fix(sds): emit empty array when no missing messages detected

Author: adklempner

packages/sds/src/message_channel/message_channel.spec.ts

@@ -282,6 +282,8 @@ describe("MessageChannel", function () {
       // and notInHistory should still be in the outgoing buffer
       const outgoingBuffer = (channelA as any).outgoingBuffer as Message[];
       expect(outgoingBuffer.length).to.equal(1);
+      console.log(outgoingBuffer);
+      console.log(notInHistory);
       expect(outgoingBuffer[0].messageId).to.equal(notInHistory!.messageId);
     });
 

packages/sds/src/message_channel/message_channel.ts

@@ -249,22 +249,29 @@ export class MessageChannel extends TypedEventEmitter<MessageChannelEvents> {
   }
 
   public _receiveMessage(message: Message): void {
-    if (this.timeReceived.has(message.messageId)) {
+    if (
+      message.content &&
+      message.content.length > 0 &&
+      this.timeReceived.has(message.messageId)
+    ) {
       // Received a duplicate message
       return;
     }
 
     if (!message.lamportTimestamp) {
       // Messages with no timestamp are ephemeral messages and should be delivered immediately
+      this.deliverMessage(message);
+      return;
+    }
+    if (message.content?.length === 0) {
       this.safeDispatchEvent(MessageChannelEvent.SyncReceived, {
         detail: message
       });
-      this.deliverMessage(message);
-      return;
+    } else {
+      this.safeDispatchEvent(MessageChannelEvent.MessageReceived, {
+        detail: message
+      });
     }
-    this.safeDispatchEvent(MessageChannelEvent.MessageReceived, {
-      detail: message
-    });
     // review ack status
     this.reviewAckStatus(message);
     // add to bloom filter (skip for messages with empty content)
@@ -347,11 +354,11 @@ export class MessageChannel extends TypedEventEmitter<MessageChannelEvents> {
     );
     // Update the incoming buffer to only include messages with no missing dependencies
     this.incomingBuffer = buffer;
-    if (missing.size > 0) {
-      this.safeDispatchEvent(MessageChannelEvent.MissedMessages, {
-        detail: Array.from(missing)
-      });
-    }
+
+    this.safeDispatchEvent(MessageChannelEvent.MissedMessages, {
+      detail: Array.from(missing)
+    });
+
     return Array.from(missing);
   }