From 6e923a9df83392053d09d803044ddc826b2ba0bb Mon Sep 17 00:00:00 2001
From: Benjamin Pasero <benjpas@microsoft.com>
Date: Fri, 21 Dec 2018 08:33:31 +0100
Subject: [PATCH] perf - avoid writing state when state did not change

---
 .../history/electron-main/historyMainService.ts  |  7 ++++++-
 src/vs/platform/menubar/electron-main/menubar.ts |  4 ----
 src/vs/platform/state/node/stateService.ts       | 16 +++++++++++++---
 3 files changed, 19 insertions(+), 8 deletions(-)

diff --git a/src/vs/platform/history/electron-main/historyMainService.ts b/src/vs/platform/history/electron-main/historyMainService.ts
index 88e7c2e5b2a..ac90272ec41 100644
--- a/src/vs/platform/history/electron-main/historyMainService.ts
+++ b/src/vs/platform/history/electron-main/historyMainService.ts
@@ -180,7 +180,6 @@ export class HistoryMainService implements IHistoryMainService {
 		// out of sync quickly over time. the attempted fix is to always set the list fresh
 		// from our MRU history data. So we clear the documents first and then set the documents
 		// again.
-
 		app.clearRecentDocuments();
 
 		const mru = this.getRecentlyOpened();
@@ -257,6 +256,7 @@ export class HistoryMainService implements IHistoryMainService {
 		if (workspaceOrFile instanceof URI) {
 			return getComparisonKey(workspaceOrFile);
 		}
+
 		return workspaceOrFile.id;
 	}
 
@@ -286,6 +286,7 @@ export class HistoryMainService implements IHistoryMainService {
 					}
 				}
 			}
+
 			if (Array.isArray(storedRecents.files2)) {
 				for (const file of storedRecents.files2) {
 					if (typeof file === 'string') {
@@ -300,11 +301,13 @@ export class HistoryMainService implements IHistoryMainService {
 				}
 			}
 		}
+
 		return result;
 	}
 
 	private saveRecentlyOpened(recent: IRecentlyOpened): void {
 		const serialized: ISerializedRecentlyOpened = { workspaces2: [], files2: [] };
+
 		for (const workspace of recent.workspaces) {
 			if (isSingleFolderWorkspaceIdentifier(workspace)) {
 				serialized.workspaces2.push(workspace.toString());
@@ -312,9 +315,11 @@ export class HistoryMainService implements IHistoryMainService {
 				serialized.workspaces2.push(workspace);
 			}
 		}
+
 		for (const file of recent.files) {
 			serialized.files2.push(file.toString());
 		}
+
 		this.stateService.setItem(HistoryMainService.recentlyOpenedStorageKey, serialized);
 	}
 
diff --git a/src/vs/platform/menubar/electron-main/menubar.ts b/src/vs/platform/menubar/electron-main/menubar.ts
index e6592a75a30..43c65fcdb05 100644
--- a/src/vs/platform/menubar/electron-main/menubar.ts
+++ b/src/vs/platform/menubar/electron-main/menubar.ts
@@ -93,10 +93,6 @@ export class Menubar {
 	}
 
 	private restoreCachedMenubarData() {
-		// TODO@sbatten remove this at some point down the road
-		const outdatedKeys = ['lastKnownAdditionalKeybindings', 'lastKnownKeybindings', 'lastKnownMenubar'];
-		outdatedKeys.forEach(key => this.stateService.removeItem(key));
-
 		const menubarData = this.stateService.getItem<IMenubarData>(Menubar.lastKnownMenubarStorageKey);
 		if (menubarData) {
 			if (menubarData.menus) {
diff --git a/src/vs/platform/state/node/stateService.ts b/src/vs/platform/state/node/stateService.ts
index 994e8b22fad..c4b5bc9bad8 100644
--- a/src/vs/platform/state/node/stateService.ts
+++ b/src/vs/platform/state/node/stateService.ts
@@ -15,6 +15,7 @@ import { readFile } from 'vs/base/node/pfs';
 export class FileStorage {
 
 	private _database: object | null = null;
+	private lastFlushedSerializedDatabase: string | null = null;
 
 	constructor(private dbPath: string, private onError: (error: Error) => void) { }
 
@@ -29,7 +30,8 @@ export class FileStorage {
 	init(): Promise<void> {
 		return readFile(this.dbPath).then(contents => {
 			try {
-				this._database = JSON.parse(contents.toString());
+				this.lastFlushedSerializedDatabase = contents.toString();
+				this._database = JSON.parse(this.lastFlushedSerializedDatabase);
 			} catch (error) {
 				this._database = {};
 			}
@@ -44,7 +46,9 @@ export class FileStorage {
 
 	private loadSync(): object {
 		try {
-			return JSON.parse(fs.readFileSync(this.dbPath).toString());
+			this.lastFlushedSerializedDatabase = fs.readFileSync(this.dbPath).toString();
+
+			return JSON.parse(this.lastFlushedSerializedDatabase);
 		} catch (error) {
 			if (error.code !== 'ENOENT') {
 				this.onError(error);
@@ -93,8 +97,14 @@ export class FileStorage {
 	}
 
 	private saveSync(): void {
+		const serializedDatabase = JSON.stringify(this.database, null, 4);
+		if (serializedDatabase === this.lastFlushedSerializedDatabase) {
+			return; // return early if the database has not changed
+		}
+
 		try {
-			writeFileAndFlushSync(this.dbPath, JSON.stringify(this.database, null, 4)); // permission issue can happen here
+			writeFileAndFlushSync(this.dbPath, serializedDatabase); // permission issue can happen here
+			this.lastFlushedSerializedDatabase = serializedDatabase;
 		} catch (error) {
 			this.onError(error);
 		}
-- 
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