Merge pull request #96 from kaleido-io/one-ack-per-batch

Only send one ack per batch

src/eventstream-proxy/eventstream-proxy.base.ts

@@ -190,12 +190,21 @@ export abstract class EventStreamProxyBase extends WebSocketEventsBase {
       return;
     }
 
-    this.logger.log(`Received ack ${data.id}`);
-    if (this.socket !== undefined && this.awaitingAck.find(msg => msg.id === data.id)) {
-      const firstAck = this.awaitingAck.find(msg => msg.id === data.id);
+    const inflight = this.awaitingAck.find(msg => msg.id === data.id)
+    this.logger.log(`Received ack ${data.id} inflight=${!!inflight}`);
+    if (this.socket !== undefined && inflight !== undefined) {
       this.awaitingAck = this.awaitingAck.filter(msg => msg.id !== data.id);
-      if (firstAck) {
-        this.socket.ack(firstAck.batchNumber);
+      if (
+        // If nothing is left awaiting an ack - then we clearly need to ack
+        this.awaitingAck.length === 0 ||
+        (
+          // Or if we have a batch number associated with this ID, then we can only ack if there
+          // are no other messages in-flight with the same batch number.
+          inflight.batchNumber !== undefined && !this.awaitingAck.find(msg => msg.batchNumber === inflight.batchNumber)
+        )
+      ) {
+        this.logger.log(`In-flight batch complete (batchNumber=${inflight.batchNumber})`);
+        this.socket.ack(inflight.batchNumber);
       }
     }
   }