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/*
 * JBoss, Home of Professional Open Source
 * Copyright 2008, Red Hat, Inc., and individual contributors
 * by the @authors tag. See the copyright.txt in the distribution for a
 * full listing of individual contributors.
 *
 * 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.weld.bean.proxy;

import java.lang.reflect.Type;
import java.util.Set;

import javax.enterprise.inject.spi.Bean;

import org.jboss.weld.Container;
import org.jboss.weld.bean.RIBean;
import org.jboss.weld.bootstrap.api.ServiceRegistry;
import org.jboss.weld.logging.BeanLogger;
import org.jboss.weld.serialization.spi.BeanIdentifier;
import org.jboss.weld.serialization.spi.ContextualStore;
import org.jboss.weld.util.Function;
import org.jboss.weld.util.Proxies;
import org.jboss.weld.util.Proxies.TypeInfo;
import org.jboss.weld.util.cache.ComputingCache;
import org.jboss.weld.util.cache.ComputingCacheBuilder;
import org.jboss.weld.util.collections.ImmutableSet;
import org.jboss.weld.util.reflection.Reflections;

/**
 * A proxy pool for holding scope adaptors (client proxies)
 *
 * @author Nicklas Karlsson
 * @see org.jboss.weld.bean.proxy.ProxyMethodHandler
 */
public class ClientProxyProvider {

    private static final Object BEAN_NOT_PROXYABLE_MARKER = new Object();

    private class CreateClientProxy implements Function, Object> {
        @Override
        public Object apply(Bean from) {
            if (Proxies.isTypesProxyable(from, services())) {
                return createClientProxy(from);
            } else {
                return BEAN_NOT_PROXYABLE_MARKER;
            }
        }
    };

    private class CreateClientProxyForType implements Function {
        @Override
        public Object apply(RequestedTypeHolder input) {
            // First, collect all interfaces
            ImmutableSet.Builder types = ImmutableSet.builder();
            for (Type type : input.bean.getTypes()) {
                if (Reflections.getRawType(type).isInterface()) {
                    types.add(type);
                }
            }
            // Object.class as a required type is often used for lookup if no required type is available (e.g. integration with frameworks where
            // only names are used to reference beans). In this case, try to use the bean class (or type of a producer) instead of Object.
            if (input.requestedType.equals(Object.class)) {
                Type beanType;
                if (input.bean instanceof RIBean) {
                    RIBean riBean = (RIBean) input.bean;
                    beanType = riBean.getType();
                } else {
                    beanType = input.bean.getBeanClass();
                }
                if (Proxies.isTypeProxyable(beanType, services())) {
                    return createClientProxy(input.bean, types.add(beanType).build());
                }
            }
            // If the requested type if proxyable use requested type + bean interfaces
            if (Proxies.isTypeProxyable(input.requestedType, services())) {
                return createClientProxy(input.bean, types.add(input.requestedType).build());
            }
            /*
             * Requested type is not proxyable. Check whether a proxyable subtype exists within the set of
             * bean types that we could use instead.
             */
            Class requestedRawType = Reflections.getRawType(input.requestedType);
            for (Type type : input.bean.getTypes()) {
                if (requestedRawType.isAssignableFrom(Reflections.getRawType(type)) && Proxies.isTypeProxyable(type, services())) {
                    return createClientProxy(input.bean, types.add(type).build());
                }
            }
            return BEAN_NOT_PROXYABLE_MARKER;
        }
    }

    private static class RequestedTypeHolder {
        private final Type requestedType;
        private final Bean bean;

        private RequestedTypeHolder(Type requestedType, Bean bean) {
            this.requestedType = requestedType;
            this.bean = bean;
        }

        @Override
        public int hashCode() {
            final int prime = 31;
            int result = 1;
            result = prime * result + ((bean == null) ? 0 : bean.hashCode());
            result = prime * result + ((requestedType == null) ? 0 : requestedType.hashCode());
            return result;
        }

        @Override
        public boolean equals(Object obj) {
            if (this == obj) {
                return true;
            }
            if (obj == null) {
                return false;
            }
            if (getClass() != obj.getClass()) {
                return false;
            }
            RequestedTypeHolder other = (RequestedTypeHolder) obj;
            if (bean == null) {
                if (other.bean != null) {
                    return false;
                }
            } else if (!bean.equals(other.bean)) {
                return false;
            }
            if (requestedType == null) {
                if (other.requestedType != null) {
                    return false;
                }
            } else if (!requestedType.equals(other.requestedType)) {
                return false;
            }
            return true;
        }
    }

    /**
     * A container/cache for previously created proxies
     *
     * @author Nicklas Karlsson
     */
    private final ComputingCache, Object> beanTypeClosureProxyPool;
    private final ComputingCache requestedTypeClosureProxyPool;

    private final String contextId;
    private volatile ServiceRegistry services;

    /**
     *
     * @param contextId
     */
    public ClientProxyProvider(String contextId) {
        ComputingCacheBuilder cacheBuilder = ComputingCacheBuilder.newBuilder();
        this.beanTypeClosureProxyPool = cacheBuilder.build(new CreateClientProxy());
        this.requestedTypeClosureProxyPool = cacheBuilder.build(new CreateClientProxyForType());
        this.contextId = contextId;
    }

    private ServiceRegistry services() {
        if (services == null) {
            synchronized (this) {
                if (services == null) {
                    this.services = Container.instance(contextId).services();
                }
            }
        }
        return this.services;
    }

    /**
     * Creates a Javassist scope adaptor (client proxy) for a bean
     * 

* Creates a Javassist proxy factory. Gets the type info. Sets the interfaces * and superclass to the factory. Hooks in the MethodHandler and creates the * proxy. * * @param bean The bean to proxy * @param beanIndex The index to the bean in the manager bean list * @return A Javassist proxy * @throws InstantiationException When the proxy couldn't be created * @throws IllegalAccessException When the proxy couldn't be created */ private T createClientProxy(Bean bean) throws RuntimeException { return createClientProxy(bean, bean.getTypes()); } private T createClientProxy(Bean bean, Set types) { BeanIdentifier id = Container.instance(contextId).services().get(ContextualStore.class).putIfAbsent(bean); if (id == null) { throw BeanLogger.LOG.beanIdCreationFailed(bean); } BeanInstance beanInstance = new ContextBeanInstance(bean, id, contextId); TypeInfo typeInfo = TypeInfo.of(types); T proxy = new ClientProxyFactory(contextId, typeInfo.getSuperClass(), types, bean).create(beanInstance); BeanLogger.LOG.createdNewClientProxyType(proxy.getClass(), bean, id); return proxy; } public T getClientProxy(final Bean bean) { T proxy = beanTypeClosureProxyPool.getCastValue(bean); if (proxy == BEAN_NOT_PROXYABLE_MARKER) { throw Proxies.getUnproxyableTypesException(bean, services()); } BeanLogger.LOG.lookedUpClientProxy(proxy.getClass(), bean); return proxy; } /** * Gets a client proxy for a bean *

* Looks for a proxy in the pool. If not found, one is created and added to * the pool if the create argument is true. * * @param bean The bean to get a proxy to * @return the client proxy for the bean */ public T getClientProxy(final Bean bean, Type requestedType) { // let's first try to use the proxy that implements all the bean types T proxy = beanTypeClosureProxyPool.getCastValue(bean); if (proxy == BEAN_NOT_PROXYABLE_MARKER) { /* * the bean may have a type that is not proxyable - this is not a problem as long as the unproxyable * type is not in the type closure of the requested type * https://issues.jboss.org/browse/WELD-1052 */ proxy = requestedTypeClosureProxyPool.getCastValue(new RequestedTypeHolder(requestedType, bean)); if (proxy == BEAN_NOT_PROXYABLE_MARKER) { throw Proxies.getUnproxyableTypeException(requestedType, services()); } } BeanLogger.LOG.lookedUpClientProxy(proxy.getClass(), bean); return proxy; } /** * Gets a string representation * * @return The string representation */ @Override public String toString() { return "Proxy pool with " + beanTypeClosureProxyPool.size() + " bean type proxies and " + requestedTypeClosureProxyPool.size() + "injection point type proxies."; } public void clear() { this.beanTypeClosureProxyPool.clear(); this.requestedTypeClosureProxyPool.clear(); } }