All Downloads are FREE. Search and download functionalities are using the official Maven repository.

io.reactivex.subscribers.DisposableSubscriber Maven / Gradle / Ivy

There is a newer version: 2.2.21
Show newest version
/**
 * Copyright (c) 2016-present, RxJava Contributors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in
 * compliance with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License is
 * distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See
 * the License for the specific language governing permissions and limitations under the License.
 */

package io.reactivex.subscribers;

import java.util.concurrent.atomic.AtomicReference;

import org.reactivestreams.Subscription;

import io.reactivex.FlowableSubscriber;
import io.reactivex.disposables.Disposable;
import io.reactivex.internal.subscriptions.SubscriptionHelper;
import io.reactivex.internal.util.EndConsumerHelper;

/**
 * An abstract Subscriber that allows asynchronous, external cancellation by implementing Disposable.
 *
 * 

All pre-implemented final methods are thread-safe. * *

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

Note that calling {@link #request(long)} from {@link #onStart()} may trigger * an immediate, asynchronous emission of data to {@link #onNext(Object)}. Make sure * all initialization happens before the call to {@code request()} in {@code onStart()}. * Calling {@link #request(long)} inside {@link #onNext(Object)} can happen at any time * because by design, {@code onNext} calls from upstream are non-reentrant and non-overlapping. * *

Like all other consumers, {@code DisposableSubscriber} can be subscribed only once. * Any subsequent attempt to subscribe it to a new source will yield an * {@link IllegalStateException} with message {@code "It is not allowed to subscribe with a(n) multiple times."}. * *

Implementation of {@link #onStart()}, {@link #onNext(Object)}, {@link #onError(Throwable)} * and {@link #onComplete()} are not allowed to throw any unchecked exceptions. * If for some reason this can't be avoided, use {@link io.reactivex.Flowable#safeSubscribe(org.reactivestreams.Subscriber)} * instead of the standard {@code subscribe()} method. * *

Example


 * Disposable d =
 *     Flowable.range(1, 5)
 *     .subscribeWith(new DisposableSubscriber<Integer>() {
 *         @Override public void onStart() {
 *             request(1);
 *         }
 *         @Override public void onNext(Integer t) {
 *             if (t == 3) {
 *                 cancel();
 *             }
 *             System.out.println(t);
 *             request(1);
 *         }
 *         @Override public void onError(Throwable t) {
 *             t.printStackTrace();
 *         }
 *         @Override public void onComplete() {
 *             System.out.println("Done!");
 *         }
 *     });
 * // ...
 * d.dispose();
 * 
* @param the received value type. */ public abstract class DisposableSubscriber implements FlowableSubscriber, Disposable { final AtomicReference upstream = new AtomicReference(); @Override public final void onSubscribe(Subscription s) { if (EndConsumerHelper.setOnce(this.upstream, s, getClass())) { onStart(); } } /** * Called once the single upstream Subscription is set via onSubscribe. */ protected void onStart() { upstream.get().request(Long.MAX_VALUE); } /** * Requests the specified amount from the upstream if its Subscription is set via * onSubscribe already. *

Note that calling this method before a Subscription is set via onSubscribe * leads to NullPointerException and meant to be called from inside onStart or * onNext. * @param n the request amount, positive */ protected final void request(long n) { upstream.get().request(n); } /** * Cancels the Subscription set via onSubscribe or makes sure a * Subscription set asynchronously (later) is cancelled immediately. *

This method is thread-safe and can be exposed as a public API. */ protected final void cancel() { dispose(); } @Override public final boolean isDisposed() { return upstream.get() == SubscriptionHelper.CANCELLED; } @Override public final void dispose() { SubscriptionHelper.cancel(upstream); } }





© 2015 - 2024 Weber Informatics LLC | Privacy Policy