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require_relative 'ivar_shared'
require_relative 'thread_arguments_shared'
module Concurrent
RSpec.describe Future do
let!(:value) { 10 }
let(:executor) { SimpleExecutorService.new }
subject do
Future.new(executor: executor){
value
}.execute.tap{ sleep(0.1) }
end
let!(:fulfilled_value) { 10 }
let!(:rejected_reason) { StandardError.new('mojo jojo') }
let(:pending_subject) do
executor = Concurrent::SingleThreadExecutor.new
executor.post{ sleep(5) }
Future.execute(executor: executor){ fulfilled_value }
end
let(:fulfilled_subject) do
Future.new(executor: :immediate){ fulfilled_value }.execute
end
let(:rejected_subject) do
Future.new(executor: :immediate){ raise rejected_reason }.execute
end
it_should_behave_like :ivar do
subject { Future.new(executor: :immediate){ value } }
def dereferenceable_subject(value, opts = {})
opts = opts.merge(executor: executor)
Future.new(opts){ value }.execute.tap{ sleep(0.1) }
end
def dereferenceable_observable(opts = {})
opts = opts.merge(executor: executor)
Future.new(opts){ 'value' }
end
def execute_dereferenceable(subject)
subject.execute
sleep(0.1)
end
def trigger_observable(observable)
observable.execute
sleep(0.1)
end
end
it_should_behave_like :thread_arguments do
def get_ivar_from_no_args
Concurrent::Future.execute{|*args| args }
end
def get_ivar_from_args(opts)
Concurrent::Future.execute(opts){|*args| args }
end
end
context '#initialize' do
let(:executor) { ImmediateExecutor.new }
it 'sets the state to :unscheduled' do
expect(Future.new(executor: executor){ nil }).to be_unscheduled
end
it 'raises an exception when no block given' do
expect {
Future.new.execute
}.to raise_error(ArgumentError)
end
it 'uses the executor given with the :executor option' do
expect(executor).to receive(:post)
Future.execute(executor: executor){ nil }
end
it 'uses the global io executor by default' do
allow(Concurrent).to receive(:global_io_executor).and_return(executor)
expect(executor).to receive(:post).and_call_original
Future.execute{ nil }
end
end
context 'instance #execute' do
it 'does nothing unless the state is :unscheduled' do
executor = ImmediateExecutor.new
expect(executor).not_to receive(:post).with(any_args)
future = Future.new(executor: executor){ nil }
future.instance_variable_set(:@state, :pending)
future.execute
future.instance_variable_set(:@state, :rejected)
future.execute
future.instance_variable_set(:@state, :fulfilled)
future.execute
end
it 'posts the block given on construction' do
expect(executor).to receive(:post).with(any_args)
future = Future.new(executor: executor){ nil }
future.execute
end
it 'sets the state to :pending' do
latch = Concurrent::CountDownLatch.new
executor = Concurrent::SingleThreadExecutor.new
executor.post{ latch.wait(2) }
future = Future.new(executor: executor){ 42 }
future.execute
expect(future).to be_pending
latch.count_down
end
it 'returns self' do
future = Future.new(executor: executor){ nil }
expect(future.execute).to be future
end
end
context 'class #execute' do
let(:executor) { ImmediateExecutor.new }
it 'creates a new Future' do
future = Future.execute(executor: executor){ nil }
expect(future).to be_a(Future)
end
it 'passes the block to the new Future' do
@expected = false
Future.execute(executor: executor){ @expected = true }
expect(@expected).to be_truthy
end
it 'calls #execute on the new Future' do
future = double('future')
allow(Future).to receive(:new).with(any_args).and_return(future)
expect(future).to receive(:execute).with(no_args)
Future.execute{ nil }
end
end
context 'fulfillment' do
let(:executor) { ImmediateExecutor.new }
it 'sets the state to :processing while the task is executing' do
start_latch = Concurrent::CountDownLatch.new
continue_latch = Concurrent::CountDownLatch.new
executor = Concurrent::SingleThreadExecutor.new
future = Future.execute(executor: executor) do
start_latch.count_down
continue_latch.wait(2)
42
end
start_latch.wait(2)
state = future.state
continue_latch.count_down
future.value
expect(state).to eq :processing
end
it 'passes all arguments to handler' do
expected = false
Future.new(executor: executor){ expected = true }.execute
expect(expected).to be_truthy
end
it 'sets the value to the result of the handler' do
future = Future.new(executor: executor){ 42 }.execute
expect(future.value).to eq 42
end
it 'sets the state to :fulfilled when the block completes' do
future = Future.new(executor: executor){ 42 }.execute
expect(future).to be_fulfilled
end
it 'sets the value to nil when the handler raises an exception' do
future = Future.new(executor: executor){ raise StandardError }.execute
expect(future.value).to be_nil
end
it 'sets the value to nil when the handler raises Exception' do
future = Future.new(executor: executor){ raise Exception }.execute
expect(future.value).to be_nil
end
it 'sets the reason to the Exception instance when the handler raises Exception' do
future = Future.new(executor: executor){ raise Exception }.execute
expect(future.reason).to be_a(Exception)
end
it 'sets the state to :rejected when the handler raises an exception' do
future = Future.new(executor: executor){ raise StandardError }.execute
expect(future).to be_rejected
end
context 'aliases' do
it 'aliases #realized? for #fulfilled?' do
expect(subject).to be_realized
end
it 'aliases #deref for #value' do
expect(subject.deref).to eq value
end
end
end
context 'cancellation' do
context '#cancel' do
it 'fails to cancel the task once processing has begun' do
start_latch = Concurrent::CountDownLatch.new
continue_latch = Concurrent::CountDownLatch.new
f = Future.execute do
start_latch.count_down
continue_latch.wait(2)
42
end
start_latch.wait(2)
cancelled = f.cancel
continue_latch.count_down
expect(cancelled).to be false
expect(f.value).to eq 42
expect(f).to be_fulfilled
end
it 'fails to cancel the task once processing is complete' do
f = Future.execute{ 42 }
f.wait
cancelled = f.cancel
expect(cancelled).to be false
expect(f.value).to eq 42
expect(f).to be_fulfilled
end
it 'cancels a pending task' do
executor = Concurrent::SingleThreadExecutor.new
latch = Concurrent::CountDownLatch.new
executor.post{ latch.wait(2) }
f = Future.execute(executor: executor){ 42 }
cancelled = f.cancel
latch.count_down
expect(cancelled).to be true
expect(f.value).to be_nil
expect(f).to be_rejected
expect(f.reason).to be_a Concurrent::CancelledOperationError
end
end
context '#wait_or_cancel' do
it 'returns true if the operation completes before timeout' do
f = Future.execute{ 42 }
success = f.wait_or_cancel(1)
expect(success).to be true
expect(f.value).to eq 42
expect(f).to be_fulfilled
end
it 'cancels the task on timeout' do
latch = Concurrent::CountDownLatch.new
executor = Concurrent::SingleThreadExecutor.new
executor.post{ latch.wait(2) }
f = Future.execute(executor: executor){ 42 }
success = f.wait_or_cancel(0.1)
latch.count_down
expect(success).to be false
expect(f.value).to be_nil
expect(f).to be_rejected
expect(f.reason).to be_a Concurrent::CancelledOperationError
end
end
end
context 'observation' do
let(:executor) { ImmediateExecutor.new }
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 fulfillment' do
future = Future.new(executor: executor){ 42 }
future.add_observer(observer)
future.execute
expect(observer.value).to eq(42)
expect(observer.reason).to be_nil
end
it 'notifies all observers on rejection' do
future = Future.new(executor: executor){ raise StandardError }
future.add_observer(observer)
future.execute
expect(observer.value).to be_nil
expect(observer.reason).to be_a(StandardError)
end
it 'notifies an observer added after fulfillment' do
future = Future.new(executor: executor){ 42 }.execute
future.add_observer(observer)
expect(observer.value).to eq(42)
end
it 'notifies an observer added after rejection' do
future = Future.new(executor: executor){ raise StandardError }.execute
future.add_observer(observer)
expect(observer.reason).to be_a(StandardError)
end
it 'does not notify existing observers when a new observer added after fulfillment' do
future = Future.new(executor: executor){ 42 }.execute
future.add_observer(observer)
expect(observer.count).to eq(1)
o2 = clazz.new
future.add_observer(o2)
expect(observer.count).to eq(1)
expect(o2.value).to eq(42)
end
it 'does not notify existing observers when a new observer added after rejection' do
future = Future.new(executor: executor){ raise StandardError }.execute
future.add_observer(observer)
expect(observer.count).to eq(1)
o2 = clazz.new
future.add_observer(o2)
expect(observer.count).to eq(1)
expect(o2.reason).to be_a(StandardError)
end
context 'deadlock avoidance' do
def reentrant_observer(future)
obs = ::Object.new
obs.define_singleton_method(:update) do |time, value, reason|
@value = future.value
end
obs.define_singleton_method(:value) { @value }
obs
end
it 'should notify observers outside mutex lock' do
future = Future.new(executor: executor){ 42 }
obs = reentrant_observer(future)
future.add_observer(obs)
future.execute
expect(obs.value).to eq 42
end
it 'should notify a new observer added after fulfillment outside lock' do
future = Future.new(executor: executor){ 42 }.execute
obs = reentrant_observer(future)
future.add_observer(obs)
expect(obs.value).to eq 42
end
end
end
end
end
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