Class ResourceSubscriber<T>
- java.lang.Object
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- io.reactivex.rxjava3.subscribers.ResourceSubscriber<T>
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- Type Parameters:
T
- the value type
- All Implemented Interfaces:
FlowableSubscriber<T>
,Disposable
,org.reactivestreams.Subscriber<T>
public abstract class ResourceSubscriber<T> extends java.lang.Object implements FlowableSubscriber<T>, Disposable
An abstract Subscriber that allows asynchronous cancellation of its subscription and associated resources.All pre-implemented final methods are thread-safe.
To release the associated resources, one has to call
dispose()
inonError()
andonComplete()
explicitly.Use
add(Disposable)
to associate resources (asDisposable
s) with thisResourceSubscriber
that will be cleaned up whendispose()
is called. Removing previously associated resources is not possible but one can create aCompositeDisposable
, associate it with thisResourceSubscriber
and then add/remove resources to/from theCompositeDisposable
freely.The default
onStart()
requestsLong.MAX_VALUE
by default. Override the method to request a custom positive amount. Use the protectedrequest(long)
to request more items anddispose()
to cancel the sequence from within anonNext
implementation.Note that calling
request(long)
fromonStart()
may trigger an immediate, asynchronous emission of data toSubscriber.onNext(Object)
. Make sure all initialization happens before the call torequest()
inonStart()
. Callingrequest(long)
insideSubscriber.onNext(Object)
can happen at any time because by design,onNext
calls from upstream are non-reentrant and non-overlapping.Like all other consumers,
ResourceSubscriber
can be subscribed only once. Any subsequent attempt to subscribe it to a new source will yield anIllegalStateException
with message"It is not allowed to subscribe with a(n) <class name> multiple times."
.Implementation of
onStart()
,Subscriber.onNext(Object)
,Subscriber.onError(Throwable)
andSubscriber.onComplete()
are not allowed to throw any unchecked exceptions. If for some reason this can't be avoided, useFlowable.safeSubscribe(org.reactivestreams.Subscriber)
instead of the standardsubscribe()
method.Example
Disposable d = Flowable.range(1, 5) .subscribeWith(new ResourceSubscriber<Integer>() { @Override public void onStart() { add(Schedulers.single() .scheduleDirect(() -> System.out.println("Time!"), 2, TimeUnit.SECONDS)); request(1); } @Override public void onNext(Integer t) { if (t == 3) { dispose(); } System.out.println(t); request(1); } @Override public void onError(Throwable t) { t.printStackTrace(); dispose(); } @Override public void onComplete() { System.out.println("Done!"); dispose(); } }); // ... d.dispose();
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Field Summary
Fields Modifier and Type Field Description private java.util.concurrent.atomic.AtomicLong
missedRequested
Remembers the request(n) counts until a subscription arrives.private ListCompositeDisposable
resources
The resource composite, can never be null.private java.util.concurrent.atomic.AtomicReference<org.reactivestreams.Subscription>
upstream
The active subscription.
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Constructor Summary
Constructors Constructor Description ResourceSubscriber()
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
add(Disposable resource)
Adds a resource to thisResourceSubscriber
.void
dispose()
Cancels the subscription (if any) and disposes the resources associated with thisResourceSubscriber
(if any).boolean
isDisposed()
Returns true if thisResourceSubscriber
has been disposed/cancelled.protected void
onStart()
Called once the upstream sets aSubscription
on thisResourceSubscriber
.void
onSubscribe(org.reactivestreams.Subscription s)
Implementors of this method should make sure everything that needs to be visible inSubscriber.onNext(Object)
is established before callingSubscription.request(long)
.protected void
request(long n)
Request the specified amount of elements from upstream.
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Field Detail
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upstream
private final java.util.concurrent.atomic.AtomicReference<org.reactivestreams.Subscription> upstream
The active subscription.
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resources
private final ListCompositeDisposable resources
The resource composite, can never be null.
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missedRequested
private final java.util.concurrent.atomic.AtomicLong missedRequested
Remembers the request(n) counts until a subscription arrives.
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Method Detail
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add
public final void add(Disposable resource)
Adds a resource to thisResourceSubscriber
.- Parameters:
resource
- the resource to add- Throws:
java.lang.NullPointerException
- ifresource
isnull
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onSubscribe
public final void onSubscribe(org.reactivestreams.Subscription s)
Description copied from interface:FlowableSubscriber
Implementors of this method should make sure everything that needs to be visible inSubscriber.onNext(Object)
is established before callingSubscription.request(long)
. In practice this means no initialization should happen after therequest()
call and additional behavior is thread safe in respect toonNext
.- Specified by:
onSubscribe
in interfaceFlowableSubscriber<T>
- Specified by:
onSubscribe
in interfaceorg.reactivestreams.Subscriber<T>
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onStart
protected void onStart()
Called once the upstream sets aSubscription
on thisResourceSubscriber
.You can perform initialization at this moment. The default implementation requests
Long.MAX_VALUE
from upstream.
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request
protected final void request(long n)
Request the specified amount of elements from upstream.This method can be called before the upstream calls
onSubscribe(Subscription)
. When the subscription happens, all missed requests are requested.- Parameters:
n
- the request amount, must be positive
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dispose
public final void dispose()
Cancels the subscription (if any) and disposes the resources associated with thisResourceSubscriber
(if any).This method can be called before the upstream calls
onSubscribe(Subscription)
at which case theSubscription
will be immediately cancelled.- Specified by:
dispose
in interfaceDisposable
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isDisposed
public final boolean isDisposed()
Returns true if thisResourceSubscriber
has been disposed/cancelled.- Specified by:
isDisposed
in interfaceDisposable
- Returns:
- true if this
ResourceSubscriber
has been disposed/cancelled
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