Index: modules/block/block.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/block/block.module,v
retrieving revision 1.223
diff -u -p -r1.223 block.module
--- modules/block/block.module	25 Aug 2006 23:54:18 -0000	1.223
+++ modules/block/block.module	27 Aug 2006 15:51:56 -0000
@@ -7,6 +7,14 @@
  */
 
 /**
+ * Constants to define the caching modes for blocks
+ */
+define('BLOCK_NOT_CACHABLE', 0);
+define('BLOCK_ALWAYS_CACHED', 1);
+define('BLOCK_CACHED_PER_USER', 2);
+define('BLOCK_CACHED_PER_ROLE', 3);
+
+/**
  * Implementation of hook_help().
  */
 function block_help($section) {
@@ -170,6 +178,9 @@ function _block_rehash() {
       foreach ($module_blocks as $delta => $block) {
         $block['module'] = $module;
         $block['delta']  = $delta;
+        $block['cache_mode']  = isset($block['cache_mode']) ? $block['cache_mode'] : BLOCK_ALWAYS_CACHED;
+        // default cache time to live is one hour
+        $block['cache_ttl']  = isset($block['cache_ttl']) ? $block['cache_ttl'] : 3600;
         // If previously written to database, load values.
         if ($old_blocks[$module][$delta]) {
           $block['status'] = $old_blocks[$module][$delta]->status;
@@ -202,7 +213,7 @@ function _block_rehash() {
 
   // Reinsert new set of blocks into table.
   foreach ($blocks as $block) {
-    db_query("INSERT INTO {blocks} (module, delta, theme, status, weight, region, visibility, pages, custom, throttle, title) VALUES ('%s', '%s', '%s', %d, %d, '%s', %d, '%s', %d, %d, '%s')", $block['module'], $block['delta'], $theme_key, $block['status'], $block['weight'], $block['region'], $block['visibility'], $block['pages'], $block['custom'], $block['throttle'], $block['title']);
+    db_query("INSERT INTO {blocks} (module, delta, theme, status, cache_mode, cache_ttl, weight, region, visibility, pages, custom, throttle, title) VALUES ('%s', '%s', '%s', %d, %d, %d, %d, '%s', %d, '%s', %d, %d, '%s')", $block['module'], $block['delta'], $theme_key, $block['status'], $block['cache_mode'], $block['cache_ttl'], $block['weight'], $block['region'], $block['visibility'], $block['pages'], $block['custom'], $block['throttle'], $block['title']);
   }
   db_unlock_tables();
 
@@ -682,9 +693,36 @@ function block_list($region) {
         // Check the current throttle status and see if block should be displayed
         // based on server load.
         if (!($block->throttle && (module_invoke('throttle', 'status') > 0))) {
-          $array = module_invoke($block->module, 'block', 'view', $block->delta);
-          if (isset($array) && is_array($array)) {
-            foreach ($array as $k => $v) {
+          switch ($block->cache_mode) {
+            case BLOCK_NOT_CACHABLE:
+              $cid = NULL;
+              break;
+            case BLOCK_ALWAYS_CACHED:
+              $cid = "$block->module:$block->delta";
+              break;
+            case BLOCK_CACHED_PER_USER:
+              $cid = "$block->module:$block->delta:$user->uid";
+              break;
+            case BLOCK_CACHED_PER_ROLE:
+              $cid = "$block->module:$block->delta:". serialize($user->roles);
+              break;
+          }
+          if ($cid) {
+            $cache = cache_get($cid, 'cache_block');
+          }
+
+          if ($cache->data) {
+            $block_view = unserialize($cache->data);
+          }
+          else {
+            $block_view = module_invoke($block->module, 'block', 'view', $block->delta);
+            if ($cid) {
+              cache_set($cid, 'cache_block', serialize($block_view), $block['cache_ttl'] ? (time() + $block['cache_ttl']) : CACHE_PERMANENT);
+            }
+          }
+
+          if (isset($block_view) && is_array($block_view)) {
+            foreach ($block_view as $k => $v) {
               $block->$k = $v;
             }
           }
Index: modules/user/user.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/user/user.module,v
retrieving revision 1.662
diff -u -p -r1.662 user.module
--- modules/user/user.module	27 Aug 2006 08:56:35 -0000	1.662
+++ modules/user/user.module	27 Aug 2006 15:51:57 -0000
@@ -506,9 +506,17 @@ function user_block($op = 'list', $delta
 
   if ($op == 'list') {
      $blocks[0]['info'] = t('User login');
+     $blocks[0]['cache_mode'] = BLOCK_ALWAYS_CACHED;
+     $blocks[0]['cache_ttl'] = 0;
      $blocks[1]['info'] = t('Navigation');
+     // The navigation block isn't cachable as it also depends on the
+     // page where it appears
+     $blocks[1]['cache_mode'] = BLOCK_NOT_CACHABLE;
      $blocks[2]['info'] = t('Who\'s new');
+     $blocks[2]['cache_mode'] = BLOCK_ALWAYS_CACHED;
+     $blocks[2]['cache_ttl'] = 900;
      $blocks[3]['info'] = t('Who\'s online');
+     $blocks[3]['cache_mode'] = BLOCK_NOT_CACHABLE;
 
      return $blocks;
   }