logger: move thread start/stop logic into LogWriterFile

src/modules/logger/log_writer.cpp

@@ -54,8 +54,17 @@ bool LogWriter::init()
 {
 	if (_log_writer_file) {
 		if (!_log_writer_file->init()) {
+			PX4_ERR("alloc failed");
 			return false;
 		}
+
+		int ret = _log_writer_file->thread_start();
+
+		if (ret) {
+			PX4_ERR("failed to create writer thread (%i)", ret);
+			return false;
+		}
+
 	}
 
 	return true;
@@ -102,15 +111,6 @@ void LogWriter::stop_log_file()
 	}
 }
 
-int LogWriter::thread_start(pthread_t &thread)
-{
-	if (_log_writer_file) {
-		return _log_writer_file->thread_start(thread);
-	}
-
-	return 0;
-}
-
 void LogWriter::thread_stop()
 {
 	if (_log_writer_file) {

src/modules/logger/log_writer.h

@@ -60,13 +60,7 @@ public:
 
 	Backend backend() const { return _backend; }
 
-	/**
-	 * start the thread
-	 * @param thread will be set to the created thread on success
-	 * @return 0 on success, error number otherwise (@see pthread_create)
-	 */
-	int thread_start(pthread_t &thread);
-
+	/** stop all running threads and wait for them to exit */
 	void thread_stop();
 
 	void start_log_file(const char *filename);

src/modules/logger/log_writer_file.cpp

@@ -108,7 +108,7 @@ void LogWriterFile::stop_log()
 	notify();
 }
 
-int LogWriterFile::thread_start(pthread_t &thread)
+int LogWriterFile::thread_start()
 {
 	pthread_attr_t thr_attr;
 	pthread_attr_init(&thr_attr);
@@ -120,7 +120,7 @@ int LogWriterFile::thread_start(pthread_t &thread)
 
 	pthread_attr_setstacksize(&thr_attr, PX4_STACK_ADJUSTED(1024));
 
-	int ret = pthread_create(&thread, &thr_attr, &LogWriterFile::run_helper, this);
+	int ret = pthread_create(&_thread, &thr_attr, &LogWriterFile::run_helper, this);
 	pthread_attr_destroy(&thr_attr);
 
 	return ret;
@@ -131,6 +131,16 @@ void LogWriterFile::thread_stop()
 	// this will terminate the main loop of the writer thread
 	_exit_thread = true;
 	_should_run = false;
+
+	notify();
+
+	// wait for thread to complete
+	int ret = pthread_join(_thread, NULL);
+
+	if (ret) {
+		PX4_WARN("join failed: %d", ret);
+	}
+
 }
 
 void *LogWriterFile::run_helper(void *context)

src/modules/logger/log_writer_file.h

@@ -58,10 +58,9 @@ public:
 
 	/**
 	 * start the thread
-	 * @param thread will be set to the created thread on success
 	 * @return 0 on success, error number otherwise (@see pthread_create)
 	 */
-	int thread_start(pthread_t &thread);
+	int thread_start();
 
 	void thread_stop();
 
@@ -144,6 +143,7 @@ private:
 	pthread_cond_t		_cv;
 	perf_counter_t _perf_write;
 	perf_counter_t _perf_fsync;
+	pthread_t _thread = 0;
 };
 
 }

src/modules/logger/logger.cpp

@@ -635,16 +635,7 @@ void Logger::run()
 
 
 	if (!_writer.init()) {
-		PX4_ERR("init of writer failed (alloc failed)");
-		return;
-	}
-
-	pthread_t writer_thread;
-
-	int ret = _writer.thread_start(writer_thread);
-
-	if (ret) {
-		PX4_ERR("failed to create writer thread (%i)", ret);
+		PX4_ERR("writer init failed");
 		return;
 	}
 
@@ -814,15 +805,6 @@ void Logger::run()
 	// stop the writer thread
 	_writer.thread_stop();
 
-	_writer.notify();
-
-	// wait for thread to complete
-	ret = pthread_join(writer_thread, NULL);
-
-	if (ret) {
-		PX4_WARN("join failed: %d", ret);
-	}
-
 	//unsubscribe
 	for (LoggerSubscription &sub : _subscriptions) {
 		for (uint8_t instance = 0; instance < ORB_MULTI_MAX_INSTANCES; instance++) {