fix race conditions when processing multiple choice polls

1 files changed, 24 insertions, 4 deletions

diff --git a/Zotlabs/Lib/Activity.php b/Zotlabs/Lib/Activity.php
index 8f4e0444c..4a14b1ba1 100644
--- a/Zotlabs/Lib/Activity.php
+++ b/Zotlabs/Lib/Activity.php
@@ -2081,16 +2081,29 @@ class Activity {
 
 	}
 
-	static function update_poll($item, $post) {
+	static function update_poll($item_id, $post) {
 
 		$multi   = false;
 		$mid     = $post['mid'];
 		$content = $post['title'];
 
+		if (!$item_id) {
+			return false;
+		}
+
+		dbq("START TRANSACTION");
+
+		$item = q("SELECT * FROM item WHERE id = %d FOR UPDATE",
+			intval($item_id)
+		);
+
 		if (!$item) {
+			dbq("COMMIT");
 			return false;
 		}
 
+		$item = $item[0];
+
 		$o = json_decode($item['obj'], true);
 		if ($o && array_key_exists('anyOf', $o)) {
 			$multi = true;
@@ -2162,16 +2175,23 @@ class Activity {
 		}
 		logger('updated_poll: ' . print_r($o, true), LOGGER_DATA);
 		if ($answer_found && !$found) {
-			q("update item set obj = '%s', edited = '%s' where id = %d",
+			$u = q("update item set obj = '%s', edited = '%s' where id = %d",
 				dbesc(json_encode($o)),
 				dbesc(datetime_convert()),
 				intval($item['id'])
 			);
 
-			Master::Summon(['Notifier', 'wall-new', $item['id'], $post['mid'] /* trick queueworker de-duplication  */ ]);
-			return true;
+			if ($u) {
+				dbq("COMMIT");
+				Master::Summon(['Notifier', 'wall-new', $item['id']/* , $post['mid'] trick queueworker de-duplication  */ ]);
+				return true;
+			}
+
+			dbq("ROLLBACK");
+
 		}
 
+		dbq("COMMIT");
 		return false;
 	}