Patch based on work of Kjartan:

- Changed cache API.

- Fixed caching bug in comment.module.  Odd this hasn't been reported yet.

- Fixed caching bug in forum.module.

- Fixed caching bug in system.module.

- Fixed caching bug in block.module.

- Simplified caching support in forum.module thanks to improved cache API.

11 files changed, 90 insertions, 64 deletions

diff --git a/includes/common.inc b/includes/common.inc
index b85c0530e..28086de9b 100644
--- a/includes/common.inc
+++ b/includes/common.inc
@@ -473,12 +473,22 @@ function cache_set($cid, $data, $expire = 0) {
   }
 }
 
-function cache_del($cid) {
-  db_query("DELETE FROM cache WHERE cid = '%s'", $cid);
+function cache_clear_all($cid = NULL) {
+  if (empty($cid)) {
+    db_query("DELETE FROM cache");
+  }
+  else {
+    db_query("DELETE FROM cache WHERE cid = '%s'", $cid);
+  }
 }
 
-function cache_clear() {
-  db_query("DELETE FROM cache WHERE expire < ". time() ." AND expire > 0");
+function cache_clear_old($cid = NULL) {
+  if (empty($cid)) {
+    db_query("DELETE FROM cache WHERE expire < ". time() ." AND expire > 0");
+  }
+  else {
+    db_query("DELETE FROM cache WHERE cid = '%s' AND expire < %s AND expire > 0", $cid, time());
+  }
 }
 
 function page_set_cache() {
@@ -486,7 +496,7 @@ function page_set_cache() {
 
   if (!$user->uid && $REQUEST_METHOD == "GET") {
     if ($data = ob_get_contents()) {
-      cache_set(request_uri(), $data, (time() + variable_get("cache_clear", 30)));
+      cache_set(request_uri(), $data, (time() + variable_get("cache_clear", 120)));
     }
   }
 }
@@ -496,7 +506,7 @@ function page_get_cache() {
 
   if (!$user->uid && $REQUEST_METHOD == "GET") {
     if ($cache = cache_get(request_uri())) {
-      cache_clear();
+      cache_clear_old();
     }
     else {
       ob_start();
diff --git a/modules/block.module b/modules/block.module
index f7ec7c24b..847b55aa8 100644
--- a/modules/block.module
+++ b/modules/block.module
@@ -77,6 +77,12 @@ function block_admin_save($edit) {
       db_query("UPDATE blocks SET region = '%s', status = '%d', custom = '%d', path = '%s', weight = '%d' WHERE module = '%s' AND delta = '%d'", $block["region"], $block["status"], $block["custom"], $block["path"], $block["weight"], $module, $delta);
     }
   }
+
+  /*
+  ** Clear the cache so the changes take effect for anonymous users.
+  */
+
+  cache_clear_all();
 }
 
 /**
diff --git a/modules/block/block.module b/modules/block/block.module
index f7ec7c24b..847b55aa8 100644
--- a/modules/block/block.module
+++ b/modules/block/block.module
@@ -77,6 +77,12 @@ function block_admin_save($edit) {
       db_query("UPDATE blocks SET region = '%s', status = '%d', custom = '%d', path = '%s', weight = '%d' WHERE module = '%s' AND delta = '%d'", $block["region"], $block["status"], $block["custom"], $block["path"], $block["weight"], $module, $delta);
     }
   }
+
+  /*
+  ** Clear the cache so the changes take effect for anonymous users.
+  */
+
+  cache_clear_all();
 }
 
 /**
diff --git a/modules/comment.module b/modules/comment.module
index 4c0dd1b64..8c1c7b57f 100644
--- a/modules/comment.module
+++ b/modules/comment.module
@@ -276,17 +276,11 @@ function comment_post($edit) {
       }
 
       /*
-      ** Clear the cache:
+      ** Clear the cache so an anonymous user can see his comment being
+      ** added.
       */
 
-      cache_clear();
-
-      /*
-      ** TODO: we'd prefer to invalidate the page or pages with the newly
-      ** inserted comment.
-      **
-      ** db_query("DELETE FROM cache WHERE cid LIKE '%s'", "%id=".$edit["nid"]."%");
-      */
+      cache_clear_all();
     }
   }
   else {
diff --git a/modules/comment/comment.module b/modules/comment/comment.module
index 4c0dd1b64..8c1c7b57f 100644
--- a/modules/comment/comment.module
+++ b/modules/comment/comment.module
@@ -276,17 +276,11 @@ function comment_post($edit) {
       }
 
       /*
-      ** Clear the cache:
+      ** Clear the cache so an anonymous user can see his comment being
+      ** added.
       */
 
-      cache_clear();
-
-      /*
-      ** TODO: we'd prefer to invalidate the page or pages with the newly
-      ** inserted comment.
-      **
-      ** db_query("DELETE FROM cache WHERE cid LIKE '%s'", "%id=".$edit["nid"]."%");
-      */
+      cache_clear_all();
     }
   }
   else {
diff --git a/modules/forum.module b/modules/forum.module
index 46dacdded..d5c1cea80 100644
--- a/modules/forum.module
+++ b/modules/forum.module
@@ -43,7 +43,6 @@ function forum_conf_options() {
   $forder = array(1 => "Date - newest first", 2 => "Date - oldest first", 3 => "Posts - most active first", 4=> "Posts - least active first");
   $output .= form_select("Default order", "forum_order", variable_get("forum_order", 1), $forder, "The default display order for topics.");
   $output .= form_textfield("Number of topics in block", "forum_block_num", variable_get("forum_block_num", "5"), 5, 5, "The number of topics in the <b>Forum topics</b>-block.  To enable the block, click ". la("here", array("mod" => "block")) .".");
-  $output .= form_select("Internal caching", "forum_cache", variable_get("forum_cache", 0), array("disabled", "enabled"), "Cache internal datastructures for both anonymous and autheticated users.  When enabled, the forum data won't be 100% up to date with regards regard to the number of posts, the number of replies and the last topic being posted.  Enable when you have busy forum.");
 
   return $output;
 }
@@ -91,9 +90,7 @@ function forum_block($op = "list", $delta = 0) {
   }
   else {
     if (user_access("access content")) {
-      if (variable_get("forum_cache", 0)) {
-        $content = cache_get("forum:block");
-      }
+      $content = cache_get("forum:block");
 
       if (!$content) {
         unset($items);
@@ -107,7 +104,7 @@ function forum_block($op = "list", $delta = 0) {
           $content .= "<div id=\"forum_more\" align=\"right\">". lm(t("more"), array("mod" => "forum")) ."</div>";
         }
 
-        cache_set("forum:block", $content, time() + 60 * 3);
+        cache_set("forum:block", $content, time() + variable_get("cache_clear", 120));
       }
 
       $blocks["subject"] = t("Forum topics");
@@ -256,10 +253,6 @@ function forum_insert($node) {
     // we created a shadow, a link to a moved topic in a new forum
     db_query("INSERT INTO forum (nid, icon, shadow) VALUES ('%d', '%s', '%d')", $node->nid, $node->icon, $node->shadow);
   }
-
-  if (variable_get("forum_cache", 0)) {
-    cache_clear();
-  }
 }
 
 function forum_update($node) {
@@ -326,9 +319,7 @@ function forum_get_forums($tid = 0) {
     $tid = 0;
   }
 
-  if (variable_get("forum_cache", 0)) {
-    $forums = unserialize(cache_get("forum:$tid"));
-  }
+  $forums = unserialize(cache_get("forum:$tid"));
 
   if (!$forums) {
     $forums = array();
@@ -347,9 +338,7 @@ function forum_get_forums($tid = 0) {
       $n++;
     }
 
-    if (variable_get("forum_cache", 0)) {
-      cache_set("forum:$tid", serialize($forums), time()+60*10);
-    }
+    cache_set("forum:$tid", serialize($forums), time() + variable_get("cache_clear", 120));
   }
 
   if ($user->uid && $forums) {
diff --git a/modules/forum/forum.module b/modules/forum/forum.module
index 46dacdded..d5c1cea80 100644
--- a/modules/forum/forum.module
+++ b/modules/forum/forum.module
@@ -43,7 +43,6 @@ function forum_conf_options() {
   $forder = array(1 => "Date - newest first", 2 => "Date - oldest first", 3 => "Posts - most active first", 4=> "Posts - least active first");
   $output .= form_select("Default order", "forum_order", variable_get("forum_order", 1), $forder, "The default display order for topics.");
   $output .= form_textfield("Number of topics in block", "forum_block_num", variable_get("forum_block_num", "5"), 5, 5, "The number of topics in the <b>Forum topics</b>-block.  To enable the block, click ". la("here", array("mod" => "block")) .".");
-  $output .= form_select("Internal caching", "forum_cache", variable_get("forum_cache", 0), array("disabled", "enabled"), "Cache internal datastructures for both anonymous and autheticated users.  When enabled, the forum data won't be 100% up to date with regards regard to the number of posts, the number of replies and the last topic being posted.  Enable when you have busy forum.");
 
   return $output;
 }
@@ -91,9 +90,7 @@ function forum_block($op = "list", $delta = 0) {
   }
   else {
     if (user_access("access content")) {
-      if (variable_get("forum_cache", 0)) {
-        $content = cache_get("forum:block");
-      }
+      $content = cache_get("forum:block");
 
       if (!$content) {
         unset($items);
@@ -107,7 +104,7 @@ function forum_block($op = "list", $delta = 0) {
           $content .= "<div id=\"forum_more\" align=\"right\">". lm(t("more"), array("mod" => "forum")) ."</div>";
         }
 
-        cache_set("forum:block", $content, time() + 60 * 3);
+        cache_set("forum:block", $content, time() + variable_get("cache_clear", 120));
       }
 
       $blocks["subject"] = t("Forum topics");
@@ -256,10 +253,6 @@ function forum_insert($node) {
     // we created a shadow, a link to a moved topic in a new forum
     db_query("INSERT INTO forum (nid, icon, shadow) VALUES ('%d', '%s', '%d')", $node->nid, $node->icon, $node->shadow);
   }
-
-  if (variable_get("forum_cache", 0)) {
-    cache_clear();
-  }
 }
 
 function forum_update($node) {
@@ -326,9 +319,7 @@ function forum_get_forums($tid = 0) {
     $tid = 0;
   }
 
-  if (variable_get("forum_cache", 0)) {
-    $forums = unserialize(cache_get("forum:$tid"));
-  }
+  $forums = unserialize(cache_get("forum:$tid"));
 
   if (!$forums) {
     $forums = array();
@@ -347,9 +338,7 @@ function forum_get_forums($tid = 0) {
       $n++;
     }
 
-    if (variable_get("forum_cache", 0)) {
-      cache_set("forum:$tid", serialize($forums), time()+60*10);
-    }
+    cache_set("forum:$tid", serialize($forums), time() + variable_get("cache_clear", 120));
   }
 
   if ($user->uid && $forums) {
diff --git a/modules/node.module b/modules/node.module
index 9424b3ac0..f086eaa0e 100644
--- a/modules/node.module
+++ b/modules/node.module
@@ -209,6 +209,13 @@ function node_save($node, $filter) {
   }
 
   /*
+  ** Clear the cache so an anonymous poster can see the node being added
+  ** or updated.
+  */
+
+  cache_clear_all();
+
+  /*
   ** Return the node ID:
   */
 
diff --git a/modules/node/node.module b/modules/node/node.module
index 9424b3ac0..f086eaa0e 100644
--- a/modules/node/node.module
+++ b/modules/node/node.module
@@ -209,6 +209,13 @@ function node_save($node, $filter) {
   }
 
   /*
+  ** Clear the cache so an anonymous poster can see the node being added
+  ** or updated.
+  */
+
+  cache_clear_all();
+
+  /*
   ** Return the node ID:
   */
 
diff --git a/modules/system.module b/modules/system.module
index 91d2524b6..4ca23b860 100644
--- a/modules/system.module
+++ b/modules/system.module
@@ -15,7 +15,7 @@ function system_system($field){
 
 function system_help_cache() {
   $output .= "<p>Drupal has a caching mechanism that stores dynamically generated pages in a database.  By caching a page, Drupal does not have to generate the page each time it is requested.  Only pages requested by anonymous users are being cached.  When a cached page is accessed, Drupal will retrieve that page with minimal overhead using one SQL query only, thus reducing both the server load and the response time.</p>";
-  $output .= "<p>Drupal's caching mechanism can be enabled and disabled by the site administrators from the 'settings' page.  He can also define how long cached pages should be kept.</p>";
+  $output .= "<p>Drupal's caching mechanism can be enabled and disabled by the site administrators from the 'settings' page.  Site administrators can also define how long cached pages should be kept.</p>";
   return $output;
 }
 
@@ -59,7 +59,7 @@ function system_view_options() {
   $output .= "<h3>" . t("Cache settings") . "</h3>\n";
   $period = array(10 => format_interval(10), 20 => format_interval(20), 30 => format_interval(30), 40 => format_interval(40), 50 => format_interval(50), 50 => format_interval(50), 60 => format_interval(60), 90 => format_interval(90), 120 => format_interval(120), 150 => format_interval(150), 180 => format_interval(180), 210 => format_interval(210), 240 => format_interval(240), 270 => format_interval(270), 300 => format_interval(300), 360 => format_interval(360), 420 => format_interval(420), 480 => format_interval(480), 540 => format_interval(540), 600 => format_interval(600), 1800 => format_interval(1800), 3600 => format_interval(3600), 7200 => format_interval(7200));
   $output .= form_select(t("Cache support"), "cache", variable_get("cache", 0), array(t("Disabled"), t("Enabled")), t("Enable or disable the caching of pages."));
-  $output .= form_select(t("Discard cached pages older than"), "cache_clear", variable_get("cache_clear", 30), $period, t("The time cached pages should be kept.  Older pages are automatically refreshed."));
+  $output .= form_select(t("Discard cached pages older than"), "cache_clear", variable_get("cache_clear", 120), $period, t("The time cached pages should be kept.  Older pages are automatically refreshed."));
   $output .= "<hr />\n";
 
   // submission settings:
@@ -105,12 +105,24 @@ function system_view_filters() {
 }
 
 function system_save($edit = array()) {
-  foreach ($edit as $name => $value) variable_set($name, $value);
+  foreach ($edit as $name => $value) {
+    variable_set($name, $value);
+  }
+
+  /*
+  ** Clear the cache so the changes take effect for anonymous users.
+  */
+
+  cache_clear_all();
+
   return t("The configuration options have been saved.");
 }
 
 function system_default($edit = array()) {
-  foreach ($edit as $name => $value) variable_del($name);
+  foreach ($edit as $name => $value) {
+    variable_del($name);
+  }
+
   return t("The configuration options have been reset to their default values.");
 }
 
@@ -197,7 +209,7 @@ function system_listing($type, $directory, $required = array()) {
       }
     }
 
-    // Clean up database.
+    // Update the contents of the system table:
     db_query("DELETE FROM system WHERE filename = '%s' AND type = '%s'", $filename, $type);
     db_query("INSERT INTO system (name, description, type, filename, status) VALUES ('%s', '%s', '%s', '%s', %d)", $info->name, $info->description, $type, $filename, $file->status);
 
diff --git a/modules/system/system.module b/modules/system/system.module
index 91d2524b6..4ca23b860 100644
--- a/modules/system/system.module
+++ b/modules/system/system.module
@@ -15,7 +15,7 @@ function system_system($field){
 
 function system_help_cache() {
   $output .= "<p>Drupal has a caching mechanism that stores dynamically generated pages in a database.  By caching a page, Drupal does not have to generate the page each time it is requested.  Only pages requested by anonymous users are being cached.  When a cached page is accessed, Drupal will retrieve that page with minimal overhead using one SQL query only, thus reducing both the server load and the response time.</p>";
-  $output .= "<p>Drupal's caching mechanism can be enabled and disabled by the site administrators from the 'settings' page.  He can also define how long cached pages should be kept.</p>";
+  $output .= "<p>Drupal's caching mechanism can be enabled and disabled by the site administrators from the 'settings' page.  Site administrators can also define how long cached pages should be kept.</p>";
   return $output;
 }
 
@@ -59,7 +59,7 @@ function system_view_options() {
   $output .= "<h3>" . t("Cache settings") . "</h3>\n";
   $period = array(10 => format_interval(10), 20 => format_interval(20), 30 => format_interval(30), 40 => format_interval(40), 50 => format_interval(50), 50 => format_interval(50), 60 => format_interval(60), 90 => format_interval(90), 120 => format_interval(120), 150 => format_interval(150), 180 => format_interval(180), 210 => format_interval(210), 240 => format_interval(240), 270 => format_interval(270), 300 => format_interval(300), 360 => format_interval(360), 420 => format_interval(420), 480 => format_interval(480), 540 => format_interval(540), 600 => format_interval(600), 1800 => format_interval(1800), 3600 => format_interval(3600), 7200 => format_interval(7200));
   $output .= form_select(t("Cache support"), "cache", variable_get("cache", 0), array(t("Disabled"), t("Enabled")), t("Enable or disable the caching of pages."));
-  $output .= form_select(t("Discard cached pages older than"), "cache_clear", variable_get("cache_clear", 30), $period, t("The time cached pages should be kept.  Older pages are automatically refreshed."));
+  $output .= form_select(t("Discard cached pages older than"), "cache_clear", variable_get("cache_clear", 120), $period, t("The time cached pages should be kept.  Older pages are automatically refreshed."));
   $output .= "<hr />\n";
 
   // submission settings:
@@ -105,12 +105,24 @@ function system_view_filters() {
 }
 
 function system_save($edit = array()) {
-  foreach ($edit as $name => $value) variable_set($name, $value);
+  foreach ($edit as $name => $value) {
+    variable_set($name, $value);
+  }
+
+  /*
+  ** Clear the cache so the changes take effect for anonymous users.
+  */
+
+  cache_clear_all();
+
   return t("The configuration options have been saved.");
 }
 
 function system_default($edit = array()) {
-  foreach ($edit as $name => $value) variable_del($name);
+  foreach ($edit as $name => $value) {
+    variable_del($name);
+  }
+
   return t("The configuration options have been reset to their default values.");
 }
 
@@ -197,7 +209,7 @@ function system_listing($type, $directory, $required = array()) {
       }
     }
 
-    // Clean up database.
+    // Update the contents of the system table:
     db_query("DELETE FROM system WHERE filename = '%s' AND type = '%s'", $filename, $type);
     db_query("INSERT INTO system (name, description, type, filename, status) VALUES ('%s', '%s', '%s', '%s', %d)", $info->name, $info->description, $type, $filename, $file->status);