Class: Salus::Future

Inherits:
Object
  • Object
show all
Includes:
Logging, Observable
Defined in:
lib/salus/thread/future.rb

Constant Summary collapse

Cancel = 
Class.new(Exception)

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Logging

#log

Methods included from Observable

#add_observer, #count_observers, #delete_observer, #delete_observers, #notify_and_delete_observers, #notify_observers, #with_observer

Constructor Details

#initialize(pool = nil, &block) ⇒ Future

Create a future with the passed block and optionally using the passed pool.

Raises:

  • (ArgumentError) 


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# File 'lib/salus/thread/future.rb', line 23

def initialize(pool = nil, &block)
  raise ArgumentError, 'no block given' unless block

  @mutex = Mutex.new

  task = proc {
    begin
      deliver block.call
      notify_and_delete_observers(Time.now, @value, nil)
    rescue Exception => e
      @exception = e
      notify_and_delete_observers(Time.now, nil, e)
      log DEBUG, @exception
      deliver nil
    end
  }

  @thread = pool ? pool.process(&task) : Thread.new(&task)

  ObjectSpace.define_finalizer self, self.class.finalizer(WeakRef.new(@thread))
end

Class Method Details

.finalizer(thread) ⇒ Object 



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# File 'lib/salus/thread/future.rb', line 46

def self.finalizer(thread)
  proc {
    if thread.weakref_alive?
      if thread.is_a? Thread
        thread.raise Cancel
      else
        thread.terminate! Cancel
      end
    end
  }
end

Instance Method Details

#cancel ⇒ Object

Cancel the future, #value will yield a Cancel exception



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# File 'lib/salus/thread/future.rb', line 82

def cancel
  return self if delivered?

  @mutex.synchronize {
    if @thread.is_a? Thread
      @thread.raise Cancel
    else
      @thread.terminate! Cancel
    end

    @exception = Cancel.new
  }

  self
end

#cancelled? ⇒ Boolean

Check if the future has been cancelled

Returns:

  • (Boolean) 


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# File 'lib/salus/thread/future.rb', line 99

def cancelled?
  @mutex.synchronize {
    @exception.is_a? Cancel
  }
end

#delivered? ⇒ Boolean Also known as: realized?

Check if the future has been called.

Returns:

  • (Boolean) 


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# File 'lib/salus/thread/future.rb', line 73

def delivered?
  @mutex.synchronize {
    instance_variable_defined? :@value
  }
end

#exception ⇒ Object

Return the raised exception.



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# File 'lib/salus/thread/future.rb', line 66

def exception
  @mutex.synchronize {
    @exception
  }
end

#exception? ⇒ Boolean

Check if an exception has been raised.

Returns:

  • (Boolean) 


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# File 'lib/salus/thread/future.rb', line 59

def exception?
  @mutex.synchronize {
    instance_variable_defined? :@exception
  }
end

#value(timeout = nil) ⇒ Object Also known as: ~

Get the value of the future, if it’s not finished running this call will block.

In case the block raises an exception, it will be raised, the exception is cached and will be raised every time you access the value.

An optional timeout can be passed which will return nil if nothing has been delivered.

Raises:



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# File 'lib/salus/thread/future.rb', line 112

def value(timeout = nil)
  raise @exception if exception?

  return @value if delivered?

  @mutex.synchronize {
    cond.wait(@mutex, *timeout)
  }

  if exception?
    raise @exception
  elsif delivered?
    return @value
  end
end

#value!(timeout = nil) ⇒ Object Also known as: !

Do the same as #value, but return nil in case of exception.



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# File 'lib/salus/thread/future.rb', line 131

def value!(timeout = nil)
  begin
    value(timeout)
  rescue Exception
    nil
  end
end