From 410756e5fda39bf88b5bca791ef998a1752690f2 Mon Sep 17 00:00:00 2001
From: eoghan <eoghan@getthere.ie>
Date: Tue, 9 Jun 2020 15:13:31 +0000
Subject: [PATCH] Avoid a build up of duplicate `adds` by delaying pushing to
 adds until emission time

---
 src/record/mutation.ts | 128 +++++++++++++++++++++--------------------
 1 file changed, 65 insertions(+), 63 deletions(-)

diff --git a/src/record/mutation.ts b/src/record/mutation.ts
index d4487a466a..31e5818d40 100644
--- a/src/record/mutation.ts
+++ b/src/record/mutation.ts
@@ -24,7 +24,6 @@ export default class MutationBuffer {
   private texts: textCursor[] = [];
   private attributes: attributeCursor[] = [];
   private removes: removedNodeMutation[] = [];
-  private adds: addedNodeMutation[] = [];
 
   private movedMap: Record<string, true> = {};
 
@@ -69,66 +68,6 @@ export default class MutationBuffer {
   public processMutations = (mutations: mutationRecord[]) => {
     mutations.forEach(this.processMutation);
 
-    /**
-     * Sometimes child node may be pushed before its newly added
-     * parent, so we init a queue to store these nodes.
-     */
-    const addQueue: Node[] = [];
-    const pushAdd = (n: Node) => {
-      const parentId = mirror.getId((n.parentNode as Node) as INode);
-      const nextId =
-        n.nextSibling && mirror.getId((n.nextSibling as unknown) as INode);
-      if (parentId === -1 || nextId === -1) {
-        return addQueue.push(n);
-      }
-      this.adds.push({
-        parentId,
-        nextId,
-        node: serializeNodeWithId(
-          n,
-          document,
-          mirror.map,
-          this.blockClass,
-          true,
-          this.inlineStylesheet,
-          this.maskAllInputs,
-        )!,
-      });
-    };
-
-    for (const n of this.movedSet) {
-      pushAdd(n);
-    }
-
-    for (const n of this.addedSet) {
-      if (
-        !isAncestorInSet(this.droppedSet, n) &&
-        !isParentRemoved(this.removes, n)
-      ) {
-        pushAdd(n);
-      } else if (isAncestorInSet(this.movedSet, n)) {
-        pushAdd(n);
-      } else {
-        this.droppedSet.add(n);
-      }
-    }
-
-    while (addQueue.length) {
-      if (
-        addQueue.every(
-          (n) => mirror.getId((n.parentNode as Node) as INode) === -1,
-        )
-      ) {
-        /**
-         * If all nodes in queue could not find a serialized parent,
-         * it may be a bug or corner case. We need to escape the
-         * dead while loop at once.
-         */
-        break;
-      }
-      pushAdd(addQueue.shift()!);
-    }
-
     if (!this.paused) {
       this.emit();
     }
@@ -237,6 +176,70 @@ export default class MutationBuffer {
   };
 
   public emit = () => {
+
+    const adds: addedNodeMutation[] = [];
+
+    /**
+     * Sometimes child node may be pushed before its newly added
+     * parent, so we init a queue to store these nodes.
+     */
+    const addQueue: Node[] = [];
+    const pushAdd = (n: Node) => {
+      const parentId = mirror.getId((n.parentNode as Node) as INode);
+      const nextId =
+        n.nextSibling && mirror.getId((n.nextSibling as unknown) as INode);
+      if (parentId === -1 || nextId === -1) {
+        return addQueue.push(n);
+      }
+      adds.push({
+        parentId,
+        nextId,
+        node: serializeNodeWithId(
+          n,
+          document,
+          mirror.map,
+          this.blockClass,
+          true,
+          this.inlineStylesheet,
+          this.maskAllInputs,
+        )!,
+      });
+    };
+
+    for (const n of this.movedSet) {
+      pushAdd(n);
+    }
+
+    for (const n of this.addedSet) {
+      if (
+        !isAncestorInSet(this.droppedSet, n) &&
+        !isParentRemoved(this.removes, n)
+      ) {
+        pushAdd(n);
+      } else if (isAncestorInSet(this.movedSet, n)) {
+        pushAdd(n);
+      } else {
+        this.droppedSet.add(n);
+      }
+    }
+
+    while (addQueue.length) {
+      if (
+        addQueue.every(
+          (n) => mirror.getId((n.parentNode as Node) as INode) === -1,
+        )
+      ) {
+        /**
+         * If all nodes in queue could not find a serialized parent,
+         * it may be a bug or corner case. We need to escape the
+         * dead while loop at once.
+         */
+        break;
+      }
+      pushAdd(addQueue.shift()!);
+    }
+
+
     const payload = {
       texts: this.texts
         .map((text) => ({
@@ -253,7 +256,7 @@ export default class MutationBuffer {
         // attribute mutation's id was not in the mirror map means the target node has been removed
         .filter((attribute) => mirror.has(attribute.id)),
       removes: this.removes,
-      adds: this.adds,
+      adds: adds,
     };
     // payload may be empty if the mutations happened in some blocked elements
     if (
@@ -270,7 +273,6 @@ export default class MutationBuffer {
     this.texts = [];
     this.attributes = [];
     this.removes = [];
-    this.adds = [];
     this.addedSet = new Set<Node>();
     this.movedSet = new Set<Node>();
     this.droppedSet = new Set<Node>();