Semaphore Objects

#Firmware/v310 #Threads

Semaphore objects provide a locking and signalling mechanism that allows threads/tasks to coordinate.

  • A counting semaphore ( semaphore.new ) can be used to signal and wake up a task that's waiting for work to do.
  • A binary semaphore mutex ( semaphore.mutex ) can be used to lock a single resource to that other tasks are blocked while the resource is in use.

Return Values

If there is an error in one of the object functions, the return values are:

  • nil
  • code - the integer error code
  • msg - a string representation of the error (or blank)

e.g.

ok,err,msg = semo:wait(50)

-- Return values
-- Timeout: nil, 209, 'OperationTimedOut'
-- Success: true