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/*
 * 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.rxjava3.subjects;

import io.reactivex.rxjava3.annotations.Nullable;
import io.reactivex.rxjava3.core.Observer;
import io.reactivex.rxjava3.disposables.Disposable;
import io.reactivex.rxjava3.internal.util.*;
import io.reactivex.rxjava3.internal.util.AppendOnlyLinkedArrayList.NonThrowingPredicate;
import io.reactivex.rxjava3.plugins.RxJavaPlugins;

/**
 * Serializes calls to the Observer methods.
 * 

All other Observable and Subject methods are thread-safe by design. * * @param the item value type */ /* public */ final class SerializedSubject extends Subject implements NonThrowingPredicate { /** The actual subscriber to serialize Subscriber calls to. */ final Subject actual; /** Indicates an emission is going on, guarded by this. */ boolean emitting; /** If not null, it holds the missed NotificationLite events. */ AppendOnlyLinkedArrayList queue; /** Indicates a terminal event has been received and all further events will be dropped. */ volatile boolean done; /** * Constructor that wraps an actual subject. * @param actual the subject wrapped */ SerializedSubject(final Subject actual) { this.actual = actual; } @Override protected void subscribeActual(Observer observer) { actual.subscribe(observer); } @Override public void onSubscribe(Disposable d) { boolean cancel; if (!done) { synchronized (this) { if (done) { cancel = true; } else { if (emitting) { AppendOnlyLinkedArrayList q = queue; if (q == null) { q = new AppendOnlyLinkedArrayList<>(4); queue = q; } q.add(NotificationLite.disposable(d)); return; } emitting = true; cancel = false; } } } else { cancel = true; } if (cancel) { d.dispose(); } else { actual.onSubscribe(d); emitLoop(); } } @Override public void onNext(T t) { if (done) { return; } synchronized (this) { if (done) { return; } if (emitting) { AppendOnlyLinkedArrayList q = queue; if (q == null) { q = new AppendOnlyLinkedArrayList<>(4); queue = q; } q.add(NotificationLite.next(t)); return; } emitting = true; } actual.onNext(t); emitLoop(); } @Override public void onError(Throwable t) { if (done) { RxJavaPlugins.onError(t); return; } boolean reportError; synchronized (this) { if (done) { reportError = true; } else { done = true; if (emitting) { AppendOnlyLinkedArrayList q = queue; if (q == null) { q = new AppendOnlyLinkedArrayList<>(4); queue = q; } q.setFirst(NotificationLite.error(t)); return; } reportError = false; emitting = true; } } if (reportError) { RxJavaPlugins.onError(t); return; } actual.onError(t); } @Override public void onComplete() { if (done) { return; } synchronized (this) { if (done) { return; } done = true; if (emitting) { AppendOnlyLinkedArrayList q = queue; if (q == null) { q = new AppendOnlyLinkedArrayList<>(4); queue = q; } q.add(NotificationLite.complete()); return; } emitting = true; } actual.onComplete(); } /** Loops until all notifications in the queue has been processed. */ void emitLoop() { for (;;) { AppendOnlyLinkedArrayList q; synchronized (this) { q = queue; if (q == null) { emitting = false; return; } queue = null; } q.forEachWhile(this); } } @Override public boolean test(Object o) { return NotificationLite.acceptFull(o, actual); } @Override public boolean hasObservers() { return actual.hasObservers(); } @Override public boolean hasThrowable() { return actual.hasThrowable(); } @Override @Nullable public Throwable getThrowable() { return actual.getThrowable(); } @Override public boolean hasComplete() { return actual.hasComplete(); } }