[rpc - client] Add mutex for stop() method since it can be called concurrently when used in local controller

Author: c-jimenez

src/rpc/RpcClient.cpp

@@ -30,7 +30,7 @@ namespace rpc
 
 /** @brief Constructor */
 RpcClient::RpcClient(ocpp::websockets::IWebsocketClient& websocket, const std::string& protocol)
-    : RpcBase(), m_protocol(protocol), m_websocket(websocket), m_listener(nullptr), m_started(false)
+    : RpcBase(), m_protocol(protocol), m_websocket(websocket), m_listener(nullptr), m_started(false), m_stop_mutex()
 {
     m_websocket.registerListener(*this);
 }
@@ -71,15 +71,22 @@ bool RpcClient::stop()
 {
     bool ret = false;
 
-    // Check if already started
-    if (m_started)
+    // Check if someone is already stopping the client
+    // May happen in local controller mode when disconnection
+    // can be triggered from central system side and charge point side
+    if (m_stop_mutex.try_lock())
     {
-        // Disconnect from websocket
-        ret = m_websocket.disconnect();
+        // Check if already started
+        if (m_started)
+        {
+            // Disconnect from websocket
+            ret = m_websocket.disconnect();
 
-        // Stop processing
-        RpcBase::stop();
-        m_started = false;
+            // Stop processing
+            RpcBase::stop();
+            m_started = false;
+        }
+        m_stop_mutex.unlock();
     }
 
     return ret;

src/rpc/RpcClient.h

@@ -115,6 +115,8 @@ class RpcClient : public RpcBase, public ocpp::websockets::IWebsocketClient::ILi
     IListener* m_listener;
     /** @brief Started state */
     bool m_started;
+    /** @brief Mutex for concurrent stop access */
+    std::mutex m_stop_mutex;
 };
 
 } // namespace rpc