org.apache.openejb.resource.jdbc.router.FailOverRouter Maven / Gradle / Ivy
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* 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.
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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.annotation.PostConstruct;
import javax.naming.NamingException;
import javax.sql.DataSource;
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.sql.SQLException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.concurrent.atomic.AtomicInteger;
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 ExceptionSelector exceptionSelectorRuntime;
private ErrorHandler errorHandlerRuntime;
private Strategy strategyRuntime;
private DataSource facade;
private final List dataSources = new CopyOnWriteArrayList<>();
private String delimiter = ",";
private String strategy = DEFAULT_STRATEGY;
private String datasourceNames = "";
@Override
public DataSource getDataSource() {
return facade;
}
@PostConstruct
public void init() {
initDataSources();
initStrategy();
initFacade();
}
public void setDatasourceNames(final String datasourceNames) {
this.datasourceNames = datasourceNames;
}
public void setDelimiter(final String delimiter) {
this.delimiter = delimiter;
}
public void setStrategy(final String strategy) {
this.strategy = strategy;
}
public void setStrategyInstance(final Strategy strategy) {
this.strategyRuntime = strategy;
}
public void setExceptionSelectorInstance(final ExceptionSelector selector) {
exceptionSelectorRuntime = selector;
}
public void setExceptionSelector(final String selector) {
try {
exceptionSelectorRuntime = "mysql".equalsIgnoreCase(selector) ?
new MySQLExceptionSelector() :
ExceptionSelector.class.cast(Thread.currentThread().getContextClassLoader()
.loadClass(selector.trim()).newInstance());
} catch (final InstantiationException | IllegalAccessException | ClassNotFoundException e) {
throw new IllegalArgumentException(e);
}
}
public void setErrorHandlerInstance(final ErrorHandler errorHandler) {
errorHandlerRuntime = errorHandler;
}
public void setErrorHandler(final String errorHandler) {
try {
errorHandlerRuntime = ErrorHandler.class.cast(
Thread.currentThread().getContextClassLoader().loadClass(errorHandler.trim()).newInstance());
} catch (final InstantiationException | IllegalAccessException | ClassNotFoundException e) {
throw new IllegalArgumentException(e);
}
}
private void initStrategy() {
switch (strategy) {
case "round-robin":
strategyRuntime = new Strategy() { // simply rotating the list each time
private final AtomicInteger idx = new AtomicInteger(0);
@Override
public Collection prepare(final Collection list) {
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<>(list);
int currentIdx = 0;
for (int i = 0; i < step; i++) {
currentIdx = idx.incrementAndGet();
}
Collections.rotate(ds, 1 + currentIdx % ds.size());
return ds;
}
@Override
public void used(final DataSourceHolder holder) {
// no-op
}
};
break;
case "random":
strategyRuntime = new Strategy() { // simply rotating the list each time
@Override
public Collection prepare(final Collection list) {
final List ds = new ArrayList<>(list);
Collections.shuffle(ds);
return ds;
}
@Override
public void used(final DataSourceHolder holder) {
// no-op
}
};
break;
case "reverse":
strategyRuntime = new Strategy() { // simply rotating the list each time
private final AtomicInteger idx = new AtomicInteger();
@Override
public Collection prepare(final Collection list) {
final List ds = new ArrayList<>(list);
final int times = idx.incrementAndGet() % ds.size();
for (int i = 0; i < times; i++) {
Collections.reverse(ds);
}
return ds;
}
@Override
public void used(final DataSourceHolder holder) {
// no-op
}
};
break;
case "static":
strategyRuntime = new Strategy() { // no auto adaption (if first ds is always faster for instance)
@Override
public Collection prepare(final Collection list) {
return list;
}
@Override
public void used(final DataSourceHolder holder) {
// no-op
}
};
break;
case DEFAULT_STRATEGY:
default:
strategyRuntime = new Strategy() { // use the list and save a working item as first one
@Override
public Collection prepare(final Collection list) {
return list;
}
@Override
public void used(final DataSourceHolder holder) {
if (dataSources.get(0) == holder) { // no lock
return;
}
synchronized (this) {
if (dataSources.get(0) == holder) {
return;
}
final DataSourceHolder old = dataSources.set(0, holder); // locks
if (old != holder) {
dataSources.set(dataSources.lastIndexOf(holder), old);
}
}
}
};
break;
}
}
private void initDataSources() {
dataSources.clear();
for (final String ds : datasourceNames.split(Pattern.quote(delimiter))) {
try {
final String name = ds.trim();
final Object o = getOpenEJBResource(name);
if (DataSource.class.isInstance(o)) {
LOGGER.debug("Found datasource '" + ds + "'");
dataSources.add(new DataSourceHolder(DataSource.class.cast(o), name));
} else {
throw new IllegalArgumentException(name + " (" + o + ") is not a datasource");
}
} catch (final NamingException error) {
throw new IllegalStateException(error);
}
}
initFacade();
}
private void initFacade() {
facade = DataSource.class.cast(Proxy.newProxyInstance(
Thread.currentThread().getContextClassLoader(),
new Class[]{DataSource.class}, new FacadeHandler(dataSources, strategyRuntime, errorHandlerRuntime, exceptionSelectorRuntime)));
}
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 final TransactionManager transactionManager;
private final Collection delegates;
private final Strategy strategy;
private final ErrorHandler handler;
private final ExceptionSelector selector;
public FacadeHandler(final Collection dataSources, final Strategy strategy,
final ErrorHandler handler, final ExceptionSelector selector) {
this.delegates = dataSources;
this.strategy = strategy;
this.handler = handler;
this.selector = selector;
this.transactionManager = OpenEJB.getTransactionManager();
}
@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 Transaction transaction = transactionManager.getTransaction();
if (transaction != null) {
final DataSource currentDs = DataSource.class.cast(SYNCHRONIZATION_REGISTRY.getResource(FacadeHandler.class.getName()));
if (currentDs != null) {
return method.invoke(currentDs, args);
}
}
int ex = 0;
final Collection sources = strategy.prepare(delegates);
final int size = sources.size();
Object out = null;
Map failed = null;
DataSourceHolder used = null;
for (final DataSourceHolder ds : sources) {
used = ds;
try {
final boolean set = method.getName().startsWith("set");
if (set) { // should set on all datasources because of failover which can happen but can also be bound to the tx
method.invoke(ds.dataSource, args);
} else { // getConnection methods are here
out = method.invoke(ds.dataSource, args);
}
if (transaction != null) { // if a tx is in progress save the datasource to use for the tx
SYNCHRONIZATION_REGISTRY.putResource(FacadeHandler.class.getName(), ds.dataSource);
break;
}
if (!set) { // if no exception and not a set all is done so return out
break;
}
} catch (final InvocationTargetException ite) {
final Throwable cause = ite.getTargetException();
if (selector != null && !selector.shouldFailover(cause)) {
if (failed != null) {
handler.onError(failed, ds);
}
throw cause;
}
if (handler != null) {
if (failed == null) {
failed = new HashMap<>();
}
failed.put(ds.name, ite.getCause());
}
ex++;
if (ex == size) { // all failed so throw the exception
if (failed != null) {
handler.onError(failed, null);
}
throw ite.getCause();
}
}
}
if (failed != null) {
handler.onError(failed, used);
}
strategy.used(used);
return out;
}
}
public interface ExceptionSelector {
boolean shouldFailover(final Throwable sqle);
}
public abstract class SQLExceptionSelector implements ExceptionSelector {
@Override
public boolean shouldFailover(final Throwable sqle) {
return SQLException.class.isInstance(sqle) && shouldFailover(SQLException.class.cast(sqle));
}
abstract boolean shouldFailover(final SQLException sqle);
}
public class MySQLExceptionSelector extends SQLExceptionSelector {
private final Class communicationException;
public MySQLExceptionSelector() {
try {
communicationException = Thread.currentThread().getContextClassLoader().loadClass("com.mysql.jdbc.CommunicationsException");
} catch (final ClassNotFoundException e) {
throw new IllegalArgumentException("com.mysql.jdbc.CommunicationsException not available, please use another ExceptionSelector");
}
}
@Override
public boolean shouldFailover(final SQLException ex) {
final String sqlState = ex.getSQLState();
return (sqlState != null && sqlState.startsWith("08")) ||
communicationException.isInstance(ex);
}
}
public interface ErrorHandler {
void onError(final Map errorByFailingDataSource, final DataSourceHolder finallyUsedOrNull);
}
public interface Strategy {
Collection prepare(final Collection list);
void used(DataSourceHolder holder);
}
public static final class DataSourceHolder {
private final DataSource dataSource;
private final String name;
public DataSourceHolder(final DataSource dataSource, final String name) {
this.dataSource = dataSource;
this.name = name;
}
}
}
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