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require 'thread'
require 'timeout'
require 'concurrent/atomic/event'
require 'concurrent/concern/dereferenceable'
module Concurrent
module Concern
module Obligation
include Concern::Dereferenceable
# NOTE: The Dereferenceable module is going away in 2.0. In the mean time
# we need it to place nicely with the synchronization layer. This means
# that the including class SHOULD be synchronized and it MUST implement a
# `#synchronize` method. Not doing so will lead to runtime errors.
# Has the obligation been fulfilled?
#
# @return [Boolean]
def fulfilled?
state == :fulfilled
end
alias_method :realized?, :fulfilled?
# Has the obligation been rejected?
#
# @return [Boolean]
def rejected?
state == :rejected
end
# Is obligation completion still pending?
#
# @return [Boolean]
def pending?
state == :pending
end
# Is the obligation still unscheduled?
#
# @return [Boolean]
def unscheduled?
state == :unscheduled
end
# Has the obligation completed processing?
#
# @return [Boolean]
def complete?
[:fulfilled, :rejected].include? state
end
# Is the obligation still awaiting completion of processing?
#
# @return [Boolean]
def incomplete?
! complete?
end
# The current value of the obligation. Will be `nil` while the state is
# pending or the operation has been rejected.
#
# @param [Numeric] timeout the maximum time in seconds to wait.
# @return [Object] see Dereferenceable#deref
def value(timeout = nil)
wait timeout
deref
end
# Wait until obligation is complete or the timeout has been reached.
#
# @param [Numeric] timeout the maximum time in seconds to wait.
# @return [Obligation] self
def wait(timeout = nil)
event.wait(timeout) if timeout != 0 && incomplete?
self
end
# Wait until obligation is complete or the timeout is reached. Will re-raise
# any exceptions raised during processing (but will not raise an exception
# on timeout).
#
# @param [Numeric] timeout the maximum time in seconds to wait.
# @return [Obligation] self
# @raise [Exception] raises the reason when rejected
def wait!(timeout = nil)
wait(timeout).tap { raise self if rejected? }
end
alias_method :no_error!, :wait!
# The current value of the obligation. Will be `nil` while the state is
# pending or the operation has been rejected. Will re-raise any exceptions
# raised during processing (but will not raise an exception on timeout).
#
# @param [Numeric] timeout the maximum time in seconds to wait.
# @return [Object] see Dereferenceable#deref
# @raise [Exception] raises the reason when rejected
def value!(timeout = nil)
wait(timeout)
if rejected?
raise self
else
deref
end
end
# The current state of the obligation.
#
# @return [Symbol] the current state
def state
synchronize { @state }
end
# If an exception was raised during processing this will return the
# exception object. Will return `nil` when the state is pending or if
# the obligation has been successfully fulfilled.
#
# @return [Exception] the exception raised during processing or `nil`
def reason
synchronize { @reason }
end
# @example allows Obligation to be risen
# rejected_ivar = Ivar.new.fail
# raise rejected_ivar
def exception(*args)
raise 'obligation is not rejected' unless rejected?
reason.exception(*args)
end
protected
# @!visibility private
def get_arguments_from(opts = {})
[*opts.fetch(:args, [])]
end
# @!visibility private
def init_obligation
@event = Event.new
@value = @reason = nil
end
# @!visibility private
def event
@event
end
# @!visibility private
def set_state(success, value, reason)
if success
@value = value
@state = :fulfilled
else
@reason = reason
@state = :rejected
end
end
# @!visibility private
def state=(value)
synchronize { ns_set_state(value) }
end
# Atomic compare and set operation
# State is set to `next_state` only if `current state == expected_current`.
#
# @param [Symbol] next_state
# @param [Symbol] expected_current
#
# @return [Boolean] true is state is changed, false otherwise
#
# @!visibility private
def compare_and_set_state(next_state, *expected_current)
synchronize do
if expected_current.include? @state
@state = next_state
true
else
false
end
end
end
# Executes the block within mutex if current state is included in expected_states
#
# @return block value if executed, false otherwise
#
# @!visibility private
def if_state(*expected_states)
synchronize do
raise ArgumentError.new('no block given') unless block_given?
if expected_states.include? @state
yield
else
false
end
end
end
protected
# Am I in the current state?
#
# @param [Symbol] expected The state to check against
# @return [Boolean] true if in the expected state else false
#
# @!visibility private
def ns_check_state?(expected)
@state == expected
end
# @!visibility private
def ns_set_state(value)
@state = value
end
end
end
end
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