fix: only call persistDoc if ydoc has changes

Author: stanley2058

src/api.js

@@ -277,8 +277,10 @@ export class Api {
     const awareness = new awarenessProtocol.Awareness(ydoc)
     awareness.setLocalState(null) // we don't want to propagate awareness state
     const now = performance.now()
+    if (docstate) { Y.applyUpdateV2(ydoc, docstate.doc) }
+    let changed = false
+    ydoc.once('afterTransaction', (tr) => { changed = tr.changed.size > 0 })
     ydoc.transact(() => {
-      if (docstate) { Y.applyUpdateV2(ydoc, docstate.doc) }
       docMessages?.messages.forEach(m => {
         const decoder = decoding.createDecoder(m)
         switch (decoding.readVarUint(decoder)) {
@@ -296,7 +298,13 @@ export class Api {
       })
     })
     logApi(`took ${performance.now() - now}ms to process messages for room: ${room}`)
-    return { ydoc, awareness, redisLastId: docMessages?.lastId.toString() || '0', storeReferences: docstate?.references || null }
+    return {
+      ydoc,
+      awareness,
+      redisLastId: docMessages?.lastId.toString() || '0',
+      storeReferences: docstate?.references || null,
+      changed
+    }
   }
 
   /**
@@ -339,9 +347,12 @@ export class Api {
       } else {
         reclaimCounts++
         const { room, docid } = decodeRedisRoomStreamName(task.stream, this.prefix)
-        const { ydoc, storeReferences, redisLastId } = await this.getDoc(room, docid)
+        const { ydoc, storeReferences, redisLastId, changed } = await this.getDoc(room, docid)
         const lastId = math.max(number.parseInt(redisLastId.split('-')[0]), number.parseInt(task.id.split('-')[0]))
-        await this.store.persistDoc(room, docid, ydoc)
+        if (changed) {
+          logWorker(`persisting changes in room: ${room}`)
+          await this.store.persistDoc(room, docid, ydoc)
+        } else logWorker(`skip persisting room: ${room} due to no changes`)
         await promise.all([
           storeReferences ? this.store.deleteReferences(room, docid, storeReferences) : promise.resolve(),
           this.redis.multi()