Package rx.internal.util

Class BackpressureDrainManager

java.lang.Object

java.lang.Number

java.util.concurrent.atomic.AtomicLong

rx.internal.util.BackpressureDrainManager

All Implemented Interfaces:

Serializable, Producer

@Experimental
public final class BackpressureDrainManager
extends AtomicLong
implements Producer

Manages the producer-backpressure-consumer interplay by matching up available elements with requested elements and/or terminal events.

Since:

1.1.0

See Also:

• Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	BackpressureDrainManager.BackpressureQueueCallback	Interface representing the minimal callbacks required to operate the drain part of a backpressure system.

Field Summary

Fields

Modifier and Type	Field	Description
(package private) final BackpressureDrainManager.BackpressureQueueCallback	actual	The callbacks to manage the drain.
(package private) boolean	emitting	Indicates if one is in emitting phase, guarded by this.
(package private) Throwable	exception	Indicates an error state, barrier is provided via terminated.
private static final long	serialVersionUID
(package private) boolean	terminated	Indicates a terminal state.

Constructor Summary

Constructors

Constructor	Description
BackpressureDrainManager(BackpressureDrainManager.BackpressureQueueCallback actual)	Constructs a backpressure drain manager with 0 requestedCount, no terminal event and not emitting.

Method Summary

Modifier and Type	Method	Description
void	drain()	Try to drain the "queued" elements and terminal events by considering the available and requested event counts.
boolean	isTerminated()	Checks if a terminal state has been reached.
void	request(long n)	Request a certain maximum number of items from this Producer.
void	terminate()	Move into a terminal state.
void	terminate(Throwable error)	Move into a terminal state with an exception.
void	terminateAndDrain()	Move into a terminal state and drain.
void	terminateAndDrain(Throwable error)	Move into a terminal state with an exception and drain.

Methods inherited from class java.util.concurrent.atomic.AtomicLong

accumulateAndGet, addAndGet, compareAndExchange, compareAndExchangeAcquire, compareAndExchangeRelease, compareAndSet, decrementAndGet, doubleValue, floatValue, get, getAcquire, getAndAccumulate, getAndAdd, getAndDecrement, getAndIncrement, getAndSet, getAndUpdate, getOpaque, getPlain, incrementAndGet, intValue, lazySet, longValue, set, setOpaque, setPlain, setRelease, toString, updateAndGet, weakCompareAndSet, weakCompareAndSetAcquire, weakCompareAndSetPlain, weakCompareAndSetRelease, weakCompareAndSetVolatile

Methods inherited from class java.lang.Number

byteValue, shortValue

Methods inherited from class java.lang.Object

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

Field Details

serialVersionUID

private static final long serialVersionUID

See Also:

• Constant Field Values

emitting

boolean emitting

Indicates if one is in emitting phase, guarded by this.

terminated

volatile boolean terminated

Indicates a terminal state.

exception

Throwable exception

Indicates an error state, barrier is provided via terminated.

actual

final BackpressureDrainManager.BackpressureQueueCallback actual

The callbacks to manage the drain.

Constructor Details

BackpressureDrainManager

public BackpressureDrainManager(BackpressureDrainManager.BackpressureQueueCallback actual)

Constructs a backpressure drain manager with 0 requestedCount, no terminal event and not emitting.

Parameters:

actual - he queue callback to check for new element availability

Method Details

isTerminated

public boolean isTerminated()

Checks if a terminal state has been reached.

Returns:

true if a terminal state has been reached

terminate

public void terminate()

Move into a terminal state. Call drain() anytime after.

terminate

public void terminate(Throwable error)

Move into a terminal state with an exception. Call drain() anytime after.

Serialized access is expected with respect to element emission.

Parameters:

error - the exception to deliver

terminateAndDrain

public void terminateAndDrain()

Move into a terminal state and drain.

terminateAndDrain

public void terminateAndDrain(Throwable error)

Move into a terminal state with an exception and drain.

Serialized access is expected with respect to element emission.

Parameters:

error - the exception to deliver

request

public void request(long n)

Description copied from interface: Producer

Request a certain maximum number of items from this Producer. This is a way of requesting backpressure. To disable backpressure, pass Long.MAX_VALUE to this method.

Requests are additive but if a sequence of requests totals more than Long.MAX_VALUE then Long.MAX_VALUE requests will be actioned and the extras may be ignored. Arriving at Long.MAX_VALUE by addition of requests cannot be assumed to disable backpressure. For example, the code below may result in Long.MAX_VALUE requests being actioned only.

 request(100);
 request(Long.MAX_VALUE-1);
 

Specified by:

request in interface Producer

Parameters:

n - the maximum number of items you want this Producer to produce, or Long.MAX_VALUE if you want the Producer to produce items at its own pace

drain

public void drain()

Try to drain the "queued" elements and terminal events by considering the available and requested event counts.