// Copyright 2006, 2007 The Apache Software Foundation
//
// 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.tapestry.ioc.internal;
import org.apache.tapestry.ioc.*;
import org.apache.tapestry.ioc.def.ContributionDef;
import org.apache.tapestry.ioc.def.DecoratorDef;
import org.apache.tapestry.ioc.def.ModuleDef;
import org.apache.tapestry.ioc.def.ServiceDef;
import org.apache.tapestry.ioc.internal.services.JustInTimeObjectCreator;
import static org.apache.tapestry.ioc.internal.util.CollectionFactory.*;
import static org.apache.tapestry.ioc.internal.util.Defense.notBlank;
import static org.apache.tapestry.ioc.internal.util.Defense.notNull;
import org.apache.tapestry.ioc.internal.util.InternalUtils;
import org.apache.tapestry.ioc.services.*;
import org.slf4j.Logger;
import java.io.ObjectStreamException;
import java.io.Serializable;
import static java.lang.String.format;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Modifier;
import java.util.*;
public class ModuleImpl implements Module
{
private final InternalRegistry _registry;
private final ServiceActivityTracker _tracker;
private final ModuleDef _moduleDef;
private final ClassFactory _classFactory;
private final Logger _logger;
// Guarded by MUTEX
private Object _moduleBuilder;
/**
* A single mutex, shared by all modules, that serializes creation of services across all
* threads. This is a bit draconian, but appears to be necessary. Fortunately, service creation
* is a very tiny part of any individual service's lifecycle.
*/
private static final Object MUTEX = new Object();
// Set to true when invoking the module constructor. Used to
// detect endless loops caused by irresponsible dependencies in
// the constructor. Guarded by MUTEX.
private boolean _insideConstructor;
/**
* Keyed on fully qualified service id; values are instantiated services (proxies).
*/
private final Map<String, Object> _services = newCaseInsensitiveMap();
public ModuleImpl(InternalRegistry registry, ServiceActivityTracker tracker, ModuleDef moduleDef,
ClassFactory classFactory, Logger logger)
{
_registry = registry;
_tracker = tracker;
_moduleDef = moduleDef;
_classFactory = classFactory;
_logger = logger;
}
public <T> T getService(String serviceId, Class<T> serviceInterface)
{
notBlank(serviceId, "serviceId");
notNull(serviceInterface, "serviceInterface");
// module may be null.
ServiceDef def = _moduleDef.getServiceDef(serviceId);
// RegistryImpl should already have checked that the service exists.
assert def != null;
Object service = findOrCreate(def, null);
try
{
return serviceInterface.cast(service);
}
catch (ClassCastException ex)
{
// This may be overkill: I don't know how this could happen
// given that the return type of the method determines
// the service interface.
throw new RuntimeException(IOCMessages.serviceWrongInterface(serviceId, def
.getServiceInterface(), serviceInterface));
}
}
public Set<DecoratorDef> findMatchingDecoratorDefs(ServiceDef serviceDef)
{
Set<DecoratorDef> result = newSet();
for (DecoratorDef def : _moduleDef.getDecoratorDefs())
{
if (def.matches(serviceDef)) result.add(def);
}
return result;
}
public List<ServiceDecorator> findDecoratorsForService(String serviceId)
{
ServiceDef sd = _moduleDef.getServiceDef(serviceId);
return _registry.findDecoratorsForService(sd);
}
@SuppressWarnings("unchecked")
public Collection<String> findServiceIdsForInterface(Class serviceInterface)
{
notNull(serviceInterface, "serviceInterface");
Collection<String> result = newList();
for (String id : _moduleDef.getServiceIds())
{
ServiceDef def = _moduleDef.getServiceDef(id);
if (serviceInterface.isAssignableFrom(def.getServiceInterface())) result.add(id);
}
return result;
}
/**
* Locates the service proxy for a particular service (from the service definition).
* <p/>
* Access is synchronized via {@link #MUTEX}.
*
* @param def defines the service
* @param eagerLoadProxies TODO
* @return the service proxy
*/
private Object findOrCreate(ServiceDef def, List<EagerLoadServiceProxy> eagerLoadProxies)
{
synchronized (MUTEX)
{
String key = def.getServiceId();
Object result = _services.get(key);
if (result == null)
{
result = create(def, eagerLoadProxies);
_services.put(key, result);
}
return result;
}
}
public void eagerLoadServices()
{
List<EagerLoadServiceProxy> proxies = newList();
synchronized (MUTEX)
{
for (String serviceId : _moduleDef.getServiceIds())
{
ServiceDef def = _moduleDef.getServiceDef(serviceId);
if (def.isEagerLoad()) findOrCreate(def, proxies);
}
for (EagerLoadServiceProxy proxy : proxies)
proxy.eagerLoadService();
}
}
/**
* Creates the service and updates the cache of created services. Access is synchronized via
* {@link #MUTEX}.
*
* @param eagerLoadProxies a list into which any eager loaded proxies should be added
*/
private Object create(ServiceDef def, List<EagerLoadServiceProxy> eagerLoadProxies)
{
String serviceId = def.getServiceId();
Logger logger = _registry.getServiceLogger(serviceId);
if (logger.isDebugEnabled()) logger.debug(IOCMessages.creatingService(serviceId));
try
{
ServiceBuilderResources resources = new ServiceResourcesImpl(_registry, this, def, _classFactory, logger);
// Build up a stack of operations that will be needed to realize the service
// (by the proxy, at a later date).
ObjectCreator creator = def.createServiceCreator(resources);
Class serviceInterface = def.getServiceInterface();
// For non-proxyable services, we immediately create the service implementation
// and return it. There's no interface to proxy, which throws out the possibility of
// deferred instantiation, service lifecycles, and decorators.
if (!serviceInterface.isInterface()) return creator.createObject();
creator = new LifecycleWrappedServiceCreator(_registry, def.getServiceScope(), resources, creator);
// Don't allow the core IOC services services to be decorated.
if (!TapestryIOCModule.class.equals(_moduleDef.getBuilderClass()))
creator = new InterceptorStackBuilder(this, serviceId, creator);
// Add a wrapper that checks for recursion.
creator = new RecursiveServiceCreationCheckWrapper(def, creator, logger);
JustInTimeObjectCreator delegate = new JustInTimeObjectCreator(_tracker, creator, serviceId);
Object proxy = createProxy(resources, delegate);
_registry.addRegistryShutdownListener(delegate);
// Occasionally service A may invoke service B from its service builder method; if
// service B
// is eager loaded, we'll hit this method but eagerLoadProxies will be null. That's OK
// ... service B
// is being realized anyway.
if (def.isEagerLoad() && eagerLoadProxies != null) eagerLoadProxies.add(delegate);
_tracker.setStatus(serviceId, Status.VIRTUAL);
return proxy;
}
catch (Exception ex)
{
throw new RuntimeException(IOCMessages.errorBuildingService(serviceId, def, ex), ex);
}
}
public Object getModuleBuilder()
{
synchronized (MUTEX)
{
if (_moduleBuilder == null) _moduleBuilder = instantiateModuleBuilder();
return _moduleBuilder;
}
}
/**
* Access synchronized by MUTEX.
*/
private Object instantiateModuleBuilder()
{
Class builderClass = _moduleDef.getBuilderClass();
Constructor[] constructors = builderClass.getConstructors();
if (constructors.length == 0) throw new RuntimeException(IOCMessages.noPublicConstructors(builderClass));
if (constructors.length > 1)
{
// Sort the constructors ascending by number of parameters (descending); this is really
// just to allow the test suite to work properly across different JVMs (which will
// often order the constructors differently).
Comparator<Constructor> comparator = new Comparator<Constructor>()
{
public int compare(Constructor c1, Constructor c2)
{
return c2.getParameterTypes().length - c1.getParameterTypes().length;
}
};
Arrays.sort(constructors, comparator);
_logger.warn(IOCMessages.tooManyPublicConstructors(builderClass, constructors[0]));
}
Constructor constructor = constructors[0];
if (_insideConstructor)
throw new RuntimeException(IOCMessages.recursiveModuleConstructor(builderClass, constructor));
ObjectLocator locator = new ObjectLocatorImpl(_registry, this);
Map<Class, Object> parameterDefaults = newMap();
parameterDefaults.put(Logger.class, _logger);
parameterDefaults.put(ObjectLocator.class, locator);
Throwable fail = null;
try
{
_insideConstructor = true;
Object[] parameterValues = InternalUtils.calculateParameters(locator, parameterDefaults,
constructor.getParameterTypes(),
constructor.getParameterAnnotations());
return constructor.newInstance(parameterValues);
}
catch (InvocationTargetException ex)
{
fail = ex.getTargetException();
}
catch (Exception ex)
{
fail = ex;
}
finally
{
_insideConstructor = false;
}
throw new RuntimeException(IOCMessages.instantiateBuilderError(builderClass, fail), fail);
}
private Object createProxy(ServiceResources resources, ObjectCreator creator)
{
String serviceId = resources.getServiceId();
Class serviceInterface = resources.getServiceInterface();
String toString = format("<Proxy for %s(%s)>", serviceId, serviceInterface.getName());
return createProxyInstance(creator, serviceId, serviceInterface, toString);
}
private Object createProxyInstance(ObjectCreator creator, String serviceId, Class serviceInterface,
String description)
{
ServiceProxyToken token = SerializationSupport.createToken(serviceId);
ClassFab classFab = _registry.newClass(serviceInterface);
classFab.addField("_creator", Modifier.PRIVATE | Modifier.FINAL, ObjectCreator.class);
classFab.addField("_token", Modifier.PRIVATE | Modifier.FINAL, ServiceProxyToken.class);
classFab.addConstructor(new Class[]{ObjectCreator.class, ServiceProxyToken.class}, null,
"{ _creator = $1; _token = $2; }");
// Make proxies serializable by writing the token to the stream.
classFab.addInterface(Serializable.class);
// This is the "magic" signature that allows an object to substitute some other
// object for itself.
MethodSignature writeReplaceSig = new MethodSignature(Object.class, "writeReplace", null,
new Class[]{ObjectStreamException.class});
classFab.addMethod(Modifier.PRIVATE, writeReplaceSig, "return _token;");
// Now delegate all the methods.
String body = format("return (%s) _creator.createObject();", serviceInterface.getName());
MethodSignature sig = new MethodSignature(serviceInterface, "_delegate", null, null);
classFab.addMethod(Modifier.PRIVATE, sig, body);
classFab.proxyMethodsToDelegate(serviceInterface, "_delegate()", description);
Class proxyClass = classFab.createClass();
try
{
return proxyClass.getConstructors()[0].newInstance(creator, token);
}
catch (Exception ex)
{
// Exceptions should not happen.
throw new RuntimeException(ex.getMessage(), ex);
}
}
public Set<ContributionDef> getContributorDefsForService(String serviceId)
{
Set<ContributionDef> result = newSet();
for (ContributionDef def : _moduleDef.getContributionDefs())
{
if (def.getServiceId().equals(serviceId)) result.add(def);
}
return result;
}
public ServiceDef getServiceDef(String serviceId)
{
return _moduleDef.getServiceDef(serviceId);
}
public String getLoggerName()
{
return _moduleDef.getLoggerName();
}
}