Class: Garcon::CopyOnWriteObserverSet

Inherits:
Object
  • Object
show all
Defined in:
lib/garcon/task/copy_on_write_observer_set.rb

Overview

A thread safe observer set implemented using copy-on-write approach: every time an observer is added or removed the whole internal data structure is duplicated and replaced with a new one.

Instance Method Summary collapse

Constructor Details

#initialize ⇒ CopyOnWriteObserverSet

Returns a new instance of CopyOnWriteObserverSet.



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# File 'lib/garcon/task/copy_on_write_observer_set.rb', line 28

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

Instance Method Details

#add_observer(observer = nil, func = :update, &block) ⇒ Object

Adds an observer to this set. If a block is passed, the observer will be created by this method and no other params should be passed

Parameters:

  • observer (Object) (defaults to: nil) —

    the observer to add

  • func (Symbol) (defaults to: :update) —

    the function to call on the observer during notification. The default is :update.

Returns:

  • (Object) —

    the added observer



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# File 'lib/garcon/task/copy_on_write_observer_set.rb', line 45

def add_observer(observer=nil, func=:update, &block)
  if observer.nil? && block.nil?
    raise ArgumentError, 'should pass observer as a first argument or block'
  elsif observer && block
    raise ArgumentError.new('cannot provide both an observer and a block')
  end

  if block
    observer = block
    func = :call
  end

  begin
    @mutex.lock
    new_observers = @observers.dup
    new_observers[observer] = func
    @observers = new_observers
    observer
  ensure
    @mutex.unlock
  end
end

#count_observers ⇒ Integer

Returns the observers count.

Returns:

  • (Integer) —

    the observers count



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# File 'lib/garcon/task/copy_on_write_observer_set.rb', line 91

def count_observers
  observers.count
end

#delete_observer(observer) ⇒ Object

Returns the deleted observer.

Parameters:

  • observer (Object) —

    the observer to remove

Returns:

  • (Object) —

    the deleted observer



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# File 'lib/garcon/task/copy_on_write_observer_set.rb', line 72

def delete_observer(observer)
  @mutex.lock
  new_observers = @observers.dup
  new_observers.delete(observer)
  @observers = new_observers
  observer
ensure
  @mutex.unlock
end

#delete_observers ⇒ CopyOnWriteObserverSet

Deletes all observers

Returns:



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# File 'lib/garcon/task/copy_on_write_observer_set.rb', line 84

def delete_observers
  self.observers = {}
  self
end

#notify_and_delete_observers(*args, &block) ⇒ CopyOnWriteObserverSet

Notifies all registered observers with optional args and deletes them.

Parameters:

  • args (Object) —

    Arguments to be passed to each observer

Returns:



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# File 'lib/garcon/task/copy_on_write_observer_set.rb', line 112

def notify_and_delete_observers(*args, &block)
  old = clear_observers_and_return_old
  notify_to(old, *args, &block)
  self
end

#notify_observers(*args, &block) ⇒ CopyOnWriteObserverSet

Notifies all registered observers with optional args

Parameters:

  • args (Object) —

    Arguments to be passed to each observer

Returns:



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# File 'lib/garcon/task/copy_on_write_observer_set.rb', line 101

def notify_observers(*args, &block)
  notify_to(observers, *args, &block)
  self
end