Add option collectWeightedSize to enable collection of caffeine_cache_weighted_size

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

Author: jhominal

prometheus-metrics-instrumentation-caffeine/src/main/java/io/prometheus/metrics/instrumentation/caffeine/CacheMetricsCollector.java

@@ -18,6 +18,7 @@
 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.
@@ -85,6 +86,7 @@ public class CacheMetricsCollector implements MultiCollector {
 
   protected final ConcurrentMap<String, Cache<?, ?>> children = new ConcurrentHashMap<>();
   private final boolean collectEvictionWeightAsCounter;
+  private final boolean collectWeightedSize;
 
   /**
    * Instantiates a {@link CacheMetricsCollector}, with the legacy parameters.
@@ -96,17 +98,20 @@ public class CacheMetricsCollector implements MultiCollector {
    */
   @Deprecated
   public CacheMetricsCollector() {
-    this(false);
+    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) {
+  protected CacheMetricsCollector(
+      boolean collectEvictionWeightAsCounter, boolean collectWeightedSize) {
     this.collectEvictionWeightAsCounter = collectEvictionWeightAsCounter;
+    this.collectWeightedSize = collectWeightedSize;
   }
 
   /**
@@ -225,13 +230,15 @@ public MetricSnapshots collect() {
         // EvictionWeight metric is unavailable, newer version of Caffeine is needed.
       }
 
-      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());
+      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(
@@ -286,6 +293,10 @@ public MetricSnapshots collect() {
       }
     }
 
+    if (collectWeightedSize) {
+      metricSnapshotsBuilder.metricSnapshot(cacheWeightedSize.build());
+    }
+
     return metricSnapshotsBuilder
         .metricSnapshot(cacheHitTotal.build())
         .metricSnapshot(cacheMissTotal.build())
@@ -298,13 +309,17 @@ public MetricSnapshots collect() {
         .metricSnapshot(cacheLoadFailure.build())
         .metricSnapshot(cacheLoadTotal.build())
         .metricSnapshot(cacheSize.build())
-        .metricSnapshot(cacheWeightedSize.build())
         .metricSnapshot(cacheLoadSummary.build())
         .build();
   }
 
   @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;
   }
 
@@ -315,14 +330,20 @@ public static Builder 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);
+      return new CacheMetricsCollector(collectEvictionWeightAsCounter, collectWeightedSize);
     }
   }
 }

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

@@ -30,13 +30,17 @@
 class CacheMetricsCollectorTest {
   // This enum was added to simplify test parametrization on argument options.
   public enum Options {
-    LEGACY(false),
-    COLLECT_EVICTION_WEIGHT_AS_COUNTER(true);
+    LEGACY(false, false),
+    COLLECT_EVICTION_WEIGHT_AS_COUNTER(true, false),
+    COLLECT_WEIGHTED_SIZE(false, true),
+    BUILDER_DEFAULT(true, true);
 
     private final boolean collectEvictionWeightAsCounter;
+    private final boolean collectWeightedSize;
 
-    Options(boolean collectEvictionWeightAsCounter) {
+    Options(boolean collectEvictionWeightAsCounter, boolean collectWeightedSize) {
       this.collectEvictionWeightAsCounter = collectEvictionWeightAsCounter;
+      this.collectWeightedSize = collectWeightedSize;
     }
   }
 
@@ -50,6 +54,7 @@ public void cacheExposesMetricsForHitMissAndEviction(Options options) {
     final CacheMetricsCollector collector =
         CacheMetricsCollector.builder()
             .collectEvictionWeightAsCounter(options.collectEvictionWeightAsCounter)
+            .collectWeightedSize(options.collectWeightedSize)
             .build();
     collector.addCache("users", cache);
 
@@ -122,6 +127,7 @@ public void weightedCacheExposesMetricsForHitMissAndEvictionWeightedSize(Options
     final CacheMetricsCollector collector =
         CacheMetricsCollector.builder()
             .collectEvictionWeightAsCounter(options.collectEvictionWeightAsCounter)
+            .collectWeightedSize(options.collectWeightedSize)
             .build();
     collector.addCache("users", cache);
 
@@ -156,6 +162,15 @@ public void weightedCacheExposesMetricsForHitMissAndEvictionWeightedSize(Options
               + "# HELP caffeine_cache_eviction_weight Weight of evicted cache entries, doesn't include manually removed entries\n"
               + "caffeine_cache_eviction_weight{cache=\"users\"} 31.0\n";
     }
+    String openMetricWeightedSizeExpectedText;
+    if (options.collectWeightedSize) {
+      openMetricWeightedSizeExpectedText =
+          "# TYPE caffeine_cache_weighted_size gauge\n"
+              + "# HELP caffeine_cache_weighted_size Approximate accumulated weight of cache entries\n"
+              + "caffeine_cache_weighted_size{cache=\"users\"} 31.0\n";
+    } else {
+      openMetricWeightedSizeExpectedText = "";
+    }
 
     final String expected =
         "# TYPE caffeine_cache_estimated_size gauge\n"
@@ -174,9 +189,7 @@ public void weightedCacheExposesMetricsForHitMissAndEvictionWeightedSize(Options
             + "# TYPE caffeine_cache_requests counter\n"
             + "# HELP caffeine_cache_requests Cache request totals, hits + misses\n"
             + "caffeine_cache_requests_total{cache=\"users\"} 3.0\n"
-            + "# TYPE caffeine_cache_weighted_size gauge\n"
-            + "# HELP caffeine_cache_weighted_size Approximate accumulated weight of cache entries\n"
-            + "caffeine_cache_weighted_size{cache=\"users\"} 31.0\n"
+            + openMetricWeightedSizeExpectedText
             + "# EOF\n";
 
     assertThat(convertToOpenMetricsFormat(registry)).isEqualTo(expected);
@@ -228,6 +241,7 @@ public void getPrometheusNamesHasSameSizeAsMetricSizeWhenScraping(Options option
     final CacheMetricsCollector collector =
         CacheMetricsCollector.builder()
             .collectEvictionWeightAsCounter(options.collectEvictionWeightAsCounter)
+            .collectWeightedSize(options.collectWeightedSize)
             .build();
 
     final PrometheusRegistry registry = new PrometheusRegistry();
@@ -245,6 +259,7 @@ public void collectedMetricNamesAreKnownPrometheusNames(Options options) {
     final CacheMetricsCollector collector =
         CacheMetricsCollector.builder()
             .collectEvictionWeightAsCounter(options.collectEvictionWeightAsCounter)
+            .collectWeightedSize(options.collectWeightedSize)
             .build();
 
     final PrometheusRegistry registry = new PrometheusRegistry();