Add large non-ssl, non-compressed WebSocket message sending optimization

src/WebSocket.h

@@ -105,6 +105,23 @@ public:
 
         /* If we are subscribers and have messages to drain we need to drain them here to stay synced */
         WebSocketData *webSocketData = (WebSocketData *) Super::getAsyncSocketData();
+
+        /* Special path for long sends of non-compressed, non-SSL messages */
+        if (message.length() >= 16 * 1024 && !compress && !SSL && !webSocketData->subscriber && getBufferedAmount() == 0 && Super::getLoopData()->corkOffset == 0) {
+            char header[14];
+            int header_length = (int) protocol::formatMessage<isServer>(header, nullptr, 0, opCode, message.length(), compress, fin);
+            int written = us_socket_write2(0, (struct us_socket_t *)this, header, header_length, message.data(), (int) message.length());
+        
+            if (written != header_length + (int) message.length()) {
+                /* Buffer up backpressure */
+                if (written > header_length) {
+                    webSocketData->buffer.append(message.data() + written, message.length() - (size_t) written);
+                } else {
+                    webSocketData->buffer.append(header + written, (size_t) header_length - (size_t) written);
+                }
+            }
+        } else {
+
             if (webSocketData->subscriber) {
                 /* This will call back into us, send. */
                 webSocketContextData->topicTree->drain(webSocketData->subscriber);
@@ -149,6 +166,8 @@ public:
                 }
             }
 
+        }
+
         /* Every successful send resets the timeout */
         if (webSocketContextData->resetIdleTimeoutOnSend) {
             Super::timeout(webSocketContextData->idleTimeoutComponents.first);