add cache for docId to Doc mapping

A Doc does not change once it is created, so it is easy to cache.
Speedup was from 1ms per Doc to 3ms for 444 Docs (0.00675ms/Doc).
This commit is contained in:
2018-11-22 19:51:07 +01:00
parent 6c546bd5b3
commit f78f69328b
6 changed files with 158 additions and 17 deletions

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@@ -1,204 +0,0 @@
package org.lucares.performance.db;
import java.time.Clock;
import java.time.Duration;
import java.time.Instant;
import java.util.Arrays;
import java.util.EnumSet;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicReference;
import java.util.function.Consumer;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.google.common.util.concurrent.ThreadFactoryBuilder;
/**
* A cache that only keeps 'hot' entries, that is entries that have been
* accessed recently. Entries that have not been accessed recently are removed.
*/
public class HotEntryCache<K, V> {
private static final Logger LOGGER = LoggerFactory.getLogger(HotEntryCache.class);
public enum EventType {
EVICTED, REMOVED
}
public interface EventListener<K, V> {
public void onEvent(Event<K, V> event);
}
public static class Event<K, V> {
private final EventType eventType;
private final K key;
private final V value;
public Event(final EventType eventType, final K key, final V value) {
super();
this.eventType = eventType;
this.key = key;
this.value = value;
}
public EventType getEventType() {
return eventType;
}
public K getKey() {
return key;
}
public V getValue() {
return value;
}
}
private final static class EventSubscribers<K, V> {
private final EnumSet<EventType> subscribedEvents;
private final EventListener<K, V> listener;
public EventSubscribers(final EnumSet<EventType> subscribedEvents, final EventListener<K, V> listener) {
super();
this.subscribedEvents = subscribedEvents;
this.listener = listener;
}
public EnumSet<EventType> getSubscribedEvents() {
return subscribedEvents;
}
public EventListener<K, V> getListener() {
return listener;
}
}
private final static class Entry<V> {
private Instant lastAccessed;
private final V value;
public Entry(final V value, final Clock clock) {
this.value = value;
lastAccessed = Instant.now(clock);
}
public Instant getLastAccessed() {
return lastAccessed;
}
public V getValue() {
return value;
}
public void touch(final Clock clock) {
lastAccessed = Instant.now(clock);
}
}
private final ConcurrentHashMap<K, Entry<V>> cache = new ConcurrentHashMap<>();
private final ScheduledExecutorService evicter = Executors.newScheduledThreadPool(1,
new ThreadFactoryBuilder().setNameFormat("eviction-%d").setDaemon(true).build());
private final CopyOnWriteArrayList<EventSubscribers<K, V>> listeners = new CopyOnWriteArrayList<>();
private final Duration timeToLive;
private Clock clock;
HotEntryCache(final Duration timeToLive, final Clock clock, final long delayForEvictionThread,
final TimeUnit timeUnit) {
this.timeToLive = timeToLive;
this.clock = clock;
evicter.scheduleWithFixedDelay(this::evict, delayForEvictionThread, delayForEvictionThread, timeUnit);
}
public HotEntryCache(final Duration timeToLive) {
this(timeToLive, Clock.systemDefaultZone(), 5, TimeUnit.SECONDS);
}
public void addListener(final EventListener<K, V> listener, final EventType... eventTypes) {
listeners.add(new EventSubscribers<>(EnumSet.copyOf(Arrays.asList(eventTypes)), listener));
}
public V get(final K key) {
final Entry<V> entry = cache.computeIfPresent(key, (k, e) -> {
if (isExpired(e)) {
handleEvent(EventType.EVICTED, k, e.getValue());
return null;
}
e.touch(clock);
return e;
});
return entry != null ? entry.getValue() : null;
}
public V put(final K key, final V value) {
final AtomicReference<Entry<V>> oldValue = new AtomicReference<>();
cache.compute(key, (k, v) -> {
oldValue.set(v);
return new Entry<>(value, clock);
});
return oldValue.get() != null ? oldValue.get().getValue() : null;
}
public V remove(final K key) {
final AtomicReference<Entry<V>> oldValue = new AtomicReference<>();
cache.computeIfPresent(key, (k, e) -> {
oldValue.set(e);
handleEvent(EventType.REMOVED, k, e.getValue());
return null;
});
return oldValue.get() != null ? oldValue.get().getValue() : null;
}
public void clear() {
for (final K key : cache.keySet()) {
remove(key);
}
}
public void forEach(final Consumer<V> consumer) {
cache.forEachValue(Long.MAX_VALUE, entry -> {
entry.touch(clock);
consumer.accept(entry.getValue());
});
}
private void evict() {
LOGGER.trace("running evict");
for (final K key : cache.keySet()) {
cache.computeIfPresent(key, (k, e) -> {
if (isExpired(e)) {
handleEvent(EventType.EVICTED, k, e.getValue());
return null;
}
return e;
});
}
}
private boolean isExpired(final Entry<V> entry) {
return entry.getLastAccessed().plus(timeToLive).isBefore(Instant.now(clock));
}
private void handleEvent(final EventType eventType, final K key, final V value) {
for (final EventSubscribers<K, V> eventSubscribers : listeners) {
if (eventSubscribers.getSubscribedEvents().contains(eventType)) {
eventSubscribers.getListener().onEvent(new Event<>(eventType, key, value));
}
}
}
}

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@@ -9,9 +9,10 @@ import java.util.function.Consumer;
import org.lucares.pdb.api.Tags;
import org.lucares.pdb.datastore.Doc;
import org.lucares.pdb.datastore.internal.DataStore;
import org.lucares.performance.db.HotEntryCache.Event;
import org.lucares.performance.db.HotEntryCache.EventListener;
import org.lucares.performance.db.HotEntryCache.EventType;
import org.lucares.utils.cache.HotEntryCache;
import org.lucares.utils.cache.HotEntryCache.Event;
import org.lucares.utils.cache.HotEntryCache.EventListener;
import org.lucares.utils.cache.HotEntryCache.EventType;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

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@@ -1,129 +0,0 @@
package org.lucares.performance.db;
import java.time.Duration;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import org.lucares.performance.db.HotEntryCache.EventType;
import org.testng.Assert;
import org.testng.annotations.Test;
@Test
public class HotEntryCacheTest {
public void testPutAndGet() throws InterruptedException, ExecutionException, TimeoutException {
final HotEntryCache<String, String> cache = new HotEntryCache<>(Duration.ofSeconds(10));
final String replacedNull = cache.put("key", "value1");
Assert.assertEquals(replacedNull, null);
final String cachedValue1 = cache.get("key");
Assert.assertEquals(cachedValue1, "value1");
final String replacedValue1 = cache.put("key", "value2");
Assert.assertEquals(replacedValue1, "value1");
final String cachedValue2 = cache.get("key");
Assert.assertEquals(cachedValue2, "value2");
}
public void testEvictOnGet() throws InterruptedException, ExecutionException, TimeoutException {
final ModifiableFixedTimeClock clock = new ModifiableFixedTimeClock();
final Duration timeToLive = Duration.ofSeconds(10);
final HotEntryCache<String, String> cache = new HotEntryCache<>(timeToLive, clock, 1, TimeUnit.MILLISECONDS);
cache.put("key", "value1");
clock.plus(timeToLive.plusMillis(1));
final String cachedValue1_evicted = cache.get("key");
Assert.assertEquals(cachedValue1_evicted, null);
}
public void testEvictionByBackgroundThread() throws InterruptedException, ExecutionException, TimeoutException {
final ModifiableFixedTimeClock clock = new ModifiableFixedTimeClock();
final Duration timeToLive = Duration.ofSeconds(10);
final HotEntryCache<String, String> cache = new HotEntryCache<>(timeToLive, clock, 1, TimeUnit.MILLISECONDS);
final CompletableFuture<String> evictionEventFuture = new CompletableFuture<>();
cache.addListener(event -> {
evictionEventFuture.complete(event.getValue());
}, EventType.EVICTED);
cache.put("key", "value1");
clock.plus(timeToLive.plusMillis(1));
final String evictedValue1 = evictionEventFuture.get(5, TimeUnit.MINUTES); // enough time for debugging
Assert.assertEquals(evictedValue1, "value1");
}
public void testRemove() throws InterruptedException, ExecutionException, TimeoutException {
final HotEntryCache<String, String> cache = new HotEntryCache<>(Duration.ofSeconds(10));
final List<String> removedValues = new ArrayList<>();
cache.addListener(event -> removedValues.add(event.getValue()), EventType.REMOVED);
cache.put("key", "value1");
final String removedValue = cache.remove("key");
Assert.assertEquals(removedValue, "value1");
Assert.assertEquals(removedValues, Arrays.asList("value1"));
Assert.assertEquals(cache.get("key"), null);
}
public void testClear() throws InterruptedException, ExecutionException, TimeoutException {
final HotEntryCache<String, String> cache = new HotEntryCache<>(Duration.ofSeconds(10));
final List<String> removedValues = new ArrayList<>();
cache.addListener(event -> removedValues.add(event.getValue()), EventType.REMOVED);
cache.put("key1", "value1");
cache.put("key2", "value2");
cache.clear();
Assert.assertEquals(cache.get("key1"), null);
Assert.assertEquals(cache.get("key2"), null);
Assert.assertEquals(removedValues, Arrays.asList("value1", "value2"));
}
public void testForEachTouches() throws InterruptedException, ExecutionException, TimeoutException {
final ModifiableFixedTimeClock clock = new ModifiableFixedTimeClock();
final Duration timeToLive = Duration.ofSeconds(10);
final HotEntryCache<String, String> cache = new HotEntryCache<>(timeToLive, clock, 1, TimeUnit.HOURS);
final CompletableFuture<String> evictionEventFuture = new CompletableFuture<>();
cache.addListener(event -> {
evictionEventFuture.complete(event.getValue());
}, EventType.EVICTED);
// add value
cache.put("key", "value1");
// seek, so that it is almost evicted
clock.plus(timeToLive.minusMillis(1));
// the for each should touch the entries
cache.forEach(s -> {
/* no-op */});
// seek again
clock.plus(timeToLive.minusMillis(1));
// if the touch didn't happen, then the value is now evicted
Assert.assertEquals(evictionEventFuture.isDone(), false);
// seek again, so that the entry will get evicted
clock.plus(timeToLive.minusMillis(1));
Assert.assertEquals(cache.get("key"), null);
}
}

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@@ -1,98 +0,0 @@
package org.lucares.performance.db;
import java.io.Serializable;
import java.time.Clock;
import java.time.Instant;
import java.time.ZoneId;
import java.time.temporal.TemporalAmount;
import java.time.temporal.TemporalUnit;
/**
* A {@link Clock} with a fixed, but modifiable, time. This {@link Clock} is
* useful in tests, so that you can explicitly set the time.
*/
public class ModifiableFixedTimeClock extends Clock implements Serializable {
private static final long serialVersionUID = 1955332545617873736L;
private Instant instant;
private final ZoneId zone;
public ModifiableFixedTimeClock() {
this(Instant.now());
}
public ModifiableFixedTimeClock(final Instant fixedInstant) {
this(fixedInstant, ZoneId.systemDefault());
}
public ModifiableFixedTimeClock(final Instant fixedInstant, final ZoneId zone) {
this.instant = fixedInstant;
this.zone = zone;
}
public void setTime(final Instant instant) {
this.instant = instant;
}
public void plus(final TemporalAmount amountToAdd) {
instant = instant.plus(amountToAdd);
}
public void plus(final long amountToAdd, final TemporalUnit unit) {
instant = instant.plus(amountToAdd, unit);
}
public void plusMillis(final long millisToAdd) {
instant = instant.plusMillis(millisToAdd);
}
public void plusNanos(final long nanosToAdd) {
instant = instant.plusNanos(nanosToAdd);
}
public void plusSeconds(final long secondsToAdd) {
instant = instant.plusSeconds(secondsToAdd);
}
@Override
public ZoneId getZone() {
return zone;
}
@Override
public Clock withZone(final ZoneId zone) {
if (zone.equals(this.zone)) { // intentional NPE
return this;
}
return new ModifiableFixedTimeClock(instant, zone);
}
@Override
public long millis() {
return instant.toEpochMilli();
}
@Override
public Instant instant() {
return instant;
}
@Override
public boolean equals(final Object obj) {
if (obj instanceof ModifiableFixedTimeClock) {
final ModifiableFixedTimeClock other = (ModifiableFixedTimeClock) obj;
return instant.equals(other.instant) && zone.equals(other.zone);
}
return false;
}
@Override
public int hashCode() {
return instant.hashCode() ^ zone.hashCode();
}
@Override
public String toString() {
return "FixedClock[" + instant + "," + zone + "]";
}
}