org.apache.cassandra.net

Class AsyncPromise<V>

java.lang.Object

org.apache.cassandra.net.AsyncPromise<V>

Type Parameters:

V -

All Implemented Interfaces:

io.netty.util.concurrent.Promise<V>, java.util.concurrent.Future<V>

Direct Known Subclasses:

AsyncChannelPromise, AsyncOneResponse

public class AsyncPromise<V>
extends java.lang.Object
implements io.netty.util.concurrent.Promise<V>

Netty's DefaultPromise uses a mutex to coordinate notifiers AND waiters between the eventLoop and the other threads. Since we register cross-thread listeners, this has the potential to block internode messaging for an unknown number of threads for an unknown period of time, if we are unlucky with the scheduler (which will certainly happen, just with some unknown but low periodicity) At the same time, we manage some other efficiencies: - We save some space when registering listeners, especially if there is only one listener, as we perform no extra allocations in this case. - We permit efficient initial state declaration, avoiding unnecessary CAS or lock acquisitions when mutating a Promise we are ourselves constructing (and can easily add more; only those we use have been added) We can also make some guarantees about our behaviour here, although we primarily mirror Netty. Specifically, we can guarantee that notifiers are always invoked in the order they are added (which may be true for netty, but was unclear and is not declared). This is useful for ensuring the correctness of some of our behaviours in OutboundConnection without having to jump through extra hoops. The implementation loosely follows that of Netty's DefaultPromise, with some slight changes; notably that we have no synchronisation on our listeners, instead using a CoW list that is cleared each time we notify listeners. We handle special values slightly differently. We do not use a special value for null, instead using a special value to indicate the result has not been set yet. This means that once isSuccess() holds, the result must be a correctly typed object (modulo generics pitfalls). All special values are also instances of FailureHolder, which simplifies a number of the logical conditions.

Constructor Summary

Constructors

Constructor and Description
AsyncPromise(io.netty.util.concurrent.EventExecutor executor)
AsyncPromise(io.netty.util.concurrent.EventExecutor executor, io.netty.util.concurrent.GenericFutureListener<? extends io.netty.util.concurrent.Future<? super V>> listener)

Method Summary

Modifier and Type	Method and Description
io.netty.util.concurrent.Promise<V>	addListener(io.netty.util.concurrent.GenericFutureListener<? extends io.netty.util.concurrent.Future<? super V>> listener)
io.netty.util.concurrent.Promise<V>	addListeners(io.netty.util.concurrent.GenericFutureListener<? extends io.netty.util.concurrent.Future<? super V>>... listeners)
io.netty.util.concurrent.Promise<V>	await()
boolean	await(long timeoutMillis)
boolean	await(long timeout, java.util.concurrent.TimeUnit unit)
io.netty.util.concurrent.Promise<V>	awaitUninterruptibly()
boolean	awaitUninterruptibly(long timeoutMillis)
boolean	awaitUninterruptibly(long timeout, java.util.concurrent.TimeUnit unit)
boolean	cancel(boolean b)
java.lang.Throwable	cause()
V	get()
V	get(long timeout, java.util.concurrent.TimeUnit unit)
V	getNow() if isSuccess(), returns the value, otherwise returns null
boolean	isCancellable()
boolean	isCancelled()
boolean	isDone()
boolean	isSuccess()
io.netty.util.concurrent.Promise<V>	removeListener(io.netty.util.concurrent.GenericFutureListener<? extends io.netty.util.concurrent.Future<? super V>> listener)
io.netty.util.concurrent.Promise<V>	removeListeners(io.netty.util.concurrent.GenericFutureListener<? extends io.netty.util.concurrent.Future<? super V>>... listeners)
io.netty.util.concurrent.Promise<V>	setFailure(java.lang.Throwable throwable)
io.netty.util.concurrent.Promise<V>	setSuccess(V v)
boolean	setUncancellable()
io.netty.util.concurrent.Promise<V>	sync() waits for completion; in case of failure rethrows the original exception without a new wrapping exception so may cause problems for reporting stack traces
io.netty.util.concurrent.Promise<V>	syncUninterruptibly() waits for completion; in case of failure rethrows the original exception without a new wrapping exception so may cause problems for reporting stack traces
java.lang.String	toString()
boolean	tryFailure(java.lang.Throwable throwable)
boolean	trySuccess(V v)
static <V> AsyncPromise<V>	uncancellable(io.netty.util.concurrent.EventExecutor executor)
static <V> AsyncPromise<V>	uncancellable(io.netty.util.concurrent.EventExecutor executor, io.netty.util.concurrent.GenericFutureListener<? extends io.netty.util.concurrent.Future<? super V>> listener)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

AsyncPromise

public AsyncPromise(io.netty.util.concurrent.EventExecutor executor)

AsyncPromise

public AsyncPromise(io.netty.util.concurrent.EventExecutor executor,
                    io.netty.util.concurrent.GenericFutureListener<? extends io.netty.util.concurrent.Future<? super V>> listener)

Method Detail

uncancellable

public static <V> AsyncPromise<V> uncancellable(io.netty.util.concurrent.EventExecutor executor)

uncancellable

public static <V> AsyncPromise<V> uncancellable(io.netty.util.concurrent.EventExecutor executor,
                                                io.netty.util.concurrent.GenericFutureListener<? extends io.netty.util.concurrent.Future<? super V>> listener)

setSuccess

public io.netty.util.concurrent.Promise<V> setSuccess(V v)

Specified by:

setSuccess in interface io.netty.util.concurrent.Promise<V>

setFailure

public io.netty.util.concurrent.Promise<V> setFailure(java.lang.Throwable throwable)

Specified by:

setFailure in interface io.netty.util.concurrent.Promise<V>

trySuccess

public boolean trySuccess(V v)

Specified by:

trySuccess in interface io.netty.util.concurrent.Promise<V>

tryFailure

public boolean tryFailure(java.lang.Throwable throwable)

Specified by:

tryFailure in interface io.netty.util.concurrent.Promise<V>

setUncancellable

public boolean setUncancellable()

Specified by:

setUncancellable in interface io.netty.util.concurrent.Promise<V>

cancel

public boolean cancel(boolean b)

Specified by:

cancel in interface java.util.concurrent.Future<V>

isSuccess

public boolean isSuccess()

isCancelled

public boolean isCancelled()

Specified by:

isCancelled in interface java.util.concurrent.Future<V>

isDone

public boolean isDone()

Specified by:

isDone in interface java.util.concurrent.Future<V>

isCancellable

public boolean isCancellable()

cause

public java.lang.Throwable cause()

getNow

public V getNow()

if isSuccess(), returns the value, otherwise returns null

get

public V get()
      throws java.lang.InterruptedException,
             java.util.concurrent.ExecutionException

Specified by:

get in interface java.util.concurrent.Future<V>

Throws:

java.lang.InterruptedException

java.util.concurrent.ExecutionException

get

public V get(long timeout,
             java.util.concurrent.TimeUnit unit)
      throws java.lang.InterruptedException,
             java.util.concurrent.ExecutionException,
             java.util.concurrent.TimeoutException

Specified by:

get in interface java.util.concurrent.Future<V>

Throws:

java.lang.InterruptedException

java.util.concurrent.ExecutionException

java.util.concurrent.TimeoutException

sync

public io.netty.util.concurrent.Promise<V> sync()
                                         throws java.lang.InterruptedException

waits for completion; in case of failure rethrows the original exception without a new wrapping exception so may cause problems for reporting stack traces

Specified by:

sync in interface io.netty.util.concurrent.Promise<V>

Throws:

java.lang.InterruptedException

syncUninterruptibly

public io.netty.util.concurrent.Promise<V> syncUninterruptibly()

waits for completion; in case of failure rethrows the original exception without a new wrapping exception so may cause problems for reporting stack traces

Specified by:

syncUninterruptibly in interface io.netty.util.concurrent.Promise<V>

addListener

public io.netty.util.concurrent.Promise<V> addListener(io.netty.util.concurrent.GenericFutureListener<? extends io.netty.util.concurrent.Future<? super V>> listener)

Specified by:

addListener in interface io.netty.util.concurrent.Promise<V>

addListeners

public io.netty.util.concurrent.Promise<V> addListeners(io.netty.util.concurrent.GenericFutureListener<? extends io.netty.util.concurrent.Future<? super V>>... listeners)

Specified by:

addListeners in interface io.netty.util.concurrent.Promise<V>

removeListener

public io.netty.util.concurrent.Promise<V> removeListener(io.netty.util.concurrent.GenericFutureListener<? extends io.netty.util.concurrent.Future<? super V>> listener)

Specified by:

removeListener in interface io.netty.util.concurrent.Promise<V>

removeListeners

public io.netty.util.concurrent.Promise<V> removeListeners(io.netty.util.concurrent.GenericFutureListener<? extends io.netty.util.concurrent.Future<? super V>>... listeners)

Specified by:

removeListeners in interface io.netty.util.concurrent.Promise<V>

await

public io.netty.util.concurrent.Promise<V> await()
                                          throws java.lang.InterruptedException

Specified by:

await in interface io.netty.util.concurrent.Promise<V>

Throws:

java.lang.InterruptedException

awaitUninterruptibly

public io.netty.util.concurrent.Promise<V> awaitUninterruptibly()

Specified by:

awaitUninterruptibly in interface io.netty.util.concurrent.Promise<V>

await

public boolean await(long timeout,
                     java.util.concurrent.TimeUnit unit)
              throws java.lang.InterruptedException

Throws:

java.lang.InterruptedException

await

public boolean await(long timeoutMillis)
              throws java.lang.InterruptedException

Throws:

java.lang.InterruptedException

awaitUninterruptibly

public boolean awaitUninterruptibly(long timeout,
                                    java.util.concurrent.TimeUnit unit)

awaitUninterruptibly

public boolean awaitUninterruptibly(long timeoutMillis)

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object