org.apache.hadoop.hbase.CompoundConfiguration Maven / Gradle / Ivy
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/*
* 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.hbase;
import java.io.DataOutput;
import java.io.IOException;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.yetus.audience.InterfaceAudience;
import org.apache.hbase.thirdparty.org.apache.commons.collections4.iterators.UnmodifiableIterator;
/**
* Do a shallow merge of multiple KV configuration pools. This is a very useful utility class to
* easily add per-object configurations in addition to wider scope settings. This is different from
* Configuration.addResource() functionality, which performs a deep merge and mutates the common
* data structure.
*
* The iterator on CompoundConfiguration is unmodifiable. Obtaining iterator is an expensive
* operation.
*
* For clarity: the shallow merge allows the user to mutate either of the configuration objects and
* have changes reflected everywhere. In contrast to a deep merge, that requires you to explicitly
* know all applicable copies to propagate changes. WARNING: The values set in the
* CompoundConfiguration are do not handle Property variable substitution. However, if they are set
* in the underlying configuration substitutions are done.
*/
@InterfaceAudience.Private
public class CompoundConfiguration extends Configuration {
private Configuration mutableConf = null;
/**
* Default Constructor. Initializes empty configuration
*/
public CompoundConfiguration() {
}
// Devs: these APIs are the same contract as their counterparts in
// Configuration.java
private interface ImmutableConfigMap extends Iterable> {
String get(String key);
String getRaw(String key);
Class getClassByName(String name) throws ClassNotFoundException;
int size();
}
private final List configs = new ArrayList<>();
static class ImmutableConfWrapper implements ImmutableConfigMap {
private final Configuration c;
ImmutableConfWrapper(Configuration conf) {
c = conf;
}
@Override
public Iterator> iterator() {
return c.iterator();
}
@Override
public String get(String key) {
return c.get(key);
}
@Override
public String getRaw(String key) {
return c.getRaw(key);
}
@Override
public Class getClassByName(String name) throws ClassNotFoundException {
return c.getClassByName(name);
}
@Override
public int size() {
return c.size();
}
@Override
public String toString() {
return c.toString();
}
}
/**
* If set has been called, it will create a mutableConf. This converts the mutableConf to an
* immutable one and resets it to allow a new mutable conf. This is used when a new map or conf is
* added to the compound configuration to preserve proper override semantics.
*/
void freezeMutableConf() {
if (mutableConf == null) {
// do nothing if there is no current mutableConf
return;
}
this.configs.add(0, new ImmutableConfWrapper(mutableConf));
mutableConf = null;
}
/**
* Add Hadoop Configuration object to config list. The added configuration overrides the previous
* ones if there are name collisions.
* @param conf configuration object
* @return this, for builder pattern
*/
public CompoundConfiguration add(final Configuration conf) {
freezeMutableConf();
if (conf instanceof CompoundConfiguration) {
this.configs.addAll(0, ((CompoundConfiguration) conf).configs);
return this;
}
// put new config at the front of the list (top priority)
this.configs.add(0, new ImmutableConfWrapper(conf));
return this;
}
/**
* Add Bytes map to config list. This map is generally created by HTableDescriptor or
* HColumnDescriptor, but can be abstractly used. The added configuration overrides the previous
* ones if there are name collisions. Bytes map
* @return this, for builder pattern
*/
public CompoundConfiguration addBytesMap(final Map map) {
freezeMutableConf();
// put new map at the front of the list (top priority)
this.configs.add(0, new ImmutableConfigMap() {
private final Map m = map;
@Override
public Iterator> iterator() {
Map ret = new HashMap<>();
for (Map.Entry entry : map.entrySet()) {
String key = Bytes.toString(entry.getKey().get());
String val = entry.getValue() == null ? null : Bytes.toString(entry.getValue().get());
ret.put(key, val);
}
return ret.entrySet().iterator();
}
@Override
public String get(String key) {
Bytes ibw = new Bytes(Bytes.toBytes(key));
if (!m.containsKey(ibw)) return null;
Bytes value = m.get(ibw);
if (value == null || value.get() == null) return null;
return Bytes.toString(value.get());
}
@Override
public String getRaw(String key) {
return get(key);
}
@Override
public Class getClassByName(String name) throws ClassNotFoundException {
return null;
}
@Override
public int size() {
return m.size();
}
@Override
public String toString() {
return m.toString();
}
});
return this;
}
/**
* Add String map to config list. This map is generally created by HTableDescriptor or
* HColumnDescriptor, but can be abstractly used. The added configuration overrides the previous
* ones if there are name collisions.
* @return this, for builder pattern
*/
public CompoundConfiguration addStringMap(final Map map) {
freezeMutableConf();
// put new map at the front of the list (top priority)
this.configs.add(0, new ImmutableConfigMap() {
private final Map m = map;
@Override
public Iterator> iterator() {
return map.entrySet().iterator();
}
@Override
public String get(String key) {
return m.get(key);
}
@Override
public String getRaw(String key) {
return get(key);
}
@Override
public Class getClassByName(String name) throws ClassNotFoundException {
return null;
}
@Override
public int size() {
return m.size();
}
@Override
public String toString() {
return m.toString();
}
});
return this;
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
sb.append("CompoundConfiguration: " + this.configs.size() + " configs");
for (ImmutableConfigMap m : this.configs) {
sb.append(m);
}
return sb.toString();
}
@Override
public String get(String key) {
if (mutableConf != null) {
String value = mutableConf.get(key);
if (value != null) {
return value;
}
}
for (ImmutableConfigMap m : this.configs) {
String value = m.get(key);
if (value != null) {
return value;
}
}
return null;
}
@Override
public String getRaw(String key) {
if (mutableConf != null) {
String value = mutableConf.getRaw(key);
if (value != null) {
return value;
}
}
for (ImmutableConfigMap m : this.configs) {
String value = m.getRaw(key);
if (value != null) {
return value;
}
}
return null;
}
@Override
public Class getClassByName(String name) throws ClassNotFoundException {
if (mutableConf != null) {
Class value = mutableConf.getClassByName(name);
if (value != null) {
return value;
}
}
for (ImmutableConfigMap m : this.configs) {
Class value = m.getClassByName(name);
if (value != null) {
return value;
}
}
throw new ClassNotFoundException();
}
// TODO: This method overestimates the number of configuration settings -- if a value is masked
// by an overriding config or map, it will be counted multiple times.
@Override
public int size() {
int ret = 0;
if (mutableConf != null) {
ret += mutableConf.size();
}
for (ImmutableConfigMap m : this.configs) {
ret += m.size();
}
return ret;
}
/**
* Get the value of the name. If the key is deprecated, it returns the value of the
* first key which replaces the deprecated key and is not null. If no such property exists, then
* defaultValue is returned. The CompooundConfiguration does not do property
* substitution. To do so we need Configuration.getProps to be protected or package visible.
* Though in hadoop2 it is protected, in hadoop1 the method is private and not accessible. All of
* the get* methods call this overridden get method.
* @param name property name.
* @param defaultValue default value.
* @return property value, or defaultValue if the property doesn't exist.
**/
@Override
public String get(String name, String defaultValue) {
String ret = get(name);
return ret == null ? defaultValue : ret;
}
@Override
public Iterator> iterator() {
Map ret = new HashMap<>();
// add in reverse order so that oldest get overridden.
if (!configs.isEmpty()) {
for (int i = configs.size() - 1; i >= 0; i--) {
ImmutableConfigMap map = configs.get(i);
Iterator> iter = map.iterator();
while (iter.hasNext()) {
Map.Entry entry = iter.next();
ret.put(entry.getKey(), entry.getValue());
}
}
}
// add mutations to this CompoundConfiguration last.
if (mutableConf != null) {
Iterator> miter = mutableConf.iterator();
while (miter.hasNext()) {
Map.Entry entry = miter.next();
ret.put(entry.getKey(), entry.getValue());
}
}
return UnmodifiableIterator.unmodifiableIterator(ret.entrySet().iterator());
}
@Override
public void set(String name, String value) {
if (mutableConf == null) {
// not thread safe
mutableConf = new Configuration(false); // an empty configuration
}
mutableConf.set(name, value);
}
/***********************************************************************************************
* These methods are unsupported, and no code using CompoundConfiguration depend upon them.
* Quickly abort upon any attempts to use them.
**********************************************************************************************/
@Override
public void clear() {
throw new UnsupportedOperationException("Immutable Configuration");
}
@Override
public void write(DataOutput out) throws IOException {
throw new UnsupportedOperationException("Immutable Configuration");
}
@Override
public void writeXml(OutputStream out) throws IOException {
throw new UnsupportedOperationException("Immutable Configuration");
}
}