- Patch #314358 by wonder95, Crell, killes, et al: add option to ignore slave servers. Finally.

1 files changed, 24 insertions, 0 deletions

diff --git a/modules/system/system.module b/modules/system/system.module
index 7a2667457..567cf8989 100644
--- a/modules/system/system.module
+++ b/modules/system/system.module
@@ -872,8 +872,32 @@ function system_init() {
   drupal_add_css(drupal_get_path('module', 'system') . '/defaults.css');
   drupal_add_css(drupal_get_path('module', 'system') . '/system.css');
   drupal_add_css(drupal_get_path('module', 'system') . '/system-menus.css');
+
+
+  // Ignore slave database servers for this request.
+  //
+  // In Drupal's distributed database structure, new data is written to the master
+  // and then propagated to the slave servers.  This means there is a lag
+  // between when data is written to the master and when it is available on the slave.
+  // At these times, we will want to avoid using a slave server temporarily.
+  // For example, if a user posts a new node then we want to disable the slave
+  // server for that user temporarily to allow the slave server to catch up.
+  // That way, that user will see their changes immediately while for other
+  // users we still get the benefits of having a slave server, just with slightly
+  // stale data.  Code that wants to disable the slave server should use the 
+  // db_set_ignore_slave() function to set $_SESSION['ignore_slave_server'] to 
+  // the timestamp after which the slave can be re-enabled.
+  if (isset($_SESSION['ignore_slave_server'])) {
+    if ($_SESSION['ignore_slave_server'] >= REQUEST_TIME) {
+      Database::ignoreTarget('default', 'slave');
+    }
+    else {
+      unset($_SESSION['ignore_slave_server']);
+    }
+  }
 }
 
+
 /**
  * Implement MODULE_preprocess_HOOK().
  */