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Swirlds is a software platform designed to build fully-distributed applications that harness the power of the cloud without servers. Now you can develop applications with fairness in decision making, speed, trust and reliability, at a fraction of the cost of traditional server-based platforms.

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/*
 * Copyright (C) 2023-2024 Hedera Hashgraph, LLC
 *
 * 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 com.swirlds.common.wiring.counters;

import static java.util.concurrent.TimeUnit.NANOSECONDS;

import edu.umd.cs.findbugs.annotations.NonNull;
import java.util.Objects;
import java.util.concurrent.ForkJoinPool.ManagedBlocker;
import java.util.concurrent.atomic.AtomicLong;

/**
 * This class is used to implement flushing in a {@link java.util.concurrent.ForkJoinPool} friendly way. Blocks until
 * the count reaches zero.
 */
class EmptyBlocker implements ManagedBlocker {

    private final AtomicLong count;
    private final long sleepNanos;

    /**
     * Constructor.
     *
     * @param count      the counter to use
     * @param sleepNanos the number of nanoseconds to sleep while blocking, or 0 to not sleep
     */
    public EmptyBlocker(@NonNull final AtomicLong count, final long sleepNanos) {
        this.count = Objects.requireNonNull(count);
        this.sleepNanos = sleepNanos;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean block() throws InterruptedException {
        if (sleepNanos > 0) {
            try {
                NANOSECONDS.sleep(sleepNanos);
            } catch (final InterruptedException e) {
                // Don't throw an interrupted exception, but allow the thread to maintain its interrupted status.
                Thread.currentThread().interrupt();
            }
        }
        return false;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean isReleasable() {
        return count.get() == 0;
    }
}