Class: QuackConcurrency::Future

Inherits:
Object
  • Object
show all
Defined in:
lib/quack_concurrency/future.rb,
lib/quack_concurrency/future/canceled.rb,
lib/quack_concurrency/future/complete.rb

Overview

Used to send a value or error from one thread to another without the need for coordination.

Defined Under Namespace

Classes: Canceled, Complete

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Future

Creates a new QuackConcurrency::Future concurrency tool.



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# File 'lib/quack_concurrency/future.rb', line 8

def initialize
  @complete = false
  @exception = false
  @mutex = ::Mutex.new
  @value = nil
  @waiter = Waiter.new
end

Instance Method Details

#cancel(exception = nil) ⇒ void

This method returns an undefined value.

Cancels it. If no exception is specified, a Canceled error will be set.

Parameters:

  • exception (Exception) (defaults to: nil) —

    custom exception to set (see #raise)

Raises:



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# File 'lib/quack_concurrency/future.rb', line 21

def cancel(exception = nil)
  exception ||= Canceled.new
  self.raise(exception)
  nil
end

#complete? ⇒ Boolean

Checks if it has a value or error set.

Returns:

  • (Boolean) 


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# File 'lib/quack_concurrency/future.rb', line 29

def complete?
  @complete
end

#get ⇒ Object

Note:

This method will block until the future has completed

Gets it’s value.

Returns:

  • (Object) —

    it’s value

Raises:

  • (Canceled) —

    if it is canceled

  • (Exception) —

    if specific error was set



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# File 'lib/quack_concurrency/future.rb', line 38

def get
  @waiter.wait
  Kernel.raise(@exception) if @exception
  @value
end

#raise(exception = nil) ⇒ void

This method returns an undefined value.

Sets it to an error.

Parameters:

  • exception (nil, Object) (defaults to: nil) —

    Exception class or instance to set, otherwise a StandardError will be set

Raises:

  • (Complete) —

    if the it has already completed



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# File 'lib/quack_concurrency/future.rb', line 48

def raise(exception = nil)
  exception = case
  when exception == nil then StandardError.new
  when exception.is_a?(Exception) then exception
  when Exception >= exception then exception.new
  else
    Kernel.raise(TypeError, "'exception' must be nil or an instance of or descendant of Exception")
  end
  @mutex.synchronize do
    Kernel.raise(Complete) if @complete
    @complete = true
    @exception = exception
    @waiter.resume_all_indefinitely
  end
  nil
end

#set(new_value = nil) ⇒ void

This method returns an undefined value.

Sets it to a value.

Parameters:

  • new_value (nil, Object) (defaults to: nil) —

    value to assign to future

Raises:

  • (Complete) —

    if it has already completed



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# File 'lib/quack_concurrency/future.rb', line 69

def set(new_value = nil)
  @mutex.synchronize do
    Kernel.raise(Complete) if @complete
    @complete = true
    @value = new_value
    @waiter.resume_all_indefinitely
  end
  nil
end