Class CacheMetricsCollector

Object

CacheMetricsCollector

All Implemented Interfaces:

MultiCollector

public class CacheMetricsCollector
extends Object
implements MultiCollector

Collect metrics from Caffeine's com.github.benmanes.caffeine.cache.Cache.

// Note that `recordStats()` is required to gather non-zero statistics
Cache<String, String> cache = Caffeine.newBuilder().recordStats().build();
CacheMetricsCollector cacheMetrics = CacheMetricsCollector.builder().build();
PrometheusRegistry.defaultRegistry.register(cacheMetrics);
cacheMetrics.addCache("mycache", cache);

Exposed metrics are labeled with the provided cache name.

With the example above, sample metric names would be:

    caffeine_cache_hit_total{cache="mycache"} 10.0
    caffeine_cache_miss_total{cache="mycache"} 3.0
    caffeine_cache_requests_total{cache="mycache"} 13.0
    caffeine_cache_eviction_total{cache="mycache"} 1.0
    caffeine_cache_estimated_size{cache="mycache"} 5.0

Additionally, if the cache includes a loader, the following metrics would be provided:

    caffeine_cache_load_failure_total{cache="mycache"} 2.0
    caffeine_cache_loads_total{cache="mycache"} 7.0
    caffeine_cache_load_duration_seconds_count{cache="mycache"} 7.0
    caffeine_cache_load_duration_seconds_sum{cache="mycache"} 0.0034

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	CacheMetricsCollector.Builder

Constructor Summary

Constructors

Constructor	Description
CacheMetricsCollector()	Deprecated.

Method Summary

Modifier and Type	Method	Description
void	addCache(String cacheName, AsyncCache<?,?> cache)	Add or replace the cache with the given name.
void	addCache(String cacheName, Cache<?,?> cache)	Add or replace the cache with the given name.
static CacheMetricsCollector.Builder	builder()
void	clear()	Remove all caches.
MetricSnapshots	collect()	Called when the Prometheus server scrapes metrics.
List<String>	getPrometheusNames()	This is called in two places: During registration to check if a metric with that name already exists.
Cache<?,?>	removeCache(String cacheName)	Remove the cache with the given name.

Methods inherited from class Object

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

Methods inherited from interface MultiCollector

collect, collect, collect

Constructor Details

CacheMetricsCollector

@Deprecated
public CacheMetricsCollector()

Deprecated.

Instantiates a CacheMetricsCollector, with the legacy parameters.

The use of this constructor is discouraged, in favor of a Builder pattern builder()

Note that the builder() API has different default values than this deprecated constructor.

Method Details

addCache

public void addCache(String cacheName,
 Cache<?,?> cache)

Add or replace the cache with the given name.

Any references any previous cache with this name is invalidated.

Parameters:

cacheName - The name of the cache, will be the metrics label value

cache - The cache being monitored

addCache

public void addCache(String cacheName,
 AsyncCache<?,?> cache)

Add or replace the cache with the given name.

Any references any previous cache with this name is invalidated.

Parameters:

cacheName - The name of the cache, will be the metrics label value

cache - The cache being monitored

removeCache

public Cache<?,?> removeCache(String cacheName)

Remove the cache with the given name.

Any references to the cache are invalidated.

Parameters:

cacheName - cache to be removed

clear

public void clear()

Remove all caches.

Any references to all caches are invalidated.

collect

public MetricSnapshots collect()

Description copied from interface: MultiCollector

Called when the Prometheus server scrapes metrics.

Specified by:

collect in interface MultiCollector

getPrometheusNames

public List<String> getPrometheusNames()

Description copied from interface: MultiCollector

This is called in two places:

1. During registration to check if a metric with that name already exists.
2. During scrape to check if the collector can be skipped because a name filter is present and all names are excluded.

Returning an empty list means checks are omitted (registration metric always succeeds), and the collector is always scraped (if a name filter is present and all names are excluded the result is dropped).

If your collector returns a constant list of metrics that have names that do not change at runtime it is a good idea to overwrite this and return the names.

Specified by:

getPrometheusNames in interface MultiCollector

builder

public static CacheMetricsCollector.Builder builder()