001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.juneau.rest.server.metrics;
018
019import java.time.*;
020
021/**
022 * Default {@link MetricsRecorder} implementation that drops every event on the floor.
023 *
024 * <p>
025 * Used whenever no consumer-provided {@code MetricsRecorder} bean is reachable from the
026 * {@code RestContext}'s bean store. Ensures the {@link MetricsRecorder} contract is always satisfied
027 * &mdash; the framework can call {@code record(...)} unconditionally without a null-check.
028 *
029 * <p>
030 * The implementation is a single static-field constant ({@link #INSTANCE}); the {@code record(...)}
031 * method does nothing, allocates nothing, and JIT-inlines to an empty method body, so the
032 * off-by-default path has no observable runtime cost.
033 *
034 * @since 10.0.0
035 */
036@SuppressWarnings({
037   "java:S6548" // Intentional process-wide no-op singleton; the Singleton pattern is required to satisfy the MetricsRecorder SPI contract with zero allocation.
038})
039public final class NoOpMetricsRecorder implements MetricsRecorder {
040
041   /** Process-wide singleton instance. */
042   public static final NoOpMetricsRecorder INSTANCE = new NoOpMetricsRecorder();
043
044   private NoOpMetricsRecorder() {}
045
046   @Override /* MetricsRecorder */
047   @SuppressWarnings({
048      "java:S6213" // 'record' is the established MetricsRecorder SPI method name; renaming would break the public API.
049   })
050   public void record(String opName, String httpMethod, String uriTemplate, int statusCode, Duration elapsed, Throwable error, String metricName, String metricTags) {
051      // Intentionally empty — the default off-by-default behaviour is to drop every event.
052   }
053}