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/*
* Copyright 2017 Red Hat, Inc.
*
* 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.jboss.as.ejb3.suspend;
import java.util.concurrent.atomic.AtomicIntegerFieldUpdater;
import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
import javax.transaction.RollbackException;
import javax.transaction.Synchronization;
import javax.transaction.SystemException;
import org.jboss.as.ejb3.deployment.DeploymentRepository;
import org.jboss.as.ejb3.logging.EjbLogger;
import org.jboss.as.server.suspend.ServerActivity;
import org.jboss.as.server.suspend.ServerActivityCallback;
import org.jboss.as.server.suspend.SuspendController;
import org.jboss.invocation.InterceptorContext;
import org.jboss.msc.service.Service;
import org.jboss.msc.service.ServiceName;
import org.jboss.msc.service.StartContext;
import org.jboss.msc.service.StopContext;
import org.jboss.msc.value.InjectedValue;
import org.wildfly.transaction.client.AbstractTransaction;
import org.wildfly.transaction.client.CreationListener;
import org.wildfly.transaction.client.LocalTransactionContext;
/**
* Controls shutdown indicating whether a remote request should be accepted or not.
*
* @author Flavia Rainone
*/
public class EJBSuspendHandlerService implements Service, ServerActivity, CreationListener,
Synchronization {
/**
* EJBSuspendHandlerService name
*/
public static final ServiceName SERVICE_NAME = ServiceName.JBOSS.append("ejb").append("suspend-handler");
/**
* Updates activeInvocationCount field
*/
private static final AtomicIntegerFieldUpdater activeInvocationCountUpdater = AtomicIntegerFieldUpdater
.newUpdater(EJBSuspendHandlerService.class, "activeInvocationCount");
/**
* Updates activeTransactionCount field
*/
private static final AtomicIntegerFieldUpdater activeTransactionCountUpdater = AtomicIntegerFieldUpdater
.newUpdater(EJBSuspendHandlerService.class, "activeTransactionCount");
/**
* Updates listener field
*/
private static final AtomicReferenceFieldUpdater listenerUpdater = AtomicReferenceFieldUpdater
.newUpdater(EJBSuspendHandlerService.class, ServerActivityCallback.class, "listener");
/**
* Model attribute: if gracefulTxnShutdown attribute is true, handler will bypass module unavailability notification
* to clients while there still active transactions, giving those transactions a chance to complete before completing
* suspension.
*/
private boolean gracefulTxnShutdown;
/**
* Injection of suspend controller, for registering server activity
*/
private final InjectedValue suspendControllerInjectedValue = new InjectedValue<>();
/**
* Injection of local transaction context for keeping track of active transactions
*/
private final InjectedValue localTransactionContextInjectedValue = new InjectedValue<>();
/**
* Injection of DeploymentRepository, for suspending and resuming deployments
*/
private final InjectedValue deploymentRepositoryInjectedValue = new InjectedValue<>();
/**
* The number of active requests that are using this entry point
*/
@SuppressWarnings("unused") private volatile int activeInvocationCount = 0;
/**
* The number of active transactions in the server
*/
@SuppressWarnings("unused") private volatile int activeTransactionCount = 0;
/**
* Keeps track of whether the server shutdown controller has requested suspension
*/
private volatile boolean suspended = false;
/**
* Listener to notify when all active transactions are complete
*/
private volatile ServerActivityCallback listener = null;
/**
* Constructor.
*
* @param gracefulTxnShutdown value of model attribute
*/
public EJBSuspendHandlerService(boolean gracefulTxnShutdown) {
this.gracefulTxnShutdown = gracefulTxnShutdown;
}
/**
* Sets a new value for {@code gracefulTxnShutdown}.
*
* @param gracefulTxnShutdown new value of the model attribute
*/
public void enableGracefulTxnShutdown(boolean gracefulTxnShutdown) {
this.gracefulTxnShutdown = gracefulTxnShutdown;
}
/**
* Returns suspend controller injected value.
*
* @return suspend controller injected value
*/
public InjectedValue getSuspendControllerInjectedValue() {
return suspendControllerInjectedValue;
}
/**
* Returns local transaction context injected value.
*
* @return local transaction context injected value
*/
public InjectedValue getLocalTransactionContextInjectedValue() {
return localTransactionContextInjectedValue;
}
/**
* Returns deployment repository injected value.
*
* @return local transaction context injected value
*/
public InjectedValue getDeploymentRepositoryInjectedValue() {
return deploymentRepositoryInjectedValue;
}
/**
* Returns service value.
*/
@Override public EJBSuspendHandlerService getValue() {
return this;
}
/**
* Starts the service. Registers server activity, sets transaction listener on local transaction context, and creates and
* installs deployment controller service.
*
* @param context start context
*/
public void start(StartContext context) {
final SuspendController suspendController = suspendControllerInjectedValue.getValue();
suspendController.registerActivity(this);
final LocalTransactionContext localTransactionContext = localTransactionContextInjectedValue.getValue();
localTransactionContext.registerCreationListener(this);
}
/**
* Stops the service. Unregisters service activity and clears transaction listener.
* @param context stop context
*/
public void stop(StopContext context) {
final SuspendController suspendController = suspendControllerInjectedValue.getValue();
suspendController.unRegisterActivity(this);
final LocalTransactionContext localTransactionContext = localTransactionContextInjectedValue.getValue();
localTransactionContext.removeCreationListener(this);
}
/**
* Pre suspend. Do nothing.
* @param listener callback listener
*/
@Override public void preSuspend(ServerActivityCallback listener) {
listener.done();
}
/**
* Notifies local transaction context that server is suspended, and only completes suspension if
* there are no active invocations nor transactions.
*
* @param listener callback listener
*/
@Override public void suspended(ServerActivityCallback listener) {
this.suspended = true;
listenerUpdater.set(this, listener);
localTransactionContextInjectedValue.getValue().suspendRequests();
final int activeInvocationCount = activeInvocationCountUpdater.get(this);
if (activeInvocationCount == 0) {
if (gracefulTxnShutdown) {
if (activeTransactionCountUpdater.get(this) == 0) {
this.doneSuspended();
} else {
EjbLogger.ROOT_LOGGER.suspensionWaitingActiveTransactions(activeInvocationCount);
}
} else {
this.doneSuspended();
}
}
}
/**
* Notifies local transaction context that server is resumed, and restarts deployment controller.
*/
@Override public void resume() {
this.suspended = false;
localTransactionContextInjectedValue.getValue().resumeRequests();
ServerActivityCallback listener = listenerUpdater.get(this);
if (listener != null) {
listenerUpdater.compareAndSet(this, listener, null);
}
deploymentRepositoryInjectedValue.getValue().resume();
}
/**
* Indicates if a invocation should be accepted: which will happen only if server is not suspended, or if the invocation
* involves a still active transaction.
*
* @param context interceptor context
* @return {@code true} if invocation can be accepted by invoking interceptor
*/
public boolean acceptInvocation(InterceptorContext context) throws SystemException {
if (suspended) {
if (!gracefulTxnShutdown)
return false;
// a null listener means that we are done suspending;
if (listenerUpdater.get(this) == null || activeTransactionCountUpdater.get(this) == 0)
return false;
// retrieve attachment only when we are not entirely suspended, meaning we are mid-suspension
if (!context.hasTransaction()) {
// all requests with no transaction must be rejected at this point
// we need also to block requests with new transactions, which is not being done here. Instead,
// we are relying on a future call to getTransaction in the same thread, before the invocation is executed;
// this call will throw an exception if the transaction is new, because this suspend handler
// has invoked clientTransactionContext.suspendRequests
return false;
}
}
activeInvocationCountUpdater.incrementAndGet(this);
return true;
}
/**
* Notifies handler that an active invocation is complete.
*/
public void invocationComplete() {
int activeInvocations = activeInvocationCountUpdater.decrementAndGet(this);
if (suspended && activeInvocations == 0 && (!gracefulTxnShutdown || (activeTransactionCountUpdater.get(this) == 0))) {
doneSuspended();
}
}
/**
* Notifies handler that a new transaction has been created.
*/
@Override public void transactionCreated(AbstractTransaction transaction, CreatedBy createdBy) {
activeTransactionCountUpdater.incrementAndGet(this);
try {
transaction.registerSynchronization(this);
} catch (RollbackException | IllegalStateException e) {
// it means the transaction is marked for rollback, or is prepared for commit, at this point we cannot register synchronization
decrementTransactionCount();
} catch (SystemException e) {
decrementTransactionCount();
EjbLogger.ROOT_LOGGER.debug("Unexpected exception", e);
throw new RuntimeException(e);
}
}
/**
* Notifies handler that an active transaction is about to complete.
*/
@Override public void beforeCompletion() {
}
/**
* Notifies handler that an active transaction has completed.
*/
@Override public void afterCompletion(int status) {
decrementTransactionCount();
}
/**
* Indicates if ejb subsystem is suspended.
*
* @return {@code true} if ejb susbsystem suspension is started (regardless of whether it completed or not)
*/
public boolean isSuspended() {
return suspended;
}
/**
* Completes suspension: stop deployment controller.
*/
private void doneSuspended() {
final ServerActivityCallback oldListener = listener;
if (oldListener != null && listenerUpdater.compareAndSet(this, oldListener, null)) {
deploymentRepositoryInjectedValue.getValue().suspend();
oldListener.done();
EjbLogger.ROOT_LOGGER.suspensionComplete();
}
}
/**
* Decrements active tranbsaction count and completes suspension if we are suspending and there are no more
* active transactions left.
*/
private void decrementTransactionCount() {
int activeTransactionCount = activeTransactionCountUpdater.decrementAndGet(this);
if (suspended && activeTransactionCount == 0 && activeInvocationCountUpdater.get(this) == 0) {
doneSuspended();
}
}
}
