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/**
*
* Copyright 2005 The Apache Software Foundation or its licensors, as applicable.
*
* 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.apache.tuscany.core.context.scope;
import org.apache.tuscany.core.builder.ContextFactory;
import org.apache.tuscany.core.context.Context;
import org.apache.tuscany.core.context.CoreRuntimeException;
import org.apache.tuscany.core.context.EventContext;
import org.apache.tuscany.core.context.AtomicContext;
import org.apache.tuscany.core.context.TargetException;
import org.apache.tuscany.core.context.Lifecycle;
import org.apache.tuscany.core.context.event.InstanceCreated;
import org.apache.tuscany.core.context.event.Event;
import org.apache.tuscany.core.context.event.RequestEnd;
import org.apache.tuscany.core.context.event.RequestStart;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.ListIterator;
import java.util.concurrent.ConcurrentHashMap;
/**
* An implementation of a request-scoped component container. This scope contexts eagerly starts contexts when
* a {@link org.apache.tuscany.core.context.event.RequestStart} event is received. If a contained context has an implementation marked to eagerly initialized,
* the an instance will be created at that time as well. Contained contexts are shutdown when a {@link org.apache.tuscany.core.context.event.RequestEnd}
* event is received in reverse order to which their implementation instances were created.
*
* @version $Rev$ $Date$
*/
public class RequestScopeContext extends AbstractScopeContext {
// A collection of service component contexts keyed by thread. Note this could have been implemented with a ThreadLocal but
// using a Map allows finer-grained concurrency.
private Map<Object, Map<String, Context>> contexts;
// stores ordered lists of contexts to shutdown for each thread.
private Map<Object, List<Context>> destroyQueues;
public RequestScopeContext(EventContext eventContext) {
super(eventContext);
setName("Request Scope");
}
public void onEvent(Event event){
if (event instanceof RequestStart){
getContexts(); // eager load
}else if (event instanceof RequestEnd){
checkInit();
getEventContext().clearIdentifiers(); // clean up current context for pooled threads
shutdownContexts();
cleanupRequestContexts();
}else if (event instanceof InstanceCreated){
checkInit();
assert(event.getSource() instanceof Context): "Context must be passed on created event";
Context context = (Context)event.getSource();
List<Context> collection = destroyQueues.get(Thread.currentThread());
collection.add(context);
}
}
public synchronized void start() {
if (lifecycleState != UNINITIALIZED) {
throw new IllegalStateException("Scope must be in UNINITIALIZED state [" + lifecycleState + "]");
}
contexts = new ConcurrentHashMap<Object, Map<String, Context>>();
destroyQueues = new ConcurrentHashMap<Object, List<Context>>();
lifecycleState = RUNNING;
}
public synchronized void stop() {
if (lifecycleState != RUNNING) {
throw new IllegalStateException("Scope in wrong state [" + lifecycleState + "]");
}
contexts = null;
destroyQueues = null;
lifecycleState = STOPPED;
}
public boolean isCacheable() {
return true;
}
public void registerFactory(ContextFactory<Context> configuration) {
contextFactories.put(configuration.getName(), configuration);
}
public Context getContext(String ctxName) {
checkInit();
Map<String, Context> contexts = getContexts();
Context ctx = contexts.get(ctxName);
if (ctx == null){
// check to see if the configuration was added after the request was started
ContextFactory<Context> configuration = contextFactories.get(ctxName);
if (configuration != null) {
ctx = configuration.createContext();
//ctx.addListener(this);
ctx.start();
contexts.put(ctx.getName(), ctx);
}
}
return ctx;
}
public Context getContextByKey(String ctxName, Object key) {
checkInit();
if (key == null) {
return null;
}
Map<String, Context> components = contexts.get(key);
if (components == null) {
return null;
}
return components.get(ctxName);
}
public void removeContext(String ctxName) {
removeContextByKey(ctxName, Thread.currentThread());
}
public void removeContextByKey(String ctxName, Object key) {
checkInit();
if (key == null || ctxName == null) {
return;
}
Map components = contexts.get(key);
if (components == null) {
return;
}
components.remove(ctxName);
}
private void cleanupRequestContexts() {
// TODO uninitialize all request-scoped components
contexts.remove(Thread.currentThread());
destroyQueues.remove(Thread.currentThread());
}
/**
* Initializes ServiceComponentContexts for the current request.
* <p>
* TODO This eagerly creates all component contexts, even if the component is never accessed during the request. This method
* should be profiled to determine if lazy initialization is more performant
* <p>
* TODO Eager initialization is not performed for request-scoped components
*/
private Map<String, Context> getContexts() throws CoreRuntimeException {
Map<String, Context> requestContexts = this.contexts.get(Thread.currentThread());
if (requestContexts == null) {
requestContexts = new ConcurrentHashMap<String, Context>();
List<Context> shutdownQueue = new ArrayList<Context>();
for (ContextFactory<Context> config : contextFactories.values()) {
Context context = config.createContext();
context.start();
requestContexts.put(context.getName(), context);
}
// initialize eager components. Note this cannot be done when we initially create each context since a component may
// contain a forward reference to a component which has not been instantiated
for (Context context : requestContexts.values()) {
if (context instanceof AtomicContext) {
AtomicContext atomic = (AtomicContext) context;
if (atomic.isEagerInit()) {
atomic.init(); // Notify the instance
synchronized(shutdownQueue){
shutdownQueue.add(context);
}
}
}
context.addListener(this);
}
contexts.put(Thread.currentThread(), requestContexts);
destroyQueues.put(Thread.currentThread(), shutdownQueue);
}
return requestContexts;
}
private void shutdownContexts() {
List<Context> destroyQueue = destroyQueues.remove(Thread.currentThread());
if (destroyQueue == null || destroyQueue.size() == 0) {
return;
}
synchronized(destroyQueue){
// shutdown destroyable instances in reverse instantiation order
ListIterator<Context> iter = destroyQueue.listIterator(destroyQueue.size());
while(iter.hasPrevious()){
Lifecycle context = iter.previous();
if (context.getLifecycleState() == RUNNING) {
try {
if (context instanceof AtomicContext){
((AtomicContext)context).destroy();
}
} catch (TargetException e) {
// TODO send a monitoring event
}
}
}
}
// shutdown contexts
Map<String,Context> currentContexts = contexts.remove(Thread.currentThread());
if (currentContexts == null){
return;
}
for (Lifecycle context: currentContexts.values()){
if (context.getLifecycleState() == RUNNING) {
context.stop();
}
}
}
}
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