block/unblock allows for safe aggregration of serial messages in a threaded environment. (#10)

Author: aentinger

examples/ts_serial/ts_serial.ino

@@ -63,6 +63,12 @@ void serial_thread_func()
     /* Print thread id and chip id value to serial. */
     char msg[64] = {0};
     snprintf(msg, sizeof(msg), "[%05lu] %s: Lorem ipsum ...", millis(), rtos::ThisThread::get_name());
+    /* Every Serial.print/println() encapsulated between
+     * block/unblock statements will only be printed after
+     * a block statement has occurred.
+     */
+    Serial.block();
     Serial.println(msg);
+    Serial.unblock();
   }
 }

keywords.txt

@@ -20,6 +20,8 @@ BusDevice	KEYWORD1
 
 transfer	KEYWORD2
 create	KEYWORD2
+block	KEYWORD2
+unblock	KEYWORD2
 
 #######################################
 # Constants (LITERAL1)

src/serial/SerialDispatcher.cpp

@@ -68,6 +68,7 @@ void SerialDispatcher::begin(unsigned long baudrate, uint16_t config)
      */
     ThreadCustomerData data;
     data.thread_id = current_thread_id;
+    data.block_tx_buffer = false;
     _thread_customer_list.push_back(data);
   }
 }
@@ -166,6 +167,21 @@ size_t SerialDispatcher::write(const uint8_t * data, size_t len)
   return bytes_written;
 }
 
+void SerialDispatcher::block()
+{
+  mbed::ScopedLock<rtos::Mutex> lock(_mutex);
+  auto iter = findThreadCustomerDataById(rtos::ThisThread::get_id());
+  iter->block_tx_buffer = true;
+}
+
+void SerialDispatcher::unblock()
+{
+  mbed::ScopedLock<rtos::Mutex> lock(_mutex);
+  auto iter = findThreadCustomerDataById(rtos::ThisThread::get_id());
+  iter->block_tx_buffer = false;
+  _cond.notify_one();
+}
+
 /**************************************************************************************
  * PRIVATE MEMBER FUNCTIONS
  **************************************************************************************/
@@ -187,9 +203,12 @@ void SerialDispatcher::threadFunc()
                     std::end  (_thread_customer_list),
                     [this](ThreadCustomerData & d)
                     {
-                      while(d.tx_buffer.available())
+                      if (!d.block_tx_buffer)
                       {
-                        _serial.write(d.tx_buffer.read_char());
+                        while(d.tx_buffer.available())
+                        {
+                          _serial.write(d.tx_buffer.read_char());
+                        }
                       }
                     });
   }

src/serial/SerialDispatcher.h

@@ -53,6 +53,8 @@ class SerialDispatcher : public arduino::HardwareSerial
   using Print::write;
   virtual operator bool() override { return _serial; }
 
+  void block();
+  void unblock();
 
 private:
 
@@ -69,6 +71,7 @@ class SerialDispatcher : public arduino::HardwareSerial
   {
     osThreadId_t thread_id;
     arduino::RingBuffer tx_buffer;
+    bool block_tx_buffer;
   } ThreadCustomerData;
 
   std::list<ThreadCustomerData> _thread_customer_list;