Module com.github.benmanes.caffeine

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

Class ConcurrentStatsCounter

java.lang.Object

com.github.benmanes.caffeine.cache.stats.ConcurrentStatsCounter

All Implemented Interfaces:

StatsCounter

public final class ConcurrentStatsCounter
extends Object
implements StatsCounter

A thread-safe StatsCounter implementation for use by Cache implementors.

Constructor Summary

Constructors

Constructor	Description
ConcurrentStatsCounter()	Constructs an instance with all counts initialized to zero.

Method Summary

Modifier and Type	Method	Description
void	incrementBy(StatsCounter other)	Increments all counters by the values in other.
void	recordEviction(int weight, RemovalCause cause)	Records the eviction of an entry from the cache.
void	recordHits(int count)	Records cache hits.
void	recordLoadFailure(long loadTime)	Records the failed load of a new entry.
void	recordLoadSuccess(long loadTime)	Records the successful load of a new entry.
void	recordMisses(int count)	Records cache misses.
CacheStats	snapshot()	Returns a snapshot of this counter's values.
String	toString()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

ConcurrentStatsCounter

public ConcurrentStatsCounter()

Constructs an instance with all counts initialized to zero.

Method Detail

recordHits

public void recordHits(int count)

Description copied from interface: StatsCounter

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

Specified by:

recordHits in interface StatsCounter

Parameters:

count - the number of hits to record

recordMisses

public void recordMisses(int count)

Description copied from interface: StatsCounter

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.

Specified by:

recordMisses in interface StatsCounter

Parameters:

count - the number of misses to record

recordLoadSuccess

public void recordLoadSuccess(long loadTime)

Description copied from interface: StatsCounter

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 StatsCounter.recordMisses(@org.checkerframework.checker.index.qual.NonNegative int), this method should only be called by the loading thread.

Specified by:

recordLoadSuccess in interface StatsCounter

Parameters:

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

recordLoadFailure

public void recordLoadFailure(long loadTime)

Description copied from interface: StatsCounter

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 StatsCounter.recordMisses(@org.checkerframework.checker.index.qual.NonNegative int), this method should only be called by the loading thread.

Specified by:

recordLoadFailure in interface StatsCounter

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

public void recordEviction(int weight,
                           RemovalCause cause)

Description copied from interface: StatsCounter

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.

Specified by:

recordEviction in interface StatsCounter

Parameters:

weight - the weight of the evicted entry

cause - the reason for which the entry was removed

snapshot

public CacheStats snapshot()

Description copied from interface: StatsCounter

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.

Specified by:

snapshot in interface StatsCounter

Returns:

a snapshot of this counter's values

incrementBy

public void incrementBy(StatsCounter other)

Increments all counters by the values in other.

Parameters:

other - the counter to increment from

toString

public String toString()

Overrides:

toString in class Object