class Concurrent::CopyOnNotifyObserverSet

prevent concurrency issues
a notification is required the internal data structure is copied to
observers are added and removed from a thread safe collection; every time
A thread safe observer set implemented using copy-on-read approach:

def add_observer(observer, func=:update)

Returns:
  • (Symbol) - the added function

Parameters:
  • func (Symbol) -- the function to call on the observer during notification. Default is :update
  • observer (Object) -- the observer to add 
def add_observer(observer, func=:update)
  @mutex.synchronize { @observers[observer] = func }
end

def count_observers

Returns:
  • (Integer) - the observers count 
def count_observers
  @mutex.synchronize { @observers.count }
end

def delete_observer(observer)

Returns:
  • (Object) - the deleted observer

Parameters:
  • observer (Object) -- the observer to remove 
def delete_observer(observer)
  @mutex.synchronize { @observers.delete(observer) }
  observer
end

def delete_observers

Returns:
  • (CopyOnWriteObserverSet) - self 
def delete_observers
  @mutex.synchronize { @observers.clear }
  self
end

def duplicate_and_clear_observers 

def duplicate_and_clear_observers
  @mutex.synchronize do
    observers = @observers.dup
    @observers.clear
    observers
  end
end

def initialize 

def initialize
  @mutex = Mutex.new
  @observers = {}
end

def notify_and_delete_observers(*args, &block)

Returns:
  • (CopyOnWriteObserverSet) - self

Parameters:
  • args (Object) -- arguments to be passed to each observer 
def notify_and_delete_observers(*args, &block)
  observers = duplicate_and_clear_observers
  notify_to(observers, *args, &block)
  self
end

def notify_observers(*args, &block)

Returns:
  • (CopyOnWriteObserverSet) - self

Parameters:
  • args (Object) -- arguments to be passed to each observer 
def notify_observers(*args, &block)
  observers = @mutex.synchronize { @observers.dup }
  notify_to(observers, *args, &block)
  self
end

def notify_to(observers, *args) 

def notify_to(observers, *args)
  raise ArgumentError.new('cannot give arguments and a block') if block_given? && ! args.empty?
  observers.each do |observer, function|
    args = yield if block_given?
    observer.send(function, *args)
  end
end