/*
* Copyright 2011-2013 the original author or authors.
*
* Licensed 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.springframework.data.hadoop.hbase;
import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Set;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hbase.client.HTableInterface;
import org.springframework.core.NamedThreadLocal;
import org.springframework.transaction.support.ResourceTransactionManager;
import org.springframework.util.Assert;
/**
* Synchronization manager handling the tracking of Hbase resources (specifically tables). Used either manually or through {@link HbaseInterceptor} to bind a table to the thread.
* Each subsequent call made through {@link HbaseTemplate} is aware of the table bound and will use it instead of retrieving a new instance.
*
* @author Costin Leau
*/
public abstract class HbaseSynchronizationManager {
private static final Log logger = LogFactory.getLog(HbaseSynchronizationManager.class);
private static final ThreadLocal<Map<String, HTableInterface>> resources = new NamedThreadLocal<Map<String, HTableInterface>>("Bound resources");
/**
* Checks whether any resource is bound for the given key.
*
* @param key key to check
* @return whether or not a resource is bound for the given key
*/
public static boolean hasResource(Object key) {
Object value = doGetResource(key);
return (value != null);
}
/**
* Returns the resource (table) associated with the given key.
*
* @param key association key
* @return associated resource (table)
*/
public static HTableInterface getResource(Object key) {
return doGetResource(key);
}
/**
* Actually checks the value of the resource that is bound for the given key.
*/
private static HTableInterface doGetResource(Object actualKey) {
Map<String, HTableInterface> tables = resources.get();
if (tables == null) {
return null;
}
return tables.get(actualKey);
}
/**
* Binds the given resource for the given key to the current thread.
* @param key the key to bind the value to (usually the resource factory)
* @param value the value to bind (usually the active resource object)
* @throws IllegalStateException if there is already a value bound to the thread
* @see ResourceTransactionManager#getResourceFactory()
*/
public static void bindResource(String key, HTableInterface value) throws IllegalStateException {
Assert.notNull(value, "Value must not be null");
Map<String, HTableInterface> map = resources.get();
// set ThreadLocal Map if none found
if (map == null) {
map = new LinkedHashMap<String, HTableInterface>();
resources.set(map);
}
HTableInterface oldValue = map.put(key, value);
if (oldValue != null) {
throw new IllegalStateException("Already value [" + oldValue + "] for key [" + key
+ "] bound to thread [" + Thread.currentThread().getName() + "]");
}
if (logger.isTraceEnabled()) {
logger.trace("Bound value [" + value + "] for key [" + key + "] to thread ["
+ Thread.currentThread().getName() + "]");
}
}
/**
* Unbinds a resource for the given key from the current thread.
* @param key the key to unbind (usually the resource factory)
* @return the previously bound value (usually the active resource object)
* @throws IllegalStateException if there is no value bound to the thread
* @see ResourceTransactionManager#getResourceFactory()
*/
public static HTableInterface unbindResource(String key) throws IllegalStateException {
HTableInterface value = doUnbindResource(key);
if (value == null) {
throw new IllegalStateException("No value for key [" + key + "] bound to thread ["
+ Thread.currentThread().getName() + "]");
}
return value;
}
/**
* Unbinds a resource for the given key from the current thread.
*
* @param key the key to unbind (usually the resource factory)
* @return the previously bound value, or <code>null</code> if none bound
*/
public static Object unbindResourceIfPossible(Object key) {
return doUnbindResource(key);
}
/**
* Actually remove the value of the resource that is bound for the given key.
*/
private static HTableInterface doUnbindResource(Object actualKey) {
Map<String, HTableInterface> map = resources.get();
if (map == null) {
return null;
}
HTableInterface value = map.remove(actualKey);
// Remove entire ThreadLocal if empty...
if (map.isEmpty()) {
resources.remove();
}
if (value != null && logger.isTraceEnabled()) {
logger.trace("Removed value [" + value + "] for key [" + actualKey + "] from thread ["
+ Thread.currentThread().getName() + "]");
}
return value;
}
/**
* Returns the bound tables (by name).
*
* @return names of bound tables
*/
public static Set<String> getTableNames() {
Map<String, HTableInterface> map = resources.get();
if (map != null && !map.isEmpty()) {
return Collections.unmodifiableSet(map.keySet());
}
return Collections.emptySet();
}
}