| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package org.apache.hadoop.metrics.spi; |
| |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.classification.InterfaceStability; |
| import org.apache.hadoop.metrics.ContextFactory; |
| import org.apache.hadoop.metrics.MetricsException; |
| |
| /** |
| * A null context which has a thread calling |
| * periodically when monitoring is started. This keeps the data sampled |
| * correctly. |
| * In all other respects, this is like the NULL context: No data is emitted. |
| * This is suitable for Monitoring systems like JMX which reads the metrics |
| * when someone reads the data from JMX. |
| * |
| * The default impl of start and stop monitoring: |
| * is the AbstractMetricsContext is good enough. |
| * |
| */ |
| @InterfaceAudience.Public |
| @InterfaceStability.Evolving |
| public class NullContextWithUpdateThread extends AbstractMetricsContext { |
| |
| private static final String PERIOD_PROPERTY = "period"; |
| |
| /** Creates a new instance of NullContextWithUpdateThread */ |
| @InterfaceAudience.Private |
| public NullContextWithUpdateThread() { |
| } |
| |
| @InterfaceAudience.Private |
| public void init(String contextName, ContextFactory factory) { |
| super.init(contextName, factory); |
| parseAndSetPeriod(PERIOD_PROPERTY); |
| } |
| |
| |
| /** |
| * Do-nothing version of emitRecord |
| */ |
| @InterfaceAudience.Private |
| protected void emitRecord(String contextName, String recordName, |
| OutputRecord outRec) |
| {} |
| |
| /** |
| * Do-nothing version of update |
| */ |
| @InterfaceAudience.Private |
| protected void update(MetricsRecordImpl record) { |
| } |
| |
| /** |
| * Do-nothing version of remove |
| */ |
| @InterfaceAudience.Private |
| protected void remove(MetricsRecordImpl record) { |
| } |
| } |