I have this function _write_port() being called from a thread, whenever I need to send a message. To ensure the whole message is written, tcdrain() is used.
void Serial_Port::_write_port(char *buf, unsigned &len)
{
// Lock
pthread_mutex_lock(&lock);
// Write packet via serial link
write(fd, buf, len);
// Wait until all data has been written
tcdrain(fd);
// Unlock
pthread_mutex_unlock(&lock);
return;
}
My problem is that tcdrain() blocks forever after a random number of executions of this function _write_port(). This will block the lock, resulting in blocking my other read thread, resulting in blocking everything.
What is a good approach to avoid tcdrain from blocking forever?
Note: I strangely noticed that if I use several printf() throughout the function, tcdrain never blocks. It does not make any sense to me to exist a relationship between printf() and write() because they write to different output files. Since I cannot explain this behaviour I assume it may be a coincidence that it worked like this on my experiments. If someone can explain this behaviour, please let me know.
