8 files changed, 39 insertions, 15 deletions
diff --git a/database/database.mysql b/database/database.mysql
index 45d864e7e..014b63c99 100644
--- a/database/database.mysql
+++ b/database/database.mysql
@@ -165,7 +165,8 @@ CREATE TABLE cache (
   expire int(11) NOT NULL default '0',
   created int(11) NOT NULL default '0',
   headers text,
-  PRIMARY KEY  (cid)
+  PRIMARY KEY  (cid),
+  INDEX expire (expire)
 ) TYPE=MyISAM;
 
 --
diff --git a/database/database.pgsql b/database/database.pgsql
index 339549516..375281dfa 100644
--- a/database/database.pgsql
+++ b/database/database.pgsql
@@ -168,6 +168,7 @@ CREATE TABLE cache (
   headers text default '',
   PRIMARY KEY  (cid)
 );
+CREATE INDEX cache_expire_idx ON cache(expire);
 
 --
 -- Table structure for comments
diff --git a/database/updates.inc b/database/updates.inc
index 9489780dc..2435492c9 100644
--- a/database/updates.inc
+++ b/database/updates.inc
@@ -81,7 +81,8 @@ $sql_updates = array(
   "2004-08-12" => "update_102",
   "2004-08-17" => "update_103",
   "2004-08-19" => "update_104",
-  "2004-09-14" => "update_105"
+  "2004-09-14" => "update_105",
+  "2004-09-15" => "update_106"
 );
 
 function update_32() {
@@ -1798,6 +1799,19 @@ function update_105() {
   return $ret;
 }
 
+function update_106() {
+  $ret = array();
+  if ($GLOBALS['db_type'] == 'mysql') {
+    $ret[] = update_sql('ALTER TABLE {cache} ADD INDEX expire (expire)');
+  }
+  else if ($GLOBALS['db_type'] == 'pgsql') {
+    // TODO: needs PGSQL equivalent.
+  }
+
+  $ret[] = update_sql('DELETE FROM {cache}');
+  return $ret;
+}
+
 function update_sql($sql) {
   $edit = $_POST["edit"];
   $result = db_query($sql);
diff --git a/includes/bootstrap.inc b/includes/bootstrap.inc
index 291eb5bbd..cf55dc173 100644
--- a/includes/bootstrap.inc
+++ b/includes/bootstrap.inc
@@ -5,6 +5,9 @@
  * @file
  * Functions that need to be loaded on every Drupal request.
  */
+ 
+define('CACHE_PERMANENT', 0);
+define('CACHE_TEMPORARY', -1);
 
 /**
  * Locate the appropriate configuration file.
@@ -126,18 +129,23 @@ function cache_get($key) {
  * @param $data
  *   The data to store in the cache. Complex data types must be serialized first.
  * @param $expire
- *   Whether the data should be removed from the cache when a cache expiration
- *   is triggered.
+ *   One of the following values:
+ *   - CACHE_PERMANENT: Indicates that the item should never be removed unless
+ *     explicitly told to using cache_clear_all() with a cache ID.
+ *   - CACHE_TEMPORARY: Indicates that the item should be removed at the next
+ *     general cache wipe.
+ *   - A Unix timestamp: Indicates that the item should be kept at least until
+ *     the given time, after which it behaves like CACHE_TEMPORARY.
  * @param $headers
  *   A string containing HTTP header information for cached pages.
  */
-function cache_set($cid, $data, $expire = 0, $headers = NULL) {
+function cache_set($cid, $data, $expire = CACHE_PERMANENT, $headers = NULL) {
   $data = db_encode_blob($data);
 
   db_query("UPDATE {cache} SET data = '%s', created = %d, expire = %d, headers = '%s' WHERE cid = '%s'", $data, time(), $expire, $headers, $cid);
   if (!db_affected_rows()) {
-   db_query("INSERT INTO {cache} (cid, data, created, expire, headers) VALUES('%s', '%s', %d, %d, '%s')", $cid, $data, time(), $expire, $headers);
- }
+    db_query("INSERT INTO {cache} (cid, data, created, expire, headers) VALUES ('%s', '%s', %d, %d, '%s')", $cid, $data, time(), $expire, $headers);
+  }
 }
 
 /**
@@ -153,7 +161,7 @@ function cache_set($cid, $data, $expire = 0, $headers = NULL) {
  */
 function cache_clear_all($cid = NULL, $wildcard = false) {
   if (empty($cid)) {
-    db_query("DELETE FROM {cache} WHERE expire <> 0");
+    db_query("DELETE FROM {cache} WHERE expire != %d AND expire < %d", CACHE_PERMANENT, time());
   }
   else {
     if ($wildcard) {
@@ -182,7 +190,7 @@ function page_set_cache() {
           $data = gzencode($data, FORCE_GZIP);
         }
       }
-      cache_set($base_url . request_uri(), $data, 1, drupal_get_headers());
+      cache_set($base_url . request_uri(), $data, CACHE_TEMPORARY, drupal_get_headers());
     }
   }
 }
diff --git a/modules/archive.module b/modules/archive.module
index 2e6a78654..21047dae7 100644
--- a/modules/archive.module
+++ b/modules/archive.module
@@ -169,7 +169,7 @@ function archive_calendar($original = 0) {
 
   $output .= "</table></div>\n\n";
 
-  cache_set("archive:calendar:$day-$month-$year", $output, 1);
+  cache_set("archive:calendar:$day-$month-$year", $output, CACHE_TEMPORARY);
 
   return $output;
 }
diff --git a/modules/archive/archive.module b/modules/archive/archive.module
index 2e6a78654..21047dae7 100644
--- a/modules/archive/archive.module
+++ b/modules/archive/archive.module
@@ -169,7 +169,7 @@ function archive_calendar($original = 0) {
 
   $output .= "</table></div>\n\n";
 
-  cache_set("archive:calendar:$day-$month-$year", $output, 1);
+  cache_set("archive:calendar:$day-$month-$year", $output, CACHE_TEMPORARY);
 
   return $output;
 }
diff --git a/modules/filter.module b/modules/filter.module
index 1cf09d48c..dece83b8e 100644
--- a/modules/filter.module
+++ b/modules/filter.module
@@ -593,9 +593,9 @@ function check_output($text, $format = FILTER_FORMAT_DEFAULT) {
       $text = module_invoke($filter->module, 'filter', 'process', $filter->delta, $format, $text);
     }
 
-    // Store in cache.
+    // Store in cache with a minimum expiration time of 1 day.
     if ($cache) {
-      cache_set($id, $text, 1);
+      cache_set($id, $text, time() + (60 * 60 * 24));
     }
   }
   else {
diff --git a/modules/filter/filter.module b/modules/filter/filter.module
index 1cf09d48c..dece83b8e 100644
--- a/modules/filter/filter.module
+++ b/modules/filter/filter.module
@@ -593,9 +593,9 @@ function check_output($text, $format = FILTER_FORMAT_DEFAULT) {
       $text = module_invoke($filter->module, 'filter', 'process', $filter->delta, $format, $text);
     }
 
-    // Store in cache.
+    // Store in cache with a minimum expiration time of 1 day.
     if ($cache) {
-      cache_set($id, $text, 1);
+      cache_set($id, $text, time() + (60 * 60 * 24));
     }
   }
   else {