methodresultcache.java

torque服务器源代码

package org.apache.torque.manager;

/* ====================================================================
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 * reserved.
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 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Apache" and "Apache Software Foundation" and
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 * 5. Products derived from this software may not be called "Apache",
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import java.io.Serializable;
import java.util.HashMap;
import java.util.Map;

import org.apache.commons.pool.ObjectPool;
import org.apache.commons.pool.impl.StackObjectPool;

import org.apache.jcs.access.GroupCacheAccess;
import org.apache.jcs.access.exception.CacheException;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.apache.torque.TorqueException;

/**
 * This class provides a cache for convenient storage of method
 * results.
 *
 * @author <a href="mailto:[e-mail]">John McNally</a>
 * @version $Id: MethodResultCache.java,v 1.19 2003/08/25 16:33:22 henning Exp $
 */
public class MethodResultCache
{
    private ObjectPool pool;
    private GroupCacheAccess jcsCache;
    private Map groups;

    /** Logging */
    private static Log log = LogFactory.getLog(MethodResultCache.class);

    public MethodResultCache(GroupCacheAccess cache)
        throws TorqueException
    {
        this.jcsCache = cache;
        groups = new HashMap();
        pool = new StackObjectPool(new MethodCacheKey.Factory(), 10000);
    }

    /**
     * Allows subclasses to have ctors that do not require a cache.
     * This is used by NullMethodResultCache which has no-op versions
     * of all methods.
     */
    protected MethodResultCache()
    {
    }

    public void clear()
    {
        if (jcsCache != null)
        {
            try
            {
                jcsCache.remove();
                groups.clear();
            }
            catch (CacheException ce)
            {
                log.error(new TorqueException(
                    "Could not clear cache due to internal JCS error.", ce));
            }
        }
    }

    protected Object getImpl(MethodCacheKey key)
    {
        Object result = null;
        if (jcsCache != null)
        {
            synchronized (this)
            {
                result = jcsCache.getFromGroup(key, key.getGroupKey());
            }
        }

        if (result != null)
        {
            if (log.isDebugEnabled())
            {
                log.debug("MethodResultCache saved expensive operation: " + key);
            }
        }
        return result;
    }


    protected Object putImpl(MethodCacheKey key, Object value)
        throws TorqueException
    {
        //register the group, if this is the first occurrence
        String group = key.getGroupKey();
        if (!groups.containsKey(group))
        {
            groups.put(group, null);
        }

        Object old = null;
        if (jcsCache != null)
        {
            try
            {
                synchronized (this)
                {
                    old = jcsCache.getFromGroup(key, group);
                    jcsCache.putInGroup(key, group, value);
                }
            }
            catch (CacheException ce)
            {
                throw new TorqueException
                    ("Could not cache due to internal JCS error", ce);
            }
        }
        return old;
    }

    protected Object removeImpl(MethodCacheKey key)
        throws TorqueException
    {
        Object old = null;
        if (jcsCache != null)
        {
            synchronized (this)
            {
                old = jcsCache.getFromGroup(key, key.getGroupKey());
                jcsCache.remove(key, key.getGroupKey());
            }
        }
        return old;
    }


    public Object get(Serializable instanceOrClass, String method)
    {
        Object result = null;
        if (jcsCache != null)
        {
            try
            {
                MethodCacheKey key = (MethodCacheKey) pool.borrowObject();
                key.init(instanceOrClass, method);
                result = getImpl(key);
                try
                {
                    pool.returnObject(key);
                }
                catch (Exception e)
                {
                    log.warn(
                        "Nonfatal error.  Could not return key to pool", e);
                }
            }
            catch (Exception e)
            {
                log.error("", e);
            }
        }
        return result;
    }

    public Object get(Serializable instanceOrClass, String method,
                      Serializable arg1)
    {
        Object result = null;
        if (jcsCache != null)
        {
            try
            {
                MethodCacheKey key = (MethodCacheKey) pool.borrowObject();
                key.init(instanceOrClass, method, arg1);
                result = getImpl(key);
                try
                {
                    pool.returnObject(key);
                }
                catch (Exception e)
                {
                    log.warn(
                        "Nonfatal error.  Could not return key to pool", e);
                }
            }
            catch (Exception e)
            {
                log.error("", e);
            }
        }
        return result;
    }

    public Object get(Serializable instanceOrClass, String method,
                      Serializable arg1, Serializable arg2)
    {
        Object result = null;
        if (jcsCache != null)
        {
            try
            {
                MethodCacheKey key = (MethodCacheKey) pool.borrowObject();
                key.init(instanceOrClass, method, arg1, arg2);
                result = getImpl(key);
                try
                {
                    pool.returnObject(key);
                }
                catch (Exception e)
                {
                    log.warn(
                        "Nonfatal error.  Could not return key to pool", e);
                }
            }
            catch (Exception e)
            {
                log.error("", e);
            }
        }
        return result;
    }

    public Object get(Serializable instanceOrClass, String method,
                      Serializable arg1, Serializable arg2,
                      Serializable arg3)
    {
        Object result = null;
        if (jcsCache != null)
        {
            try
            {
                MethodCacheKey key = (MethodCacheKey) pool.borrowObject();
                key.init(instanceOrClass, method, arg1, arg2, arg3);
                result = getImpl(key);
                try
                {
                    pool.returnObject(key);
                }