Optimize IndexedDB cache persistence to prevent unnecessary writes.

Author: FactorioBlueprints

src/localStorage.ts

@@ -734,9 +734,67 @@ interface Persister {
 }
 
 export function createIDBPersister(idbValidKey: string = STORAGE_KEYS.QUERY_CACHE): Persister {
+	let lastPersistedHash: string | null = null;
+
+	// Extract only the actual query data, excluding metadata that changes on every access
+	const extractQueryData = (client: any): any => {
+		if (!client || !client.clientState) {
+			return client;
+		}
+
+		// Create a copy with only the actual data from queries
+		const dataOnly = {
+			queries: client.clientState.queries?.map((query: any) => ({
+				queryKey: query.queryKey,
+				queryHash: query.queryHash,
+				data: query.state?.data,
+				// Only include error if it exists
+				...(query.state?.error ? {error: query.state.error} : {}),
+			})),
+			mutations: client.clientState.mutations?.map((mutation: any) => ({
+				mutationKey: mutation.mutationKey,
+				state: mutation.state?.status,
+				data: mutation.state?.data,
+				error: mutation.state?.error,
+			})),
+		};
+
+		return dataOnly;
+	};
+
+	const hashObject = (obj: any): string => {
+		const str = JSON.stringify(obj);
+		let hash = 0;
+		for (let i = 0; i < str.length; i++) {
+			const char = str.charCodeAt(i);
+			hash = (hash << 5) - hash + char;
+			hash = hash & hash; // Convert to 32bit integer
+		}
+		return hash.toString(36);
+	};
+
 	const debouncedPersist = debounce(
 		async (client: any) => {
 			try {
+				// Extract only the data portion for comparison
+				const dataOnly = extractQueryData(client);
+				const currentHash = hashObject(dataOnly);
+
+				// Debug logging
+				console.log('[IndexedDB] Hash comparison:', {
+					current: currentHash,
+					last: lastPersistedHash,
+					equal: lastPersistedHash === currentHash,
+					hasClientState: !!client?.clientState,
+					queryCount: client?.clientState?.queries?.length || 0,
+				});
+
+				// Skip persistence if state hasn't changed
+				if (lastPersistedHash === currentHash) {
+					console.log('[IndexedDB] Cache state unchanged, skipping persistence');
+					return;
+				}
+
 				// 🗜️ Compress data before storing
 				const compressedData = compressForStorage(client);
 				const originalSize = JSON.stringify(client).length;
@@ -788,6 +846,9 @@ export function createIDBPersister(idbValidKey: string = STORAGE_KEYS.QUERY_CACH
 
 				if (result && 'success' in result && !result.success) {
 					console.warn('[IndexedDB] Persistence operation did not succeed, but continuing gracefully');
+				} else {
+					// Update the hash only after successful persistence
+					lastPersistedHash = currentHash;
 				}
 			} catch (error) {
 				console.error('[IndexedDB] Error persisting to IndexedDB:', error);
@@ -901,6 +962,8 @@ export function createIDBPersister(idbValidKey: string = STORAGE_KEYS.QUERY_CACH
 		removeClient: async () => {
 			try {
 				await workerOperation('delete', idbValidKey);
+				// Reset the hash when cache is removed
+				lastPersistedHash = null;
 			} catch (error) {
 				console.error('[IndexedDB] Error removing from IndexedDB:', error);
 			}