT data, created, headers, expire FROM {cache} WHERE cid = '%s'", $key));
   if (isset($cache->data)) {
-    // If data is permanent or using strict caching, always return data.
-    if ($cache->expire == CACHE_PERMANENT || variable_get('cache', CACHE_DISABLED) == CACHE_ENABLED_STRICT) {
+    // If the data is permanent or we're not enforcing a minimum cache lifetime
+    // always return the cached data.
+    if ($cache->expire == CACHE_PERMANENT || !variable_get('cache_lifetime', 0)) {
       $cache->data = db_decode_blob($cache->data);
     }
-    // If using loose caching, validate data is current before we return it by
-    // making sure the cache entry was created before the timestamp in the
-    // current session's cache timer.  The cache variable is already loaded
-    // into the $user object by sess_read in session.inc.
+    // If enforcing a minimum cache lifetime, validate that the data is
+    // currenly valid for this user before we return it by making sure the
+    // cache entry was created before the timestamp in the current session's
+    // cache timer.  The cache variable is loaded into the $user object by
+    // sess_read() in session.inc.
     else {
       if ($user->cache > $cache->created) {
         // This cache data is too old and thus not valid for us, ignore it.
@@ -343,28 +344,28 @@ function cache_clear_all($cid = NULL, $wildcard = false) {
   global $user;
 
   if (empty($cid)) {
-    if (variable_get('cache', CACHE_DISABLED) == CACHE_ENABLED_STRICT) {
-      // Strict caching, flush all temporary cache entries:
-      db_query("DELETE FROM {cache} WHERE expire != %d AND expire < %d", CACHE_PERMANENT, time());
-    }
-    else {
-      $cache_flush = variable_get('cache_flush', 0);
-      // Loose caching, only flush temporary cache entries that have been
-      // invalidated for more than maximum allowable time.
-      if ($cache_flush && ($cache_flush + variable_get('cache_flush_delay', 300) <= time())) {
-        // Only flush cache data older than $cache_flush, as newer data may
-        // now be valid.
-        db_query("DELETE FROM {cache} WHERE expire != %d AND expire <= %d", CACHE_PERMANENT, $cache_flush);
-        variable_set('cache_flush', 0);
-      }
-      // Invalidate temporary cache data only for current user/session.  We
-      // set $user->cache, which gets saved into the sessions table by
-      // sess_write() in session.inc.
+    if (variable_get('cache_lifetime', 0)) {
+      // We store the time in the current user's $user->cache variable which
+      // will be saved into the sessions table by sess_write().  We then
+      // simulate that the cache was flushed for this user by not returning
+      // cached data that was cached before the timestamp.
       $user->cache = time();
-      if (variable_get('cache_flush', 0) == 0) {
-        // Set timestamp to know which cache entries we eventually clear:
+
+      $cache_flush = variable_get('cache_flush', 0);
+      if ($cache_flush == 0) {
+        // This is the first request to clear the cache, start a timer.
         variable_set('cache_flush', time());
       }
+      else if (time() > ($cache_flush + variable_get('cache_lifetime', 0))) {
+        // Clear the cache for everyone, cache_flush_delay seconds have
+        // passed since the first request to clear the cache.
+        db_query("DELETE FROM {cache} WHERE expire != %d AND expire < %d", CACHE_PERMANENT, time());
+        variable_set('cache_flush', 0);
+      }
+    }
+    else {
+      // No minimum cache lifetime, flush all temporary cache entries now.
+      db_query("DELETE FROM {cache} WHERE expire != %d AND expire < %d", CACHE_PERMANENT, time());
     }
   }
   else {
@@ -484,6 +485,7 @@ function drupal_lookup_path($action, $path = '') {
   static $map = array();
   static $count = NULL;
 
+
   if ($count === NULL) {
     $count = db_result(db_query('SELECT COUNT(pid) FROM {url_alias}'));
   }
@@ -493,6 +495,8 @@ function drupal_lookup_path($action, $path = '') {
   }
   elseif ($count > 0 && $path != '') {
     if ($action == 'source') {
+      if (TRUE) return;
+
       if (isset($map[$path])) {
         return $map[$path];
       }
@@ -879,4 +883,4 @@ function drupal_maintenance_theme() {
   $theme = '';
 }
 
-?>
\ No newline at end of file
+?>