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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) 2016-2024 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.threading.locks.internal;

import com.swirlds.common.threading.locks.AutoClosableLock;
import com.swirlds.common.threading.locks.locked.Locked;
import com.swirlds.common.threading.locks.locked.MaybeLocked;
import edu.umd.cs.findbugs.annotations.NonNull;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.Condition;

/**
 * Has similar semantics to {@link AutoLock}, except that it doesn't actually lock anything.
 */
public final class AutoNoOpLock implements AutoClosableLock {

    private static final Locked locked = () -> {
        // intentional no-op
    };

    private static final MaybeLocked maybeLocked = new MaybeLocked() {
        @Override
        public boolean isLockAcquired() {
            return true;
        }

        @Override
        public void close() {
            // intentional no-op
        }
    };
    private static final AutoClosableLock instance = new AutoNoOpLock();

    /**
     * Intentionally private. Use {@link #getInstance()} to get an instance.
     */
    private AutoNoOpLock() {}

    /**
     * Get an instance of a no-op auto lock. A no-op lock doesn't have any state, so we can reuse the
     * same one each time.
     *
     * @return an instance of a no-op auto-lock
     */
    @NonNull
    public static AutoClosableLock getInstance() {
        return instance;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    @NonNull
    public Locked lock() {
        return locked;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    @NonNull
    public Locked lockInterruptibly() {
        return locked;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    @NonNull
    public MaybeLocked tryLock() {
        return maybeLocked;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    @NonNull
    public MaybeLocked tryLock(final long time, @NonNull final TimeUnit unit) {
        return maybeLocked;
    }

    /**
     * Unsupported.
     *
     * @throws UnsupportedOperationException
     * 		if called
     */
    @Override
    @NonNull
    public Condition newCondition() {
        throw new UnsupportedOperationException();
    }
}