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require_relative 'ivar_shared'
module Concurrent
RSpec.describe IVar do
let!(:value) { 10 }
let!(:fulfilled_value) { 10 }
let(:rejected_reason) { StandardError.new('Boom!') }
subject { IVar.new(value) }
let(:pending_subject) do
ivar = IVar.new
in_thread do
sleep(0.1)
ivar.set(fulfilled_value)
end
ivar
end
let(:fulfilled_subject) do
IVar.new.set(fulfilled_value)
end
let(:rejected_subject) do
IVar.new.fail(rejected_reason)
end
it_should_behave_like :ivar do
subject{ IVar.new }
def dereferenceable_subject(value, opts = {})
IVar.new(value, opts)
end
def dereferenceable_observable(opts = {})
IVar.new(NULL, opts)
end
def execute_dereferenceable(subject)
subject.set('value')
end
def trigger_observable(observable)
observable.set('value')
end
end
context '#initialize' do
it 'does not have to set an initial value' do
i = IVar.new
expect(i).to be_incomplete
end
it 'does not set an initial value if you pass NULL' do
i = IVar.new(NULL)
expect(i).to be_incomplete
end
it 'can set an initial value' do
i = IVar.new(14)
expect(i).to be_complete
expect(i.value).to eq 14
end
it 'can set an initial value with a block' do
i = IVar.new{ 42 }
expect(i).to be_complete
expect(i.value).to eq 42
end
it 'raises an exception if given both a value and a block' do
expect {
IVar.new(42){ 42 }
}.to raise_error(ArgumentError)
end
end
context 'observation' do
let(:clazz) do
Class.new do
attr_reader :value
attr_reader :reason
attr_reader :count
define_method(:update) do |time, value, reason|
@count ||= 0
@count = @count.to_i + 1
@value = value
@reason = reason
end
end
end
let(:observer) { clazz.new }
it 'notifies all observers on #set' do
i = IVar.new
i.add_observer(observer)
i.set(42)
expect(observer.value).to eq(42)
expect(observer.reason).to be_nil
end
context 'deadlock avoidance' do
def reentrant_observer(i)
obs = ::Object.new
obs.define_singleton_method(:update) do |time, value, reason|
@value = i.value
end
obs.define_singleton_method(:value) { @value }
obs
end
it 'should notify observers outside mutex lock' do
i = IVar.new
obs = reentrant_observer(i)
i.add_observer(obs)
i.set(42)
expect(obs.value).to eq 42
end
it 'should notify a new observer added after fulfillment outside lock' do
i = IVar.new
i.set(42)
obs = reentrant_observer(i)
i.add_observer(obs)
expect(obs.value).to eq 42
end
end
end
end
end
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