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Add caffeine_cache_weighted_size gauge metric to caffeine-instrumentation
Signed-off-by: Jean Hominal <[email protected]>
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‎prometheus-metrics-instrumentation-caffeine/src/main/java/io/prometheus/metrics/instrumentation/caffeine/CacheMetricsCollector.java

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Original file line numberDiff line numberDiff line change
@@ -3,6 +3,7 @@
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import com.github.benmanes.caffeine.cache.AsyncCache;
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import com.github.benmanes.caffeine.cache.Cache;
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import com.github.benmanes.caffeine.cache.LoadingCache;
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import com.github.benmanes.caffeine.cache.Policy;
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import com.github.benmanes.caffeine.cache.stats.CacheStats;
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import io.prometheus.metrics.model.registry.MultiCollector;
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import io.prometheus.metrics.model.snapshots.CounterSnapshot;
@@ -14,6 +15,7 @@
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import java.util.Collections;
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import java.util.List;
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import java.util.Map;
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import java.util.Optional;
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import java.util.concurrent.ConcurrentHashMap;
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import java.util.concurrent.ConcurrentMap;
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@@ -63,6 +65,7 @@ public class CacheMetricsCollector implements MultiCollector {
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private static final String METRIC_NAME_CACHE_LOAD_FAILURE = "caffeine_cache_load_failure";
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private static final String METRIC_NAME_CACHE_LOADS = "caffeine_cache_loads";
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private static final String METRIC_NAME_CACHE_ESTIMATED_SIZE = "caffeine_cache_estimated_size";
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private static final String METRIC_NAME_CACHE_WEIGHTED_SIZE = "caffeine_cache_weighted_size";
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private static final String METRIC_NAME_CACHE_LOAD_DURATION_SECONDS =
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"caffeine_cache_load_duration_seconds";
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@@ -77,6 +80,7 @@ public class CacheMetricsCollector implements MultiCollector {
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METRIC_NAME_CACHE_LOAD_FAILURE,
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METRIC_NAME_CACHE_LOADS,
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METRIC_NAME_CACHE_ESTIMATED_SIZE,
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METRIC_NAME_CACHE_WEIGHTED_SIZE,
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METRIC_NAME_CACHE_LOAD_DURATION_SECONDS));
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protected final ConcurrentMap<String, Cache<?, ?>> children = new ConcurrentHashMap<>();
@@ -162,6 +166,11 @@ public MetricSnapshots collect() {
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final GaugeSnapshot.Builder cacheSize =
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GaugeSnapshot.builder().name(METRIC_NAME_CACHE_ESTIMATED_SIZE).help("Estimated cache size");
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final GaugeSnapshot.Builder cacheWeightedSize =
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GaugeSnapshot.builder()
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.name(METRIC_NAME_CACHE_WEIGHTED_SIZE)
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.help("Approximate accumulated weight of cache entries");
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final SummarySnapshot.Builder cacheLoadSummary =
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SummarySnapshot.builder()
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.name(METRIC_NAME_CACHE_LOAD_DURATION_SECONDS)
@@ -183,6 +192,15 @@ public MetricSnapshots collect() {
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// EvictionWeight metric is unavailable, newer version of Caffeine is needed.
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}
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final Optional<? extends Policy.Eviction<?, ?>> eviction = c.getValue().policy().eviction();
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if (eviction.isPresent() && eviction.get().weightedSize().isPresent()) {
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cacheWeightedSize.dataPoint(
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GaugeSnapshot.GaugeDataPointSnapshot.builder()
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.labels(labels)
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.value(eviction.get().weightedSize().getAsLong())
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.build());
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}
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cacheHitTotal.dataPoint(
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CounterSnapshot.CounterDataPointSnapshot.builder()
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.labels(labels)
@@ -244,6 +262,7 @@ public MetricSnapshots collect() {
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.metricSnapshot(cacheLoadFailure.build())
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.metricSnapshot(cacheLoadTotal.build())
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.metricSnapshot(cacheSize.build())
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.metricSnapshot(cacheWeightedSize.build())
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.metricSnapshot(cacheLoadSummary.build())
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.build();
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}

‎prometheus-metrics-instrumentation-caffeine/src/test/java/io/prometheus/metrics/instrumentation/caffeine/CacheMetricsCollectorTest.java

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@@ -78,6 +78,66 @@ public void cacheExposesMetricsForHitMissAndEviction() {
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assertThat(convertToOpenMetricsFormat(registry)).isEqualTo(expected);
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}
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@Test
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public void cacheExposesMetricsForHitMissAndEvictionForWeightedCache() {
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// Run cleanup in same thread, to remove async behavior with evictions
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final Cache<String, String> cache =
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Caffeine.newBuilder()
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.weigher((String k, String v) -> k.length() + v.length())
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.maximumWeight(35)
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.recordStats()
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.executor(Runnable::run)
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.build();
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final CacheMetricsCollector collector = new CacheMetricsCollector();
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collector.addCache("users", cache);
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final PrometheusRegistry registry = new PrometheusRegistry();
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registry.register(collector);
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cache.getIfPresent("user1");
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cache.getIfPresent("user1");
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cache.put("user1", "First User");
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cache.getIfPresent("user1");
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// Add to cache to trigger eviction.
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cache.put("user2", "Second User");
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cache.put("user3", "Third User");
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cache.put("user4", "Fourth User");
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assertCounterMetric(registry, "caffeine_cache_hit", "users", 1.0);
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assertCounterMetric(registry, "caffeine_cache_miss", "users", 2.0);
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assertCounterMetric(registry, "caffeine_cache_requests", "users", 3.0);
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assertCounterMetric(registry, "caffeine_cache_eviction", "users", 2.0);
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assertCounterMetric(registry, "caffeine_cache_eviction_weight", "users", 31.0);
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final String expected =
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"# TYPE caffeine_cache_estimated_size gauge\n"
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+ "# HELP caffeine_cache_estimated_size Estimated cache size\n"
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+ "caffeine_cache_estimated_size{cache=\"users\"} 2.0\n"
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+ "# TYPE caffeine_cache_eviction counter\n"
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+ "# HELP caffeine_cache_eviction Cache eviction totals, doesn't include manually removed entries\n"
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+ "caffeine_cache_eviction_total{cache=\"users\"} 2.0\n"
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+ "# TYPE caffeine_cache_eviction_weight counter\n"
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+ "# HELP caffeine_cache_eviction_weight Weight of evicted cache entries, doesn't include manually removed entries\n"
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+ "caffeine_cache_eviction_weight_total{cache=\"users\"} 31.0\n"
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+ "# TYPE caffeine_cache_hit counter\n"
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+ "# HELP caffeine_cache_hit Cache hit totals\n"
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+ "caffeine_cache_hit_total{cache=\"users\"} 1.0\n"
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+ "# TYPE caffeine_cache_miss counter\n"
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+ "# HELP caffeine_cache_miss Cache miss totals\n"
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+ "caffeine_cache_miss_total{cache=\"users\"} 2.0\n"
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+ "# TYPE caffeine_cache_requests counter\n"
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+ "# HELP caffeine_cache_requests Cache request totals, hits + misses\n"
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+ "caffeine_cache_requests_total{cache=\"users\"} 3.0\n"
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+ "# TYPE caffeine_cache_weighted_size gauge\n"
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+ "# HELP caffeine_cache_weighted_size Approximate accumulated weight of cache entries\n"
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+ "caffeine_cache_weighted_size{cache=\"users\"} 31.0\n"
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+ "# EOF\n";
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assertThat(convertToOpenMetricsFormat(registry)).isEqualTo(expected);
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}
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@SuppressWarnings("unchecked")
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@Test
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public void loadingCacheExposesMetricsForLoadsAndExceptions() throws Exception {

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