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.apache98.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.apache98.hadoop.hbase; import java.io.IOException; import java.lang.reflect.InvocationTargetException; import java.lang.reflect.Method; import java.util.Map.Entry; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apache98.hadoop.conf.Configuration; import org.apache98.hadoop.hbase.classification.InterfaceAudience; import org.apache98.hadoop.hbase.classification.InterfaceStability; import org.apache98.hadoop.hbase.util.VersionInfo; /** * Adds HBase configuration files to a Configuration */ @InterfaceAudience.Public @InterfaceStability.Stable public class HBaseConfiguration extends Configuration { private static final Log LOG = LogFactory.getLog(HBaseConfiguration.class); // a constant to convert a fraction to a percentage private static final int CONVERT_TO_PERCENTAGE = 100; public static Configuration addHbaseResources(Configuration conf) { conf.addResource("hbase-default98.xml"); conf.addResource("hbase-site98.xml"); checkDefaultsVersion(conf); checkForClusterFreeMemoryLimit(conf); return conf; } /** * Creates a Configuration with HBase resources * * @return a Configuration with HBase resources */ public static Configuration create() { Configuration conf = new Configuration(); return addHbaseResources(conf); } /** * @param that * Configuration to clone. * @return a Configuration created with the hbase-*.xml files plus * the given configuration. */ public static Configuration create(final Configuration that) { Configuration conf = create(); merge(conf, that); return conf; } /** * Get the value of the <code>name</code> property as an <code>int</code>, possibly * referring to the deprecated name of the configuration property. * If no such property exists, the provided default value is returned, * or if the specified value is not a valid <code>int</code>, * then an error is thrown. * * @param name * property name. * @param deprecatedName * a deprecatedName for the property to use * if non-deprecated name is not used * @param defaultValue * default value. * @throws NumberFormatException * when the value is invalid * @return property value as an <code>int</code>, * or <code>defaultValue</code>. */ // TODO: developer note: This duplicates the functionality of deprecated // property support in Configuration in Hadoop 2. But since Hadoop-1 does not // contain these changes, we will do our own as usual. Replace these when H2 is default. public static int getInt(Configuration conf, String name, String deprecatedName, int defaultValue) { if (conf.get(deprecatedName) != null) { LOG.warn( String.format("Config option \"%s\" is deprecated. Instead, use \"%s\"", deprecatedName, name)); return conf.getInt(deprecatedName, defaultValue); } else { return conf.getInt(name, defaultValue); } } /** * Get the password from the Configuration instance using the * getPassword method if it exists. If not, then fall back to the * general get method for configuration elements. * * @param conf * configuration instance for accessing the passwords * @param alias * the name of the password element * @param defPass * the default password * @return String password or default password * @throws IOException */ public static String getPassword(Configuration conf, String alias, String defPass) throws IOException { String passwd = null; try { Method m = Configuration.class.getMethod("getPassword", String.class); char[] p = (char[]) m.invoke(conf, alias); if (p != null) { LOG.debug(String.format( "Config option \"%s\" was found through" + " the Configuration getPassword method.", alias)); passwd = new String(p); } else { LOG.debug(String.format("Config option \"%s\" was not found. Using provided default value", alias)); passwd = defPass; } } catch (NoSuchMethodException e) { // this is a version of Hadoop where the credential // provider API doesn't exist yet LOG.debug(String .format("Credential.getPassword method is not available." + " Falling back to configuration.")); passwd = conf.get(alias, defPass); } catch (SecurityException e) { throw new IOException(e.getMessage(), e); } catch (IllegalAccessException e) { throw new IOException(e.getMessage(), e); } catch (IllegalArgumentException e) { throw new IOException(e.getMessage(), e); } catch (InvocationTargetException e) { throw new IOException(e.getMessage(), e); } return passwd; } /** * @return whether to show HBase Configuration in servlet */ public static boolean isShowConfInServlet() { boolean isShowConf = false; try { if (Class.forName("org.apache98.hadoop.conf.ConfServlet") != null) { isShowConf = true; } } catch (LinkageError e) { // should we handle it more aggressively in addition to log the error? LOG.warn("Error thrown: ", e); } catch (ClassNotFoundException ce) { LOG.debug("ClassNotFound: ConfServlet"); // ignore } return isShowConf; } /** * For debugging. Dump configurations to system output as xml format. * Master and RS configurations can also be dumped using * http services. e.g. "curl http://master:60010/dump" */ public static void main(String[] args) throws Exception { HBaseConfiguration.create().writeXml(System.out); } /** * Merge two configurations. * * @param destConf * the configuration that will be overwritten with items * from the srcConf * @param srcConf * the source configuration **/ public static void merge(Configuration destConf, Configuration srcConf) { for (Entry<String, String> e : srcConf) { destConf.set(e.getKey(), e.getValue()); } } private static void checkDefaultsVersion(Configuration conf) { if (conf.getBoolean("hbase.defaults.for.version.skip", Boolean.FALSE)) { return; } String defaultsVersion = conf.get("hbase.defaults.for.version"); String thisVersion = VersionInfo.getVersion(); if (!thisVersion.equals(defaultsVersion)) { throw new RuntimeException("hbase-default.xml file seems to be for and old version of HBase (" + defaultsVersion + "), this version is " + thisVersion); } } private static void checkForClusterFreeMemoryLimit(Configuration conf) { float globalMemstoreLimit = conf.getFloat("hbase.regionserver.global.memstore.upperLimit", 0.4f); int gml = (int) (globalMemstoreLimit * CONVERT_TO_PERCENTAGE); float blockCacheUpperLimit = conf.getFloat(HConstants.HFILE_BLOCK_CACHE_SIZE_KEY, HConstants.HFILE_BLOCK_CACHE_SIZE_DEFAULT); int bcul = (int) (blockCacheUpperLimit * CONVERT_TO_PERCENTAGE); if (CONVERT_TO_PERCENTAGE - (gml + bcul) < (int) (CONVERT_TO_PERCENTAGE * HConstants.HBASE_CLUSTER_MINIMUM_MEMORY_THRESHOLD)) { throw new RuntimeException("Current heap configuration for MemStore and BlockCache exceeds " + "the threshold required for successful cluster operation. " + "The combined value cannot exceed 0.8. Please check " + "the settings for hbase.regionserver.global.memstore.upperLimit and " + "hfile.block.cache.size in your configuration. " + "hbase.regionserver.global.memstore.upperLimit is " + globalMemstoreLimit + " hfile.block.cache.size is " + blockCacheUpperLimit); } } /** * Instantinating HBaseConfiguration() is deprecated. Please use * HBaseConfiguration#create() to construct a plain Configuration */ @Deprecated public HBaseConfiguration() { // TODO:replace with private constructor, HBaseConfiguration should not extend Configuration super(); addHbaseResources(this); LOG.warn("instantiating HBaseConfiguration() is deprecated. Please use" + " HBaseConfiguration#create() to construct a plain Configuration"); } /** * Instantiating HBaseConfiguration() is deprecated. Please use * HBaseConfiguration#create(conf) to construct a plain Configuration */ @Deprecated public HBaseConfiguration(final Configuration c) { // TODO:replace with private constructor this(); merge(this, c); } }