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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.internal.operators.mixed;

import java.util.concurrent.atomic.*;

import io.reactivex.*;
import io.reactivex.disposables.Disposable;
import io.reactivex.exceptions.Exceptions;
import io.reactivex.functions.Function;
import io.reactivex.internal.disposables.DisposableHelper;
import io.reactivex.internal.functions.ObjectHelper;
import io.reactivex.internal.fuseable.SimplePlainQueue;
import io.reactivex.internal.queue.SpscLinkedArrayQueue;
import io.reactivex.internal.util.*;
import io.reactivex.plugins.RxJavaPlugins;

/**
 * Maps each upstream item into a {@link SingleSource}, subscribes to them one after the other terminates
 * and relays their success values, optionally delaying any errors till the main and inner sources
 * terminate.
 * 

History: 2.1.11 - experimental * @param the upstream element type * @param the output element type * @since 2.2 */ public final class ObservableConcatMapSingle extends Observable { final Observable source; final Function> mapper; final ErrorMode errorMode; final int prefetch; public ObservableConcatMapSingle(Observable source, Function> mapper, ErrorMode errorMode, int prefetch) { this.source = source; this.mapper = mapper; this.errorMode = errorMode; this.prefetch = prefetch; } @Override protected void subscribeActual(Observer observer) { if (!ScalarXMapZHelper.tryAsSingle(source, mapper, observer)) { source.subscribe(new ConcatMapSingleMainObserver(observer, mapper, prefetch, errorMode)); } } static final class ConcatMapSingleMainObserver extends AtomicInteger implements Observer, Disposable { private static final long serialVersionUID = -9140123220065488293L; final Observer downstream; final Function> mapper; final AtomicThrowable errors; final ConcatMapSingleObserver inner; final SimplePlainQueue queue; final ErrorMode errorMode; Disposable upstream; volatile boolean done; volatile boolean cancelled; R item; volatile int state; /** No inner SingleSource is running. */ static final int STATE_INACTIVE = 0; /** An inner SingleSource is running but there are no results yet. */ static final int STATE_ACTIVE = 1; /** The inner SingleSource succeeded with a value in {@link #item}. */ static final int STATE_RESULT_VALUE = 2; ConcatMapSingleMainObserver(Observer downstream, Function> mapper, int prefetch, ErrorMode errorMode) { this.downstream = downstream; this.mapper = mapper; this.errorMode = errorMode; this.errors = new AtomicThrowable(); this.inner = new ConcatMapSingleObserver(this); this.queue = new SpscLinkedArrayQueue(prefetch); } @Override public void onSubscribe(Disposable d) { if (DisposableHelper.validate(upstream, d)) { upstream = d; downstream.onSubscribe(this); } } @Override public void onNext(T t) { queue.offer(t); drain(); } @Override public void onError(Throwable t) { if (errors.addThrowable(t)) { if (errorMode == ErrorMode.IMMEDIATE) { inner.dispose(); } done = true; drain(); } else { RxJavaPlugins.onError(t); } } @Override public void onComplete() { done = true; drain(); } @Override public void dispose() { cancelled = true; upstream.dispose(); inner.dispose(); if (getAndIncrement() == 0) { queue.clear(); item = null; } } @Override public boolean isDisposed() { return cancelled; } void innerSuccess(R item) { this.item = item; this.state = STATE_RESULT_VALUE; drain(); } void innerError(Throwable ex) { if (errors.addThrowable(ex)) { if (errorMode != ErrorMode.END) { upstream.dispose(); } this.state = STATE_INACTIVE; drain(); } else { RxJavaPlugins.onError(ex); } } void drain() { if (getAndIncrement() != 0) { return; } int missed = 1; Observer downstream = this.downstream; ErrorMode errorMode = this.errorMode; SimplePlainQueue queue = this.queue; AtomicThrowable errors = this.errors; for (;;) { for (;;) { if (cancelled) { queue.clear(); item = null; break; } int s = state; if (errors.get() != null) { if (errorMode == ErrorMode.IMMEDIATE || (errorMode == ErrorMode.BOUNDARY && s == STATE_INACTIVE)) { queue.clear(); item = null; Throwable ex = errors.terminate(); downstream.onError(ex); return; } } if (s == STATE_INACTIVE) { boolean d = done; T v = queue.poll(); boolean empty = v == null; if (d && empty) { Throwable ex = errors.terminate(); if (ex == null) { downstream.onComplete(); } else { downstream.onError(ex); } return; } if (empty) { break; } SingleSource ss; try { ss = ObjectHelper.requireNonNull(mapper.apply(v), "The mapper returned a null SingleSource"); } catch (Throwable ex) { Exceptions.throwIfFatal(ex); upstream.dispose(); queue.clear(); errors.addThrowable(ex); ex = errors.terminate(); downstream.onError(ex); return; } state = STATE_ACTIVE; ss.subscribe(inner); break; } else if (s == STATE_RESULT_VALUE) { R w = item; item = null; downstream.onNext(w); state = STATE_INACTIVE; } else { break; } } missed = addAndGet(-missed); if (missed == 0) { break; } } } static final class ConcatMapSingleObserver extends AtomicReference implements SingleObserver { private static final long serialVersionUID = -3051469169682093892L; final ConcatMapSingleMainObserver parent; ConcatMapSingleObserver(ConcatMapSingleMainObserver parent) { this.parent = parent; } @Override public void onSubscribe(Disposable d) { DisposableHelper.replace(this, d); } @Override public void onSuccess(R t) { parent.innerSuccess(t); } @Override public void onError(Throwable e) { parent.innerError(e); } void dispose() { DisposableHelper.dispose(this); } } } }





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