Avoid using temporary directory if possible (#720)

Miniflare 2 persisted data in-memory between `setOptions()` calls when `*Persist` options were disabled. Whilst `workerd` has in-memory storage for Durable Objects, this is reset when `workerd` is restarted (i.e. when `setOptions()` is called). To retain Miniflare 2 behaviour in Miniflare 3, we actually persist to a temporary directory when `*Persist` options are disabled. There are cases where we don't need the temporary directory though: if we have no storage bindings configured, `cache` is `false`, and `unsafeEphemeralDurableObjects` is `true`. This change ensures we don't write to the temporary directory in these cases.
cloudflare · Nov 1, 2023 · 8cbe08d · 8cbe08d
1 parent 1438598
commit 8cbe08d
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Showing 4 changed files with 63 additions and 48 deletions.
diff --git a/packages/miniflare/src/index.ts b/packages/miniflare/src/index.ts
@@ -943,6 +943,8 @@ export class Miniflare {
 			}
 
 			// Collect all services required by this worker
+			const unsafeEphemeralDurableObjects =
+				workerOpts.core.unsafeEphemeralDurableObjects ?? false;
 			const pluginServicesOptionsBase: Omit<
 				PluginServicesOptions<z.ZodTypeAny, undefined>,
 				"options" | "sharedOptions"
@@ -954,6 +956,7 @@ export class Miniflare {
 				tmpPath: this.#tmpPath,
 				workerNames,
 				durableObjectClassNames,
+				unsafeEphemeralDurableObjects,
 				queueConsumers,
 			};
 			for (const [key, plugin] of PLUGIN_ENTRIES) {

diff --git a/packages/miniflare/src/plugins/cache/index.ts b/packages/miniflare/src/plugins/cache/index.ts
@@ -85,57 +85,58 @@ export const CACHE_PLUGIN: Plugin<
 				],
 			};
 		}
+		const services: Service[] = [
+			{ name: getCacheServiceName(workerIndex), worker: entryWorker },
+		];
 
-		const uniqueKey = `miniflare-${CACHE_OBJECT_CLASS_NAME}`;
+		if (cache) {
+			const uniqueKey = `miniflare-${CACHE_OBJECT_CLASS_NAME}`;
 
-		const persist = sharedOptions.cachePersist;
-		const persistPath = getPersistPath(CACHE_PLUGIN_NAME, tmpPath, persist);
-		await fs.mkdir(persistPath, { recursive: true });
-		const storageService: Service = {
-			name: CACHE_STORAGE_SERVICE_NAME,
-			disk: { path: persistPath, writable: true },
-		};
-		const objectService: Service = {
-			name: CACHE_SERVICE_PREFIX,
-			worker: {
-				compatibilityDate: "2023-07-24",
-				compatibilityFlags: ["nodejs_compat", "experimental"],
-				modules: [
-					{
-						name: "cache.worker.js",
-						esModule: SCRIPT_CACHE_OBJECT(),
-					},
-				],
-				durableObjectNamespaces: [
-					{
-						className: CACHE_OBJECT_CLASS_NAME,
-						uniqueKey,
-					},
-				],
-				// Store Durable Object SQL databases in persist path
-				durableObjectStorage: { localDisk: CACHE_STORAGE_SERVICE_NAME },
-				// Bind blob disk directory service to object
-				bindings: [
-					{
-						name: SharedBindings.MAYBE_SERVICE_BLOBS,
-						service: { name: CACHE_STORAGE_SERVICE_NAME },
-					},
-					{
-						name: SharedBindings.MAYBE_SERVICE_LOOPBACK,
-						service: { name: SERVICE_LOOPBACK },
-					},
-				],
-			},
-		};
+			const persist = sharedOptions.cachePersist;
+			const persistPath = getPersistPath(CACHE_PLUGIN_NAME, tmpPath, persist);
+			await fs.mkdir(persistPath, { recursive: true });
+			const storageService: Service = {
+				name: CACHE_STORAGE_SERVICE_NAME,
+				disk: { path: persistPath, writable: true },
+			};
+			const objectService: Service = {
+				name: CACHE_SERVICE_PREFIX,
+				worker: {
+					compatibilityDate: "2023-07-24",
+					compatibilityFlags: ["nodejs_compat", "experimental"],
+					modules: [
+						{
+							name: "cache.worker.js",
+							esModule: SCRIPT_CACHE_OBJECT(),
+						},
+					],
+					durableObjectNamespaces: [
+						{
+							className: CACHE_OBJECT_CLASS_NAME,
+							uniqueKey,
+						},
+					],
+					// Store Durable Object SQL databases in persist path
+					durableObjectStorage: { localDisk: CACHE_STORAGE_SERVICE_NAME },
+					// Bind blob disk directory service to object
+					bindings: [
+						{
+							name: SharedBindings.MAYBE_SERVICE_BLOBS,
+							service: { name: CACHE_STORAGE_SERVICE_NAME },
+						},
+						{
+							name: SharedBindings.MAYBE_SERVICE_LOOPBACK,
+							service: { name: SERVICE_LOOPBACK },
+						},
+					],
+				},
+			};
+			services.push(storageService, objectService);
 
-		// NOTE: not migrating here as applications should be able to recover from
-		// cache evictions, and we'd need to locate all named caches
+			// NOTE: not migrating here as applications should be able to recover from
+			// cache evictions, and we'd need to locate all named caches
+		}
 
-		const services: Service[] = [
-			{ name: getCacheServiceName(workerIndex), worker: entryWorker },
-			storageService,
-			objectService,
-		];
 		return services;
 	},
 };
diff --git a/packages/miniflare/src/plugins/do/index.ts b/packages/miniflare/src/plugins/do/index.ts
@@ -71,7 +71,12 @@ export const DURABLE_OBJECTS_PLUGIN: Plugin<
 		const objects = Object.keys(options.durableObjects ?? {});
 		return Object.fromEntries(objects.map((name) => [name, kProxyNodeBinding]));
 	},
-	async getServices({ sharedOptions, tmpPath, durableObjectClassNames }) {
+	async getServices({
+		sharedOptions,
+		tmpPath,
+		durableObjectClassNames,
+		unsafeEphemeralDurableObjects,
+	}) {
 		// Check if we even have any Durable Object bindings, if we don't, we can
 		// skip creating the storage directory
 		let hasDurableObjects = false;
@@ -83,6 +88,11 @@ export const DURABLE_OBJECTS_PLUGIN: Plugin<
 		}
 		if (!hasDurableObjects) return;
 
+		// If this worker has enabled `unsafeEphemeralDurableObjects`, it won't need
+		// the Durable Object storage service. If all workers have this enabled, we
+		// don't need to create the storage service at all.
+		if (unsafeEphemeralDurableObjects) return;
+
 		const storagePath = getPersistPath(
 			DURABLE_OBJECTS_PLUGIN_NAME,
 			tmpPath,

diff --git a/packages/miniflare/src/plugins/shared/index.ts b/packages/miniflare/src/plugins/shared/index.ts
@@ -40,6 +40,7 @@ export interface PluginServicesOptions<
 
 	// ~~Leaky abstractions~~ "Plugin specific options" :)
 	durableObjectClassNames: DurableObjectClassNames;
+	unsafeEphemeralDurableObjects: boolean;
 	queueConsumers: QueueConsumers;
 }