[BACKPORT] Performance Tuning for Ember 3.13

packages/@glimmer/reference/lib/validators.ts

@@ -175,20 +175,27 @@ function _combine(tags: Tag[]): Tag {
 export abstract class CachedTag extends RevisionTag {
   private lastChecked: Option<Revision> = null;
   private lastValue: Option<Revision> = null;
+  private isUpdating = false;
 
   value(): Revision {
     let { lastChecked } = this;
 
     if (lastChecked !== $REVISION) {
+      this.isUpdating = true;
       this.lastChecked = $REVISION;
-      this.lastValue = this.compute();
+
+      try {
+        this.lastValue = this.compute();
+      } finally {
+        this.isUpdating = false;
+      }
     }
 
-    return this.lastValue as Revision;
-  }
+    if (this.isUpdating) {
+      this.lastChecked = ++$REVISION;
+    }
 
-  protected invalidate() {
-    this.lastChecked = null;
+    return this.lastValue as Revision;
   }
 
   protected abstract compute(): Revision;
@@ -244,30 +251,33 @@ class TagsCombinator extends CachedTag {
 register(TagsCombinator);
 
 export class UpdatableTag extends CachedTag {
-  static create(tag: Tag): TagWrapper<UpdatableTag> {
+  static create(tag: Tag = CONSTANT_TAG): TagWrapper<UpdatableTag> {
     return new TagWrapper(this.id, new UpdatableTag(tag));
   }
 
   private tag: Tag;
-  private lastUpdated: number;
+  private revision: Revision;
 
-  private constructor(tag: Tag) {
+  private constructor(tag: Tag, revision = $REVISION) {
     super();
     this.tag = tag;
-    this.lastUpdated = INITIAL;
+    this.revision = revision;
   }
 
   protected compute(): Revision {
-    return Math.max(this.lastUpdated, this.tag.value());
+    return Math.max(this.tag.value(), this.revision);
   }
 
   update(tag: Tag) {
     if (tag !== this.tag) {
       this.tag = tag;
-      this.lastUpdated = $REVISION;
-      this.invalidate();
+      ++$REVISION;
     }
   }
+
+  dirty() {
+    this.revision = ++$REVISION;
+  }
 }
 
 register(UpdatableTag);