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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.joins;

import java.util.Map;
import java.util.concurrent.atomic.AtomicReference;

import hu.akarnokd.rxjava2.functions.Consumer4;
import io.reactivex.Observer;
import io.reactivex.functions.*;

/**
 * Represents an execution plan for join patterns.
 * @param  the first value type
 * @param  the second value type
 * @param  the third value type
 * @param  the fourth value type
 * @param  the result type
 */
final class Plan4 extends Plan {
    protected final Pattern4 expression;
    protected final Function4 selector;

    Plan4(Pattern4 expression, Function4 selector) {
        this.expression = expression;
        this.selector = selector;
    }

    @Override
    public ActivePlan0 activate(Map externalSubscriptions,
            final Observer observer, final Consumer deactivate) {
        Consumer onError = onErrorFrom(observer);

        final JoinObserver1 jo1 = createObserver(externalSubscriptions, expression.o1(), onError);
        final JoinObserver1 jo2 = createObserver(externalSubscriptions, expression.o2(), onError);
        final JoinObserver1 jo3 = createObserver(externalSubscriptions, expression.o3(), onError);
        final JoinObserver1 jo4 = createObserver(externalSubscriptions, expression.o4(), onError);

        final AtomicReference self = new AtomicReference();

        ActivePlan0 activePlan = new ActivePlan4(
                jo1, jo2, jo3, jo4,
                new Consumer4() {
                    @Override
                    public void accept(T1 t1, T2 t2, T3 t3, T4 t4) {
                        R result;
                        try {
                            result = selector.apply(t1, t2, t3, t4);
                        } catch (Throwable t) {
                            observer.onError(t);
                            return;
                        }
                        observer.onNext(result);
                    }
                },
                new Action() {
                    @Override
                    public void run() throws Exception {
                        ActivePlan0 ap = self.get();
                        jo1.removeActivePlan(ap);
                        jo2.removeActivePlan(ap);
                        jo3.removeActivePlan(ap);
                        jo4.removeActivePlan(ap);
                        deactivate.accept(ap);
                    }
                });

        self.set(activePlan);

        jo1.addActivePlan(activePlan);
        jo2.addActivePlan(activePlan);
        jo3.addActivePlan(activePlan);
        jo4.addActivePlan(activePlan);

        return activePlan;
    }

}