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Caffeine instrumentation: add weighted size metric (#1251)
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* Change caffeine_cache_eviction_weight from Gauge to Counter

Signed-off-by: Jean Hominal <[email protected]>

* Add caffeine_cache_weighted_size gauge metric to caffeine-instrumentation

Signed-off-by: Jean Hominal <[email protected]>

* Add Builder pattern for caffeine CacheMetricsCollector

Signed-off-by: Jean Hominal <[email protected]>

* Add option collectEvictionWeightAsCounter to collect caffeine_cache_eviction_weight as an incremental counter

Signed-off-by: Jean Hominal <[email protected]>

* Add option collectWeightedSize to enable collection of caffeine_cache_weighted_size

Signed-off-by: Jean Hominal <[email protected]>

---------

Signed-off-by: Jean Hominal <[email protected]>
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@jhominal
jhominal authored Jan 20, 2025
1 parent e05ca38 commit ec06ab9
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Showing 2 changed files with 247 additions and 17 deletions.
102 changes: 98 additions & 4 deletions ...e/src/main/java/io/prometheus/metrics/instrumentation/caffeine/CacheMetricsCollector.java
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@
import com.github.benmanes.caffeine.cache.AsyncCache;
import com.github.benmanes.caffeine.cache.Cache;
import com.github.benmanes.caffeine.cache.LoadingCache;
import com.github.benmanes.caffeine.cache.Policy;
import com.github.benmanes.caffeine.cache.stats.CacheStats;
import io.prometheus.metrics.model.registry.MultiCollector;
import io.prometheus.metrics.model.snapshots.CounterSnapshot;
Expand All @@ -14,8 +15,10 @@
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.Optional;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.stream.Collectors;

/**
* Collect metrics from Caffeine's com.github.benmanes.caffeine.cache.Cache.
Expand All @@ -25,7 +28,7 @@
* <pre>{@code
* // Note that `recordStats()` is required to gather non-zero statistics
* Cache<String, String> cache = Caffeine.newBuilder().recordStats().build();
* CacheMetricsCollector cacheMetrics = new CacheMetricsCollector();
* CacheMetricsCollector cacheMetrics = CacheMetricsCollector.builder().build();
* PrometheusRegistry.defaultRegistry.register(cacheMetrics);
* cacheMetrics.addCache("mycache", cache);
*
Expand Down Expand Up @@ -63,6 +66,7 @@ public class CacheMetricsCollector implements MultiCollector {
private static final String METRIC_NAME_CACHE_LOAD_FAILURE = "caffeine_cache_load_failure";
private static final String METRIC_NAME_CACHE_LOADS = "caffeine_cache_loads";
private static final String METRIC_NAME_CACHE_ESTIMATED_SIZE = "caffeine_cache_estimated_size";
private static final String METRIC_NAME_CACHE_WEIGHTED_SIZE = "caffeine_cache_weighted_size";
private static final String METRIC_NAME_CACHE_LOAD_DURATION_SECONDS =
"caffeine_cache_load_duration_seconds";

Expand All @@ -77,9 +81,38 @@ public class CacheMetricsCollector implements MultiCollector {
METRIC_NAME_CACHE_LOAD_FAILURE,
METRIC_NAME_CACHE_LOADS,
METRIC_NAME_CACHE_ESTIMATED_SIZE,
METRIC_NAME_CACHE_WEIGHTED_SIZE,
METRIC_NAME_CACHE_LOAD_DURATION_SECONDS));

protected final ConcurrentMap<String, Cache<?, ?>> children = new ConcurrentHashMap<>();
private final boolean collectEvictionWeightAsCounter;
private final boolean collectWeightedSize;

/**
* Instantiates a {@link CacheMetricsCollector}, with the legacy parameters.
*
* <p>The use of this constructor is discouraged, in favor of a Builder pattern {@link #builder()}
*
* <p>Note that the {@link #builder()} API has different default values than this deprecated
* constructor.
*/
@Deprecated
public CacheMetricsCollector() {
this(false, false);
}

/**
* Instantiate a {@link CacheMetricsCollector}
*
* @param collectEvictionWeightAsCounter If true, {@code caffeine_cache_eviction_weight} will be
* observed as an incrementing counter instead of a gauge.
* @param collectWeightedSize If true, {@code caffeine_cache_weighted_size} will be observed.
*/
protected CacheMetricsCollector(
boolean collectEvictionWeightAsCounter, boolean collectWeightedSize) {
this.collectEvictionWeightAsCounter = collectEvictionWeightAsCounter;
this.collectWeightedSize = collectWeightedSize;
}

/**
* Add or replace the cache with the given name.
Expand Down Expand Up @@ -146,10 +179,14 @@ public MetricSnapshots collect() {
.name(METRIC_NAME_CACHE_EVICTION)
.help("Cache eviction totals, doesn't include manually removed entries");

final GaugeSnapshot.Builder cacheEvictionWeight =
final CounterSnapshot.Builder cacheEvictionWeight =
CounterSnapshot.builder()
.name(METRIC_NAME_CACHE_EVICTION_WEIGHT)
.help("Weight of evicted cache entries, doesn't include manually removed entries");
final GaugeSnapshot.Builder cacheEvictionWeightLegacyGauge =
GaugeSnapshot.builder()
.name(METRIC_NAME_CACHE_EVICTION_WEIGHT)
.help("Cache eviction weight");
.help("Weight of evicted cache entries, doesn't include manually removed entries");

final CounterSnapshot.Builder cacheLoadFailure =
CounterSnapshot.builder().name(METRIC_NAME_CACHE_LOAD_FAILURE).help("Cache load failures");
Expand All @@ -162,6 +199,11 @@ public MetricSnapshots collect() {
final GaugeSnapshot.Builder cacheSize =
GaugeSnapshot.builder().name(METRIC_NAME_CACHE_ESTIMATED_SIZE).help("Estimated cache size");

final GaugeSnapshot.Builder cacheWeightedSize =
GaugeSnapshot.builder()
.name(METRIC_NAME_CACHE_WEIGHTED_SIZE)
.help("Approximate accumulated weight of cache entries");

final SummarySnapshot.Builder cacheLoadSummary =
SummarySnapshot.builder()
.name(METRIC_NAME_CACHE_LOAD_DURATION_SECONDS)
Expand All @@ -175,6 +217,11 @@ public MetricSnapshots collect() {

try {
cacheEvictionWeight.dataPoint(
CounterSnapshot.CounterDataPointSnapshot.builder()
.labels(labels)
.value(stats.evictionWeight())
.build());
cacheEvictionWeightLegacyGauge.dataPoint(
GaugeSnapshot.GaugeDataPointSnapshot.builder()
.labels(labels)
.value(stats.evictionWeight())
Expand All @@ -183,6 +230,17 @@ public MetricSnapshots collect() {
// EvictionWeight metric is unavailable, newer version of Caffeine is needed.
}

if (collectWeightedSize) {
final Optional<? extends Policy.Eviction<?, ?>> eviction = c.getValue().policy().eviction();
if (eviction.isPresent() && eviction.get().weightedSize().isPresent()) {
cacheWeightedSize.dataPoint(
GaugeSnapshot.GaugeDataPointSnapshot.builder()
.labels(labels)
.value(eviction.get().weightedSize().getAsLong())
.build());
}
}

cacheHitTotal.dataPoint(
CounterSnapshot.CounterDataPointSnapshot.builder()
.labels(labels)
Expand Down Expand Up @@ -235,12 +293,19 @@ public MetricSnapshots collect() {
}
}

if (collectWeightedSize) {
metricSnapshotsBuilder.metricSnapshot(cacheWeightedSize.build());
}

return metricSnapshotsBuilder
.metricSnapshot(cacheHitTotal.build())
.metricSnapshot(cacheMissTotal.build())
.metricSnapshot(cacheRequestsTotal.build())
.metricSnapshot(cacheEvictionTotal.build())
.metricSnapshot(cacheEvictionWeight.build())
.metricSnapshot(
collectEvictionWeightAsCounter
? cacheEvictionWeight.build()
: cacheEvictionWeightLegacyGauge.build())
.metricSnapshot(cacheLoadFailure.build())
.metricSnapshot(cacheLoadTotal.build())
.metricSnapshot(cacheSize.build())
Expand All @@ -250,6 +315,35 @@ public MetricSnapshots collect() {

@Override
public List<String> getPrometheusNames() {
if (!collectWeightedSize) {
return ALL_METRIC_NAMES.stream()
.filter(s -> !METRIC_NAME_CACHE_WEIGHTED_SIZE.equals(s))
.collect(Collectors.toList());
}
return ALL_METRIC_NAMES;
}

public static Builder builder() {
return new Builder();
}

public static class Builder {

private boolean collectEvictionWeightAsCounter = true;
private boolean collectWeightedSize = true;

public Builder collectEvictionWeightAsCounter(boolean collectEvictionWeightAsCounter) {
this.collectEvictionWeightAsCounter = collectEvictionWeightAsCounter;
return this;
}

public Builder collectWeightedSize(boolean collectWeightedSize) {
this.collectWeightedSize = collectWeightedSize;
return this;
}

public CacheMetricsCollector build() {
return new CacheMetricsCollector(collectEvictionWeightAsCounter, collectWeightedSize);
}
}
}
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