Restore percentile and bucket data to JSON metrics output (#7849)

Author: tjquinno

webserver/observe/metrics/src/main/java/io/helidon/webserver/observe/metrics/JsonFormatter.java

@@ -22,6 +22,7 @@
 import java.util.HashSet;
 import java.util.Iterator;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Optional;
 import java.util.Set;
@@ -43,6 +44,7 @@
 import io.helidon.metrics.api.DistributionSummary;
 import io.helidon.metrics.api.FunctionalCounter;
 import io.helidon.metrics.api.Gauge;
+import io.helidon.metrics.api.HistogramSnapshot;
 import io.helidon.metrics.api.Meter;
 import io.helidon.metrics.api.MeterRegistry;
 import io.helidon.metrics.api.MeterRegistryFormatter;
@@ -451,14 +453,16 @@ protected void apply(JsonObjectBuilder builder) {
                         sameNameBuilder.add(valueId("count", childID), typedChild.count());
                     } else if (child instanceof DistributionSummary typedChild) {
                         sameNameBuilder.add(valueId("count", childID), typedChild.count());
-                        sameNameBuilder.add(valueId("max", childID), typedChild.snapshot().max());
-                        sameNameBuilder.add(valueId("mean", childID), typedChild.snapshot().mean());
+                        sameNameBuilder.add(valueId("max", childID), typedChild.max());
+                        sameNameBuilder.add(valueId("mean", childID), typedChild.mean());
                         sameNameBuilder.add(valueId("total", childID), typedChild.totalAmount());
+                        addDetails(typedChild.snapshot(), childID, null);
                     } else if (child instanceof Timer typedChild) {
                         sameNameBuilder.add(valueId("count", childID), typedChild.count());
-                        sameNameBuilder.add(valueId("elapsedTime", childID), typedChild.totalTime(TimeUnit.SECONDS));
                         sameNameBuilder.add(valueId("max", childID), typedChild.max(TimeUnit.SECONDS));
                         sameNameBuilder.add(valueId("mean", childID), typedChild.mean(TimeUnit.SECONDS));
+                        sameNameBuilder.add(valueId("elapsedTime", childID), typedChild.totalTime(TimeUnit.SECONDS));
+                        addDetails(typedChild.snapshot(), childID, timeUnit(typedChild));
                     } else if (child instanceof FunctionalCounter typedChild) {
                         sameNameBuilder.add(valueId("count", childID), typedChild.count());
                     } else if (child instanceof Gauge typedChild) {
@@ -471,6 +475,42 @@ protected void apply(JsonObjectBuilder builder) {
                 builder.add(meterId.name(), sameNameBuilder);
             }
 
+            private void addDetails(HistogramSnapshot snapshot, Meter.Id childId, TimeUnit timeUnit) {
+                snapshot.percentileValues().forEach(vap ->
+                                                            sameNameBuilder
+                                                                    .add(valueId(percentileName(vap.percentile()),
+                                                                                 childId),
+                                                                         timeUnit != null
+                                                                                 ? vap.value(timeUnit)
+                                                                                 : vap.value()));
+                snapshot.histogramCounts().forEach(bucket ->
+                                                           sameNameBuilder
+                                                                   .add(valueId(bucketName(timeUnit != null
+                                                                                                   ? bucket.boundary(timeUnit)
+                                                                                                   : bucket.boundary()),
+                                                                                childId),
+                                                                        bucket.count()));
+            }
+
+            private static String percentileName(double percentile) {
+                return "p" + percentile;
+            }
+
+            private static String bucketName(double boundary) {
+                return "b" + boundary;
+            }
+
+            private static TimeUnit timeUnit(Timer timer) {
+                if (timer.baseUnit().isPresent()) {
+                    try {
+                        return TimeUnit.valueOf(timer.baseUnit().get().toUpperCase(Locale.getDefault()));
+                    } catch (IllegalArgumentException ex) {
+                        return TimeUnit.SECONDS;
+                    }
+                }
+                return TimeUnit.SECONDS;
+            }
+
             private static String valueId(String valueName, Meter.Id meterId) {
                 return valueName + tagsPortion(meterId);
             }