setCloseClientOnQueueFull(bool): Allow to choose between discard message or close client on queue full

README.md

@@ -29,6 +29,7 @@ This fork is based on [yubox-node-org/ESPAsyncWebServer](https://github.com/yubo
 - Depends on `mathieucarbou/Async TCP @ ^3.1.4`
 - Arduino 3 / ESP-IDF 5.1 compatibility
 - Added all flavors of `binary()`, `text()`, `binaryAll()` and `textAll()` in `AsyncWebSocket`
+- Added `setCloseClientOnQueueFull(bool)` which can be set on a client to either close the connection or discard messages but not close the connection when the queue is full
 
 ## Documentation
 

docs/index.md

@@ -29,6 +29,7 @@ This fork is based on [yubox-node-org/ESPAsyncWebServer](https://github.com/yubo
 - Depends on `mathieucarbou/Async TCP @ ^3.1.4`
 - Arduino 3 / ESP-IDF 5.1 compatibility
 - Added all flavors of `binary()`, `text()`, `binaryAll()` and `textAll()` in `AsyncWebSocket`
+- Added `setCloseClientOnQueueFull(bool)` which can be set on a client to either close the connection or discard messages but not close the connection when the queue is full
 
 ## Documentation
 

src/AsyncWebSocket.cpp

@@ -461,13 +461,22 @@ void AsyncWebSocketClient::_queueMessage(std::shared_ptr<std::vector<uint8_t>> b
         if (_messageQueue.size() >= WS_MAX_QUEUED_MESSAGES)
         {
             l.unlock();
+            if(closeWhenFull)
+            {
 #ifdef ESP8266
-            ets_printf("AsyncWebSocketClient::_queueMessage: Too many messages queued, closing connection\n");
+                ets_printf("AsyncWebSocketClient::_queueMessage: Too many messages queued: closing connection\n");
 #else
-            log_e("Too many messages queued: closing connection");
+                log_e("Too many messages queued: closing connection");
 #endif
-            _status = WS_DISCONNECTED;
+                _status = WS_DISCONNECTED;
-            if (_client) _client->close(true);
+                if (_client) _client->close(true);
+            } else {
+#ifdef ESP8266
+                ets_printf("AsyncWebSocketClient::_queueMessage: Too many messages queued: discarding new message\n");
+#else
+                log_e("Too many messages queued: discarding new message");
+#endif
+            }
             return;
         }
         else

src/AsyncWebSocket.h

@@ -137,6 +137,7 @@ class AsyncWebSocketClient {
 
     std::deque<AsyncWebSocketControl> _controlQueue;
     std::deque<AsyncWebSocketMessage> _messageQueue;
+    bool closeWhenFull = true;
 
     uint8_t _pstate;
     AwsFrameInfo _pinfo;
@@ -164,6 +165,27 @@ class AsyncWebSocketClient {
     const AsyncWebSocket *server() const { return _server; }
     AwsFrameInfo const &pinfo() const { return _pinfo; }
 
+    //  - If "true" (default), the connection will be closed if the message queue is full.
+    // This is the default behavior in yubox-node-org, which is not silently discarding messages but instead closes the connection.
+    // The big issue with this behavior is  that is can cause the UI to automatically re-create a new WS connection, which can be filled again, 
+    // and so on, causing a resource exhaustion.
+    // 
+    // - If "false", the incoming message will be discarded if the queue is full.
+    // This is the default behavior in the original ESPAsyncWebServer library from me-no-dev.
+    // This behavior allows the best performance at the expense of unreliable message delivery in case the queue is full (some messages may be lost).
+    // 
+    // - In any case, when the queue is full, a message is logged.
+    // - IT is recommended to use the methods queueIsFull(), availableForWriteAll(), availableForWrite(clientId) to check if the queue is full before sending a message.
+    // 
+    // Usage:
+    //  - can be set in the onEvent listener when connecting (event type is: WS_EVT_CONNECT)
+    // 
+    // Use cases:, 
+    // - if using websocket to send logging messages, maybe some loss is acceptable.
+    // - But if using websocket to send UI update messages, maybe the connection should be closed and the UI redrawn.
+    void setCloseClientOnQueueFull(bool close) { closeWhenFull = close; }
+    bool willCloseClientOnQueueFull() const { return closeWhenFull; }
+
     IPAddress remoteIP() const;
     uint16_t  remotePort() const;