| using Lucene.Net.Support; |
| using System; |
| using System.Threading; |
| |
| namespace Lucene.Net.Store |
| { |
| /* |
| * 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. |
| */ |
| |
| /// <summary> |
| /// Abstract base class to rate limit IO. Typically implementations are |
| /// shared across multiple <see cref="IndexInput"/>s or <see cref="IndexOutput"/>s (for example |
| /// those involved all merging). Those <see cref="IndexInput"/>s and |
| /// <see cref="IndexOutput"/>s would call <see cref="Pause"/> whenever they |
| /// want to read bytes or write bytes. |
| /// </summary> |
| public abstract class RateLimiter |
| { |
| /// <summary> |
| /// Sets an updated mb per second rate limit. |
| /// </summary> |
| public abstract void SetMbPerSec(double mbPerSec); |
| |
| /// <summary> |
| /// The current mb per second rate limit. |
| /// </summary> |
| public abstract double MbPerSec { get; } |
| |
| /// <summary> |
| /// Pauses, if necessary, to keep the instantaneous IO |
| /// rate at or below the target. |
| /// <para> |
| /// Note: the implementation is thread-safe |
| /// </para> |
| /// </summary> |
| /// <returns> the pause time in nano seconds </returns> |
| public abstract long Pause(long bytes); |
| |
| /// <summary> |
| /// Simple class to rate limit IO. |
| /// </summary> |
| public class SimpleRateLimiter : RateLimiter |
| { |
| private double mbPerSec; |
| private double nsPerByte; |
| private long lastNS; |
| |
| // TODO: we could also allow eg a sub class to dynamically |
| // determine the allowed rate, eg if an app wants to |
| // change the allowed rate over time or something |
| |
| /// <summary> |
| /// <paramref name="mbPerSec"/> is the MB/sec max IO rate </summary> |
| public SimpleRateLimiter(double mbPerSec) |
| { |
| SetMbPerSec(mbPerSec); |
| } |
| |
| /// <summary> |
| /// Sets an updated mb per second rate limit. |
| /// </summary> |
| public override void SetMbPerSec(double mbPerSec) |
| { |
| this.mbPerSec = mbPerSec; |
| if (mbPerSec == 0) |
| nsPerByte = 0; |
| else |
| nsPerByte = 1000000000.0 / (1024 * 1024 * mbPerSec); |
| } |
| |
| /// <summary> |
| /// The current mb per second rate limit. |
| /// </summary> |
| public override double MbPerSec => this.mbPerSec; |
| |
| /// <summary> |
| /// Pauses, if necessary, to keep the instantaneous IO |
| /// rate at or below the target. NOTE: multiple threads |
| /// may safely use this, however the implementation is |
| /// not perfectly thread safe but likely in practice this |
| /// is harmless (just means in some rare cases the rate |
| /// might exceed the target). It's best to call this |
| /// with a biggish count, not one byte at a time. </summary> |
| /// <returns> the pause time in nano seconds </returns> |
| public override long Pause(long bytes) |
| { |
| if (bytes == 1) |
| { |
| return 0; |
| } |
| |
| // TODO: this is purely instantaneous rate; maybe we |
| // should also offer decayed recent history one? |
| var targetNS = lastNS = lastNS + ((long)(bytes * nsPerByte)); |
| long startNS; |
| var curNS = startNS = Time.NanoTime() /* ns */; |
| if (lastNS < curNS) |
| { |
| lastNS = curNS; |
| } |
| |
| // While loop because Thread.sleep doesn't always sleep |
| // enough: |
| while (true) |
| { |
| var pauseNS = targetNS - curNS; |
| if (pauseNS > 0) |
| { |
| //#if FEATURE_THREAD_INTERRUPT |
| // try |
| // { |
| //#endif |
| Thread.Sleep(TimeSpan.FromMilliseconds(pauseNS / 1000000)); |
| //#if FEATURE_THREAD_INTERRUPT // LUCENENET NOTE: Senseless to catch and rethrow the same exception type |
| // } |
| // catch (ThreadInterruptedException ie) |
| // { |
| // throw new ThreadInterruptedException(ie.ToString(), ie); |
| // } |
| //#endif |
| curNS = Time.NanoTime(); |
| continue; |
| } |
| break; |
| } |
| return curNS - startNS; |
| } |
| } |
| } |
| } |