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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.internal.operators.flowable;

import java.util.concurrent.atomic.*;

import org.reactivestreams.*;

import io.reactivex.rxjava3.core.*;
import io.reactivex.rxjava3.disposables.Disposable;
import io.reactivex.rxjava3.internal.disposables.DisposableHelper;
import io.reactivex.rxjava3.internal.subscriptions.SubscriptionHelper;
import io.reactivex.rxjava3.internal.util.*;
import io.reactivex.rxjava3.operators.SimplePlainQueue;
import io.reactivex.rxjava3.operators.SpscArrayQueue;

/**
 * Merges an Observable and a Maybe by emitting the items of the Observable and the success
 * value of the Maybe and waiting until both the Observable and Maybe terminate normally.
 * 

History: 2.1.10 - experimental * @param the element type of the Observable * @since 2.2 */ public final class FlowableMergeWithMaybe extends AbstractFlowableWithUpstream { final MaybeSource other; public FlowableMergeWithMaybe(Flowable source, MaybeSource other) { super(source); this.other = other; } @Override protected void subscribeActual(Subscriber subscriber) { MergeWithObserver parent = new MergeWithObserver<>(subscriber); subscriber.onSubscribe(parent); source.subscribe(parent); other.subscribe(parent.otherObserver); } static final class MergeWithObserver extends AtomicInteger implements FlowableSubscriber, Subscription { private static final long serialVersionUID = -4592979584110982903L; final Subscriber downstream; final AtomicReference mainSubscription; final OtherObserver otherObserver; final AtomicThrowable errors; final AtomicLong requested; final int prefetch; final int limit; volatile SimplePlainQueue queue; T singleItem; volatile boolean cancelled; volatile boolean mainDone; volatile int otherState; long emitted; int consumed; static final int OTHER_STATE_HAS_VALUE = 1; static final int OTHER_STATE_CONSUMED_OR_EMPTY = 2; MergeWithObserver(Subscriber downstream) { this.downstream = downstream; this.mainSubscription = new AtomicReference<>(); this.otherObserver = new OtherObserver<>(this); this.errors = new AtomicThrowable(); this.requested = new AtomicLong(); this.prefetch = bufferSize(); this.limit = prefetch - (prefetch >> 2); } @Override public void onSubscribe(Subscription s) { SubscriptionHelper.setOnce(mainSubscription, s, prefetch); } @Override public void onNext(T t) { if (compareAndSet(0, 1)) { long e = emitted; if (requested.get() != e) { SimplePlainQueue q = queue; if (q == null || q.isEmpty()) { emitted = e + 1; downstream.onNext(t); int c = consumed + 1; if (c == limit) { consumed = 0; mainSubscription.get().request(c); } else { consumed = c; } } else { q.offer(t); } } else { SimplePlainQueue q = getOrCreateQueue(); q.offer(t); } if (decrementAndGet() == 0) { return; } } else { SimplePlainQueue q = getOrCreateQueue(); q.offer(t); if (getAndIncrement() != 0) { return; } } drainLoop(); } @Override public void onError(Throwable ex) { if (errors.tryAddThrowableOrReport(ex)) { DisposableHelper.dispose(otherObserver); drain(); } } @Override public void onComplete() { mainDone = true; drain(); } @Override public void request(long n) { BackpressureHelper.add(requested, n); drain(); } @Override public void cancel() { cancelled = true; SubscriptionHelper.cancel(mainSubscription); DisposableHelper.dispose(otherObserver); errors.tryTerminateAndReport(); if (getAndIncrement() == 0) { queue = null; singleItem = null; } } void otherSuccess(T value) { if (compareAndSet(0, 1)) { long e = emitted; if (requested.get() != e) { emitted = e + 1; downstream.onNext(value); otherState = OTHER_STATE_CONSUMED_OR_EMPTY; } else { singleItem = value; otherState = OTHER_STATE_HAS_VALUE; if (decrementAndGet() == 0) { return; } } } else { singleItem = value; otherState = OTHER_STATE_HAS_VALUE; if (getAndIncrement() != 0) { return; } } drainLoop(); } void otherError(Throwable ex) { if (errors.tryAddThrowableOrReport(ex)) { SubscriptionHelper.cancel(mainSubscription); drain(); } } void otherComplete() { otherState = OTHER_STATE_CONSUMED_OR_EMPTY; drain(); } SimplePlainQueue getOrCreateQueue() { SimplePlainQueue q = queue; if (q == null) { q = new SpscArrayQueue<>(bufferSize()); queue = q; } return q; } void drain() { if (getAndIncrement() == 0) { drainLoop(); } } void drainLoop() { Subscriber actual = this.downstream; int missed = 1; long e = emitted; int c = consumed; int lim = limit; for (;;) { long r = requested.get(); while (e != r) { if (cancelled) { singleItem = null; queue = null; return; } if (errors.get() != null) { singleItem = null; queue = null; errors.tryTerminateConsumer(downstream); return; } int os = otherState; if (os == OTHER_STATE_HAS_VALUE) { T v = singleItem; singleItem = null; otherState = OTHER_STATE_CONSUMED_OR_EMPTY; os = OTHER_STATE_CONSUMED_OR_EMPTY; actual.onNext(v); e++; continue; } boolean d = mainDone; SimplePlainQueue q = queue; T v = q != null ? q.poll() : null; boolean empty = v == null; if (d && empty && os == OTHER_STATE_CONSUMED_OR_EMPTY) { queue = null; actual.onComplete(); return; } if (empty) { break; } actual.onNext(v); e++; if (++c == lim) { c = 0; mainSubscription.get().request(lim); } } if (e == r) { if (cancelled) { singleItem = null; queue = null; return; } if (errors.get() != null) { singleItem = null; queue = null; errors.tryTerminateConsumer(downstream); return; } boolean d = mainDone; SimplePlainQueue q = queue; boolean empty = q == null || q.isEmpty(); if (d && empty && otherState == 2) { queue = null; actual.onComplete(); return; } } emitted = e; consumed = c; missed = addAndGet(-missed); if (missed == 0) { break; } } } static final class OtherObserver extends AtomicReference implements MaybeObserver { private static final long serialVersionUID = -2935427570954647017L; final MergeWithObserver parent; OtherObserver(MergeWithObserver parent) { this.parent = parent; } @Override public void onSubscribe(Disposable d) { DisposableHelper.setOnce(this, d); } @Override public void onSuccess(T t) { parent.otherSuccess(t); } @Override public void onError(Throwable e) { parent.otherError(e); } @Override public void onComplete() { parent.otherComplete(); } } } }





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