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add maxSize parameter to HotEntryCache

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This commit is contained in:
Andreas Huber
2019-08-24 19:24:20 +02:00
parent 00c20dae6b
commit 6eaf4e10fc
5 changed files with 168 additions and 44 deletions
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108
pdb-utils/src/main/java/org/lucares/utils/cache/HotEntryCache.java vendored
View File

@@ -14,12 +14,12 @@ import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicReference;
import java.util.function.Consumer;
import java.util.function.Function;
import javax.annotation.concurrent.GuardedBy;
import org.lucares.collections.LongList;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
@@ -74,7 +74,7 @@ public class HotEntryCache<K, V> {
}
private final static class Entry<V> {
private long lastAccessed;
private volatile long lastAccessed;
private V value;
@@ -135,7 +135,7 @@ public class HotEntryCache<K, V> {
synchronized (lock) {
keySet.addAll(weakCaches.keySet());
}
LOGGER.trace("update time");
// LOGGER.trace("update time");
for (final HotEntryCache<?, ?> cache : keySet) {
cache.updateTime();
}
@@ -149,7 +149,6 @@ public class HotEntryCache<K, V> {
private static final class EvictionThread extends Thread {
@GuardedBy("lock")
private final WeakHashMap<HotEntryCache<?, ?>, Void> weakCaches = new WeakHashMap<>();
private final AtomicReference<CompletableFuture<Void>> future = new AtomicReference<>(null);
private final Object lock = new Object();
@@ -219,6 +218,7 @@ public class HotEntryCache<K, V> {
caches.addAll(weakCaches.keySet());
}
for (final HotEntryCache<?, ?> cache : caches) {
// TODO remember nextEvictionTime on cache so that we can skip a cache
final long nextEvictionTime = cache.evict();
minNextEvictionTime = Math.min(minNextEvictionTime, nextEvictionTime);
}
@@ -272,8 +272,6 @@ public class HotEntryCache<K, V> {
TIME_UPDATER.start();
}
private static long now;
/**
* Mapping of the key to the value.
* <p>
@@ -283,14 +281,19 @@ public class HotEntryCache<K, V> {
private final CopyOnWriteArrayList<EventListener<K, V>> listeners = new CopyOnWriteArrayList<>();
private final Duration timeToLive;
private final long timeToLive;
private volatile long now = 0;
private Clock clock;
private final String name;
HotEntryCache(final Duration timeToLive, final Clock clock, final String name) {
this.timeToLive = timeToLive;
private int maxSize;
HotEntryCache(final Duration timeToLive, final int maxSize, final Clock clock, final String name) {
this.timeToLive = timeToLive.toMillis();
this.maxSize = maxSize;
this.clock = clock;
this.name = name;
now = clock.millis();
@@ -299,16 +302,16 @@ public class HotEntryCache<K, V> {
TIME_UPDATER.addCache(this);
}
HotEntryCache(final Duration timeToLive, final Clock clock) {
this(timeToLive, clock, UUID.randomUUID().toString());
HotEntryCache(final Duration timeToLive, final int maxSize, final Clock clock) {
this(timeToLive, maxSize, clock, UUID.randomUUID().toString());
}
public HotEntryCache(final Duration timeToLive, final String name) {
this(timeToLive, Clock.systemDefaultZone(), name);
public HotEntryCache(final Duration timeToLive, final int maxSize, final String name) {
this(timeToLive, maxSize, Clock.systemDefaultZone(), name);
}
public HotEntryCache(final Duration timeToLive) {
this(timeToLive, Clock.systemDefaultZone(), UUID.randomUUID().toString());
public HotEntryCache(final Duration timeToLive, final int maxSize) {
this(timeToLive, maxSize, Clock.systemDefaultZone(), UUID.randomUUID().toString());
}
public int size() {
@@ -350,6 +353,8 @@ public class HotEntryCache<K, V> {
public V put(final K key, final V value) {
removeEldestCacheTooBig();
final boolean wasEmptyBefore = cache.isEmpty();
final AtomicReference<V> oldValueAtomicReference = new AtomicReference<>();
cache.compute(key, (k, oldEntry) -> {
@@ -391,6 +396,8 @@ public class HotEntryCache<K, V> {
*/
public V putIfAbsent(final K key, final Function<K, V> mappingFunction) {
removeEldestCacheTooBig();
final boolean wasEmptyBefore = cache.isEmpty();
final Entry<V> entry = cache.computeIfAbsent(key, (k) -> {
final V value = mappingFunction.apply(k);
@@ -433,27 +440,76 @@ public class HotEntryCache<K, V> {
});
}
private void removeEldestCacheTooBig() {
if (cache.size() >= maxSize) {
removeEldest();
}
}
private synchronized void removeEldest() {
if (cache.size() >= maxSize) {
final LongList lastAccessTimes = new LongList(cache.size());
for (final java.util.Map.Entry<K, Entry<V>> mapEntry : cache.entrySet()) {
final Entry<V> entry = mapEntry.getValue();
final long lastAccessed = entry.getLastAccessed();
lastAccessTimes.add(lastAccessed);
}
lastAccessTimes.sort();
final int numEntriesToRemove = Math.max((int) (maxSize * 0.2), 1);
final long oldestValuesToKeep = lastAccessTimes.get(numEntriesToRemove - 1) + 1;
evictInternal(oldestValuesToKeep, numEntriesToRemove);
}
}
private long evict() {
final long now = now();
final long oldestValuesToKeep = now - timeToLive.toMillis();
long lastAccessTime = Long.MAX_VALUE;
final long oldestValuesToKeep = now - timeToLive;
LOGGER.trace("{}: oldestValuesToKeep = {} = {} - {}", name, oldestValuesToKeep, now, timeToLive);
return evictInternal(oldestValuesToKeep, Integer.MAX_VALUE);
}
private long evictInternal(final long oldestValuesToKeep, final int maxEntriesToRemove) {
long oldestAccessTime = Long.MAX_VALUE;
LOGGER.trace("{}: cache size before eviction {}", name, cache.size());
LOGGER.trace("{}: oldest value to keep {}", name, oldestValuesToKeep);
final AtomicInteger removedEntries = new AtomicInteger();
for (final java.util.Map.Entry<K, Entry<V>> mapEntry : cache.entrySet()) {
final Entry<V> entry = mapEntry.getValue();
final long lastAccessed = entry.getLastAccessed();
lastAccessTime = Math.min(lastAccessTime, lastAccessed);
oldestAccessTime = Math.min(oldestAccessTime, lastAccessed);
if (lastAccessed > oldestValuesToKeep) {
if (removedEntries.get() >= maxEntriesToRemove) {
// finish iterating over all entries so that this method return the correct
// nextEvictionTime
LOGGER.trace("{}: removedEntries >= maxEntriesToRemove = {} >= {}", name, removedEntries.get(),
maxEntriesToRemove);
continue;
}
if (lastAccessed >= oldestValuesToKeep) {
LOGGER.trace("{}: lastAccessed >= oldestValuesToKeep = {} >= {}", name, lastAccessed,
oldestValuesToKeep);
continue;
}
final K keyToBeRemoved = mapEntry.getKey();
LOGGER.trace("{}: atomically removing key {}", name, keyToBeRemoved);
cache.computeIfPresent(keyToBeRemoved, (k, e) -> {
if (isExpired(e, now)) {
if (entry.getLastAccessed() < oldestValuesToKeep) {
LOGGER.trace("{}: removing value from {}", name, entry.getLastAccessed());
removedEntries.incrementAndGet();
handleEvent(k, e.getValue());
return null;
} else {
LOGGER.trace("{}: keeping value from {}", name, entry.getLastAccessed());
}
return e;
});
@@ -461,8 +517,8 @@ public class HotEntryCache<K, V> {
}
LOGGER.trace("{}: cache size after eviction {}", name, cache.size());
final long nextEvictionTime = lastAccessTime == Long.MAX_VALUE ? Long.MAX_VALUE
: lastAccessTime + timeToLive.toMillis();
final long nextEvictionTime = oldestAccessTime == Long.MAX_VALUE ? Long.MAX_VALUE
: oldestAccessTime + timeToLive;
return nextEvictionTime;
}
@@ -473,6 +529,7 @@ public class HotEntryCache<K, V> {
// visible for test
void updateTime() {
now = clock.millis();
LOGGER.trace("{}: update time to {}", name, now);
}
private void touch(final K key, final Entry<V> entry) {
@@ -483,12 +540,9 @@ public class HotEntryCache<K, V> {
}
}
private boolean isExpired(final Entry<V> entry, final long now) {
return (entry.getLastAccessed() + timeToLive.toMillis()) < now;
}
private void handleEvent(final K key, final V value) {
LOGGER.trace("{}: calling {} listeners for {} -> {}", name, listeners.size(), key, value);
for (final EventListener<K, V> eventSubscribers : listeners) {
eventSubscribers.onRemove(key, value);

96
pdb-utils/src/test/java/org/lucares/utils/cache/HotEntryCacheTest.java vendored
View File

@@ -2,9 +2,12 @@ package org.lucares.utils.cache;
import java.time.Duration;
import java.time.Instant;
import java.time.temporal.ChronoUnit;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Set;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutionException;
@@ -15,6 +18,8 @@ import java.util.concurrent.TimeoutException;
import org.apache.logging.log4j.Level;
import org.apache.logging.log4j.core.config.Configurator;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.testng.Assert;
import org.testng.annotations.Test;
@@ -25,11 +30,17 @@ public class HotEntryCacheTest {
Configurator.setRootLevel(Level.TRACE);
}
private static final Logger LOGGER = LoggerFactory.getLogger(HotEntryCacheTest.class);
private int cacheId = 0;
@Test(invocationCount = 1)
public void testRemovalListenerCalledOnExpire() throws InterruptedException {
LOGGER.info("");
LOGGER.info("");
LOGGER.info("start: testRemovalListenerCalledOnExpire");
final long originalMinSleepPeriod = HotEntryCache.getMinSleepPeriod();
final long originalMaxSleepPeriod = HotEntryCache.getMaxSleepPeriod();
try {
@@ -37,9 +48,10 @@ public class HotEntryCacheTest {
final String value = "value";
final CountDownLatch latch = new CountDownLatch(1);
final HotEntryCache<String, String> cache = new HotEntryCache<>(Duration.ofMillis(1), "cache-" + ++cacheId);
final HotEntryCache<String, String> cache = new HotEntryCache<>(Duration.ofMillis(1), 10,
"cache-" + ++cacheId);
HotEntryCache.setMinSleepPeriod(1);
HotEntryCache.setMaxSleepPeriod(10);
HotEntryCache.setMaxSleepPeriod(2);
cache.addListener((k, v) -> {
Assert.assertEquals(k, key);
Assert.assertEquals(v, value);
@@ -56,7 +68,7 @@ public class HotEntryCacheTest {
}
public void testPutAndGet() throws InterruptedException, ExecutionException, TimeoutException {
final HotEntryCache<String, String> cache = new HotEntryCache<>(Duration.ofSeconds(10));
final HotEntryCache<String, String> cache = new HotEntryCache<>(Duration.ofSeconds(10), 10);
final String replacedNull = cache.put("key", "value1");
Assert.assertEquals(replacedNull, null);
@@ -74,7 +86,7 @@ public class HotEntryCacheTest {
public void testPutTouches() throws InterruptedException, ExecutionException, TimeoutException {
final ModifiableFixedTimeClock clock = new ModifiableFixedTimeClock();
final Duration timeToLive = Duration.ofSeconds(10);
final HotEntryCache<String, String> cache = new HotEntryCache<>(timeToLive, clock);
final HotEntryCache<String, String> cache = new HotEntryCache<>(timeToLive, 10, clock);
cache.put("key", "value1");
@@ -102,7 +114,7 @@ public class HotEntryCacheTest {
public void testGetTouches() throws Exception {
final ModifiableFixedTimeClock clock = new ModifiableFixedTimeClock();
final Duration timeToLive = Duration.ofSeconds(10);
final HotEntryCache<String, String> cache = new HotEntryCache<>(timeToLive, clock);
final HotEntryCache<String, String> cache = new HotEntryCache<>(timeToLive, 10, clock);
cache.put("key", "value1");
@@ -121,7 +133,7 @@ public class HotEntryCacheTest {
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);
final HotEntryCache<String, String> cache = new HotEntryCache<>(timeToLive, 10, clock);
final CompletableFuture<String> evictionEventFuture = new CompletableFuture<>();
cache.addListener((key, value) -> {
@@ -142,7 +154,11 @@ public class HotEntryCacheTest {
}
public void testRemove() throws InterruptedException, ExecutionException, TimeoutException {
final HotEntryCache<String, String> cache = new HotEntryCache<>(Duration.ofSeconds(10));
LOGGER.info("");
LOGGER.info("");
LOGGER.info("start: testRemove");
final HotEntryCache<String, String> cache = new HotEntryCache<>(Duration.ofSeconds(10), 10);
final List<String> removedValues = new ArrayList<>();
cache.addListener((key, value) -> removedValues.add(value));
@@ -158,7 +174,7 @@ public class HotEntryCacheTest {
}
public void testClear() throws InterruptedException, ExecutionException, TimeoutException {
final HotEntryCache<String, String> cache = new HotEntryCache<>(Duration.ofSeconds(10));
final HotEntryCache<String, String> cache = new HotEntryCache<>(Duration.ofSeconds(10), 10);
final List<String> removedValues = new ArrayList<>();
cache.addListener((key, value) -> removedValues.add(value));
@@ -177,7 +193,7 @@ public class HotEntryCacheTest {
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);
final HotEntryCache<String, String> cache = new HotEntryCache<>(timeToLive, 10, clock);
final CompletableFuture<String> evictionEventFuture = new CompletableFuture<>();
cache.addListener((key, value) -> {
@@ -220,7 +236,7 @@ public class HotEntryCacheTest {
* @throws Exception
*/
public void testPutIfAbsentIsAtomic() throws Exception {
final HotEntryCache<String, String> cache = new HotEntryCache<>(Duration.ofSeconds(10));
final HotEntryCache<String, String> cache = new HotEntryCache<>(Duration.ofSeconds(10), 10);
final ExecutorService pool = Executors.newCachedThreadPool();
try {
@@ -255,7 +271,7 @@ public class HotEntryCacheTest {
}
public void testPutIfAbsentReturnsExistingValue() throws Exception {
final HotEntryCache<String, String> cache = new HotEntryCache<>(Duration.ofSeconds(10));
final HotEntryCache<String, String> cache = new HotEntryCache<>(Duration.ofSeconds(10), 10);
final String key = "key";
final String valueA = "A";
@@ -271,7 +287,7 @@ public class HotEntryCacheTest {
}
public void testPutIfAbsentDoesNotAddNull() throws Exception {
final HotEntryCache<String, String> cache = new HotEntryCache<>(Duration.ofSeconds(10));
final HotEntryCache<String, String> cache = new HotEntryCache<>(Duration.ofSeconds(10), 10);
final String key = "key";
final String returnedByPutIfAbsent = cache.putIfAbsent(key, k -> null);
@@ -281,6 +297,60 @@ public class HotEntryCacheTest {
Assert.assertEquals(actualInCache, null);
}
public void testMaxSizeIsRespected() {
final int maxSize = 10;
final ModifiableFixedTimeClock clock = new ModifiableFixedTimeClock();
final HotEntryCache<String, String> cache = new HotEntryCache<>(Duration.ofHours(1), maxSize, clock);
final Set<String> removedKeys = new LinkedHashSet<>();
cache.addListener((key, value) -> removedKeys.add(key));
// fill the cache
int count = 0;
for (count = 0; count < maxSize; count++) {
cache.put("key" + count, "value" + count);
clock.plus(2L, ChronoUnit.MILLIS);
cache.updateTime();
}
Assert.assertEquals(cache.size(), maxSize, "cache is full");
Assert.assertEquals(removedKeys, List.of(), "removed keys at point A");
// add an item to a full cache -> the oldest 20% of the entries will be evicted
// before the new entry is added
cache.put("key" + count, "value" + count);
clock.plus(2L, ChronoUnit.MILLIS);
cache.updateTime();
count++;
Assert.assertEquals(cache.size(), maxSize - 1, "cache was full, 20% (2 items) were removed and one added");
Assert.assertEquals(removedKeys, Set.of("key0", "key1"), "removed keys at point B");
}
public void testEvictionDueToSizeLimitDoesNotRemoveMoreThan20Percent() {
final int maxSize = 10;
final ModifiableFixedTimeClock clock = new ModifiableFixedTimeClock();
final HotEntryCache<String, String> cache = new HotEntryCache<>(Duration.ofHours(1), maxSize, clock);
final Set<String> removedKeys = new LinkedHashSet<>();
cache.addListener((key, value) -> removedKeys.add(key));
// fill the cache
int count = 0;
for (count = 0; count < maxSize; count++) {
// all entries get the same eviction time due to the fixed clock
cache.put("key" + count, "value" + count);
}
Assert.assertEquals(cache.size(), maxSize, "cache is full");
Assert.assertEquals(removedKeys, List.of(), "removed keys at point A");
// add an item to a full cache -> the oldest 20% of the entries will be evicted
// before the new entry is added
cache.put("key" + count, "value" + count);
count++;
Assert.assertEquals(cache.size(), maxSize - 1, "cache was full, 20% (2 items) were removed and one added");
Assert.assertEquals(removedKeys.size(), (int) (maxSize * 0.2), "number of removed keys at point B");
}
private void sleep(final TimeUnit timeUnit, final long timeout) {
try {
timeUnit.sleep(timeout);
@@ -302,7 +372,7 @@ public class HotEntryCacheTest {
Configurator.setRootLevel(Level.TRACE);
final Duration timeToLive = Duration.ofSeconds(1);
final HotEntryCache<String, String> cache = new HotEntryCache<>(timeToLive);
final HotEntryCache<String, String> cache = new HotEntryCache<>(timeToLive, 10);
cache.addListener((key, value) -> {
System.out.println(Instant.now() + " evicting: " + key + " -> " + value);