CompletableScheduledFuture.java

/*
 * Copyright (c) 2020, Stein Eldar Johnsen
 *
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you 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 net.morimekta.testing.concurrent.internal;

import net.morimekta.testing.concurrent.FakeClock;

import java.time.Instant;
import java.util.Objects;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.Delayed;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicReference;

import static java.util.Objects.requireNonNull;
import static java.util.concurrent.TimeUnit.MILLISECONDS;

@SuppressWarnings("PreferJavaTimeOverload")
public class CompletableScheduledFuture<T> extends CompletableFuture<T> implements ScheduledFuture<T> {
    private final FakeClock                clock;
    private final AtomicReference<Instant> nextExecution;

    public CompletableScheduledFuture(FakeClock clock, AtomicReference<Instant> nextExecution) {
        this.clock = requireNonNull(clock, "clock == null");
        this.nextExecution = requireNonNull(nextExecution, "nextExecution == null");
    }

    @Override
    public long getDelay(TimeUnit timeUnit) {
        Instant now = clock.instant();
        Instant next = nextExecution.get();
        if (now.isAfter(next)) {
            return 0L;
        }
        return timeUnit.convert(next.toEpochMilli() - now.toEpochMilli(), MILLISECONDS);
    }

    @Override
    public int compareTo(Delayed delayed) {
        long otherDelay = delayed.getDelay(MILLISECONDS);
        long myDelay = getDelay(MILLISECONDS);
        return Long.compare(myDelay, otherDelay);
    }

    @Override
    @SuppressWarnings("unchecked")
    public boolean equals(Object o) {
        if (this == o) {
            return true;
        }
        if (!(o instanceof CompletableScheduledFuture)) {
            return false;
        }
        CompletableScheduledFuture<Object> that = (CompletableScheduledFuture<Object>) o;
        return isDone() == that.isDone() &&
               isCancelled() == that.isCancelled() &&
               Objects.equals(nextExecution.get(), that.nextExecution.get()) &&
               Objects.equals(getNow((T) ABSENT), that.getNow(ABSENT));
    }

    @Override
    @SuppressWarnings("unchecked")
    public int hashCode() {
        return Objects.hash(isDone(), isCancelled(), nextExecution.get(), getNow((T) ABSENT));
    }

    private static final Object ABSENT = new Object();
}