impr: bridge cleanup and get_last_client_error method

fix: monitor trying to connect even if bridge begin fails + monitor._read is private
mod: implementation is Arduino only, better mux usage

Author: eigen-value

src/bridge.h

@@ -35,12 +35,12 @@ class BridgeClass {
     HardwareSerial* serial_ptr = nullptr;
     ITransport* transport = nullptr;
 
-    struct k_mutex read_mutex;
-    struct k_mutex write_mutex;
+    struct k_mutex read_mutex{};
+    struct k_mutex write_mutex{};
 
-    k_tid_t upd_tid;
-    k_thread_stack_t *upd_stack_area;
-    struct k_thread upd_thread_data;
+    k_tid_t upd_tid{};
+    k_thread_stack_t *upd_stack_area{};
+    struct k_thread upd_thread_data{};
 
     bool started = false;
 
@@ -50,7 +50,7 @@ class BridgeClass {
         serial_ptr = &serial;
     }
 
-    explicit operator bool() const {
+    operator bool() const {
         return started;
     }
 
@@ -133,7 +133,7 @@ class BridgeClass {
     }
 
     template<typename RType, typename... Args>
-    bool call(const MsgPack::str_t method, RType& result, Args&&... args) {
+    bool call(const MsgPack::str_t& method, RType& result, Args&&... args) {
 
         uint32_t msg_id_wait;
 
@@ -182,6 +182,10 @@ class BridgeClass {
         return static_cast<uint8_t>(client->lastError.code);
     }
 
+    RpcError& get_last_client_error() const {
+        return client->lastError;
+    }
+
 private:
 
     void update_safe() {

src/monitor.h

@@ -27,10 +27,9 @@
 template<size_t BufferSize=DEFAULT_MONITOR_BUF_SIZE>
 class BridgeMonitor: public Stream {
 
-private:
     BridgeClass* bridge;
     RingBufferN<BufferSize> temp_buffer;
-    struct k_mutex monitor_mutex;
+    struct k_mutex monitor_mutex{};
     bool is_connected = false;
 
 public:
@@ -40,10 +39,12 @@ class BridgeMonitor: public Stream {
 
     bool begin() {
         k_mutex_init(&monitor_mutex);
-        if (!(*bridge)) {
-            bridge->begin();
+
+        bool bridge_started = (*bridge);
+        if (!bridge_started) {
+            bridge_started = bridge->begin();
         }
-        return bridge->call(MON_CONNECTED_METHOD, is_connected);
+        return bridge_started && bridge->call(MON_CONNECTED_METHOD, is_connected);
     }
 
     explicit operator bool() const {
@@ -91,18 +92,14 @@ class BridgeMonitor: public Stream {
 
     size_t write(const uint8_t* buffer, size_t size) override {
 
-        MsgPack::str_t send_buffer;
+        String send_buffer;
 
         for (size_t i = 0; i < size; ++i) {
-#ifdef ARDUINO
             send_buffer += static_cast<char>(buffer[i]);
-#else
-            send_buffer.push_back(static_cast<char>(buffer[i]));
-#endif
         }
 
         size_t written;
-        bool ret = bridge->call(MON_WRITE_METHOD, written, send_buffer);
+        const bool ret = bridge->call(MON_WRITE_METHOD, written, send_buffer);
         if (ret) {
             return written;
         }
@@ -119,14 +116,16 @@ class BridgeMonitor: public Stream {
         return (ok && res);
     }
 
+private:
     void _read(size_t size) {
 
         if (size == 0) return;
 
+        k_mutex_lock(&monitor_mutex, K_FOREVER);
+
         MsgPack::arr_t<uint8_t> message;
         bool ret = bridge->call(MON_READ_METHOD, message, size);
 
-        k_mutex_lock(&monitor_mutex, K_FOREVER);
         if (ret) {
             for (size_t i = 0; i < message.size(); ++i) {
                 temp_buffer.store_char(static_cast<char>(message[i]));