Class AbstractCache.SimpleStatsCounter

java.lang.Object

com.google.common.cache.AbstractCache.SimpleStatsCounter

All Implemented Interfaces:

AbstractCache.StatsCounter

Enclosing class:

AbstractCache<K,V>

public static final class AbstractCache.SimpleStatsCounter
extends Object
implements AbstractCache.StatsCounter

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

Each counter is updated atomically, but the counters are not updated together: For performance, this class does not lock, so a snapshot() taken concurrently with updates may reflect only part of an update. For example, it may include the increment of the load-success count from a call to recordLoadSuccess(long) but not the corresponding load time. As a result, values derived from a snapshot, like CacheStats.averageLoadPenalty(), may be briefly inconsistent.

Since:

10.0

Author:

Charles Fry

Constructor Summary

Constructors

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

Method Summary

Modifier and Type	Method	Description
void	incrementBy(AbstractCache.StatsCounter other)	Increments all counters by the values in other.
void	recordEviction()	Records the eviction of an entry from the cache.
void	recordHits(int count)	Records cache hits.
void	recordLoadException(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.

Methods inherited from class Object

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

Constructor Details

SimpleStatsCounter

public SimpleStatsCounter()

Constructs an instance with all counts initialized to zero.

Method Details

recordHits

public void recordHits(int count)

Description copied from interface: AbstractCache.StatsCounter

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

Specified by:

recordHits in interface AbstractCache.StatsCounter

Parameters:

count - the number of hits to record

Since:

11.0

recordMisses

public void recordMisses(int count)

Description copied from interface: AbstractCache.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 recordLoadException and multiple calls to this method, despite all being served by the results of a single load operation.

Specified by:

recordMisses in interface AbstractCache.StatsCounter

Parameters:

count - the number of misses to record

Since:

11.0

recordLoadSuccess

public void recordLoadSuccess(long loadTime)

Description copied from interface: AbstractCache.StatsCounter

Records the successful load of a new entry. This should be called when a cache request causes an entry to be loaded, and the loading completes successfully. In contrast to AbstractCache.StatsCounter.recordMisses(int), this method should only be called by the loading thread.

Specified by:

recordLoadSuccess in interface AbstractCache.StatsCounter

Parameters:

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

recordLoadException

public void recordLoadException(long loadTime)

Description copied from interface: AbstractCache.StatsCounter

Records the failed load of a new entry. This should be called when a cache request causes an entry to be loaded, but an exception is thrown while loading the entry. In contrast to AbstractCache.StatsCounter.recordMisses(int), this method should only be called by the loading thread.

Specified by:

recordLoadException in interface AbstractCache.StatsCounter

Parameters:

loadTime - the number of nanoseconds the cache spent computing or retrieving the new value prior to an exception being thrown

recordEviction

public void recordEviction()

Description copied from interface: AbstractCache.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 AbstractCache.StatsCounter

snapshot

public CacheStats snapshot()

Description copied from interface: AbstractCache.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.

Specified by:

snapshot in interface AbstractCache.StatsCounter

incrementBy

public void incrementBy(AbstractCache.StatsCounter other)

Increments all counters by the values in other.