hu.akarnokd.rxjava2.operators.FlowableOrderedMerge Maven / Gradle / Ivy

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rxjava2-extensions developed by David Karnok
There is a newer version: 0.20.10
/*
 * Copyright 2016-2018 David Karnok
 *
 * 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 hu.akarnokd.rxjava2.operators;

import java.util.Arrays;
import java.util.Comparator;

import org.reactivestreams.Publisher;
import org.reactivestreams.Subscriber;

import io.reactivex.Flowable;
import io.reactivex.exceptions.Exceptions;
import io.reactivex.internal.functions.ObjectHelper;
import io.reactivex.internal.subscriptions.EmptySubscription;

/**
 * Merges a fixed set of sources by picking the next smallest
 * available element from any of the sources based on a comparator.
 * 
 * @param  the source value types
 * 
 * @since 0.8.0
 */
final class FlowableOrderedMerge extends Flowable {

    final Publisher[] sources;

    final Iterable> sourcesIterable;

    final Comparator comparator;

    final boolean delayErrors;

    final int prefetch;

    FlowableOrderedMerge(Publisher[] sources, Iterable> sourcesIterable,
            Comparator comparator,
            boolean delayErrors, int prefetch) {
        this.sources = sources;
        this.sourcesIterable = sourcesIterable;
        this.comparator = comparator;
        this.delayErrors = delayErrors;
        this.prefetch = prefetch;
    }

    @SuppressWarnings("unchecked")
    @Override
    protected void subscribeActual(Subscriber s) {
        Publisher[] array = sources;
        int n;

        if (array == null) {
            array = new Publisher[8];
            n = 0;
            try {
                for (Publisher p : sourcesIterable) {
                    if (n == array.length) {
                        array = Arrays.copyOf(array, n << 1);
                    }
                    array[n++] = ObjectHelper.requireNonNull(p, "a source is null");
                }
            } catch (Throwable ex) {
                Exceptions.throwIfFatal(ex);
                EmptySubscription.error(ex, s);
                return;
            }
        } else {
            n = array.length;
        }

        if (n == 0) {
            EmptySubscription.complete(s);
            return;
        }

        if (n == 1) {
            array[0].subscribe(s);
            return;
        }

        BasicMergeSubscription parent = new BasicMergeSubscription(s, comparator, n, prefetch, delayErrors);
        s.onSubscribe(parent);
        parent.subscribe(array, n);
    }
}