open_source / mqtt-cpp

  /* ****************************************************************************
   * Copyright 2019 Open Systems Development BV                                 *
   *                                                                            *
   * Permission is hereby granted, free of charge, to any person obtaining a    *
   * copy of this software and associated documentation files (the "Software"), *
   * to deal in the Software without restriction, including without limitation  *
   * the rights to use, copy, modify, merge, publish, distribute, sublicense,   *
   * and/or sell copies of the Software, and to permit persons to whom the      *
   * Software is furnished to do so, subject to the following conditions:       *
   *                                                                            *
   * The above copyright notice and this permission notice shall be included in *
   * all copies or substantial portions of the Software.                        *
   *                                                                            *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR *
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,   *
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL    *
   * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER *
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING    *
   * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER        *
   * DEALINGS IN THE SOFTWARE.                                                  *
   * ***************************************************************************/

  #include "mqttclient.h"
  

  // osdev::components::logger
  #include "log.h"
   

  // osdev::components::mqtt
  #include "clientpaho.h"
  #include "mqttutil.h"
  #include "mqttidgenerator.h"
  #include "mqtttypeconverter.h"

  #include "lockguard.h"
  #include "uriparser.h"
  
  // std
  #include <numeric>
  #include <iostream>

  #include <string>

  
  using namespace osdev::components::mqtt;

  using namespace osdev::components::log;

  
  namespace {
  /**
   * @brief Generate a unique client id so that a new client does not steal the connection from an existing client.
   * @param clientId The base client identifier.
   * @param clientNumber The next client that is derived from the base client identifier.
   * @return A unique client identifier string.
   */
  std::string generateUniqueClientId(const std::string& clientId, std::size_t clientNumber)
  {
      return clientId + "_" + std::to_string(clientNumber) + "_" + MqttTypeConverter::toStdString(MqttIdGenerator::generate());
  }
  
  } // namespace
  
  MqttClient::MqttClient(const std::string& _clientId, const std::function<void(const Token& token)>& deliveryCompleteCallback)
      : m_interfaceMutex()
      , m_internalMutex()

      , m_subscriptionMutex()

      , m_endpoint()
      , m_clientId(_clientId)
      , m_activeTokens()
      , m_activeTokensCV()
      , m_deliveryCompleteCallback(deliveryCompleteCallback)
      , m_serverState(this)
      , m_principalClient()
      , m_additionalClients()
      , m_eventQueue(_clientId)

      , m_workerThread( std::thread( &MqttClient::eventHandler, this ) )

      , m_deferredSubscriptions()

  {

      Log::init( "mqtt-library" );
      LogInfo( "MQTT Client started", "[MqttClient::MqttClient]");

  }
  
  MqttClient::~MqttClient()
  {

      {

          // LogDebug( "MqttClient", std::string( m_clientId + " - disconnect" ) );

          this->disconnect();
          decltype(m_principalClient) principalClient{};
  
          OSDEV_COMPONENTS_LOCKGUARD(m_internalMutex);

          LogDebug( "MqttClient", std::string( m_clientId + " - cleanup principal client" ) );

          m_principalClient.swap(principalClient);
      }

      LogDebug( "MqttClient", std::string( m_clientId + " - dtor stop queue" ) );

      m_eventQueue.stop();
      if (m_workerThread.joinable()) {
          m_workerThread.join();
      }

      LogDebug( "MqttClient", std::string( m_clientId + " - dtor ready" ) );

  }
  
  std::string MqttClient::clientId() const
  {
      return m_clientId;
  }
  
  StateChangeCallbackHandle MqttClient::registerStateChangeCallback(const SlotStateChange& cb)
  {
      OSDEV_COMPONENTS_LOCKGUARD(m_interfaceMutex);
      OSDEV_COMPONENTS_LOCKGUARD(m_internalMutex);
      return m_serverState.registerStateChangeCallback(cb);
  }
  
  void MqttClient::unregisterStateChangeCallback(StateChangeCallbackHandle handle)
  {
      OSDEV_COMPONENTS_LOCKGUARD(m_interfaceMutex);
      OSDEV_COMPONENTS_LOCKGUARD(m_internalMutex);
      m_serverState.unregisterStateChangeCallback(handle);
  }
  
  void MqttClient::clearAllStateChangeCallbacks()
  {
      OSDEV_COMPONENTS_LOCKGUARD(m_interfaceMutex);
      OSDEV_COMPONENTS_LOCKGUARD(m_internalMutex);
      m_serverState.clearAllStateChangeCallbacks();
  }
  
  StateEnum MqttClient::state() const
  {
      OSDEV_COMPONENTS_LOCKGUARD(m_interfaceMutex);
      OSDEV_COMPONENTS_LOCKGUARD(m_internalMutex);
      return m_serverState.state();
  }
  

  void MqttClient::connect(const std::string& host, int port, const Credentials &credentials, const mqtt_LWT &lwt, bool blocking )

  {

      osdev::components::mqtt::ParsedUri _endpoint = {
          { "scheme", "tcp" },
          { "user", credentials.username() },
          { "password", credentials.password() },
          { "host", host },
          { "port", std::to_string(port) }
      };

      this->connect( UriParser::toString( _endpoint ), lwt, blocking );

  }
  

  void MqttClient::connect( const std::string &_endpoint, const mqtt_LWT &lwt, bool blocking )

  {

      LogInfo( "MqttClient", std::string( m_clientId + " - Request connect" ) );

      OSDEV_COMPONENTS_LOCKGUARD(m_interfaceMutex);
      IMqttClientImpl* client(nullptr);
      {
          OSDEV_COMPONENTS_LOCKGUARD(m_internalMutex);
          if (m_principalClient && m_principalClient->connectionStatus() != ConnectionStatus::Disconnected) {
              if (_endpoint == m_endpoint)
              {
                  // idempotent
                  return;
              }
              else
              {

                  LogError( "MqttClient", std::string( m_clientId + " - Cannot connect to different endpoint. Disconnect first." ) );

                  return;

              }
          }
          m_endpoint = _endpoint;

          if (!m_principalClient)
          {

              std::string derivedClientId(generateUniqueClientId(m_clientId, 1));
              m_principalClient = std::make_unique<ClientPaho>(
                  m_endpoint,
                  derivedClientId,
                  [this](const std::string& id, ConnectionStatus cs) { this->connectionStatusChanged(id, cs); },
                  [this](std::string clientId, std::int32_t token) { this->deliveryComplete(clientId, token); });
          }
          client = m_principalClient.get();
      }

      client->connect( blocking, lwt );

  }
  
  void MqttClient::disconnect()
  {

      LogInfo( "MqttClient", std::string( m_clientId + " - Request disconnect" ) );

      OSDEV_COMPONENTS_LOCKGUARD(m_interfaceMutex);
  
      decltype(m_additionalClients) additionalClients{};
      std::vector<IMqttClientImpl*> clients{};
      {
          OSDEV_COMPONENTS_LOCKGUARD(m_internalMutex);

          if (!m_principalClient || m_principalClient->connectionStatus() == ConnectionStatus::Disconnected || m_principalClient->connectionStatus() == ConnectionStatus::DisconnectInProgress)
          {

              LogDebug( "MqttClient", std::string( m_clientId + " - Principal client not connected" ) );

              return;
          }

          m_additionalClients.swap( additionalClients );

          for (const auto& c : additionalClients)
          {
              clients.push_back( c.get() );

          }

          clients.push_back( m_principalClient.get() );

      }
  

      LogDebug( "MqttClient", std::string( m_clientId +  " - Unsubscribe and disconnect clients" ) );

      for ( auto& cl : clients )
      {

          cl->unsubscribeAll();
      }
      this->waitForCompletionInternal(clients, std::chrono::milliseconds(2000), std::set<Token>{});
  
      for (auto& cl : clients) {
          cl->disconnect(false, 2000);
      }
      this->waitForCompletionInternal(clients, std::chrono::milliseconds(3000), std::set<Token>{});
  }
  
  Token MqttClient::publish(const MqttMessage& message, int qos)
  {
      if (hasWildcard(message.topic()) || !isValidTopic(message.topic())) {
          return Token(m_clientId, -1);
      }
      OSDEV_COMPONENTS_LOCKGUARD(m_interfaceMutex);
      IMqttClientImpl* client(nullptr);
      {
          OSDEV_COMPONENTS_LOCKGUARD(m_internalMutex);
          if (!m_principalClient || m_principalClient->connectionStatus() == ConnectionStatus::Disconnected)
          {
              if( !m_principalClient )
              {

                  LogInfo( "[MqttClient::publish]", std::string( "Principal client not initialized") );

              }
  
              if( m_principalClient->connectionStatus() == ConnectionStatus::Disconnected )
              {
                  std::cout << "Unable to publish, not connected.." << std::endl;
              }

              LogError("MqttClient", std::string( m_clientId + " - Unable to publish, not connected" ) );
  

              return Token(m_clientId, -1);

          }
          client = m_principalClient.get();
      }
      return Token(client->clientId(), client->publish(message, qos));
  }
  
  Token MqttClient::subscribe(const std::string& topic, int qos, const std::function<void(MqttMessage)>& cb)
  {

      LogDebug( "[MqttClient::subscribe]", std::string( m_clientId + " - Subscribe to topic " + topic ) );

      // OSDEV_COMPONENTS_LOCKGUARD(m_interfaceMutex);
      bool clientFound = false;
      IMqttClientImpl* client(nullptr);
      {
          // OSDEV_COMPONENTS_LOCKGUARD(m_internalMutex);

          if (!m_principalClient || m_principalClient->connectionStatus() != ConnectionStatus::Connected)

          {

              LogError("MqttClient", std::string( m_clientId + " - Unable to subscribe, not connected" ) );

              // Store the subscription in the buffer for later processing.
              {
                  OSDEV_COMPONENTS_LOCKGUARD(m_subscriptionMutex);
                  m_deferredSubscriptions.push_back( Subscription( topic, qos, cb ) );
              }
  

              return Token(m_clientId, -1);

          }

          if (!m_principalClient->isOverlapping(topic))
          {

              client = m_principalClient.get();
              clientFound = true;
          }

          else
          {
              for (const auto& c : m_additionalClients)
              {

                  if (!c->isOverlapping(topic)) {
                      client = c.get();
                      clientFound = true;
                      break;
                  }
              }
          }

          if (!clientFound)
          {

              LogDebug("[MqttClient::subscribe]", std::string( m_clientId + " - Creating new ClientPaho instance for subscription on topic " + topic ) );

              std::string derivedClientId(generateUniqueClientId(m_clientId, m_additionalClients.size() + 2)); // principal client is nr 1.
              m_additionalClients.emplace_back(std::make_unique<ClientPaho>(
                  m_endpoint,
                  derivedClientId,
                  [this](const std::string& id, ConnectionStatus cs) { this->connectionStatusChanged(id, cs); },
                  std::function<void(const std::string&, std::int32_t)>{}));
              client = m_additionalClients.back().get();
          }
      }

      if (!clientFound)
      {

          client->connect( true );

      }
      return Token{ client->clientId(), client->subscribe(topic, qos, cb) };
  }
  
  std::set<Token> MqttClient::unsubscribe(const std::string& topic, int qos)
  {

      LogDebug("[MqttClient::unsubscribe]", std::string( m_clientId + " - Unsubscribe from topic " + topic ) );

      OSDEV_COMPONENTS_LOCKGUARD(m_interfaceMutex);
      std::vector<IMqttClientImpl*> clients{};
      {
          OSDEV_COMPONENTS_LOCKGUARD(m_internalMutex);
          if (!m_principalClient || m_principalClient->connectionStatus() == ConnectionStatus::Disconnected) {

              LogError("[MqttClient::unsubscribe]", std::string( m_clientId + " - Unable to unsubscribe, not connected" ) );

              // Throw (MqttException, "Not connected");

              return std::set<Token>();

          }
          clients.push_back(m_principalClient.get());
          for (const auto& c : m_additionalClients) {
              clients.push_back(c.get());
          }
      }
      std::set<Token> tokens{};
      for (auto* c : clients) {
          auto token = c->unsubscribe(topic, qos);
          if (-1 != token) {
              tokens.emplace(Token{ c->clientId(), token });
          }
      }
      return tokens;
  }
  
  bool MqttClient::waitForCompletion(std::chrono::milliseconds waitFor) const
  {
      return this->waitForCompletion(waitFor, std::set<Token>{});
  }
  
  bool MqttClient::waitForCompletion(std::chrono::milliseconds waitFor, const Token& token) const
  {
      if (-1 == token.token()) {
          return false;
      }
      return this->waitForCompletion(waitFor, std::set<Token>{ token });
  }
  
  bool MqttClient::waitForCompletion(std::chrono::milliseconds waitFor, const std::set<Token>& tokens) const
  {
      OSDEV_COMPONENTS_LOCKGUARD(m_interfaceMutex);
      std::vector<IMqttClientImpl*> clients{};
      {
          OSDEV_COMPONENTS_LOCKGUARD(m_internalMutex);
          if (m_principalClient) {
              clients.push_back(m_principalClient.get());
          }
          for (const auto& c : m_additionalClients) {
              clients.push_back(c.get());
          }
      }
      return waitForCompletionInternal(clients, waitFor, tokens);
  }
  
  boost::optional<bool> MqttClient::commandResult(const Token& token) const
  {
      OSDEV_COMPONENTS_LOCKGUARD(m_interfaceMutex);
      std::vector<IMqttClientImpl*> clients{};
      {
          OSDEV_COMPONENTS_LOCKGUARD(m_internalMutex);
          if (m_principalClient) {
              clients.push_back(m_principalClient.get());
          }
          for (const auto& c : m_additionalClients) {
              clients.push_back(c.get());
          }
      }
      for (auto* c : clients) {
          if (token.clientId() == c->clientId()) {
              return c->operationResult(token.token());
          }
      }
      return boost::optional<bool>{};
  }
  
  std::string MqttClient::endpoint() const
  {
      auto ep = UriParser::parse(m_endpoint);
      if (ep.find("user") != ep.end()) {
          ep["user"].clear();
      }
      if (ep.find("password") != ep.end()) {
          ep["password"].clear();
      }
      return UriParser::toString(ep);
  }
  
  void MqttClient::connectionStatusChanged(const std::string& id, ConnectionStatus cs)
  {

      LogDebug("[MqttClient::connectionStatusChanged]", std::string( m_clientId + " - connection status of wrapped client " + id + " changed to " + std::to_string( static_cast<int>(cs) ) ) );

      IMqttClientImpl* principalClient{ nullptr };
      std::vector<IMqttClientImpl*> clients{};
      std::vector<ConnectionStatus> connectionStates{};
      {
          OSDEV_COMPONENTS_LOCKGUARD(m_internalMutex);

  
          if (m_principalClient)
          {

              principalClient = m_principalClient.get();
              clients.push_back(principalClient);
              connectionStates.push_back(m_principalClient->connectionStatus());
          }

  
          for (const auto& c : m_additionalClients)
          {

              clients.push_back(c.get());
              connectionStates.push_back(c->connectionStatus());
          }
      }

      auto newState = determineState(connectionStates);

      // bool resubscribe = (StateEnum::ConnectionFailure == m_serverState.state() && StateEnum::Good == newState);
      bool resubscribe = ( StateEnum::Good == newState );

      if (resubscribe)
      {

          // First activate pending subscriptions
          {
              OSDEV_COMPONENTS_LOCKGUARD(m_subscriptionMutex);
              LogDebug( "[MqttClient::connectionsStatusChanged]", std::string( m_clientId + " - Number of pending subscriptions : " + std::to_string(m_deferredSubscriptions.size() ) ) );
              while( m_deferredSubscriptions.size() > 0 )
              {
                  auto subscription = m_deferredSubscriptions.at( 0 );
                  this->subscribe( subscription.getTopic(), subscription.getQoS(), subscription.getCallBack() );
                  m_deferredSubscriptions.erase( m_deferredSubscriptions.begin() );
              }
          }
  

          LogDebug( "[MqttClient::connectionStatusChanged]",
                    std::string( m_clientId + " - Resubscribing..." ) );

          {
              OSDEV_COMPONENTS_LOCKGUARD(m_internalMutex);
              m_activeTokens.clear();
          }

  
          for (auto* cl : clients)
          {
              try
              {
                  LogDebug( "[MqttClient::connectionStatusChanged]", std::string( m_clientId + " - Client " + cl->clientId() + " has " + std::string( cl->hasPendingSubscriptions() ? "" : "no" ) + " pending subscriptions" ) );

                  cl->resubscribe();
              }

              catch (const std::exception& e)
              {

                  LogError("[MqttClient::connectionStatusChanged]", std::string( m_clientId + " - resubscribe on wrapped client " + cl->clientId() + " in context of connection status change in wrapped client : " + id + " => FAILED : " + e.what() ) );

              }
          }
          m_activeTokensCV.notify_all();
      }
  
      // The server state change and a possible resubscription are done in the context of the MqttClient worker thread
      // The wrapper is free to pick up new work such as the acknowledment of the just recreated subscriptions.
      this->pushEvent([this, resubscribe, clients, principalClient, newState]() {

          if (resubscribe)
          {

              // Just wait for the subscription commands to complete. We do not use waitForCompletionInternal because that call will always timeout when there are active tokens.
              // Active tokens are removed typically by work done on the worker thread. The wait action is also performed on the worker thread.
              auto waitFor = std::chrono::milliseconds(1000);

              if (!waitForCompletionInternalClients(clients, waitFor, std::set<Token>{}))
              {
                  if (std::accumulate(clients.begin(),
                                      clients.end(),
                                      false,
                                      [](bool hasPending, IMqttClientImpl* client)
                                      {
                                          return hasPending || client->hasPendingSubscriptions();
                                      }))
                  {

                      LogWarning("[MqttClient::connectionStatusChanged]", std::string( m_clientId + " - subscriptions are not recovered within timeout." ) );

                  }
              }

              if (principalClient)
              {
                  try
                  {

                      principalClient->publishPending();
                  }

                  catch (const std::exception& e)
                  {

                      LogError( "[MqttClient::connectionStatusChanged]", std::string( m_clientId + " - publishPending on wrapped client " + principalClient->clientId() + " => FAILED " + e.what() ) );

                  }
              }
          }
          m_serverState.emitStateChanged(newState);
      });
  }
  
  void MqttClient::deliveryComplete(const std::string& _clientId, std::int32_t token)
  {
      if (!m_deliveryCompleteCallback) {
          return;
      }
  
      Token t(_clientId, token);
      {
          OSDEV_COMPONENTS_LOCKGUARD(m_internalMutex);
          if (!m_activeTokens.insert(t).second) {
              // This should not happen. This means that some callback on the wrapper never came.

              LogDebug("[MqttClient::deliveryComplete]", std::string( m_clientId + " - deliveryComplete, token is already active" ) );

          }
      }
      this->pushEvent([this, t]() {
          OSDEV_COMPONENTS_SCOPEGUARD(m_activeTokens, [this, &t]() {
              {
                  OSDEV_COMPONENTS_LOCKGUARD(m_internalMutex);
                  m_activeTokens.erase(t);
              }
              m_activeTokensCV.notify_all();
          });
          m_deliveryCompleteCallback(t);
      });
  }
  
  bool MqttClient::waitForCompletionInternal(const std::vector<IMqttClientImpl*>& clients, std::chrono::milliseconds waitFor, const std::set<Token>& tokens) const
  {
      if (!waitForCompletionInternalClients(clients, waitFor, tokens)) {
          return false;
      }
      std::unique_lock<std::mutex> lck(m_internalMutex);
      return m_activeTokensCV.wait_for(lck, waitFor, [this, &tokens]() {
          if (tokens.empty()) { // wait for all operations to end
              return m_activeTokens.empty();
          }
          else if (tokens.size() == 1) {
              return m_activeTokens.find(*tokens.cbegin()) == m_activeTokens.end();
          }
          std::vector<Token> intersect{};
          std::set_intersection(m_activeTokens.begin(), m_activeTokens.end(), tokens.begin(), tokens.end(), std::back_inserter(intersect));
          return intersect.empty(); });
  }
  
  bool MqttClient::waitForCompletionInternalClients(const std::vector<IMqttClientImpl*>& clients, std::chrono::milliseconds& waitFor, const std::set<Token>& tokens) const
  {
      for (auto* c : clients) {
          std::set<std::int32_t> clientTokens{};
          for (const auto& token : tokens) {
              if (c->clientId() == token.clientId()) {
                  clientTokens.insert(token.token());
              }
          }
          if (tokens.empty() || !clientTokens.empty()) {
              waitFor -= c->waitForCompletion(waitFor, clientTokens);
          }
      }
      if (waitFor > std::chrono::milliseconds(0)) {
          return true;
      }
      waitFor = std::chrono::milliseconds(0);
      return false;
  }
  
  StateEnum MqttClient::determineState(const std::vector<ConnectionStatus>& connectionStates)
  {
      std::size_t unknownStates = 0;
      std::size_t goodStates = 0;
      std::size_t reconnectStates = 0;
      for (auto cst : connectionStates) {
          switch (cst) {
              case ConnectionStatus::Disconnected:
                  ++unknownStates;
                  break;
              case ConnectionStatus::DisconnectInProgress: // count as unknown because we don't want resubscribes to trigger when a wrapper is in this state.
                  ++unknownStates;
                  break;
              case ConnectionStatus::ConnectInProgress: // count as unknown because the wrapper is not connected yet.
                  ++unknownStates;
                  break;
              case ConnectionStatus::ReconnectInProgress:
                  ++reconnectStates;
                  break;
              case ConnectionStatus::Connected:
                  ++goodStates;
                  break;
          }
      }
      auto newState = StateEnum::Unknown;
      if (reconnectStates > 0) {
          newState = StateEnum::ConnectionFailure;
      }
      else if (unknownStates > 0) {
          newState = StateEnum::Unknown;
      }
      else if (connectionStates.size() == goodStates) {
          newState = StateEnum::Good;
      }
      return newState;
  }
  
  void MqttClient::pushEvent(std::function<void()> ev)
  {
      m_eventQueue.push(ev);
  }
  
  void MqttClient::eventHandler()
  {

      LogInfo("[MqttClient::eventHandler]", std::string( m_clientId + " - starting event handler." ) );
      for (;;)
      {

          std::vector<std::function<void()>> events;
          if (!m_eventQueue.pop(events))
          {
              break;
          }
          for (const auto& ev : events)
          {
              ev();
          }
      }

      LogInfo("[MqttClient::eventHandler]", std::string( m_clientId + " - leaving event handler." ) );

  }