module Concurrent
module Concurrent::Async
module Concurrent::Async::ClassMethods
module Concurrent::AtomicDirectUpdate
module Concurrent::AtomicNumericCompareAndSetWrapper
module Concurrent::Collection
module Concurrent::Concern
module Concurrent::Concern::Deprecation
module Concurrent::Concern::Dereferenceable
module Concurrent::Concern::Logging
module Concurrent::Concern::Obligation
module Concurrent::Concern::Observable
module Concurrent::ExecutorService
module Concurrent::ImmutableStruct
module Concurrent::MutableStruct
module Concurrent::Options
module Concurrent::Promises
module Concurrent::Promises::FactoryMethods
module Concurrent::Promises::FactoryMethods::Configuration
module Concurrent::Promises::InternalStates
module Concurrent::Promises::Resolvable
module Concurrent::ReInclude
module Concurrent::SerialExecutorService
module Concurrent::SettableStruct
module Concurrent::Synchronization
module Concurrent::Synchronization::AbstractStruct
module Concurrent::Synchronization::ConditionSignalling
module Concurrent::Synchronization::SafeInitialization
module Concurrent::Synchronization::Volatile
module Concurrent::Synchronization::Volatile::ClassMethods
module Concurrent::ThreadSafe
module Concurrent::ThreadSafe::Util
module Concurrent::ThreadSafe::Util::Volatile
module Concurrent::ThreadSafe::Util::XorShiftRandom
module Concurrent::Utility
module Concurrent::Utility::EngineDetector
module Concurrent::Utility::NativeExtensionLoader
module Concurrent::Utility::NativeInteger
module TruffleRuby
class Concurrent::AbstractExchanger
class Concurrent::AbstractExecutorService
class Concurrent::AbstractLocals
class Concurrent::Agent
class Concurrent::Agent::Error
class Concurrent::Agent::ValidationError
class Concurrent::Array
class Concurrent::ArrayImplementation::JRubyArray
class Concurrent::ArrayImplementation::TruffleRubyArray
class Concurrent::Async::AsyncDelegator
class Concurrent::Async::AwaitDelegator
class Concurrent::Atom
class Concurrent::AtomicBoolean
class Concurrent::AtomicFixnum
class Concurrent::AtomicMarkableReference
class Concurrent::AtomicReference
class Concurrent::AtomicReferenceImplementation::CAtomicReference
class Concurrent::AtomicReferenceImplementation::JavaAtomicReference
class Concurrent::AtomicReferenceImplementation::TruffleRubyAtomicReference
class Concurrent::CachedThreadPool
class Concurrent::Collection::CopyOnNotifyObserverSet
class Concurrent::Collection::CopyOnWriteObserverSet
class Concurrent::Collection::JavaNonConcurrentPriorityQueue
class Concurrent::Collection::MriMapBackend
class Concurrent::Collection::NonConcurrentMapBackend
class Concurrent::Collection::NonConcurrentPriorityQueue
class Concurrent::Collection::RubyNonConcurrentPriorityQueue
class Concurrent::Collection::SynchronizedMapBackend
class Concurrent::Collection::TruffleRubyMapBackend
class Concurrent::ConcurrentUpdateError
class Concurrent::CountDownLatch
class Concurrent::CyclicBarrier
class Concurrent::DaemonThreadFactory
class Concurrent::Delay
class Concurrent::DependencyCounter
class Concurrent::Event
class Concurrent::Exchanger
class Concurrent::FiberLocalVar
class Concurrent::FiberLocals
class Concurrent::FixedThreadPool
class Concurrent::Future
class Concurrent::Hash
class Concurrent::HashImplementation::JRubyHash
class Concurrent::HashImplementation::TruffleRubyHash
class Concurrent::IVar
class Concurrent::ImmediateExecutor
class Concurrent::IndirectImmediateExecutor
class Concurrent::JavaCountDownLatch
class Concurrent::JavaExchanger
class Concurrent::JavaExecutorService
class Concurrent::JavaExecutorService::Job
class Concurrent::JavaSingleThreadExecutor
class Concurrent::JavaThreadPoolExecutor
class Concurrent::LockFreeStack
class Concurrent::LockFreeStack::Node
class Concurrent::LockLocalVar
class Concurrent::MVar
class Concurrent::Map
class Concurrent::Maybe
class Concurrent::MultipleAssignmentError
class Concurrent::MultipleErrors
class Concurrent::MutexAtomicBoolean
class Concurrent::MutexAtomicFixnum
class Concurrent::MutexAtomicReference
class Concurrent::MutexCountDownLatch
class Concurrent::MutexSemaphore
class Concurrent::Promise
class Concurrent::Promises::AbstractAnyPromise
class Concurrent::Promises::AbstractEventFuture
class Concurrent::Promises::AbstractFlatPromise
class Concurrent::Promises::AbstractPromise
class Concurrent::Promises::AnyFulfilledFuturePromise
class Concurrent::Promises::AnyResolvedEventPromise
class Concurrent::Promises::AnyResolvedFuturePromise
class Concurrent::Promises::BlockedPromise
class Concurrent::Promises::BlockedTaskPromise
class Concurrent::Promises::ChainPromise
class Concurrent::Promises::DelayPromise
class Concurrent::Promises::Event
class Concurrent::Promises::EventWrapperPromise
class Concurrent::Promises::FlatEventPromise
class Concurrent::Promises::FlatFuturePromise
class Concurrent::Promises::Future
class Concurrent::Promises::FutureWrapperPromise
class Concurrent::Promises::ImmediateEventPromise
class Concurrent::Promises::ImmediateFuturePromise
class Concurrent::Promises::InnerPromise
class Concurrent::Promises::InternalStates::Fulfilled
class Concurrent::Promises::InternalStates::FulfilledArray
class Concurrent::Promises::InternalStates::PartiallyRejected
class Concurrent::Promises::InternalStates::Pending
class Concurrent::Promises::InternalStates::Rejected
class Concurrent::Promises::InternalStates::Reserved
class Concurrent::Promises::InternalStates::ResolvedWithResult
class Concurrent::Promises::InternalStates::State
class Concurrent::Promises::RescuePromise
class Concurrent::Promises::ResolvableEvent
class Concurrent::Promises::ResolvableEventPromise
class Concurrent::Promises::ResolvableFuture
class Concurrent::Promises::ResolvableFuturePromise
class Concurrent::Promises::RunFuturePromise
class Concurrent::Promises::ScheduledPromise
class Concurrent::Promises::ThenPromise
class Concurrent::Promises::ZipEventEventPromise
class Concurrent::Promises::ZipEventsPromise
class Concurrent::Promises::ZipFutureEventPromise
class Concurrent::Promises::ZipFuturesPromise
class Concurrent::ReadWriteLock
class Concurrent::ReentrantReadWriteLock
class Concurrent::RubyExchanger
class Concurrent::RubyExchanger::Node
class Concurrent::RubyExecutorService
class Concurrent::RubySingleThreadExecutor
class Concurrent::RubyThreadPoolExecutor
class Concurrent::RubyThreadPoolExecutor::Worker
class Concurrent::SafeTaskExecutor
class Concurrent::ScheduledTask
class Concurrent::Semaphore
class Concurrent::SerializedExecution
class Concurrent::SerializedExecutionDelegator
class Concurrent::Set
class Concurrent::SetImplementation::CRubySet
class Concurrent::SetImplementation::JRubySet
class Concurrent::SetImplementation::TruffleRubySet
class Concurrent::SimpleExecutorService
class Concurrent::SingleThreadExecutor
class Concurrent::Synchronization::AbstractLockableObject
class Concurrent::Synchronization::AbstractObject
class Concurrent::Synchronization::Condition
class Concurrent::Synchronization::JRubyLockableObject
class Concurrent::Synchronization::Lock
class Concurrent::Synchronization::LockableObject
class Concurrent::Synchronization::MonitorLockableObject
class Concurrent::Synchronization::MutexLockableObject
class Concurrent::Synchronization::Object
class Concurrent::SynchronizedDelegator
class Concurrent::TVar
class Concurrent::ThreadLocalVar
class Concurrent::ThreadLocals
class Concurrent::ThreadPoolExecutor
class Concurrent::ThreadSafe::Util::Adder
class Concurrent::ThreadSafe::Util::PowerOfTwoTuple
class Concurrent::ThreadSafe::Util::Striped64
class Concurrent::ThreadSafe::Util::Striped64::Cell
class Concurrent::TimerSet
class Concurrent::TimerTask
class Concurrent::Transaction
class Concurrent::Tuple
class Concurrent::Utility::ProcessorCounter
concurrent-ruby
1.3.5
# peek
def peek empty? ? nil : @queue[1] end