FirebaseArduino: allow mixing stream and non-stream commands

With this change non-streaming operation will stop the stream and
reuse the underlying http client.

Call FirebaseArduino::stream again in order to reuse the stream.

Fixes: #48

src/Firebase.cpp

@@ -92,6 +92,15 @@ FirebaseCall::FirebaseCall(const std::string& host, const std::string& auth,
                            const char* method, const std::string& path,
                            const std::string& data, FirebaseHttpClient* http) : http_(http) {
   std::string path_with_auth = makeFirebaseURL(path, auth);
+  if ((method == "STREAM") && (path == http->getStreamingPath())){
+    // already streaming requested path.
+    return;
+  }
+  if (http_->isStreaming()) {
+    // closing streaming connection.
+    http_->setReuseConnection(false);
+    http_->end();
+  }
   http_->setReuseConnection(true);
   http_->begin(host, path_with_auth);
 
@@ -130,11 +139,14 @@ FirebaseCall::FirebaseCall(const std::string& host, const std::string& auth,
   // if not streaming.
   if (!followRedirect) {
     response_ = http_->getString();
+    http_->setStreaming("");
+  } else {
+    http_->setStreaming(path);
   }
 }
 
 FirebaseCall::~FirebaseCall() {
-  if (http_) {
+  if (http_ && !http_->isStreaming()) {
     http_->end();
   }
 }
@@ -189,6 +201,9 @@ FirebaseStream::FirebaseStream(const std::string& host, const std::string& auth,
 }
 
 bool FirebaseStream::available() {
+  if (http_->getStreamPtr() == nullptr) {
+    return false;
+  }
   return http_->getStreamPtr()->available();
 }
 

src/FirebaseArduino.cpp

@@ -131,6 +131,9 @@ void FirebaseArduino::stream(const String& path) {
 }
 
 bool FirebaseArduino::available() {
+  if (http_->getStreamPtr() == nullptr) {
+    return false;
+  }
   return http_->getStreamPtr()->available();
 }
 

src/FirebaseArduino.h

@@ -189,9 +189,6 @@ class FirebaseArduino {
    * You should check success() after calling.
    * This changes the state of this object. Once this is called you may start
    * monitoring available() and calling readEvent() to get new events.
-   * WARNING: Currently you cannot make another call while the stream is
-   * running, otherwise you will crash due to memory issues. See:
-   * https://github.com/googlesamples/firebase-arduino/issues/48
    * \param path The path inside of your db to the node you wish to monitor.
    */
   void stream(const String& path);

src/FirebaseHttpClient.h

@@ -33,7 +33,18 @@ class FirebaseHttpClient {
 
   virtual std::string errorToString(int error_code) = 0;
 
+  bool isStreaming() const {
+    return _streaming != "";
+  }
+  std::string getStreamingPath() const {
+    return _streaming;
+  }
+  void setStreaming(const std::string& path) {
+    _streaming = path;
+  }
  protected:
+  std::string _streaming = "";
+
   static const uint16_t kFirebasePort = 443;
 };