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Groovy example source code file (ThreadManagedMetaBeanProperty.java)

This example Groovy source code file (ThreadManagedMetaBeanProperty.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Groovy tags/keywords

cachedclass, class, closure, managedconcurrentmap, managedconcurrentmap, metamethod, object, object, reflection, string, string, threadboundgetter, threadboundsetter, threadboundsetter, threading, threadmanagedmetabeanproperty, threads

The Groovy ThreadManagedMetaBeanProperty.java source code

/*
 * Copyright 2003-2007 the original author or authors.
 *
 * 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.codehaus.groovy.runtime.metaclass;

import groovy.lang.Closure;
import groovy.lang.MetaBeanProperty;
import groovy.lang.MetaMethod;
import org.codehaus.groovy.reflection.CachedClass;
import org.codehaus.groovy.reflection.ReflectionCache;
import org.codehaus.groovy.util.ManagedConcurrentMap;
import org.codehaus.groovy.util.ReferenceBundle;

import java.lang.reflect.Modifier;
import java.util.concurrent.ConcurrentHashMap;

/**
 * This MetaBeanProperty will create a pseudo property whose value is bound to an object
 * using weak references. The values will go out of scope and be garbage collected when
 * the the object is collected
 *
 * In fact, this class should be called ExpandoProperty.
 *
 * @author Graeme Rocher
 * @author Alex Tkachman
 * @since 1.5
 */
public class ThreadManagedMetaBeanProperty extends MetaBeanProperty {
    private static final ConcurrentHashMap<String,ManagedConcurrentMap> PROPNAME_TO_MAP = new ConcurrentHashMap();

    private final ManagedConcurrentMap instance2Prop;

    private Class declaringClass;
    private ThreadBoundGetter getter;
    private ThreadBoundSetter setter;
    private Object initialValue;
    private Closure initialValueCreator;
    
    private static final ReferenceBundle SOFT_BUNDLE = ReferenceBundle.getSoftBundle();

    /**
     * Retrieves the initial value of the ThreadBound property
     *
     * @return The initial value
     */
    public synchronized Object getInitialValue() {
        return getInitialValue(null);
    }

    public synchronized Object getInitialValue(Object object) {
        if (initialValueCreator != null) {
            return initialValueCreator.call(object);
        }
        return initialValue;

    }

    /**
     * Closure responsible for creating the initial value of thread-managed bean properties
     *
     * @param callable The closure responsible for creating the initial value
     */
    public void setInitialValueCreator(Closure callable) {
        this.initialValueCreator = callable;
    }

    /**
     * Constructs a new ThreadManagedBeanProperty for the given arguments
     *
     * @param declaringClass The class that declares the property
     * @param name           The name of the property
     * @param type           The type of the property
     * @param iv             The properties initial value
     */
    public ThreadManagedMetaBeanProperty(Class declaringClass, String name, Class type, Object iv) {
        super(name, type, null, null);
        this.type = type;
        this.declaringClass = declaringClass;

        this.getter = new ThreadBoundGetter(name);
        this.setter = new ThreadBoundSetter(name);
        initialValue = iv;

        instance2Prop = getInstance2PropName(name);
    }

    /**
     * Constructs a new ThreadManagedBeanProperty for the given arguments
     *
     * @param declaringClass      The class that declares the property
     * @param name                The name of the property
     * @param type                The type of the property
     * @param initialValueCreator The closure responsible for creating the initial value
     */
    public ThreadManagedMetaBeanProperty(Class declaringClass, String name, Class type, Closure initialValueCreator) {
        super(name, type, null, null);
        this.type = type;
        this.declaringClass = declaringClass;

        this.getter = new ThreadBoundGetter(name);
        this.setter = new ThreadBoundSetter(name);
        this.initialValueCreator = initialValueCreator;

        instance2Prop = getInstance2PropName(name);
    }

    private static ManagedConcurrentMap getInstance2PropName(String name) {
        ManagedConcurrentMap res = PROPNAME_TO_MAP.get(name);
        if (res == null) {
            res = new ManagedConcurrentMap(SOFT_BUNDLE);
            ManagedConcurrentMap ores = PROPNAME_TO_MAP.putIfAbsent(name, res);
            if (ores != null)
              return ores;
        }
        return res;
    }

    /* (non-Javadoc)
      * @see groovy.lang.MetaBeanProperty#getGetter()
      */
    public MetaMethod getGetter() {
        return this.getter;
    }

    /* (non-Javadoc)
      * @see groovy.lang.MetaBeanProperty#getSetter()
      */
    public MetaMethod getSetter() {
        return this.setter;
    }


    /**
     * Accesses the ThreadBound state of the property as a getter
     *
     * @author Graeme Rocher
     */
    class ThreadBoundGetter extends MetaMethod {
        private final String name;


        public ThreadBoundGetter(String name) {
            setParametersTypes(new CachedClass[0]);
            this.name = getGetterName(name, type);
        }


        public int getModifiers() {
            return Modifier.PUBLIC;
        }

        public String getName() {
            return name;
        }

        public Class getReturnType() {
            return type;
        }

        public CachedClass getDeclaringClass() {
            return ReflectionCache.getCachedClass(declaringClass);
        }

        /* (non-Javadoc)
           * @see groovy.lang.MetaMethod#invoke(java.lang.Object, java.lang.Object[])
           */
        public Object invoke(Object object, Object[] arguments) {
            return instance2Prop.getOrPut(object, getInitialValue()).getValue();
        }
    }

    /**
     * Sets the ThreadBound state of the property like a setter
     */
    private class ThreadBoundSetter extends MetaMethod {
        private final String name;

        public ThreadBoundSetter(String name) {
            setParametersTypes (new CachedClass [] {ReflectionCache.getCachedClass(type)} );
            this.name = getSetterName(name);
        }


        public int getModifiers() {
            return Modifier.PUBLIC;
        }

        /* (non-Javadoc)
         * @see groovy.lang.MetaMethod#getName()
         */

        public String getName() {
            return name;
        }

        public Class getReturnType() {
            return type;
        }

        public CachedClass getDeclaringClass() {
            return ReflectionCache.getCachedClass(declaringClass);
        }

        /* (non-Javadoc)
           * @see groovy.lang.MetaMethod#invoke(java.lang.Object, java.lang.Object[])
           */
        public Object invoke(Object object, Object[] arguments) {
            instance2Prop.put(object, arguments[0]);
            return null;
        }
    }
}

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