From 6906bc4f5ecc691f51078625e30f8c9be421aaaf Mon Sep 17 00:00:00 2001
From: Andras Schmelczer <andras@schmelczer.dev>
Date: Sat, 22 Mar 2025 14:06:17 +0000
Subject: [PATCH] Avoid duplication from initial sync

---
 .../sync-client/src/persistence/database.ts   | 77 +++++++++++++++----
 .../sync-client/src/sync-operations/syncer.ts | 38 ++++++++-
 2 files changed, 97 insertions(+), 18 deletions(-)

diff --git a/frontend/sync-client/src/persistence/database.ts b/frontend/sync-client/src/persistence/database.ts
index 617cfbf1..f6379c53 100644
--- a/frontend/sync-client/src/persistence/database.ts
+++ b/frontend/sync-client/src/persistence/database.ts
@@ -1,4 +1,5 @@
 import type { Logger } from "../tracing/logger";
+import { EMPTY_HASH } from "../utils/hash";
 
 export type VaultUpdateId = number;
 export type DocumentId = string;
@@ -19,6 +20,7 @@ export interface StoredDocumentMetadata {
 export interface StoredDatabase {
 	documents: StoredDocumentMetadata[];
 	lastSeenUpdateId: VaultUpdateId | undefined;
+	hasInitialSyncCompleted: boolean;
 }
 
 /**
@@ -39,6 +41,7 @@ export interface DocumentRecord {
 export class Database {
 	private documents: DocumentRecord[];
 	private lastSeenUpdateId: VaultUpdateId | undefined;
+	private hasInitialSyncCompleted: boolean;
 
 	public constructor(
 		private readonly logger: Logger,
@@ -66,6 +69,12 @@ export class Database {
 		this.logger.debug(
 			`Loaded last seen update id: ${this.lastSeenUpdateId}`
 		);
+
+		this.hasInitialSyncCompleted =
+			initialState.hasInitialSyncCompleted ?? false;
+		this.logger.debug(
+			`Loaded hasInitialSyncCompleted: ${this.hasInitialSyncCompleted}`
+		);
 	}
 
 	public get length(): number {
@@ -105,21 +114,6 @@ export class Database {
 		});
 	}
 
-	public getLastSeenUpdateId(): VaultUpdateId | undefined {
-		return this.lastSeenUpdateId;
-	}
-
-	public setLastSeenUpdateId(value: VaultUpdateId | undefined): void {
-		this.lastSeenUpdateId = value;
-		this.save();
-	}
-
-	public reset(): void {
-		this.documents = [];
-		this.lastSeenUpdateId = 0;
-		this.save();
-	}
-
 	public updateDocumentMetadata(
 		metadata: {
 			parentVersionId: VaultUpdateId;
@@ -215,6 +209,29 @@ export class Database {
 		return entry;
 	}
 
+	public createNewEmptyDocument(
+		documentId: DocumentId,
+		parentVersionId: VaultUpdateId,
+		relativePath: RelativePath
+	): DocumentRecord {
+		const entry = {
+			relativePath,
+			documentId,
+			metadata: {
+				parentVersionId,
+				hash: EMPTY_HASH
+			},
+			isDeleted: false,
+			updates: [],
+			parallelVersion: 0
+		};
+
+		this.documents.push(entry);
+		this.save();
+
+		return entry;
+	}
+
 	public getDocumentByDocumentId(
 		find: DocumentId
 	): DocumentRecord | undefined {
@@ -260,6 +277,31 @@ export class Database {
 		candidate.isDeleted = true;
 	}
 
+	public getHasInitialSyncCompleted(): boolean {
+		return this.hasInitialSyncCompleted;
+	}
+
+	public setHasInitialSyncCompleted(value: boolean): void {
+		this.hasInitialSyncCompleted = value;
+		this.save();
+	}
+
+	public getLastSeenUpdateId(): VaultUpdateId | undefined {
+		return this.lastSeenUpdateId;
+	}
+
+	public setLastSeenUpdateId(value: VaultUpdateId | undefined): void {
+		this.lastSeenUpdateId = value;
+		this.save();
+	}
+
+	public reset(): void {
+		this.documents = [];
+		this.lastSeenUpdateId = 0;
+		this.hasInitialSyncCompleted = false;
+		this.save();
+	}
+
 	private save(): void {
 		this.ensureConsistency();
 		void this.saveData({
@@ -268,10 +310,11 @@ export class Database {
 					documentId,
 					relativePath,
 					// eslint-disable-next-line @typescript-eslint/no-non-null-assertion
-					...metadata! // resolvedDocuments only returns docs with metadata set
+					...metadata! // `resolvedDocuments` only returns docs with metadata set
 				})
 			),
-			lastSeenUpdateId: this.lastSeenUpdateId
+			lastSeenUpdateId: this.lastSeenUpdateId,
+			hasInitialSyncCompleted: this.hasInitialSyncCompleted
 		});
 	}
 
diff --git a/frontend/sync-client/src/sync-operations/syncer.ts b/frontend/sync-client/src/sync-operations/syncer.ts
index 7a7ba286..861dac00 100644
--- a/frontend/sync-client/src/sync-operations/syncer.ts
+++ b/frontend/sync-client/src/sync-operations/syncer.ts
@@ -36,7 +36,7 @@ export class Syncer {
 			concurrency: settings.getSettings().syncConcurrency
 		});
 
-		settings.addOnSettingsChangeHandlers((newSettings, oldSettings) => {
+		settings.addOnSettingsChangeListener((newSettings, oldSettings) => {
 			if (newSettings.syncConcurrency === oldSettings.syncConcurrency) {
 				return;
 			}
@@ -310,6 +310,8 @@ export class Syncer {
 	}
 
 	private async internalScheduleSyncForOfflineChanges(): Promise<void> {
+		await this.createFakeDocumentsFromRemoteState();
+
 		const allLocalFiles = await this.operations.listAllFiles();
 
 		let locallyPossiblyDeletedFiles = [
@@ -387,4 +389,38 @@ export class Syncer {
 
 		await Promise.all([updates, deletes]);
 	}
+
+	/**
+	 * Create fake documents in the database for all files that are present locally
+	 * and also exist remotely. This will stop the subequent syncs from duplicating
+	 * the documents by creating the same documents from multiple clients.
+	 */
+	private async createFakeDocumentsFromRemoteState(): Promise<void> {
+		if (this.database.getHasInitialSyncCompleted()) {
+			return;
+		}
+
+		const [allLocalFiles, remote] = await Promise.all([
+			this.operations.listAllFiles(),
+			this.syncQueue.add(async () => this.syncService.getAll())
+		]);
+
+		if (remote !== undefined) {
+			remote.latestDocuments
+				.filter(
+					(remoteDocument) =>
+						allLocalFiles.includes(remoteDocument.relativePath) &&
+						!remoteDocument.isDeleted
+				)
+				.forEach((remoteDocument) => {
+					this.database.createNewEmptyDocument(
+						remoteDocument.documentId,
+						remoteDocument.vaultUpdateId,
+						remoteDocument.relativePath
+					);
+				});
+		}
+
+		this.database.setHasInitialSyncCompleted(true);
+	}
 }