Java tutorial
/** * * 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.bookkeeper.server.service; import static com.google.common.base.Preconditions.checkArgument; import static org.apache.bookkeeper.bookie.ScrubberStats.DETECTED_FATAL_SCRUB_ERRORS; import static org.apache.bookkeeper.bookie.ScrubberStats.DETECTED_SCRUB_ERRORS; import static org.apache.bookkeeper.bookie.ScrubberStats.RUN_DURATION; import com.google.common.util.concurrent.RateLimiter; import io.netty.util.concurrent.DefaultThreadFactory; import java.io.IOException; import java.util.List; import java.util.Optional; import java.util.Random; import java.util.concurrent.Executors; import java.util.concurrent.ScheduledExecutorService; import java.util.concurrent.TimeUnit; import java.util.concurrent.atomic.AtomicBoolean; import org.apache.bookkeeper.bookie.ExitCode; import org.apache.bookkeeper.bookie.LedgerStorage; import org.apache.bookkeeper.server.component.ServerLifecycleComponent; import org.apache.bookkeeper.server.conf.BookieConfiguration; import org.apache.bookkeeper.stats.Counter; import org.apache.bookkeeper.stats.OpStatsLogger; import org.apache.bookkeeper.stats.StatsLogger; import org.apache.bookkeeper.util.MathUtils; import org.slf4j.Logger; import org.slf4j.LoggerFactory; /** * A {@link org.apache.bookkeeper.common.component.LifecycleComponent} that runs the scrubber background service. */ public class ScrubberService extends ServerLifecycleComponent { private static final Logger LOG = LoggerFactory.getLogger(ScrubberService.class); private static final String NAME = "scrubber"; private final ScheduledExecutorService executor; private final Random rng = new Random(); private final long scrubPeriod; private final Optional<RateLimiter> scrubRateLimiter; private final AtomicBoolean stop = new AtomicBoolean(false); private final LedgerStorage ledgerStorage; private final OpStatsLogger scrubCounter; private final Counter errorCounter; private final Counter fatalErrorCounter; public ScrubberService(StatsLogger logger, BookieConfiguration conf, LedgerStorage ledgerStorage) { super(NAME, conf, logger); this.executor = Executors.newSingleThreadScheduledExecutor(new DefaultThreadFactory("ScrubThread")); this.scrubPeriod = conf.getServerConf().getLocalScrubPeriod(); checkArgument(scrubPeriod > 0, "localScrubInterval must be > 0 for ScrubberService to be used"); double rateLimit = conf.getServerConf().getLocalScrubRateLimit(); this.scrubRateLimiter = rateLimit == 0 ? Optional.empty() : Optional.of(RateLimiter.create(rateLimit)); this.ledgerStorage = ledgerStorage; this.scrubCounter = logger.getOpStatsLogger(RUN_DURATION); this.errorCounter = logger.getCounter(DETECTED_SCRUB_ERRORS); this.fatalErrorCounter = logger.getCounter(DETECTED_FATAL_SCRUB_ERRORS); } private long getNextPeriodMS() { return (long) (((double) scrubPeriod) * (1.5 - rng.nextDouble()) * 1000); } private void doSchedule() { executor.schedule(this::run, getNextPeriodMS(), TimeUnit.MILLISECONDS); } private void run() { boolean success = false; long start = MathUtils.nowInNano(); try { List<LedgerStorage.DetectedInconsistency> errors = ledgerStorage .localConsistencyCheck(scrubRateLimiter); if (errors.size() > 0) { errorCounter.add(errors.size()); LOG.error("Found inconsistency during localConsistencyCheck:"); for (LedgerStorage.DetectedInconsistency error : errors) { LOG.error("Ledger {}, entry {}: ", error.getLedgerId(), error.getEntryId(), error.getException()); } } success = true; } catch (IOException e) { fatalErrorCounter.inc(); LOG.error("Got fatal exception {} running localConsistencyCheck", e.toString()); } if (success) { scrubCounter.registerSuccessfulEvent(MathUtils.elapsedNanos(start), TimeUnit.NANOSECONDS); } else { scrubCounter.registerFailedEvent(MathUtils.elapsedNanos(start), TimeUnit.NANOSECONDS); Runtime.getRuntime().exit(ExitCode.BOOKIE_EXCEPTION); } if (!stop.get()) { doSchedule(); } } @Override protected void doStart() { doSchedule(); } @Override protected void doStop() { stop.set(true); executor.shutdown(); } @Override protected void doClose() throws IOException { // no-op } }