Class: FutureResource

Inherits:
Object
  • Object
show all
Defined in:
lib/future-resource.rb,
lib/future-resource/version.rb

Overview

future-resource allows you to wait on a final value being set for a placeholder, which may occur asynchronously.

Examples:

false printed first, followed by a delay before :foo is printed

fr = FutureResource.new

Thread.new do
  sleep 10
  fr.resource = :foo
end

p fr.set_yet?
p fr.resource

Author:

  • Ben Langfeld

  • Jay Phillips

Defined Under Namespace

Classes: ResourceAlreadySetException

Constant Summary collapse

VERSION = 
"1.0.0"

Instance Method Summary collapse

Constructor Details

#initialize ⇒ FutureResource

Create a new FutureResource.



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# File 'lib/future-resource.rb', line 26

def initialize
  @resource_lock          = Monitor.new
  @resource_value_blocker = @resource_lock.new_cond
end

Instance Method Details

#resource(timeout = nil) ⇒ Object

Returns the value of a specific resource, optionally waiting for timeout seconds before raising a Timeout::Error exception. When called on a not set resource without a timeout, raises a deadlock.

Parameters:

  • (defaults to: nil)

    number of seconds to wait for the resource to become ready

Returns:

Raises:

  • if timeout expires and resource is not ready



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# File 'lib/future-resource.rb', line 50

def resource(timeout = nil)
  Timeout::timeout timeout do
    @resource_lock.synchronize do
      @resource_value_blocker.wait unless defined? @resource
      @resource
    end
  end
end

#resource=(resource) ⇒ Object

Sets the value for the resource, making it available for all waiting and following reads. Resourcs values can only be set once.

Parameters:

  • any value to be set for the resource

Raises:

  • if resource is already set



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# File 'lib/future-resource.rb', line 66

def resource=(resource)
  @resource_lock.synchronize do
    raise ResourceAlreadySetException if defined? @resource
    @resource = resource
    @resource_value_blocker.broadcast
    @resource_value_blocker = nil # Don't really need it anymore.
  end
end

#set_yet? ⇒ Boolean

Checks if the value of the resource placeholder has been set yet.

Returns:



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# File 'lib/future-resource.rb', line 36

def set_yet?
  !!@resource_lock.synchronize { defined? @resource }
end