/* * Copyright (C) 2012, 2016 higherfrequencytrading.com * Copyright (C) 2016 Roman Leventov * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU Lesser General Public License as published by * the Free Software Foundation, either version 3 of the License. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public License * along with this program. If not, see <http://www.gnu.org/licenses/>. */ package net.openhft.chronicle.map; import net.openhft.chronicle.core.io.Closeable; import net.openhft.chronicle.hash.ChronicleHashBuilderPrivateAPI; import net.openhft.chronicle.hash.ReplicatedHashSegmentContext; import net.openhft.chronicle.hash.replication.ReplicableEntry; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import java.lang.ref.WeakReference; import java.util.Random; import java.util.concurrent.ThreadLocalRandom; import java.util.concurrent.TimeUnit; import java.util.concurrent.locks.LockSupport; import java.util.function.Predicate; import static net.openhft.chronicle.hash.replication.TimeProvider.currentTime; import static net.openhft.chronicle.hash.replication.TimeProvider.systemTimeIntervalBetween; class OldDeletedEntriesCleanupThread extends Thread implements Closeable, Predicate<ReplicableEntry> { private static final Logger LOG = LoggerFactory.getLogger(OldDeletedEntriesCleanupThread.class); /** * Don't store a strong ref to a map in order to avoid it's leaking, if the user forgets to * close() map, from where this thread is shut down explicitly. Dereference map within * a single method, {@link #cleanupSegment()}. The map has a chance to be collected by GC when * this thread is sleeping after cleaning up a segment. */ private final WeakReference<ReplicatedChronicleMap<?, ?, ?>> mapRef; /** * {@code cleanupTimeout}, {@link #cleanupTimeoutUnit} and {@link #segments} are parts of the * cleaned Map's state, extracted in order to minimize accesses to the map. * * @see ChronicleHashBuilderPrivateAPI#removedEntryCleanupTimeout(long, TimeUnit) */ private final long cleanupTimeout; private final TimeUnit cleanupTimeoutUnit; private final int segments; /** * {@code segmentsPermutation} and {@link #inverseSegmentsPermutation} determine random order, * in which segments are cleaned up. */ private final int[] segmentsPermutation; private final int[] inverseSegmentsPermutation; /** * This object is used to determine that this thread is parked from {@link #sleepMillis(long)} * or {@link #sleepNanos(long)}, not somewhere inside ChronicleMap logic, to interrupt() * selectively in {@link #close()}. */ private final Object cleanupSleepingHandle = new Object(); private volatile boolean shutdown; private long prevSegment0ScanStart = -1; private long removedCompletely; OldDeletedEntriesCleanupThread(ReplicatedChronicleMap<?, ?, ?> map) { super("Cleanup Thread for " + map.toIdentityString()); setDaemon(true); this.mapRef = new WeakReference<>(map); cleanupTimeout = map.cleanupTimeout; cleanupTimeoutUnit = map.cleanupTimeoutUnit; segments = map.segments(); segmentsPermutation = randomPermutation(map.segments()); inverseSegmentsPermutation = inversePermutation(segmentsPermutation); } @Override public void run() { while (!shutdown) { int nextSegmentIndex = cleanupSegment(); if (nextSegmentIndex == -1) return; if (nextSegmentIndex == 0) { long currentTime = currentTime(); long mapScanTime = systemTimeIntervalBetween( prevSegment0ScanStart, currentTime, cleanupTimeoutUnit); LOG.debug("Old deleted entries scan time: {} {}", mapScanTime, cleanupTimeoutUnit); if (mapScanTime < cleanupTimeout) { long timeToSleep = cleanupTimeoutUnit.toMillis(cleanupTimeout - mapScanTime); if (timeToSleep > 0) { sleepMillis(timeToSleep); } else { sleepNanos(cleanupTimeoutUnit.toNanos(cleanupTimeout - mapScanTime)); } } } } } /** * @return next segment index to cleanup, or -1 if cleanup thread should be shut down */ private int cleanupSegment() { ReplicatedChronicleMap<?, ?, ?> map = mapRef.get(); if (map == null) return -1; int segmentIndex = map.globalMutableState().getCurrentCleanupSegmentIndex(); int nextSegmentIndex; try (MapSegmentContext<?, ?, ?> context = map.segmentContext(segmentIndex)) { if (segmentIndex == 0) prevSegment0ScanStart = currentTime(); removedCompletely = 0; if (((ReplicatedHashSegmentContext<?, ?>) context) .forEachSegmentReplicableEntryWhile(this)) { LOG.debug("Removed {} old deleted entries in the segment {}", removedCompletely, segmentIndex); nextSegmentIndex = nextSegmentIndex(segmentIndex); map.globalMutableState().setCurrentCleanupSegmentIndex(nextSegmentIndex); return nextSegmentIndex; } else { // forEachWhile returned false => interrupted => shutdown = true assert shutdown; return -1; } } } @Override public boolean test(ReplicableEntry e) { if (shutdown) return false; if (e instanceof MapAbsentEntry) { long deleteTimeout = systemTimeIntervalBetween( e.originTimestamp(), currentTime(), cleanupTimeoutUnit); if (deleteTimeout > cleanupTimeout && !e.isChanged()) { e.doRemoveCompletely(); removedCompletely++; } } return true; } private void sleepMillis(long millis) { long deadline = System.currentTimeMillis() + millis; while (System.currentTimeMillis() < deadline && !shutdown) LockSupport.parkUntil(cleanupSleepingHandle, deadline); } private void sleepNanos(long nanos) { long deadline = System.nanoTime() + nanos; while (System.nanoTime() < deadline && !shutdown) LockSupport.parkNanos(cleanupSleepingHandle, deadline); } @Override public void close() { shutdown = true; // this means blocked in sleepMillis() or sleepNanos() if (LockSupport.getBlocker(this) == cleanupSleepingHandle) this.interrupt(); // unblock } private int nextSegmentIndex(int segmentIndex) { int permutationIndex = inverseSegmentsPermutation[segmentIndex]; int nextPermutationIndex = (permutationIndex + 1) % segments; return segmentsPermutation[nextPermutationIndex]; } private static int[] randomPermutation(int n) { int[] a = new int[n]; for (int i = 0; i < n; i++) { a[i] = i; } shuffle(a); return a; } // Implementing Fisher–Yates shuffle private static void shuffle(int[] a) { Random rnd = ThreadLocalRandom.current(); for (int i = a.length - 1; i > 0; i--) { int index = rnd.nextInt(i + 1); int e = a[index]; a[index] = a[i]; a[i] = e; } } private static int[] inversePermutation(int[] permutation) { int n = permutation.length; int[] inverse = new int[n]; for (int i = 0; i < n; i++) { inverse[permutation[i]] = i; } return inverse; } }