public abstract class

ResourceSubscriber

extends Object
implements FlowableSubscriber<T> Disposable
java.lang.Object
   ↳ io.reactivex.subscribers.ResourceSubscriber<T>

Class Overview

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() in onError() and onComplete() explicitly.

Use add(Disposable) to associate resources (as Disposables) with this ResourceSubscriber that will be cleaned up when dispose() is called. Removing previously associated resources is not possible but one can create a CompositeDisposable, associate it with this ResourceSubscriber and then add/remove resources to/from the CompositeDisposable freely.

The default onStart() requests Long.MAX_VALUE by default. Override the method to request a custom positive amount. Use the protected request(long) to request more items and dispose() to cancel the sequence from within an onNext implementation.

Note that calling request(long) from onStart() may trigger an immediate, asynchronous emission of data to onNext(Object). Make sure all initialization happens before the call to request() in onStart(). Calling request(long) inside 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 an IllegalStateException with message "It is not allowed to subscribe with a(n) <class name> multiple times.".

Implementation of onStart(), onNext(Object), onError(Throwable) and onComplete() are not allowed to throw any unchecked exceptions. If for some reason this can't be avoided, use safeSubscribe(org.reactivestreams.Subscriber) instead of the standard subscribe() 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();
 

Summary

Public Constructors
ResourceSubscriber()
Public Methods
final void add(Disposable resource)
Adds a resource to this AsyncObserver.
final void dispose()
Cancels the subscription (if any) and disposes the resources associated with this AsyncObserver (if any).
final boolean isDisposed()
Returns true if this AsyncObserver has been disposed/cancelled.
final void onSubscribe(Subscription s)
Implementors of this method should make sure everything that needs to be visible in onNext(Object) is established before calling request(long).
Protected Methods
void onStart()
Called once the upstream sets a Subscription on this AsyncObserver.
final void request(long n)
Request the specified amount of elements from upstream.
[Expand]
Inherited Methods
From class java.lang.Object
From interface io.reactivex.FlowableSubscriber
From interface io.reactivex.disposables.Disposable
From interface org.reactivestreams.Subscriber

Public Constructors

public ResourceSubscriber ()

Public Methods

public final void add (Disposable resource)

Adds a resource to this AsyncObserver.

Parameters
resource the resource to add
Throws
NullPointerException if resource is null

public final void dispose ()

Cancels the subscription (if any) and disposes the resources associated with this AsyncObserver (if any).

This method can be called before the upstream calls onSubscribe at which case the Subscription will be immediately cancelled.

public final boolean isDisposed ()

Returns true if this AsyncObserver has been disposed/cancelled.

Returns
  • true if this AsyncObserver has been disposed/cancelled

public final void onSubscribe (Subscription s)

Implementors of this method should make sure everything that needs to be visible in onNext(Object) is established before calling request(long). In practice this means no initialization should happen after the request() call and additional behavior is thread safe in respect to onNext.

Protected Methods

protected void onStart ()

Called once the upstream sets a Subscription on this AsyncObserver.

You can perform initialization at this moment. The default implementation requests Long.MAX_VALUE from upstream.

protected final void request (long n)

Request the specified amount of elements from upstream.

This method can be called before the upstream calls onSubscribe(). When the subscription happens, all missed requests are requested.

Parameters
n the request amount, must be positive