Merge "Do not re-render a <gr-comment-thread> when the thread has not changed"
diff --git a/polygerrit-ui/app/elements/shared/gr-comment-thread/gr-comment-thread.ts b/polygerrit-ui/app/elements/shared/gr-comment-thread/gr-comment-thread.ts
index a895a5b..7a4b6f2 100644
--- a/polygerrit-ui/app/elements/shared/gr-comment-thread/gr-comment-thread.ts
+++ b/polygerrit-ui/app/elements/shared/gr-comment-thread/gr-comment-thread.ts
@@ -69,6 +69,7 @@
import {classMap} from 'lit/directives/class-map';
import {ShortcutController} from '../../lit/shortcut-controller';
import {ValueChangedEvent} from '../../../types/events';
+import {notDeepEqual} from '../../../utils/deep-util';
const NEWLINE_PATTERN = /\n/g;
@@ -112,8 +113,17 @@
@queryAll('gr-comment')
commentElements?: NodeList;
- /** Required to be set by parent. */
- @property()
+ /**
+ * Required to be set by parent.
+ *
+ * Lit's `hasChanged` change detection defaults to just checking strict
+ * equality (===). Here it makes sense to install a proper `deepEqual`
+ * check, because of how the comments-model and ChangeComments are setup:
+ * Each thread object is recreated on the slightest model change. So when you
+ * have 100 comment threads and there is an update to one thread, then you
+ * want to avoid re-rendering the other 99 threads.
+ */
+ @property({hasChanged: notDeepEqual})
thread?: CommentThread;
/**
diff --git a/polygerrit-ui/app/utils/deep-util.ts b/polygerrit-ui/app/utils/deep-util.ts
index ff19635..694a8d7 100644
--- a/polygerrit-ui/app/utils/deep-util.ts
+++ b/polygerrit-ui/app/utils/deep-util.ts
@@ -37,6 +37,10 @@
return false;
}
+export function notDeepEqual<T>(a: T, b: T): boolean {
+ return !deepEqual(a, b);
+}
+
/**
* @param obj Object
*/
