// Copyright 2006, 2007, 2008, 2009, 2010 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.tapestry5.internal.services;
import org.apache.tapestry5.TapestryConstants;
import org.apache.tapestry5.internal.event.InvalidationEventHubImpl;
import org.apache.tapestry5.internal.parser.ComponentTemplate;
import org.apache.tapestry5.internal.parser.TemplateToken;
import org.apache.tapestry5.internal.util.MultiKey;
import org.apache.tapestry5.ioc.Location;
import org.apache.tapestry5.ioc.Resource;
import org.apache.tapestry5.ioc.annotations.Primary;
import org.apache.tapestry5.ioc.internal.util.CollectionFactory;
import org.apache.tapestry5.ioc.internal.util.URLChangeTracker;
import org.apache.tapestry5.ioc.services.ClasspathURLConverter;
import org.apache.tapestry5.model.ComponentModel;
import org.apache.tapestry5.services.InvalidationEventHub;
import org.apache.tapestry5.services.UpdateListener;
import org.apache.tapestry5.services.templates.ComponentTemplateLocator;
import java.util.Collections;
import java.util.List;
import java.util.Locale;
import java.util.Map;
/**
* Service implementation that manages a cache of parsed component templates.
*/
public final class ComponentTemplateSourceImpl extends InvalidationEventHubImpl implements ComponentTemplateSource,
UpdateListener
{
private final TemplateParser parser;
private final ComponentTemplateLocator locator;
private final URLChangeTracker tracker;
/**
* Caches from a key (combining component name and locale) to a resource. Often, many different keys will point to
* the same resource (i.e., "foo:en_US", "foo:en_UK", and "foo:en" may all be parsed from the same "foo.tml"
* resource). The resource may end up being null, meaning the template does not exist in any locale.
*/
private final Map<MultiKey, Resource> templateResources = CollectionFactory.newConcurrentMap();
/**
* Cache of parsed templates, keyed on resource.
*/
private final Map<Resource, ComponentTemplate> templates = CollectionFactory.newConcurrentMap();
private final ComponentTemplate missingTemplate = new ComponentTemplate()
{
public Map<String, Location> getComponentIds()
{
return Collections.emptyMap();
}
public Resource getResource()
{
return null;
}
public List<TemplateToken> getTokens()
{
return Collections.emptyList();
}
public boolean isMissing()
{
return true;
}
public List<TemplateToken> getExtensionPointTokens(String extensionPointId)
{
return null;
}
public boolean isExtension()
{
return false;
}
};
public ComponentTemplateSourceImpl(TemplateParser parser, @Primary
ComponentTemplateLocator templateLocator, ClasspathURLConverter classpathURLConverter)
{
this(parser, templateLocator, new URLChangeTracker(classpathURLConverter));
}
ComponentTemplateSourceImpl(TemplateParser parser, ComponentTemplateLocator locator, URLChangeTracker tracker)
{
this.parser = parser;
this.locator = locator;
this.tracker = tracker;
}
/**
* Resolves the component name to a localized {@link Resource} (using the {@link ComponentTemplateLocator} chain of
* command service). The localized resource is used as the key to a cache of {@link ComponentTemplate}s.
* <p/>
* If a template doesn't exist, then the missing ComponentTemplate is returned.
*/
public ComponentTemplate getTemplate(ComponentModel componentModel, Locale locale)
{
String componentName = componentModel.getComponentClassName();
MultiKey key = new MultiKey(componentName, locale);
// First cache is key to resource.
Resource resource = templateResources.get(key);
if (resource == null)
{
resource = locateTemplateResource(componentModel, locale);
templateResources.put(key, resource);
}
// If we haven't yet parsed the template into the cache, do so now.
ComponentTemplate result = templates.get(resource);
if (result == null)
{
result = parseTemplate(resource);
templates.put(resource, result);
}
return result;
}
private ComponentTemplate parseTemplate(Resource r)
{
// In a race condition, we may parse the same template more than once. This will likely add
// the resource to the tracker multiple times. Not likely this will cause a big issue.
if (!r.exists())
return missingTemplate;
tracker.add(r.toURL());
return parser.parseTemplate(r);
}
private Resource locateTemplateResource(ComponentModel initialModel, Locale locale)
{
ComponentModel model = initialModel;
while (model != null)
{
Resource localized = locator.locateTemplate(model, locale);
if (localized != null)
return localized;
// Otherwise, this component doesn't have its own template ... lets work up to its
// base class and check there.
model = model.getParentModel();
}
// This will be a Resource whose URL is null, which will be picked up later and force the
// return of the empty template.
return initialModel.getBaseResource().withExtension(TapestryConstants.TEMPLATE_EXTENSION);
}
/**
* Checks to see if any parsed resource has changed. If so, then all internal caches are cleared, and an
* invalidation event is fired. This is brute force ... a more targeted dependency management strategy may come
* later.
*/
public void checkForUpdates()
{
if (tracker.containsChanges())
{
tracker.clear();
templateResources.clear();
templates.clear();
fireInvalidationEvent();
}
}
public InvalidationEventHub getInvalidationEventHub()
{
return this;
}
}