Events Source Message Queue (#129)

* Events Source Message Queue
 - Fixes problem where events sent close together are silently dropped.

* Update AsyncEventSource.cpp

error

src/AsyncEventSource.cpp

@@ -104,9 +104,53 @@ static String generateEventMessage(const char *message, const char *event, uint3
   return ev;
 }
 
+// Message
+
+AsyncEventSourceMessage::AsyncEventSourceMessage(const char * data, size_t len)
+: _status(EVS_MSG_ERROR), _data(nullptr), _len(len), _sent(0)
+{
+  _data = (uint8_t*)malloc(_len+1);
+  if(_data == NULL){
+    _len = 0;
+    _status = EVS_MSG_ERROR;
+  } else {
+    _status = EVS_MSG_SENDING;
+    memcpy(_data, data, len);
+    _data[_len] = 0;
+    String temp = data;
+  }
+
+  
+}
+
+AsyncEventSourceMessage::~AsyncEventSourceMessage() {
+     if(_data != NULL)
+        free(_data);
+}
+
+void AsyncEventSourceMessage::ack(size_t len, uint32_t time) {
+  if(_len == len && _sent == _len){
+     _status = EVS_MSG_SENT;
+  }
+}
+
+size_t AsyncEventSourceMessage::send(AsyncClient *client) {
+  if(!client->canSend()){
+    return 0;
+  }
+  if(client->space() < _len){
+    return 0;
+  }
+  size_t sent = client->write((const char *)_data, _len);
+  _sent = sent;
+  return sent; 
+}
+
 // Client
 
-AsyncEventSourceClient::AsyncEventSourceClient(AsyncWebServerRequest *request, AsyncEventSource *server){
+AsyncEventSourceClient::AsyncEventSourceClient(AsyncWebServerRequest *request, AsyncEventSource *server)
+: _messageQueue(LinkedList<AsyncEventSourceMessage *>([](AsyncEventSourceMessage *m){ delete  m; }))
+{
   _client = request->client();
   _server = server;
   _lastId = 0;
@@ -115,19 +159,50 @@ AsyncEventSourceClient::AsyncEventSourceClient(AsyncWebServerRequest *request, A
     
   _client->setRxTimeout(0);
   _client->onError(NULL, NULL);
-  _client->onAck(NULL, NULL);
-  _client->onPoll(NULL, NULL);
+  _client->onAck([](void *r, AsyncClient* c, size_t len, uint32_t time){ ((AsyncEventSourceClient*)(r))->_onAck(len, time); }, this);
+  _client->onPoll([](void *r, AsyncClient* c){ ((AsyncEventSourceClient*)(r))->_onPoll(); }, this);
   _client->onData(NULL, NULL);
-  _client->onTimeout([](void *r, AsyncClient* c __attribute__((unused)), uint32_t time){ ((AsyncEventSourceClient*)(r))->_onTimeout(time); }, this);
-  _client->onDisconnect([](void *r, AsyncClient* c){ ((AsyncEventSourceClient*)(r))->_onDisconnect(); delete c; }, this);
+  _client->onTimeout([this](void *r, AsyncClient* c __attribute__((unused)), uint32_t time){ ((AsyncEventSourceClient*)(r))->_onTimeout(time); }, this);
+  _client->onDisconnect([this](void *r, AsyncClient* c){ ((AsyncEventSourceClient*)(r))->_onDisconnect(); delete c; }, this);
+
   _server->_addClient(this);
   delete request;
 }
 
 AsyncEventSourceClient::~AsyncEventSourceClient(){
+   _messageQueue.free();
   close();
 }
 
+void AsyncEventSourceClient::_queueMessage(AsyncEventSourceMessage *dataMessage){
+  if(dataMessage == NULL)
+    return;
+  if(!connected()){
+    delete dataMessage;
+    return;
+  }
+
+  _messageQueue.add(dataMessage);
+
+  if(_client->canSend()) { _runQueue(); } 
+}
+
+void AsyncEventSourceClient::_onAck(size_t len, uint32_t time){
+
+  if(len && !_messageQueue.isEmpty()){
+    _messageQueue.front()->ack(len, time);
+  }
+
+  _runQueue();
+}
+
+void AsyncEventSourceClient::_onPoll(){
+  if(_client->canSend() && !_messageQueue.isEmpty()){
+    _runQueue();
+  }
+}
+
+
 void AsyncEventSourceClient::_onTimeout(uint32_t time __attribute__((unused))){
   _client->close(true);
 }
@@ -143,18 +218,22 @@ void AsyncEventSourceClient::close(){
 }
 
 void AsyncEventSourceClient::write(const char * message, size_t len){
-  if(!_client->canSend()){
-    return;
-  }
-  if(_client->space() < len){
-    return;
-  }
-  _client->write(message, len);
+  _queueMessage(new AsyncEventSourceMessage(message, len));
 }
 
 void AsyncEventSourceClient::send(const char *message, const char *event, uint32_t id, uint32_t reconnect){
   String ev = generateEventMessage(message, event, id, reconnect);
-  write(ev.c_str(), ev.length());
+  _queueMessage(new AsyncEventSourceMessage(ev.c_str(), ev.length()));
+}
+
+void AsyncEventSourceClient::_runQueue(){
+  while(!_messageQueue.isEmpty() && _messageQueue.front()->finished()){
+    _messageQueue.remove(_messageQueue.front());
+  }
+
+  if(!_messageQueue.isEmpty()){
+    _messageQueue.front()->send(_client);
+  }
 }
 
 
@@ -210,8 +289,9 @@ void AsyncEventSource::send(const char *message, const char *event, uint32_t id,
 
   String ev = generateEventMessage(message, event, id, reconnect);
   for(const auto &c: _clients){
-    if(c->connected())
+    if(c->connected()) {
       c->write(ev.c_str(), ev.length());
+    }
   }
 }
 
@@ -257,3 +337,4 @@ size_t AsyncEventSourceResponse::_ack(AsyncWebServerRequest *request, size_t len
   }
   return 0;
 }
+

src/AsyncEventSource.h

@@ -29,11 +29,33 @@ class AsyncEventSourceResponse;
 class AsyncEventSourceClient;
 typedef std::function<void(AsyncEventSourceClient *client)> ArEventHandlerFunction;
 
+typedef enum { EVS_MSG_SENDING, EVS_MSG_SENT, EVS_MSG_ERROR } EventSourceMessageStatus;
+
+
+class AsyncEventSourceMessage {
+  private:
+    EventSourceMessageStatus _status;
+    uint8_t * _data; 
+    size_t _len;
+    size_t _sent;
+    //size_t _ack;
+    //size_t _acked; 
+  public:
+    AsyncEventSourceMessage(const char * data, size_t len);
+    ~AsyncEventSourceMessage();
+    void ack(size_t len __attribute__((unused)), uint32_t time __attribute__((unused)));
+    size_t send(AsyncClient *client __attribute__((unused)));
+    bool finished(){ return _status != EVS_MSG_SENDING; }
+};
+
 class AsyncEventSourceClient {
   private:
     AsyncClient *_client;
     AsyncEventSource *_server;
     uint32_t _lastId;
+    LinkedList<AsyncEventSourceMessage *> _messageQueue;
+    void _queueMessage(AsyncEventSourceMessage *dataMessage);
+    void _runQueue();
 
   public:
 
@@ -48,6 +70,8 @@ class AsyncEventSourceClient {
     uint32_t lastId() const { return _lastId; }
 
     //system callbacks (do not call)
+    void _onAck(size_t len, uint32_t time);
+    void _onPoll(); 
     void _onTimeout(uint32_t time);
     void _onDisconnect();
 };