BreakingBot

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6 threads are used by the robot and they use mutex on global variables and conditions

beginnerthread() {
   //contains all the movements of the robot starting as a beginner
   }
finisherthread() { 
   //contains all the movements of the robot starting as a finisher
   }
   
serverthread() {
   //listens to the messages sent by the server
   }
int main() {
   //the main thread
   }

On the small arena only :

positionthread() {
   //determines in real time the position of the robot
   } 
messagethread() {
   //sends the position of the robot to the server every 2 seconds
   }

We also use global variables, conditions and mutexes dealing with the threads.

x_robot ( + mutex_x_robot) //the abscissa of the robot
y_robot ( + mutex_y_robot) // the ordinate of the robot

The mutexes on x_robot and y_robot are needed because both the messagethread and the positionthread use those variables.

moving ( + mutex_moving) // boolean: 0 if the robot is moving, 1 if not

The mutex is needed, because the beginner/finisher thread, the server thread and the message thread use this variable. For instance, when the robot is a beginner, when it reaches the top right corner of the arena, the beginner thread has to set moving on 1 to stop the robot, while the message thread needs the value of this variable to send the position of the robot (if moving = 1, there is no need to send the position), and the message thread is waiting for a NEXT to come in order to set moving on 0. Three threads are trying to use/modify a value at the same time, so a mutex is needed.

condition_moving : thread condition to tell the robot when it has to move : when the condition is delivered by the server thread to the finisher/beginner thread (when receiving a NEXT message from the server), moving = 0 and the robot can move.

stop is a boolean: 1 if the robot has to stop because of the server. It is modified by the message thread to tell the main thread to stop.