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package com.codahale.metrics.ehcache;
import com.codahale.metrics.MetricRegistry;
import com.codahale.metrics.Timer;
import net.sf.ehcache.CacheException;
import net.sf.ehcache.Ehcache;
import net.sf.ehcache.Element;
import net.sf.ehcache.constructs.EhcacheDecoratorAdapter;
import net.sf.ehcache.statistics.StatisticsGateway;
import java.io.Serializable;
import static com.codahale.metrics.MetricRegistry.name;
/**
* An instrumented {@link Ehcache} instance.
*/
public class InstrumentedEhcache extends EhcacheDecoratorAdapter {
/**
* Instruments the given {@link Ehcache} instance with get and put timers
* and a set of gauges for Ehcache's built-in statistics:
*
*
* Ehcache timered metrics
*
* {@code hits}
* The number of times a requested item was found in the
* cache.
*
*
* {@code in-memory-hits}
* Number of times a requested item was found in the memory
* store.
*
*
* {@code off-heap-hits}
* Number of times a requested item was found in the off-heap
* store.
*
*
* {@code on-disk-hits}
* Number of times a requested item was found in the disk
* store.
*
*
* {@code misses}
* Number of times a requested item was not found in the
* cache.
*
*
* {@code in-memory-misses}
* Number of times a requested item was not found in the memory
* store.
*
*
* {@code off-heap-misses}
* Number of times a requested item was not found in the
* off-heap store.
*
*
* {@code on-disk-misses}
* Number of times a requested item was not found in the disk
* store.
*
*
* {@code objects}
* Number of elements stored in the cache.
*
*
* {@code in-memory-objects}
* Number of objects in the memory store.
*
*
* {@code off-heap-objects}
* Number of objects in the off-heap store.
*
*
* {@code on-disk-objects}
* Number of objects in the disk store.
*
*
* {@code mean-get-time}
* The average get time. Because ehcache support JDK1.4.2, each
* get time uses {@link System#currentTimeMillis()}, rather than
* nanoseconds. The accuracy is thus limited.
*
*
* {@code mean-search-time}
* The average execution time (in milliseconds) within the last
* sample period.
*
*
* {@code eviction-count}
* The number of cache evictions, since the cache was created,
* or statistics were cleared.
*
*
* {@code searches-per-second}
* The number of search executions that have completed in the
* last second.
*
*
* {@code accuracy}
* A human readable description of the accuracy setting. One of
* "None", "Best Effort" or "Guaranteed".
*
*
*
* N.B.: This enables Ehcache's sampling statistics with an accuracy
* level of "none."
*
* @param cache an {@link Ehcache} instance
* @param registry a {@link MetricRegistry}
* @return an instrumented decorator for {@code cache}
* @see StatisticsGateway
*/
public static Ehcache instrument(MetricRegistry registry, final Ehcache cache) {
final String prefix = name(cache.getClass(), cache.getName());
registry.registerGauge(name(prefix, "hits"),
() -> cache.getStatistics().cacheHitCount());
registry.registerGauge(name(prefix, "in-memory-hits"),
() -> cache.getStatistics().localHeapHitCount());
registry.registerGauge(name(prefix, "off-heap-hits"),
() -> cache.getStatistics().localOffHeapHitCount());
registry.registerGauge(name(prefix, "on-disk-hits"),
() -> cache.getStatistics().localDiskHitCount());
registry.registerGauge(name(prefix, "misses"),
() -> cache.getStatistics().cacheMissCount());
registry.registerGauge(name(prefix, "in-memory-misses"),
() -> cache.getStatistics().localHeapMissCount());
registry.registerGauge(name(prefix, "off-heap-misses"),
() -> cache.getStatistics().localOffHeapMissCount());
registry.registerGauge(name(prefix, "on-disk-misses"),
() -> cache.getStatistics().localDiskMissCount());
registry.registerGauge(name(prefix, "objects"),
() -> cache.getStatistics().getSize());
registry.registerGauge(name(prefix, "in-memory-objects"),
() -> cache.getStatistics().getLocalHeapSize());
registry.registerGauge(name(prefix, "off-heap-objects"),
() -> cache.getStatistics().getLocalOffHeapSize());
registry.registerGauge(name(prefix, "on-disk-objects"),
() -> cache.getStatistics().getLocalDiskSize());
registry.registerGauge(name(prefix, "mean-get-time"),
() -> cache.getStatistics().cacheGetOperation().latency().average().value());
registry.registerGauge(name(prefix, "mean-search-time"),
() -> cache.getStatistics().cacheSearchOperation().latency().average().value());
registry.registerGauge(name(prefix, "eviction-count"),
() -> cache.getStatistics().cacheEvictionOperation().count().value());
registry.registerGauge(name(prefix, "searches-per-second"),
() -> cache.getStatistics().cacheSearchOperation().rate().value());
registry.registerGauge(name(prefix, "writer-queue-size"),
() -> cache.getStatistics().getWriterQueueLength());
return new InstrumentedEhcache(registry, cache);
}
private final Timer getTimer, putTimer;
private InstrumentedEhcache(MetricRegistry registry, Ehcache cache) {
super(cache);
this.getTimer = registry.timer(name(cache.getClass(), cache.getName(), "gets"));
this.putTimer = registry.timer(name(cache.getClass(), cache.getName(), "puts"));
}
@Override
public Element get(Object key) throws IllegalStateException, CacheException {
final Timer.Context ctx = getTimer.time();
try {
return underlyingCache.get(key);
} finally {
ctx.stop();
}
}
@Override
public Element get(Serializable key) throws IllegalStateException, CacheException {
final Timer.Context ctx = getTimer.time();
try {
return underlyingCache.get(key);
} finally {
ctx.stop();
}
}
@Override
public void put(Element element) throws IllegalArgumentException, IllegalStateException, CacheException {
final Timer.Context ctx = putTimer.time();
try {
underlyingCache.put(element);
} finally {
ctx.stop();
}
}
@Override
public void put(Element element, boolean doNotNotifyCacheReplicators) throws IllegalArgumentException, IllegalStateException, CacheException {
final Timer.Context ctx = putTimer.time();
try {
underlyingCache.put(element, doNotNotifyCacheReplicators);
} finally {
ctx.stop();
}
}
@Override
public Element putIfAbsent(Element element) throws NullPointerException {
final Timer.Context ctx = putTimer.time();
try {
return underlyingCache.putIfAbsent(element);
} finally {
ctx.stop();
}
}
}