com.pinterest.pinlater.QueueRateLimiter.java Source code

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Here is the source code for com.pinterest.pinlater.QueueRateLimiter.java

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/**
 * 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 com.pinterest.pinlater;

import com.google.common.util.concurrent.RateLimiter;

/**
 * Simple wrapper class for Guava's RateLimiter. This is necessary because the Guava
 * implementation does not allow rate to be zero, something which we need.
 */
public final class QueueRateLimiter {

    private QueueRateLimiter() {
    }

    public static interface IFace {

        public boolean allowDequeue(int numJobs);

        public double getRate();
    }

    public static IFace create(double maxRequestsPerSecond) {
        if (maxRequestsPerSecond <= 0.0) {
            return ALLOW_NONE;
        }

        final RateLimiter rateLimiter = RateLimiter.create(maxRequestsPerSecond);
        return new IFace() {
            @Override
            public boolean allowDequeue(int numJobs) {
                return rateLimiter.tryAcquire(numJobs);
            }

            @Override
            public double getRate() {
                return rateLimiter.getRate();
            }
        };
    }

    private static final IFace ALLOW_NONE = new IFace() {
        @Override
        public boolean allowDequeue(int numJobs) {
            return false;
        }

        @Override
        public double getRate() {
            return 0.0;
        }
    };
}