Add a method for timing non-throwing functions. (#1224)

metrics-core/src/main/java/com/codahale/metrics/Timer.java

@@ -2,6 +2,7 @@
 
 import java.util.concurrent.Callable;
 import java.util.concurrent.TimeUnit;
+import java.util.function.Supplier;
 
 /**
  * A timer metric which aggregates timing durations and provides duration statistics, plus
@@ -106,6 +107,24 @@ public <T> T time(Callable<T> event) throws Exception {
         }
     }
 
+    /**
+     * Times and records the duration of event. Should not throw exceptions, for that use the
+     * {@link #time(Callable)} method.
+     *
+     * @param event a {@link Supplier} whose {@link Supplier#get()} method implements a process
+     *              whose duration should be timed
+     * @param <T>   the type of the value returned by {@code event}
+     * @return the value returned by {@code event}
+     */
+    public <T> T timeSupplier(Supplier<T> event) {
+        final long startTime = clock.getTick();
+        try {
+            return event.get();
+        } finally {
+            update(clock.getTick() - startTime);
+        }
+    }
+
     /**
      * Times and records the duration of event.
      *