org.apache.openejb.resource.jdbc.router.FailOverRouter 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.openejb.resource.jdbc.router;
import org.apache.openejb.OpenEJB;
import org.apache.openejb.loader.SystemInstance;
import org.apache.openejb.util.LogCategory;
import org.apache.openejb.util.Logger;
import javax.naming.NamingException;
import javax.sql.DataSource;
import javax.sql.XADataSource;
import javax.transaction.Transaction;
import javax.transaction.TransactionManager;
import javax.transaction.TransactionSynchronizationRegistry;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.Locale;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicReference;
import java.util.regex.Pattern;
public class FailOverRouter extends AbstractRouter {
private static final Logger LOGGER = Logger.getInstance(LogCategory.OPENEJB_SERVER, FailOverRouter.class);
public static final String DEFAULT_STRATEGY = "default";
private final AtomicReference facade = new AtomicReference();
private final Collection dataSources = new CopyOnWriteArrayList();
private String delimiter = ",";
private String strategy = DEFAULT_STRATEGY;
private String datasourceNames = "";
@Override
public DataSource getDataSource() {
return facade.get();
}
public void setDatasourceNames(final String datasourceNames) {
this.datasourceNames = datasourceNames;
initDataSources();
}
public void setDelimiter(final String delimiter) {
this.delimiter = delimiter;
initDataSources();
}
public void setStrategy(final String strategy) {
if (strategy == null) {
this.strategy = DEFAULT_STRATEGY;
} else {
this.strategy = strategy.toLowerCase(Locale.ENGLISH).trim();
}
initFacade();
}
private void initDataSources() {
dataSources.clear();
for (final String ds : datasourceNames.split(Pattern.quote(delimiter))) {
try {
final Object o = getOpenEJBResource(ds.trim());
if (DataSource.class.isInstance(o)) {
LOGGER.debug("Found datasource '" + ds + "'");
dataSources.add(DataSource.class.cast(o));
}
} catch (final NamingException error) {
LOGGER.error("Can't find datasource '" + ds + "'", error);
}
}
initFacade();
}
private void initFacade() {
Class clazz = DataSource.class;
int xads = 0;
for (final DataSource ds : dataSources) {
if (XADataSource.class.isInstance(ds)) {
xads++;
}
}
if (xads > 0 && xads == dataSources.size()) {
clazz = XADataSource.class;
}
facade.set(DataSource.class.cast(Proxy.newProxyInstance(
Thread.currentThread().getContextClassLoader(),
new Class[]{clazz}, new FacadeHandler(dataSources, strategy))));
}
public Collection getDataSources() {
return dataSources;
}
public void updateDataSources(final Collection ds) {
dataSources.clear();
dataSources.addAll(ds);
initFacade();
}
private static class FacadeHandler implements InvocationHandler {
private static final TransactionSynchronizationRegistry SYNCHRONIZATION_REGISTRY = SystemInstance.get().getComponent(TransactionSynchronizationRegistry.class);
private static final String DATASOURCE_KEY = "router_datasource_in_use";
private final Collection delegates;
private final String strategy;
private final AtomicInteger currentIdx = new AtomicInteger(0); // used by some strategies
public FacadeHandler(final Collection dataSources, final String strategy) {
this.delegates = dataSources;
this.strategy = strategy;
}
@Override
public Object invoke(final Object proxy, final Method method, final Object[] args) throws Throwable {
if (Object.class.equals(method.getDeclaringClass())) {
if ("toString".equals(method.getName())) {
return "DataSourceFacade" + delegates;
}
if ("hashCode".equals(method.getName())) {
return delegates.hashCode();
}
if ("equals".equals(method.getName())) {
return method.invoke(this, args);
}
}
final TransactionManager txMgr = OpenEJB.getTransactionManager();
final Transaction transaction = txMgr.getTransaction();
if (transaction != null) {
final DataSource currentDs = DataSource.class.cast(SYNCHRONIZATION_REGISTRY.getResource(DATASOURCE_KEY));
if (currentDs != null) {
return method.invoke(currentDs, args);
}
}
int ex = 0;
final Collection sources = sortFollowingStrategy(strategy, delegates, currentIdx);
final int size = sources.size();
Object out = null;
for (final DataSource ds : sources) {
try {
final boolean set = method.getName().startsWith("set");
if (set) { // set on all datasources because of failover which can happen
method.invoke(ds, args);
} else { // getConnection methods are here
out = method.invoke(ds, args);
}
if (transaction != null) { // if a tx is in progress save the datasource to use for the tx
SYNCHRONIZATION_REGISTRY.putResource(DATASOURCE_KEY, ds);
break;
}
if (!set) { // if no exception and not a set all is done so return out
break;
}
} catch (final InvocationTargetException ite) {
ex++;
if (ex == size) { // all failed so throw the exception
throw ite.getCause();
}
}
}
return out;
}
}
private static Collection sortFollowingStrategy(final String strategy, final Collection delegates, final AtomicInteger idx) {
if (strategy == null) {
return delegates;
}
if (DEFAULT_STRATEGY.equals(strategy) || strategy.isEmpty()) {
return delegates;
}
//
// take care next strategies can break multiple calls on the facade
// it is only intended to be used for connection selection
//
if ("random".equals(strategy)) {
final List ds = new ArrayList(delegates);
Collections.shuffle(ds);
return ds;
}
if ("reverse".equals(strategy)) {
final List ds = new ArrayList(delegates);
final int times = idx.incrementAndGet() % ds.size();
for (int i = 0; i < times; i++) {
Collections.reverse(ds);
}
return ds;
}
if (strategy.startsWith("round-robin")) {
final int step;
if (strategy.contains("%")) {
step = Math.max(1, Integer.parseInt(strategy.substring(strategy.lastIndexOf("%") + 1)));
} else {
step = 1;
}
final List ds = new ArrayList(delegates);
int currentIdx = 0;
for (int i = 0; i < step; i++) {
currentIdx = idx.incrementAndGet();
}
Collections.rotate(ds, 1 + currentIdx % ds.size());
return ds;
}
return delegates;
}
}
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