From 1946db376632c68967d99dbb4031023d73fad015 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=EF=BD=81=EF=BD=99=EF=BD=95=EF=BD=8D=EF=BD=89=C2=A0=20?=
 =?UTF-8?q?=EF=BD=99=EF=BD=95?= <ayumi@ayumiyu.com>
Date: Sun, 22 Jan 2017 18:32:40 -0800
Subject: [PATCH] Sync: Apply records asynchronously

Fix https://github.com/brave/sync/issues/44

Auditors: @diracdeltas

Test Plan:
1. Start Pyramid 1 which has a bunch of syncable data. Sync should enabled.
2. Setup Pyramid 2 (add `"start2": "node ./tools/start.js --user-data-dir=brave-development-2 --debug=5859 --enable-logging --v=0 --enable-extension-activity-logging --enable-sandbox-logging --enable-dcheck",` to package.json) and specify the Pyramid 1 Sync credentials.
3. When Pyramid 2 restarts and begins syncing data, Brave should be somewhat usable (not completely frozen for 60s).
---
 app/sync.js          |  2 +-
 js/state/syncUtil.js | 13 +++++++++++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/app/sync.js b/app/sync.js
index 3529c9c0948..38b576ba449 100644
--- a/app/sync.js
+++ b/app/sync.js
@@ -201,7 +201,7 @@ module.exports.onSyncReady = (isFirstRun, e) => {
       return
     }
     log(`applying resolved ${records.length} ${categoryName}.`)
-    for (let record of records) { syncUtil.applySyncRecord(record) }
+    syncUtil.applySyncRecords(records)
   })
   // Periodically poll for new records
   let startAt = appState.getIn(['sync', 'lastFetchTimestamp']) || 0
diff --git a/js/state/syncUtil.js b/js/state/syncUtil.js
index f39b037157c..03715be31a9 100644
--- a/js/state/syncUtil.js
+++ b/js/state/syncUtil.js
@@ -155,6 +155,19 @@ module.exports.applySyncRecord = (record) => {
   }
 }
 
+/**
+ * Apply several SyncRecords in a less blocking manner.
+ * @param {Array<Object>} records
+ */
+module.exports.applySyncRecords = (records) => {
+  if (!records || records.length === 0) { return }
+  setImmediate(() => {
+    const record = records.shift()
+    this.applySyncRecord(record)
+    this.applySyncRecords(records)
+  })
+}
+
 /**
  * Given a category and SyncRecord, get an existing browser object.
  * Used to respond to IPC GET_EXISTING_OBJECTS.