Hack Timer UX without copying the Builder

micrometer-core/src/main/java/io/micrometer/core/instrument/Timer.java

@@ -27,11 +27,7 @@
 import java.util.Arrays;
 import java.util.concurrent.Callable;
 import java.util.concurrent.TimeUnit;
-import java.util.function.BooleanSupplier;
-import java.util.function.DoubleSupplier;
-import java.util.function.IntSupplier;
-import java.util.function.LongSupplier;
-import java.util.function.Supplier;
+import java.util.function.*;
 
 /**
  * Timer intended to track of a large number of short running events. Example would be
@@ -430,6 +426,10 @@ public Builder description(String description) {
             return super.description(description);
         }
 
+        public Function<Tags, Timer> with(MeterRegistry registry) {
+            return extraTags -> register(registry, tags.and(extraTags));
+        }
+
         /**
          * Add the timer to a single registry, or return an existing timer in that
          * registry. The returned timer will be unique for each registry, but each
@@ -439,6 +439,10 @@ public Builder description(String description) {
          * @return A new or existing timer.
          */
         public Timer register(MeterRegistry registry) {
+            return register(registry, tags);
+        }
+
+        private Timer register(MeterRegistry registry, Tags tags) {
             // the base unit for a timer will be determined by the monitoring system
             // implementation
             return registry.timer(new Meter.Id(name, tags, null, description, Type.TIMER),

samples/micrometer-samples-core/src/main/java/io/micrometer/core/samples/Demo.java

@@ -0,0 +1,33 @@
+package io.micrometer.core.samples;
+
+import io.micrometer.core.instrument.Tags;
+import io.micrometer.core.instrument.Timer;
+import io.micrometer.prometheus.PrometheusConfig;
+import io.micrometer.prometheus.PrometheusMeterRegistry;
+
+import java.time.Duration;
+import java.util.function.Function;
+
+public class Demo {
+
+    private static final PrometheusMeterRegistry registry = new PrometheusMeterRegistry(PrometheusConfig.DEFAULT);
+
+    private static final Function<Tags, Timer> timerFactory = Timer.builder("cache.initialization.latency")
+        .description("Time initialize cache from database")
+        .tag("static", "abc")
+        .publishPercentiles(0.99, 0.999)
+        .publishPercentileHistogram()
+        .minimumExpectedValue(Duration.ofSeconds(10))
+        .maximumExpectedValue(Duration.ofSeconds(600))
+        .with(registry);
+
+    public static void main(String[] args) {
+        doSomething("test");
+    }
+
+    private static void doSomething(String cacheName) {
+        timerFactory.apply(Tags.of("cacheName", cacheName)).record(Duration.ofMillis(100));
+        System.out.println(registry.scrape());
+    }
+
+}