Class DeferredScalarSubscription<T>
- java.lang.Object
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- java.lang.Number
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- java.util.concurrent.atomic.AtomicInteger
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- io.reactivex.rxjava3.internal.subscriptions.BasicIntQueueSubscription<T>
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- io.reactivex.rxjava3.internal.subscriptions.DeferredScalarSubscription<T>
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- Type Parameters:
T
- the value type
- All Implemented Interfaces:
QueueFuseable<T>
,QueueSubscription<T>
,SimpleQueue<T>
,java.io.Serializable
,org.reactivestreams.Subscription
- Direct Known Subclasses:
AsyncProcessor.AsyncSubscription
,DeferredScalarSubscriber
,FlowableAll.AllSubscriber
,FlowableAny.AnySubscriber
,FlowableCollect.CollectSubscriber
,FlowableCollectWithCollector.CollectorSubscriber
,FlowableCount.CountSubscriber
,FlowableElementAt.ElementAtSubscriber
,FlowableFromCompletionStage.CompletionStageHandler
,FlowableReduce.ReduceSubscriber
,FlowableSequenceEqual.EqualCoordinator
,FlowableSingle.SingleElementSubscriber
,FlowableTakeLastOne.TakeLastOneSubscriber
,FlowableToList.ToListSubscriber
,MaybeToFlowable.MaybeToFlowableSubscriber
,ParallelCollector.ParallelCollectorSubscriber
,ParallelReduceFull.ParallelReduceFullMainSubscriber
,SingleToFlowable.SingleToFlowableObserver
public class DeferredScalarSubscription<@NonNull T> extends BasicIntQueueSubscription<T>
A subscription that signals a single value eventually.Note that the class leaks all methods of
AtomicLong
. Usecomplete(Object)
to signal the single value.The this atomic integer stores a bit field:
bit 0: indicates that there is a value available
bit 1: indicates that there was a request made
bit 2: indicates there was a cancellation, exclusively set
bit 3: indicates in fusion mode but no value yet, exclusively set
bit 4: indicates in fusion mode and value is available, exclusively set
bit 5: indicates in fusion mode and value has been consumed, exclusively set
Where exclusively set means any other bits are 0 when that bit is set.- See Also:
- Serialized Form
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Field Summary
Fields Modifier and Type Field Description (package private) static int
CANCELLED
Indicates the Subscription has been cancelled.protected org.reactivestreams.Subscriber<? super T>
downstream
The Subscriber to emit the value to.(package private) static int
FUSED_CONSUMED
Indicates this Subscription is in fusion mode and its value has been consumed.(package private) static int
FUSED_EMPTY
Indicates this Subscription is in fusion mode and is currently empty.(package private) static int
FUSED_READY
Indicates this Subscription is in fusion mode and has a value.(package private) static int
HAS_REQUEST_HAS_VALUE
Indicates this Subscription has both request and value.(package private) static int
HAS_REQUEST_NO_VALUE
Indicates this Subscription has been requested but there is no value yet.(package private) static int
NO_REQUEST_HAS_VALUE
Indicates this Subscription has a value but not requested yet.(package private) static int
NO_REQUEST_NO_VALUE
Indicates this Subscription has no value and not requested yet.private static long
serialVersionUID
protected T
value
The value is stored here if there is no request yet or in fusion mode.
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Constructor Summary
Constructors Constructor Description DeferredScalarSubscription(org.reactivestreams.Subscriber<? super @NonNull T> downstream)
Creates a DeferredScalarSubscription by wrapping the given Subscriber.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
cancel()
void
clear()
Removes all enqueued items from this queue.void
complete(@NonNull T v)
Completes this subscription by indicating the given value should be emitted when the first request arrives.boolean
isCancelled()
Returns true if this Subscription has been cancelled.boolean
isEmpty()
Returns true if the queue is empty.T
poll()
Tries to dequeue a value (non-null) or returns null if the queue is empty.void
request(long n)
int
requestFusion(int mode)
Request a fusion mode from the upstream.boolean
tryCancel()
Atomically sets a cancelled state and returns true if the current thread did it successfully.-
Methods inherited from class io.reactivex.rxjava3.internal.subscriptions.BasicIntQueueSubscription
offer, offer
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Methods inherited from class java.util.concurrent.atomic.AtomicInteger
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
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Field Detail
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serialVersionUID
private static final long serialVersionUID
- See Also:
- Constant Field Values
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downstream
protected final org.reactivestreams.Subscriber<? super T> downstream
The Subscriber to emit the value to.
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value
protected T value
The value is stored here if there is no request yet or in fusion mode.
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NO_REQUEST_NO_VALUE
static final int NO_REQUEST_NO_VALUE
Indicates this Subscription has no value and not requested yet.- See Also:
- Constant Field Values
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NO_REQUEST_HAS_VALUE
static final int NO_REQUEST_HAS_VALUE
Indicates this Subscription has a value but not requested yet.- See Also:
- Constant Field Values
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HAS_REQUEST_NO_VALUE
static final int HAS_REQUEST_NO_VALUE
Indicates this Subscription has been requested but there is no value yet.- See Also:
- Constant Field Values
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HAS_REQUEST_HAS_VALUE
static final int HAS_REQUEST_HAS_VALUE
Indicates this Subscription has both request and value.- See Also:
- Constant Field Values
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CANCELLED
static final int CANCELLED
Indicates the Subscription has been cancelled.- See Also:
- Constant Field Values
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FUSED_EMPTY
static final int FUSED_EMPTY
Indicates this Subscription is in fusion mode and is currently empty.- See Also:
- Constant Field Values
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FUSED_READY
static final int FUSED_READY
Indicates this Subscription is in fusion mode and has a value.- See Also:
- Constant Field Values
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FUSED_CONSUMED
static final int FUSED_CONSUMED
Indicates this Subscription is in fusion mode and its value has been consumed.- See Also:
- Constant Field Values
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Method Detail
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request
public final void request(long n)
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complete
public final void complete(@NonNull T v)
Completes this subscription by indicating the given value should be emitted when the first request arrives.Make sure this is called exactly once.
- Parameters:
v
- the value to signal, not null (not validated)
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requestFusion
public final int requestFusion(int mode)
Description copied from interface:QueueFuseable
Request a fusion mode from the upstream.This should be called before
onSubscribe
returns.Calling this method multiple times or after
onSubscribe
finished is not allowed and may result in undefined behavior.- Parameters:
mode
- the requested fusion mode, allowed values areQueueFuseable.SYNC
,QueueFuseable.ASYNC
,QueueFuseable.ANY
combined withQueueFuseable.BOUNDARY
(e.g.,requestFusion(SYNC | BOUNDARY)
).- Returns:
- the established fusion mode:
QueueFuseable.NONE
,QueueFuseable.SYNC
,QueueFuseable.ASYNC
.
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poll
@Nullable public final T poll()
Description copied from interface:SimpleQueue
Tries to dequeue a value (non-null) or returns null if the queue is empty.If the producer uses
SimpleQueue.offer(Object, Object)
and when polling in pairs, if the first poll() returns a non-null item, the second poll() is guaranteed to return a non-null item as well.- Returns:
- the item or null to indicate an empty queue
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isEmpty
public final boolean isEmpty()
Description copied from interface:SimpleQueue
Returns true if the queue is empty.Note however that due to potential fused functions in
SimpleQueue.poll()
it is possible this method returns false but then poll() returns null because the fused function swallowed the available item(s).- Returns:
- true if the queue is empty
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clear
public final void clear()
Description copied from interface:SimpleQueue
Removes all enqueued items from this queue.
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cancel
public void cancel()
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isCancelled
public final boolean isCancelled()
Returns true if this Subscription has been cancelled.- Returns:
- true if this Subscription has been cancelled
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tryCancel
public final boolean tryCancel()
Atomically sets a cancelled state and returns true if the current thread did it successfully.- Returns:
- true if the current thread cancelled
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