Class ScalarSubscription<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.ScalarSubscription<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
public final class ScalarSubscription<T> extends java.util.concurrent.atomic.AtomicInteger implements QueueSubscription<T>
A Subscription that holds a constant value and emits it only when requested.- See Also:
- Serialized Form
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Field Summary
Fields Modifier and Type Field Description (package private) static int
CANCELLED
Cancel has been called.(package private) static int
NO_REQUEST
No request has been issued yet.(package private) static int
REQUESTED
Request has been called.private static long
serialVersionUID
(package private) org.reactivestreams.Subscriber<? super T>
subscriber
The actual subscriber.(package private) T
value
The single value to emit, set to null.
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Constructor Summary
Constructors Constructor Description ScalarSubscription(org.reactivestreams.Subscriber<? super T> subscriber, T value)
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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.boolean
isCancelled()
Returns true if this Subscription was cancelled.boolean
isEmpty()
Returns true if the queue is empty.boolean
offer(T e)
Atomically enqueue a single value.boolean
offer(T v1, T v2)
Atomically enqueue two values.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.-
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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value
final T value
The single value to emit, set to null.
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subscriber
final org.reactivestreams.Subscriber<? super T> subscriber
The actual subscriber.
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NO_REQUEST
static final int NO_REQUEST
No request has been issued yet.- See Also:
- Constant Field Values
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REQUESTED
static final int REQUESTED
Request has been called.- See Also:
- Constant Field Values
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CANCELLED
static final int CANCELLED
Cancel has been called.- See Also:
- Constant Field Values
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Method Detail
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request
public void request(long n)
- Specified by:
request
in interfaceorg.reactivestreams.Subscription
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cancel
public void cancel()
- Specified by:
cancel
in interfaceorg.reactivestreams.Subscription
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isCancelled
public boolean isCancelled()
Returns true if this Subscription was cancelled.- Returns:
- true if this Subscription was cancelled
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offer
public boolean offer(T e)
Description copied from interface:SimpleQueue
Atomically enqueue a single value.- Specified by:
offer
in interfaceSimpleQueue<T>
- Parameters:
e
- the value to enqueue, not null- Returns:
- true if successful, false if the value was not enqueued likely due to reaching the queue capacity)
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offer
public boolean offer(T v1, T v2)
Description copied from interface:SimpleQueue
Atomically enqueue two values.- Specified by:
offer
in interfaceSimpleQueue<T>
- Parameters:
v1
- the first value to enqueue, not nullv2
- the second value to enqueue, not null- Returns:
- true if successful, false if the value was not enqueued likely due to reaching the queue capacity)
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poll
@Nullable public 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.- Specified by:
poll
in interfaceSimpleQueue<T>
- Returns:
- the item or null to indicate an empty queue
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isEmpty
public 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).- Specified by:
isEmpty
in interfaceSimpleQueue<T>
- Returns:
- true if the queue is empty
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clear
public void clear()
Description copied from interface:SimpleQueue
Removes all enqueued items from this queue.- Specified by:
clear
in interfaceSimpleQueue<T>
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requestFusion
public 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.- Specified by:
requestFusion
in interfaceQueueFuseable<T>
- 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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