    001    // Copyright 2006, 2008, 2010 The Apache Software Foundation
    002    //
    003    // Licensed under the Apache License, Version 2.0 (the "License");
    004    // you may not use this file except in compliance with the License.
    005    // You may obtain a copy of the License at
    006    //
    007    // http://www.apache.org/licenses/LICENSE-2.0
    008    //
    009    // Unless required by applicable law or agreed to in writing, software
    010    // distributed under the License is distributed on an "AS IS" BASIS,
    011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    012    // See the License for the specific language governing permissions and
    013    // limitations under the License.
    014
    015    package org.apache.tapestry5.ioc.internal.services;
    016
    017    import org.apache.tapestry5.ioc.ObjectCreator;
    018    import org.apache.tapestry5.ioc.services.PerThreadValue;
    019    import org.apache.tapestry5.ioc.services.PerthreadManager;
    020
    021    /**
    022     * Provides per-thread implementations of services.
    023     */
    024    public class PerThreadServiceCreator implements ObjectCreator
    025    {
    026        private final PerThreadValue<Object> perThreadValue;
    027
    028        private final ObjectCreator delegate;
    029
    030        public PerThreadServiceCreator(PerthreadManager perthreadManager, ObjectCreator delegate)
    031        {
    032            perThreadValue = perthreadManager.createValue();
    033
    034            this.delegate = delegate;
    035        }
    036
    037        /**
    038         * For each thread, the first call will use the delegate {@link org.apache.tapestry5.ioc.ObjectCreator} to create
    039         * an instance, and later calls will reuse the same per-thread instance. The instance is stored in the
    040         * {@link org.apache.tapestry5.ioc.services.PerthreadManager} and will be released at the end of the request.
    041         */
    042        public Object createObject()
    043        {
    044            if (perThreadValue.exists())
    045                return perThreadValue.get();
    046
    047            return perThreadValue.set(delegate.createObject());
    048        }
    049    }