| /* |
| * 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.lucene.index; |
| |
| |
| import org.apache.lucene.store.RateLimiter; |
| import org.apache.lucene.util.ThreadInterruptedException; |
| |
| import java.util.concurrent.TimeUnit; |
| import java.util.concurrent.atomic.AtomicLong; |
| |
| import org.apache.lucene.index.MergePolicy.OneMergeProgress; |
| import org.apache.lucene.index.MergePolicy.OneMergeProgress.PauseReason; |
| |
| /** This is the {@link RateLimiter} that {@link IndexWriter} assigns to each running merge, to |
| * give {@link MergeScheduler}s ionice like control. |
| * |
| * @lucene.internal */ |
| |
| public class MergeRateLimiter extends RateLimiter { |
| |
| private final static int MIN_PAUSE_CHECK_MSEC = 25; |
| |
| private final static long MIN_PAUSE_NS = TimeUnit.MILLISECONDS.toNanos(2); |
| private final static long MAX_PAUSE_NS = TimeUnit.MILLISECONDS.toNanos(250); |
| |
| private volatile double mbPerSec; |
| private volatile long minPauseCheckBytes; |
| |
| private long lastNS; |
| |
| private AtomicLong totalBytesWritten = new AtomicLong(); |
| |
| private final OneMergeProgress mergeProgress; |
| |
| /** Sole constructor. */ |
| public MergeRateLimiter(OneMergeProgress mergeProgress) { |
| // Initially no IO limit; use setter here so minPauseCheckBytes is set: |
| this.mergeProgress = mergeProgress; |
| setMBPerSec(Double.POSITIVE_INFINITY); |
| } |
| |
| @Override |
| public void setMBPerSec(double mbPerSec) { |
| // Synchronized to make updates to mbPerSec and minPauseCheckBytes atomic. |
| synchronized (this) { |
| // 0.0 is allowed: it means the merge is paused |
| if (mbPerSec < 0.0) { |
| throw new IllegalArgumentException("mbPerSec must be positive; got: " + mbPerSec); |
| } |
| this.mbPerSec = mbPerSec; |
| |
| // NOTE: Double.POSITIVE_INFINITY casts to Long.MAX_VALUE |
| this.minPauseCheckBytes = Math.min(1024*1024, (long) ((MIN_PAUSE_CHECK_MSEC / 1000.0) * mbPerSec * 1024 * 1024)); |
| assert minPauseCheckBytes >= 0; |
| } |
| |
| mergeProgress.wakeup(); |
| } |
| |
| @Override |
| public double getMBPerSec() { |
| return mbPerSec; |
| } |
| |
| /** Returns total bytes written by this merge. */ |
| public long getTotalBytesWritten() { |
| return totalBytesWritten.get(); |
| } |
| |
| @Override |
| public long pause(long bytes) throws MergePolicy.MergeAbortedException { |
| totalBytesWritten.addAndGet(bytes); |
| |
| // While loop because we may wake up and check again when our rate limit |
| // is changed while we were pausing: |
| long paused = 0; |
| long delta; |
| while ((delta = maybePause(bytes, System.nanoTime())) >= 0) { |
| // Keep waiting. |
| paused += delta; |
| } |
| |
| return paused; |
| } |
| |
| /** Total NS merge was stopped. */ |
| public long getTotalStoppedNS() { |
| return mergeProgress.getPauseTimes().get(PauseReason.STOPPED); |
| } |
| |
| /** Total NS merge was paused to rate limit IO. */ |
| public long getTotalPausedNS() { |
| return mergeProgress.getPauseTimes().get(PauseReason.PAUSED); |
| } |
| |
| /** |
| * Returns the number of nanoseconds spent in a paused state or <code>-1</code> |
| * if no pause was applied. If the thread needs pausing, this method delegates |
| * to the linked {@link OneMergeProgress}. |
| */ |
| private long maybePause(long bytes, long curNS) throws MergePolicy.MergeAbortedException { |
| // Now is a good time to abort the merge: |
| if (mergeProgress.isAborted()) { |
| throw new MergePolicy.MergeAbortedException("Merge aborted."); |
| } |
| |
| double rate = mbPerSec; // read from volatile rate once. |
| double secondsToPause = (bytes/1024./1024.) / rate; |
| |
| // Time we should sleep until; this is purely instantaneous |
| // rate (just adds seconds onto the last time we had paused to); |
| // maybe we should also offer decayed recent history one? |
| long targetNS = lastNS + (long) (1000000000 * secondsToPause); |
| |
| long curPauseNS = targetNS - curNS; |
| |
| // We don't bother with thread pausing if the pause is smaller than 2 msec. |
| if (curPauseNS <= MIN_PAUSE_NS) { |
| // Set to curNS, not targetNS, to enforce the instant rate, not |
| // the "averaged over all history" rate: |
| lastNS = curNS; |
| return -1; |
| } |
| |
| // Defensive: don't sleep for too long; the loop above will call us again if |
| // we should keep sleeping and the rate may be adjusted in between. |
| if (curPauseNS > MAX_PAUSE_NS) { |
| curPauseNS = MAX_PAUSE_NS; |
| } |
| |
| long start = System.nanoTime(); |
| try { |
| mergeProgress.pauseNanos( |
| curPauseNS, |
| rate == 0.0 ? PauseReason.STOPPED : PauseReason.PAUSED, |
| () -> rate == mbPerSec); |
| } catch (InterruptedException ie) { |
| throw new ThreadInterruptedException(ie); |
| } |
| return System.nanoTime() - start; |
| } |
| |
| @Override |
| public long getMinPauseCheckBytes() { |
| return minPauseCheckBytes; |
| } |
| } |