Use Horde_Lock to lock the resource calendar.

Lock the resource calnedar right before we check availability, and
unlock it either after the invitation is denied, or if accepted,
after the event is added to the resource's calendar.

diff --git a/kronolith/lib/Event.php b/kronolith/lib/Event.php
index d33c460..da5caf0 100644 (file)
--- a/kronolith/lib/Event.php
+++ b/kronolith/lib/Event.php
@@ -317,25 +317,45 @@ abstract class Kronolith_Event
         }
 
         /* Check for acceptance/denial of this event's resources.
-         *
-         * @TODO: Need to look at how to lock the resource to avoid two events
-         * inadvertantly getting accepted. (Two simultaneous requests, both
-         * return RESPONSE_ACCEPTED from getResponse()) Maybe Horde_Lock?
          */
         $add_events = array();
+        $locks = Horde_Lock::singleton($GLOBALS['conf']['lock']['driver']);
+        $lock = array();
+        $failed_resources = array();
         foreach ($this->getResources() as $id => $resourceData) {
+
+            /* Get the resource and protect against infinite recursion in case
+             * someone is silly enough to add a resource to it's own event.*/
             $resource = Kronolith::getDriver('Resource')->getResource($id);
-            // Protect against infinite recursion if someone tries to add a
-            // resource to it's own event.
-            if ($resource->get('calendar') == $this->getCalendar()) {
+            if ($rcal = $resource->get('calendar') == $this->getCalendar()) {
                 continue;
             }
-            $response = $resource->getResponse($this);
+
+            /* Lock the resource and get the response */
+            $principle = 'calendar/' . $rcal;
+            $lock[$resource->getId()] = $locks->setLock(Horde_Auth::getAuth(), 'kronolith', $principle, 5, Horde_Lock::TYPE_EXCLUSIVE);
+            if (!$lock[$resource->getId()]) {
+                // Already locked
+                // For now, just fail. Not sure how else to capture the locked
+                // resources and notify the user.
+                return PEAR::raiseError(sprintf(_("The resource \"%s\" was locked. Please try again."), $resource->get('name')));
+            } else {
+                $response = $resource->getResponse($this);
+            }
+
+            /* Remember accepted resources so we can add the event to their
+             * calendars. Otherwise, clear the lock. */
             if ($response == Kronolith::RESPONSE_ACCEPTED) {
                 $add_events[] = $resource;
+            } else {
+                $locks->clearLock($lock[$resource->getId()]);
             }
+
+            /* Add the resource to the event */
             $this->addResource($resource, $response);
         }
+
+        /* Save */
         $this->toDriver();
         $result = $this->getDriver()->saveEvent($this);
         if (is_a($result, 'PEAR_Error')) {
@@ -351,6 +371,9 @@ abstract class Kronolith_Event
          */
         foreach ($add_events as $resource) {
             $resource->addEvent($this);
+            if ($resource->get('response_type') == Kronolith_Resource::RESPONSETYPE_AUTO) {
+                $locks->clearLock($lock[$resource->getId()]);
+            }
         }
 
         if (!empty($GLOBALS['conf']['alarms']['driver'])) {