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.net.URL; import java.net.URLClassLoader; import static java.security.AccessController.*; import java.security.PrivilegedAction; import java.util.Iterator; import java.util.Locale; import java.util.Map; import java.util.regex.Matcher; import java.util.regex.Pattern; import com.google.common.base.Joiner; import com.google.common.base.Splitter; import com.google.common.collect.Iterables; import com.google.common.collect.Maps; 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.metrics2.filter.GlobFilter; import org.apache.hadoop.util.StringUtils; /** * Metrics configuration for MetricsSystemImpl */ 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 // For testing, this will have the priority. static final String PERIOD_MILLIS_KEY = "periodMillis"; 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 String START_MBEANS_KEY = "source.start_mbeans"; static final String PLUGIN_URLS_KEY = "plugin.urls"; 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("([^.*]+)\\..+"); static final Splitter SPLITTER = Splitter.on(',').trimResults(); private ClassLoader pluginLoader; MetricsConfig(Configuration c, String prefix) { super(c, StringUtils.toLowerCase(prefix), "."); } static MetricsConfig create(String prefix) { return loadFirst(prefix, "hadoop-metrics2-" + StringUtils.toLowerCase(prefix) + ".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); LOG.debug(toString(cf)); MetricsConfig mc = new MetricsConfig(cf, prefix); LOG.debug(mc); return mc; } catch (ConfigurationException e) { if (e.getMessage().startsWith("Cannot locate configuration")) { continue; } throw new MetricsConfigException(e); } } LOG.warn("Cannot locate configuration: tried " + Joiner.on(",").join(fileNames)); // default to an empty configuration return new MetricsConfig(new PropertiesConfiguration(), prefix); } @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) { Map<String, MetricsConfig> map = Maps.newHashMap(); 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") @Override 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) { if (LOG.isDebugEnabled()) { LOG.debug("poking parent '" + getParent().getClass().getSimpleName() + "' for key: " + key); } return getParent().getProperty(key.startsWith(PREFIX_DEFAULT) ? key : PREFIX_DEFAULT + key); } if (LOG.isDebugEnabled()) { LOG.debug("returning '" + value + "' for key: " + key); } return value; } <T extends MetricsPlugin> T getPlugin(String name) { String clsName = getClassName(name); if (clsName == null) return null; try { Class<?> cls = Class.forName(clsName, true, getPluginLoader()); @SuppressWarnings("unchecked") T plugin = (T) cls.newInstance(); plugin.init(name.isEmpty() ? this : subset(name)); return plugin; } catch (Exception e) { throw new MetricsConfigException("Error creating plugin: " + clsName, e); } } String getClassName(String prefix) { String classKey = prefix.isEmpty() ? "class" : prefix + ".class"; String clsName = getString(classKey); LOG.debug(clsName); if (clsName == null || clsName.isEmpty()) { return null; } return clsName; } ClassLoader getPluginLoader() { if (pluginLoader != null) return pluginLoader; final ClassLoader defaultLoader = getClass().getClassLoader(); Object purls = super.getProperty(PLUGIN_URLS_KEY); if (purls == null) return defaultLoader; Iterable<String> jars = SPLITTER.split((String) purls); int len = Iterables.size(jars); if (len > 0) { final URL[] urls = new URL[len]; try { int i = 0; for (String jar : jars) { LOG.debug(jar); urls[i++] = new URL(jar); } } catch (Exception e) { throw new MetricsConfigException(e); } if (LOG.isDebugEnabled()) { LOG.debug("using plugin jars: " + Iterables.toString(jars)); } pluginLoader = doPrivileged(new PrivilegedAction<ClassLoader>() { @Override public ClassLoader run() { return new URLClassLoader(urls, defaultLoader); } }); return pluginLoader; } if (parent instanceof MetricsConfig) { return ((MetricsConfig) parent).getPluginLoader(); } return defaultLoader; } @Override public void clear() { super.clear(); // pluginLoader.close(); // jdk7 is saner } MetricsFilter getFilter(String prefix) { // don't create filter instances without out options MetricsConfig conf = subset(prefix); if (conf.isEmpty()) return null; MetricsFilter filter = getPlugin(prefix); if (filter != null) return filter; // glob filter is assumed if pattern is specified but class is not. filter = new GlobFilter(); filter.init(conf); return filter; } @Override public String toString() { return toString(this); } static String toString(Configuration c) { ByteArrayOutputStream buffer = new ByteArrayOutputStream(); try { PrintStream ps = new PrintStream(buffer, false, "UTF-8"); PropertiesConfiguration tmp = new PropertiesConfiguration(); tmp.copy(c); tmp.save(ps); return buffer.toString("UTF-8"); } catch (Exception e) { throw new MetricsConfigException(e); } } }