com.norconex.collector.http.delay.impl.CrawlerDelay.java Source code

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Here is the source code for com.norconex.collector.http.delay.impl.CrawlerDelay.java

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/* Copyright 2010-2014 Norconex Inc.
 *
 * 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.norconex.collector.http.delay.impl;

import org.apache.commons.lang3.mutable.MutableLong;

import com.norconex.commons.lang.Sleeper;

/**
 * It is assumed there will be one instance of this class per crawler defined.
 * @author Pascal Essiembre
 */
public class CrawlerDelay extends AbstractDelay {

    private MutableLong lastHitEpochNanos = new MutableLong(-1);
    private boolean sleeping = false;

    public void delay(long expectedDelayNanos, String url) {
        if (expectedDelayNanos <= 0) {
            return;
        }
        try {
            synchronized (lastHitEpochNanos) {
                while (sleeping) {
                    Sleeper.sleepNanos(Math.min(TINY_SLEEP_MS, expectedDelayNanos));
                }
                sleeping = true;
            }
            delay(expectedDelayNanos, lastHitEpochNanos.longValue());
            lastHitEpochNanos.setValue(System.nanoTime());
        } finally {
            sleeping = false;
        }
    }
}