Java tutorial
/** * 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.metrics2.impl; import java.io.ByteArrayOutputStream; import java.io.PrintStream; import java.util.HashMap; import java.util.Iterator; import java.util.Locale; import java.util.Map; import java.util.regex.Matcher; import java.util.regex.Pattern; import org.apache.commons.configuration.Configuration; import org.apache.commons.configuration.ConfigurationException; import org.apache.commons.configuration.PropertiesConfiguration; import org.apache.commons.configuration.SubsetConfiguration; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apache.hadoop.metrics2.MetricsFilter; import org.apache.hadoop.metrics2.MetricsPlugin; import org.apache.hadoop.util.StringUtils; class MetricsConfig extends SubsetConfiguration { static final Log LOG = LogFactory.getLog(MetricsConfig.class); static final String DEFAULT_FILE_NAME = "hadoop-metrics2.properties"; static final String PREFIX_DEFAULT = "*."; static final String PERIOD_KEY = "period"; static final int PERIOD_DEFAULT = 10; // seconds static final String QUEUE_CAPACITY_KEY = "queue.capacity"; static final int QUEUE_CAPACITY_DEFAULT = 1; static final String RETRY_DELAY_KEY = "retry.delay"; static final int RETRY_DELAY_DEFAULT = 10; // seconds static final String RETRY_BACKOFF_KEY = "retry.backoff"; static final int RETRY_BACKOFF_DEFAULT = 2; // back off factor static final String RETRY_COUNT_KEY = "retry.count"; static final int RETRY_COUNT_DEFAULT = 1; static final String JMX_CACHE_TTL_KEY = "jmx.cache.ttl"; static final int JMX_CACHE_TTL_DEFAULT = 10000; // millis static final String CONTEXT_KEY = "context"; static final String NAME_KEY = "name"; static final String DESC_KEY = "description"; static final String SOURCE_KEY = "source"; static final String SINK_KEY = "sink"; static final String METRIC_FILTER_KEY = "metric.filter"; static final String RECORD_FILTER_KEY = "record.filter"; static final String SOURCE_FILTER_KEY = "source.filter"; static final Pattern INSTANCE_REGEX = Pattern.compile("([^.*]+)\\..+"); MetricsConfig(Configuration c, String prefix) { super(c, prefix.toLowerCase(Locale.US), "."); } static MetricsConfig create(String prefix) { return loadFirst(prefix, "hadoop-metrics2-" + prefix.toLowerCase(Locale.US) + ".properties", DEFAULT_FILE_NAME); } static MetricsConfig create(String prefix, String... fileNames) { return loadFirst(prefix, fileNames); } /** * Load configuration from a list of files until the first successful load * @param conf the configuration object * @param files the list of filenames to try * @return the configuration object */ static MetricsConfig loadFirst(String prefix, String... fileNames) { for (String fname : fileNames) { try { Configuration cf = new PropertiesConfiguration(fname).interpolatedConfiguration(); LOG.info("loaded properties from " + fname); return new MetricsConfig(cf, prefix); } catch (ConfigurationException e) { if (e.getMessage().startsWith("Cannot locate configuration")) { continue; } throw new MetricsConfigException(e); } } throw new MetricsConfigException("Cannot locate configuration: tried " + StringUtils.join(", ", fileNames)); } @Override public MetricsConfig subset(String prefix) { return new MetricsConfig(this, prefix); } /** * Return sub configs for instance specified in the config. * Assuming format specified as follows:<pre> * [type].[instance].[option] = [value]</pre> * Note, '*' is a special default instance, which is excluded in the result. * @param type of the instance * @return a map with [instance] as key and config object as value */ Map<String, MetricsConfig> getInstanceConfigs(String type) { HashMap<String, MetricsConfig> map = new HashMap<String, MetricsConfig>(); MetricsConfig sub = subset(type); for (String key : sub.keys()) { Matcher matcher = INSTANCE_REGEX.matcher(key); if (matcher.matches()) { String instance = matcher.group(1); if (!map.containsKey(instance)) { map.put(instance, sub.subset(instance)); } } } return map; } Iterable<String> keys() { return new Iterable<String>() { @SuppressWarnings("unchecked") public Iterator<String> iterator() { return (Iterator<String>) getKeys(); } }; } /** * Will poke parents for defaults * @param key to lookup * @return the value or null */ @Override public Object getProperty(String key) { Object value = super.getProperty(key); if (value == null) { LOG.debug("poking parent " + getParent().getClass().getSimpleName() + " for " + key); return getParent().getProperty(key.startsWith(PREFIX_DEFAULT) ? key : PREFIX_DEFAULT + key); } return value; } <T extends MetricsPlugin> T getPlugin(String name) { String classKey = name.isEmpty() ? "class" : name + ".class"; String pluginClassName = getString(classKey); if (pluginClassName == null || pluginClassName.isEmpty()) { return null; } try { Class<?> pluginClass = Class.forName(pluginClassName); @SuppressWarnings("unchecked") T plugin = (T) pluginClass.newInstance(); plugin.init(name.isEmpty() ? this : subset(name)); return plugin; } catch (Exception e) { throw new MetricsConfigException("Error creating plugin: " + pluginClassName, e); } } MetricsFilter getFilter(String prefix) { // don't create filter instances without out options if (subset(prefix).isEmpty()) return null; return (MetricsFilter) getPlugin(prefix); } @Override public String toString() { return toString(this); } String toString(Configuration c) { ByteArrayOutputStream buffer = new ByteArrayOutputStream(); PrintStream ps = new PrintStream(buffer); PropertiesConfiguration tmp = new PropertiesConfiguration(); tmp.copy(c); try { tmp.save(ps); } catch (Exception e) { throw new MetricsConfigException(e); } return buffer.toString(); } }