org.apache.aurora.scheduler.async.GatingDelayExecutor.java Source code

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Here is the source code for org.apache.aurora.scheduler.async.GatingDelayExecutor.java

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/**
 * 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 org.apache.aurora.scheduler.async;

import java.util.Queue;
import java.util.concurrent.ScheduledExecutorService;

import javax.inject.Inject;

import com.google.common.collect.Iterables;
import com.google.common.collect.Lists;

import org.apache.aurora.common.quantity.Amount;
import org.apache.aurora.common.quantity.Time;

import static java.util.Objects.requireNonNull;

/**
 * An executor that may be temporarily gated with {@link #closeDuring(GatedOperation)}.  When the
 * executor is gated, newly-submitted work will be enqueued and executed once the gate is opened as
 * a result of {@link #closeDuring(GatedOperation)} returning.
 */
class GatingDelayExecutor implements DelayExecutor, GatedWorkQueue {

    private final ScheduledExecutorService gated;
    private final Queue<Runnable> queue = Lists.newLinkedList();

    /**
     * Creates a gating delay executor that will gate work from the provided executor.
     *
     * @param gated Delegate to execute work with when ungated.
     */
    @Inject
    GatingDelayExecutor(ScheduledExecutorService gated) {
        this.gated = requireNonNull(gated);
    }

    private final ThreadLocal<Boolean> isOpen = new ThreadLocal<Boolean>() {
        @Override
        protected Boolean initialValue() {
            return true;
        }
    };

    @Override
    public <T, E extends Exception> T closeDuring(GatedOperation<T, E> operation) throws E {
        boolean startedOpen = isOpen.get();
        isOpen.set(false);

        try {
            return operation.doWithGateClosed();
        } finally {
            if (startedOpen) {
                isOpen.set(true);
                flush();
            }
        }
    }

    synchronized int getQueueSize() {
        return queue.size();
    }

    private synchronized void enqueue(Runnable work) {
        if (isOpen.get()) {
            work.run();
        } else {
            queue.add(work);
        }
    }

    private synchronized void flush() {
        for (Runnable work : Iterables.consumingIterable(queue)) {
            work.run();
        }
    }

    @Override
    public synchronized void execute(Runnable command) {
        enqueue(() -> gated.execute(command));
    }

    @Override
    public synchronized void execute(Runnable work, Amount<Long, Time> minDelay) {
        enqueue(() -> gated.schedule(work, minDelay.getValue(), minDelay.getUnit().getTimeUnit()));
    }
}