support split master/slave backends for the primary database

db-backends.php

@@ -25,7 +25,7 @@ function noblogs_load_backends($db_config_file, $hashptr) {
         "password" => $backend_url_data["pass"],
         "name" => substr($backend_url_data["path"], 1),
         "dataset" => $dataset,
-        "read" => 1, "write" => 1, "timeout" => 2
+        "read" => 1, "write" => 1, "timeout" => 10
         );
     $wpdb->add_database($backend);
     $hashptr->addTarget($dataset);
@@ -34,3 +34,17 @@ function noblogs_load_backends($db_config_file, $hashptr) {
   fclose($fp);
   return $backend_map;
 }
+
+function noblogs_load_master($master_file) {
+  $master_url = trim(file_get_contents($master_file));
+  $mdata = parse_url($master_url);
+  return array(
+      "host" => $mdata["host"] . ":" . $mdata["port"],
+      "user" => $mdata["user"],
+      "password" => $mdata["pass"],
+      "name" => substr($mdata["path"], 1),
+      "dataset" => "global",
+      "read" => 0, "write" => 1, "timeout" => 10
+      );
+}
+