io.vlingo.common.completes.sources.InMemorySource Maven / Gradle / Ivy

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These are just a few common tools shared across various vlingo projects.

There is a newer version: 1.7.5

// Copyright © 2012-2020 VLINGO LABS. All rights reserved.
//
// This Source Code Form is subject to the terms of the
// Mozilla Public License, v. 2.0. If a copy of the MPL
// was not distributed with this file, You can obtain
// one at https://mozilla.org/MPL/2.0/.

package io.vlingo.common.completes.sources;

import io.vlingo.common.Completes;
import io.vlingo.common.completes.LazySource;
import io.vlingo.common.completes.Sink;

import java.util.ArrayDeque;
import java.util.Queue;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.function.Consumer;

public class InMemorySource implements LazySource {
    private Queue>> queue;
    private Sink subscriber;
    private AtomicBoolean active;

    public InMemorySource() {
        this.queue = new ArrayDeque<>();
        this.subscriber = null;
        this.active = new AtomicBoolean(false);
    }

    @Override
    public void emitOutcome(Exposes outcome) {
        if (active.get()) {
            this.subscriber.onOutcome(outcome);
        } else {
            this.queue.add(e -> e.onOutcome(outcome));
        }
    }

    @Override
    public void emitError(Exception cause) {
        if (active.get()) {
            this.subscriber.onError(cause);
        } else {
            this.queue.add(e -> e.onError(cause));
        }
    }

    @Override
    public void emitCompletion() {
        if (active.get()) {
            this.subscriber.onCompletion();
        } else {
            this.queue.add(Sink::onCompletion);
        }
    }

    @Override
    public void subscribe(Sink subscriber) {
        this.subscriber = subscriber;
    }

    @Override
    public void activate() {
        if (this.subscriber == null) {
            throw new UnsupportedOperationException("Source must have a subscriber before being able to activate it.");
        }

        if (this.active.compareAndSet(false, true)) {
            if (!this.queue.isEmpty()) {
                this.queue.forEach(e -> e.accept(subscriber));
                this.queue = null;
            }
        }

    }

    public static  InMemorySource fromCompletes(Completes completes) {
        InMemorySource source = new InMemorySource<>();
        completes.andFinallyConsume(s -> {
            source.emitOutcome(s);
            source.emitCompletion();
        });

        return source;
    }

    @Override
    public String toString() {
        return "InMemorySource{" +
                "queue=" + queue +
                ", subscriber=" + subscriber +
                ", active=" + active +
                '}';
    }
}