| /* |
| * |
| * 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 org.apache.qpid.junit.extensions; |
| |
| /** |
| * SleepThrottle is a Throttle implementation that generates short pauses using the thread sleep methods. As the pauses |
| * get shorter, this technique gets more innacurate. In practice, around 100 Hz is the cap rate for accuracy. |
| * |
| * <p/><table id="crc"><caption>CRC Card</caption> |
| * <tr><th> Responsibilities <th> Collaborations |
| * <tr><td> Accept throttling rate in operations per second. |
| * <tr><td> Inject short pauses to fill out processing cycles to a specified rate. |
| * <tr><td> Check against a throttle speed without waiting. |
| * </table> |
| * |
| * @author Rupert Smith |
| */ |
| public class SleepThrottle extends BaseThrottle implements Throttle |
| { |
| /** Holds the time of the last call to the throttle method in nano seconds. */ |
| private long lastTimeNanos; |
| |
| /** |
| * This method can only be called at the rate set by the {@link #setRate} method, if it is called faster than this |
| * it will inject short pauses to restrict the call rate to that rate. |
| */ |
| public void throttle() |
| { |
| // Get the current time in nanos. |
| long currentTimeNanos = System.nanoTime(); |
| |
| // Don't introduce any pause on the first call. |
| if (!firstCall) |
| { |
| // Check if there is any time left in the cycle since the last call to this method and introduce a short pause |
| // to fill that time if there is. |
| long remainingTimeNanos = cycleTimeNanos - (currentTimeNanos - lastTimeNanos); |
| |
| if (remainingTimeNanos > 0) |
| { |
| long milliPause = remainingTimeNanos / 1000000; |
| int nanoPause = (int) (remainingTimeNanos % 1000000); |
| |
| try |
| { |
| Thread.sleep(milliPause, nanoPause); |
| } |
| catch (InterruptedException e) |
| { |
| // Restore the interrupted thread, in-case the caller is checking for it. |
| Thread.currentThread().interrupt(); |
| } |
| } |
| } |
| else |
| { |
| firstCall = false; |
| } |
| |
| // Update the last time stamp. |
| lastTimeNanos = System.nanoTime(); |
| } |
| } |