EVENT module

About this

In programming, multiple threads can communicate with each other by signaling events and handling events. An event, then, is like a message from one thread to another thread.

Example 1:

In a MP3 player one thread scans a set of keys while the main thread is playing a song. When a key is pressed an event is send to the main thread, for example to stop the playing.

Example 2:

In a home automation application, a thread may be monitoring the presence of fire. If fire is detected the thread generates an alarm event to 2 threads: one to establish a communication with the firemen, and another to activate a series of actuators to extinguish the fire.

To use this module you must take into consideration the following:

1. Create an event using the event.create function. The create function returns an event instance. You must store this instance into a variable for further operation with it.

   keyPressed = event.create()

2. Use the event instance and call to the wait function when a thread requires to wait for the event. When the event is processed call to the done function.

   while true do
      keyPressed:wait()
      print("a key is pressed")
      keyPressed:done()
   end

3. Use the event instance an call to the broadcast function when you need to inform the waiting threads that the event has occurred.

   keyPressed:broadcast()

   The broadcast function accepts a boolean argument to indicate if the calling thread must wait for the process of the event by all the waiting threads.