Module com.github.benmanes.caffeine

Package com.github.benmanes.caffeine.cache.stats

Interface StatsCounter

All Known Implementing Classes:

ConcurrentStatsCounter

public interface StatsCounter

Accumulates statistics during the operation of a Cache for presentation by Cache.stats(). This is solely intended for consumption by Cache implementors.

Method Summary

Modifier and Type	Method	Description
static StatsCounter	disabledStatsCounter()	Returns an accumulator that does not record any cache events.
static StatsCounter	guardedStatsCounter(StatsCounter statsCounter)	Returns an accumulator that suppresses and logs any exception thrown by the delegate statsCounter.
void	recordEviction(@org.checkerframework.checker.index.qual.NonNegative int weight, RemovalCause cause)	Records the eviction of an entry from the cache.
void	recordHits(@org.checkerframework.checker.index.qual.NonNegative int count)	Records cache hits.
void	recordLoadFailure(@org.checkerframework.checker.index.qual.NonNegative long loadTime)	Records the failed load of a new entry.
void	recordLoadSuccess(@org.checkerframework.checker.index.qual.NonNegative long loadTime)	Records the successful load of a new entry.
void	recordMisses(@org.checkerframework.checker.index.qual.NonNegative int count)	Records cache misses.
CacheStats	snapshot()	Returns a snapshot of this counter's values.

Method Detail

recordHits

void recordHits(@org.checkerframework.checker.index.qual.NonNegative int count)

Records cache hits. This should be called when a cache request returns a cached value.

Parameters:

count - the number of hits to record

recordMisses

void recordMisses(@org.checkerframework.checker.index.qual.NonNegative int count)

Records cache misses. This should be called when a cache request returns a value that was not found in the cache. This method should be called by the loading thread, as well as by threads blocking on the load. Multiple concurrent calls to Cache lookup methods with the same key on an absent value should result in a single call to either recordLoadSuccess or recordLoadFailure and multiple calls to this method, despite all being served by the results of a single load operation.

Parameters:

count - the number of misses to record

recordLoadSuccess

void recordLoadSuccess(@org.checkerframework.checker.index.qual.NonNegative long loadTime)

Records the successful load of a new entry. This method should be called when a cache request causes an entry to be loaded (such as by Cache.get(K, java.util.function.Function<? super K, ? extends V>) or Map.computeIfAbsent(K, java.util.function.Function<? super K, ? extends V>)) and the loading completes successfully. In contrast to recordMisses(@org.checkerframework.checker.index.qual.NonNegative int), this method should only be called by the loading thread.

Parameters:

loadTime - the number of nanoseconds the cache spent computing or retrieving the new value

recordLoadFailure

void recordLoadFailure(@org.checkerframework.checker.index.qual.NonNegative long loadTime)

Records the failed load of a new entry. This method should be called when a cache request causes an entry to be loaded (such as by Cache.get(K, java.util.function.Function<? super K, ? extends V>) or Map.computeIfAbsent(K, java.util.function.Function<? super K, ? extends V>)), but an exception is thrown while loading the entry or the loading function returns null. In contrast to recordMisses(@org.checkerframework.checker.index.qual.NonNegative int), this method should only be called by the loading thread.

Parameters:

loadTime - the number of nanoseconds the cache spent computing or retrieving the new value prior to discovering the value doesn't exist or an exception being thrown

recordEviction

void recordEviction(@org.checkerframework.checker.index.qual.NonNegative int weight,
                    RemovalCause cause)

Records the eviction of an entry from the cache. This should only been called when an entry is evicted due to the cache's eviction strategy, and not as a result of manual invalidations.

Parameters:

weight - the weight of the evicted entry

cause - the reason for which the entry was removed

snapshot

CacheStats snapshot()

Returns a snapshot of this counter's values. Note that this may be an inconsistent view, as it may be interleaved with update operations.

Note: the values of the metrics are undefined in case of overflow (though it is guaranteed not to throw an exception). If you require specific handling, we recommend implementing your own stats collector.

Returns:

a snapshot of this counter's values

disabledStatsCounter

static StatsCounter disabledStatsCounter()

Returns an accumulator that does not record any cache events.

Returns:

an accumulator that does not record metrics

guardedStatsCounter

static StatsCounter guardedStatsCounter(StatsCounter statsCounter)

Returns an accumulator that suppresses and logs any exception thrown by the delegate statsCounter.

Parameters:

statsCounter - the accumulator to delegate to

Returns:

an accumulator that suppresses and logs any exception thrown by the delegate