Use cache for base time unit strings

Closes gh-4352
micrometer-metrics · Dec 11, 2023 · a28324b · a28324b
1 parent 29e437b
commit a28324b
Showing 1 changed file with 7 additions and 1 deletion.
diff --git a/micrometer-core/src/main/java/io/micrometer/core/instrument/MeterRegistry.java b/micrometer-core/src/main/java/io/micrometer/core/instrument/MeterRegistry.java
@@ -36,6 +36,7 @@
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.function.*;
+import java.util.stream.Collectors;
 
 import static java.lang.String.format;
 import static java.util.Collections.emptyList;
@@ -279,8 +280,13 @@ protected String getConventionName(Meter.Id id) {
      */
     protected abstract DistributionStatisticConfig defaultHistogramConfig();
 
+    private static final EnumMap<TimeUnit, String> BASE_TIME_UNIT_STRING_CACHE = Arrays.stream(TimeUnit.values())
+        .collect(Collectors.toMap(Function.identity(), (timeUnit) -> timeUnit.toString().toLowerCase(), (l, r) -> {
+            throw new IllegalStateException("Duplicate keys should not exist.");
+        }, () -> new EnumMap<>(TimeUnit.class)));
+
     private String getBaseTimeUnitStr() {
-        return getBaseTimeUnit().toString().toLowerCase();
+        return BASE_TIME_UNIT_STRING_CACHE.get(getBaseTimeUnit());
     }
 
     /**