fix: should wait a while before clearing resource

src/y-socket-io/utils.js

@@ -0,0 +1,17 @@
+/**
+ * Basically Promise.withResolvers()
+ * @template T
+ * @see https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Promise/withResolvers
+ */
+export function promiseWithResolvers() {
+  /** @type {(value: T | PromiseLike<T>) => void} */
+  let res = () => {}
+  /** @type {(reason?: Error) => void} */
+  let rej = () => {}
+  /** @type {Promise<T>} */
+  const promise = new Promise((resolve, reject) => {
+    res = resolve
+    rej = reject
+  })
+  return { promise, resolve: res, reject: rej }
+}

src/y-socket-io/y-socket-io.js

@@ -13,12 +13,14 @@ import { isDeepStrictEqual } from 'util'
 import { User } from './user.js'
 import { createModuleLogger } from 'lib0/logging'
 import toobusy from 'toobusy-js'
+import { promiseWithResolvers } from './utils.js'
 
 const logSocketIO = createModuleLogger('@y/socket-io/server')
 const PERSIST_INTERVAL = number.parseInt(env.getConf('y-socket-io-server-persist-interval') || '3000')
 const MAX_PERSIST_INTERVAL = number.parseInt(env.getConf('y-socket-io-server-max-persist-interval') || '30000')
 const REVALIDATE_TIMEOUT = number.parseInt(env.getConf('y-socket-io-server-revalidate-timeout') || '60000')
 const WORKER_DISABLED = env.getConf('y-worker-disabled') === 'true'
+const DEFAULT_CLEAR_TIMEOUT = number.parseInt(env.getConf('y-socket-io-default-clear-timeout') || '30000')
 
 process.on('SIGINT', function () {
   // calling .shutdown allows your process to exit normally
@@ -137,11 +139,17 @@ export class YSocketIO {
    */
   namespacePersistentMap = new Map()
   /**
-   * @type {Map<string, () => void>}
+   * @type {Map<string, { promise: Promise<void>, resolve: () => void }>}
    * @private
    * @readonly
    */
   awaitingPersistMap = new Map()
+  /**
+   * @type {Map<string, NodeJS.Timeout>}
+   * @private
+   * @readonly
+   */
+  awaitingCleanupNamespace = new Map()
 
   /**
    * YSocketIO constructor.
@@ -213,6 +221,12 @@ export class YSocketIO {
         'index',
         redisPrefix
       )
+      const prevAwaitCleanup = this.awaitingCleanupNamespace.get(namespace)
+      if (prevAwaitCleanup) {
+        clearTimeout(prevAwaitCleanup)
+        this.cleanupNamespace(namespace, stream)
+      }
+
       if (!this.namespaceMap.has(namespace)) {
         this.namespaceMap.set(namespace, socket.nsp)
       }
@@ -346,13 +360,9 @@ export class YSocketIO {
         if (!ns) continue
         const nsp = this.namespaceMap.get(ns)
         if (nsp?.sockets.size === 0 && stream) {
-          this.subscriber.unsubscribe(stream, this.redisMessageSubscriber)
-          this.namespaceStreamMap.delete(ns)
-          this.streamNamespaceMap.delete(stream)
-          this.namespaceMap.delete(ns)
-          this.namespaceDocMap.get(ns)?.ydoc.destroy()
-          this.namespaceDocMap.delete(ns)
-          this.namespacePersistentMap.delete(ns)
+          this.cleanupNamespace(ns, stream, DEFAULT_CLEAR_TIMEOUT)
+          const doc = this.namespaceDocMap.get(ns)
+          if (doc) this.debouncedPersist(ns, doc.ydoc, true)
         }
       }
     })
@@ -398,18 +408,13 @@ export class YSocketIO {
    * @param {Array<Uint8Array>} messages
    */
   redisMessageSubscriber = async (stream, messages) => {
+    console.log('[DEBUG]', { stream, messages })
     const namespace = this.streamNamespaceMap.get(stream)
     if (!namespace) return
     const nsp = this.namespaceMap.get(namespace)
     if (!nsp) return
     if (nsp.sockets.size === 0 && this.subscriber) {
-      this.subscriber.unsubscribe(stream, this.redisMessageSubscriber)
-      this.namespaceStreamMap.delete(namespace)
-      this.streamNamespaceMap.delete(stream)
-      this.namespaceMap.delete(namespace)
-      this.namespaceDocMap.get(namespace)?.ydoc.destroy()
-      this.namespaceDocMap.delete(namespace)
-      this.namespacePersistentMap.delete(namespace)
+      this.cleanupNamespace(namespace, stream, DEFAULT_CLEAR_TIMEOUT)
     }
 
     /** @type {Uint8Array[]} */
@@ -463,9 +468,9 @@ export class YSocketIO {
     const lastPersistCalledAt = this.namespacePersistentMap.get(namespace) ?? 0
     const now = Date.now()
     const shouldPersist = now - lastPersistCalledAt > MAX_PERSIST_INTERVAL
-    if (changed || shouldPersist) {
+    if (changed || shouldPersist || nsp.sockets.size === 0) {
       this.namespacePersistentMap.set(namespace, now)
-      this.debouncedPersist(namespace, doc.ydoc)
+      this.debouncedPersist(namespace, doc.ydoc, nsp.sockets.size === 0)
     }
     this.namespaceDocMap.get(namespace)?.ydoc.destroy()
     this.namespaceDocMap.set(namespace, doc)
@@ -474,47 +479,50 @@ export class YSocketIO {
   /**
    * @param {string} namespace
    * @param {Y.Doc} doc
+   * @param {boolean=} immediate
    */
-  async debouncedPersist (namespace, doc) {
+  debouncedPersist (namespace, doc, immediate = false) {
     this.debouncedPersistDocMap.set(namespace, doc)
-    if (this.debouncedPersistMap.has(namespace)) return
+    if (this.debouncedPersistMap.has(namespace)) {
+      if (!immediate) return
+      clearTimeout(this.debouncedPersistMap.get(namespace) || undefined)
+    }
+    const timeoutInterval = immediate
+      ? 0
+      : PERSIST_INTERVAL + (Math.random() - 0.5) * PERSIST_INTERVAL
     const timeout = setTimeout(
       async () => {
         try {
           assert(this.client)
           const doc = this.debouncedPersistDocMap.get(namespace)
           logSocketIO(`trying to persist ${namespace}`)
           if (!doc) return
-          /** @type {Promise<void> | null} */
-          let workerPromise = null
           if (this.client.persistWorker) {
-            workerPromise = new Promise((resolve) => {
-              assert(this.client?.persistWorker)
-              this.awaitingPersistMap.set(namespace, resolve)
-
-              const docState = Y.encodeStateAsUpdateV2(doc)
-              const buf = new Uint8Array(new SharedArrayBuffer(docState.length))
-              buf.set(docState)
-              this.client.persistWorker.postMessage({
-                room: namespace,
-                docstate: buf
-              })
+            /** @type {ReturnType<typeof promiseWithResolvers<void>>} */
+            const { promise, resolve } = promiseWithResolvers()
+            assert(this.client?.persistWorker)
+            this.awaitingPersistMap.set(namespace, { promise, resolve })
+
+            const docState = Y.encodeStateAsUpdateV2(doc)
+            const buf = new Uint8Array(new SharedArrayBuffer(docState.length))
+            buf.set(docState)
+            this.client.persistWorker.postMessage({
+              room: namespace,
+              docstate: buf
             })
-            if (workerPromise) {
-              await workerPromise
-            }
+            await promise
           } else {
             await this.client.store.persistDoc(namespace, 'index', doc)
           }
-          await this.client.trimRoomStream(namespace, 'index', true)
+          await this.client.trimRoomStream(namespace, 'index')
         } catch (e) {
           console.error(e)
         } finally {
           this.debouncedPersistDocMap.delete(namespace)
           this.debouncedPersistMap.delete(namespace)
         }
       },
-      PERSIST_INTERVAL + (Math.random() - 0.5) * PERSIST_INTERVAL
+      timeoutInterval
     )
 
     this.debouncedPersistMap.set(namespace, timeout)
@@ -608,7 +616,45 @@ export class YSocketIO {
   registerPersistWorkerResolve () {
     if (!this.client?.persistWorker) return
     this.client.persistWorker.on('message', ({ event, room }) => {
-      if (event === 'persisted') this.awaitingPersistMap.get(room)?.()
+      if (event === 'persisted') this.awaitingPersistMap.get(room)?.resolve()
     })
   }
+
+  /**
+   * @param {string} namespace 
+   * @param {string} stream 
+   * @param {number=} removeAfterWait
+   */
+  cleanupNamespace (namespace, stream, removeAfterWait) {
+    if (!removeAfterWait) {
+      this.awaitingCleanupNamespace.delete(namespace)
+      return this.cleanupNamespaceImpl(namespace, stream)
+    }
+    if (this.awaitingCleanupNamespace.has(namespace)) return
+
+    const timer = setTimeout(async () => {
+      const awaitingPersist = this.awaitingPersistMap.get(namespace)
+      if (awaitingPersist) await awaitingPersist.promise
+      this.cleanupNamespaceImpl(namespace, stream)
+      this.awaitingCleanupNamespace.delete(namespace)
+      logSocketIO(`no active connection, namespace: ${namespace} cleared`)
+    }, removeAfterWait)
+    this.awaitingCleanupNamespace.set(namespace, timer)
+  }
+
+  /**
+   * @param {string} namespace 
+   * @param {string} stream 
+   * @private
+   */
+  cleanupNamespaceImpl (namespace, stream) {
+    this.subscriber?.unsubscribe(stream, this.redisMessageSubscriber)
+    this.namespaceStreamMap.delete(namespace)
+    this.streamNamespaceMap.delete(stream)
+    this.namespaceMap.delete(namespace)
+    this.namespaceDocMap.get(namespace)?.ydoc.destroy()
+    this.namespaceDocMap.delete(namespace)
+    this.namespacePersistentMap.delete(namespace)
+    this.client?.trimRoomStream(namespace, 'index', true)
+  }
 }