Jetty example source code file (ResourceCache.java)

This example Jetty source code file (ResourceCache.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 - Jetty tags/keywords

abstractlifecycle, buffer, buffer, content, content, httpcontent, inputstream, io, ioexception, ioexception, resource, resource, resourcecache, string, util, view

The Jetty ResourceCache.java source code

// ========================================================================
// Copyright 2000-2005 Mort Bay Consulting Pty. Ltd.
// ------------------------------------------------------------------------
// 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.mortbay.jetty;

import java.io.IOException;
import java.io.InputStream;
import java.io.Serializable;
import java.util.HashMap;
import java.util.Map;

import org.mortbay.component.AbstractLifeCycle;
import org.mortbay.io.Buffer;
import org.mortbay.io.ByteArrayBuffer;
import org.mortbay.io.View;
import org.mortbay.resource.Resource;
import org.mortbay.resource.ResourceFactory;


/* ------------------------------------------------------------ */
/** 
 * @author Greg Wilkins
 */
public class ResourceCache extends AbstractLifeCycle implements Serializable
{   
    private int _maxCachedFileSize =1024*1024;
    private int _maxCachedFiles=2048;
    private int _maxCacheSize =16*1024*1024;
    private MimeTypes _mimeTypes;
    
    protected transient Map _cache;
    protected transient int _cachedSize;
    protected transient int _cachedFiles;
    protected transient Content _mostRecentlyUsed;
    protected transient Content _leastRecentlyUsed;


    /* ------------------------------------------------------------ */
    /** Constructor.
     */
    public ResourceCache(MimeTypes mimeTypes)
    {
        _mimeTypes=mimeTypes;
    }

    /* ------------------------------------------------------------ */
    public int getCachedSize()
    {
        return _cachedSize;
    }
    
    /* ------------------------------------------------------------ */
    public int getCachedFiles()
    {
        return _cachedFiles;
    }
    
    
    /* ------------------------------------------------------------ */
    public int getMaxCachedFileSize()
    {
        return _maxCachedFileSize;
    }

    /* ------------------------------------------------------------ */
    public void setMaxCachedFileSize(int maxCachedFileSize)
    {
        _maxCachedFileSize = maxCachedFileSize;
        flushCache();
    }

    /* ------------------------------------------------------------ */
    public int getMaxCacheSize()
    {
        return _maxCacheSize;
    }

    /* ------------------------------------------------------------ */
    public void setMaxCacheSize(int maxCacheSize)
    {
        _maxCacheSize = maxCacheSize;
        flushCache();
    }

    /* ------------------------------------------------------------ */
    /**
     * @return Returns the maxCachedFiles.
     */
    public int getMaxCachedFiles()
    {
        return _maxCachedFiles;
    }
    
    /* ------------------------------------------------------------ */
    /**
     * @param maxCachedFiles The maxCachedFiles to set.
     */
    public void setMaxCachedFiles(int maxCachedFiles)
    {
        _maxCachedFiles = maxCachedFiles;
    }
    
    /* ------------------------------------------------------------ */
    public void flushCache()
    {
        if (_cache!=null)
        {
            synchronized(this)
            {
                _cache.clear();
                _cachedSize=0;
                _cachedFiles=0;
                _mostRecentlyUsed=null;
                _leastRecentlyUsed=null;
            }
        }
    }

    /* ------------------------------------------------------------ */
    /** Get a Entry from the cache.
     * Get either a valid entry object or create a new one if possible.
     *
     * @param pathInContext The key into the cache
     * @param factory If no matching entry is found, this {@link ResourceFactory} will be used to create the {@link Resource} 
     *                for the new enry that is created.
     * @return The entry matching <code>pathInContext, or a new entry if no matching entry was found
     */
    public Content lookup(String pathInContext, ResourceFactory factory)
        throws IOException
    {
        Content content=null;
        
        // Look up cache operations
        synchronized(_cache)
        {
            // Look for it in the cache
            content = (Content)_cache.get(pathInContext);
        
            if (content!=null && content.isValid())
            {
                return content;
            }    
        }
        Resource resource=factory.getResource(pathInContext);
        return load(pathInContext,resource);
    }
    
    public Content lookup(String pathInContext, Resource resource)
        throws IOException
    {
        Content content=null;
        
        // Look up cache operations
        synchronized(_cache)
        {
            // Look for it in the cache
            content = (Content)_cache.get(pathInContext);
        
            if (content!=null && content.isValid())
            {
                return content;
            }    
        }
        return load(pathInContext,resource);
    }

    private Content load(String pathInContext, Resource resource)
        throws IOException
    {
        Content content=null;
        if (resource!=null && resource.exists() && !resource.isDirectory())
        {
            long len = resource.length();
            if (len>0 && len<_maxCachedFileSize && len<_maxCacheSize)
            {
                content = new Content(resource);
                fill(content);

                synchronized(_cache)
                {
                    // check that somebody else did not fill this spot.
                    Content content2 =(Content)_cache.get(pathInContext);
                    if (content2!=null)
                    {
                        content.release();
                        return content2;
                    }

                    int must_be_smaller_than=_maxCacheSize-(int)len;
                    while(_cachedSize>must_be_smaller_than || (_maxCachedFiles>0 && _cachedFiles>=_maxCachedFiles))
                        _leastRecentlyUsed.invalidate();
                    content.cache(pathInContext);
                    
                    return content;
                }
            }
        }

        return null; 
    }


    /* ------------------------------------------------------------ */
    public synchronized void doStart()
        throws Exception
    {
        _cache=new HashMap();
        _cachedSize=0;
        _cachedFiles=0;
    }

    /* ------------------------------------------------------------ */
    /** Stop the context.
     */
    public void doStop()
        throws InterruptedException
    {
        flushCache();
    }

    /* ------------------------------------------------------------ */
    protected void fill(Content content)
        throws IOException
    {
        try
        {
            InputStream in = content.getResource().getInputStream();
            int len=(int)content.getResource().length();
            Buffer buffer = new ByteArrayBuffer(len);
            buffer.readFrom(in,len);
            in.close();
            content.setBuffer(buffer);
        }
        finally
        {
            content.getResource().release();
        }
    }
    
    /* ------------------------------------------------------------ */
    /* ------------------------------------------------------------ */
    /** MetaData associated with a context Resource.
     */
    public class Content implements HttpContent
    {
        String _key;
        Resource _resource;
        long _lastModified;
        Content _prev;
        Content _next;
        
        Buffer _lastModifiedBytes;
        Buffer _contentType;
        Buffer _buffer;

        /* ------------------------------------------------------------ */
        Content(Resource resource)
        {
            _resource=resource;

            _next=this;
            _prev=this;
            _contentType=_mimeTypes.getMimeByExtension(_resource.toString());
            
            _lastModified=resource.lastModified();
        }

        /* ------------------------------------------------------------ */
        void cache(String pathInContext)
        {
            _key=pathInContext;
            _next=_mostRecentlyUsed;
            _mostRecentlyUsed=this;
            if (_next!=null)
                _next._prev=this;
            _prev=null;
            if (_leastRecentlyUsed==null)
                _leastRecentlyUsed=this;

            _cache.put(_key,this);
            _cachedSize+=_buffer.length();
            _cachedFiles++;
            if (_lastModified!=-1)
                _lastModifiedBytes=new ByteArrayBuffer(HttpFields.formatDate(_lastModified,false));
        }

        /* ------------------------------------------------------------ */
        public String getKey()
        {
            return _key;
        }

        /* ------------------------------------------------------------ */
        public boolean isCached()
        {
            return _key!=null;
        }

        /* ------------------------------------------------------------ */
        public Resource getResource()
        {
            return _resource;
        }
        
        /* ------------------------------------------------------------ */
        boolean isValid()
        {
            if (_lastModified==_resource.lastModified())
            {
                if (_mostRecentlyUsed!=this)
                {
                    Content tp = _prev;
                    Content tn = _next;

                    _next=_mostRecentlyUsed;
                    _mostRecentlyUsed=this;
                    if (_next!=null)
                        _next._prev=this;
                    _prev=null;

                    if (tp!=null)
                        tp._next=tn;
                    if (tn!=null)
                        tn._prev=tp;

                    if (_leastRecentlyUsed==this && tp!=null)
                        _leastRecentlyUsed=tp;
                }
                return true;
            }

            invalidate();
            return false;
        }

        /* ------------------------------------------------------------ */
        public void invalidate()
        {
            synchronized(this)
            {
                // Invalidate it
                _cache.remove(_key);
                _key=null;
                _cachedSize=_cachedSize-(int)_buffer.length();
                _cachedFiles--;
                
                if (_mostRecentlyUsed==this)
                    _mostRecentlyUsed=_next;
                else
                    _prev._next=_next;
                
                if (_leastRecentlyUsed==this)
                    _leastRecentlyUsed=_prev;
                else
                    _next._prev=_prev;
                
                _prev=null;
                _next=null;
                _resource=null;
                
            }
        }

        /* ------------------------------------------------------------ */
        public Buffer getLastModified()
        {
            return _lastModifiedBytes;
        }

        /* ------------------------------------------------------------ */
        public Buffer getContentType()
        {
            return _contentType;
        }

        /* ------------------------------------------------------------ */
        public void setContentType(Buffer type)
        {
            _contentType=type;
        }

        /* ------------------------------------------------------------ */
        public void release()
        {
        }

        /* ------------------------------------------------------------ */
        public Buffer getBuffer()
        {
            if (_buffer==null)
                return null;
            return new View(_buffer);
        }
        
        /* ------------------------------------------------------------ */
        public void setBuffer(Buffer buffer)
        {
            _buffer=buffer;
        }

        /* ------------------------------------------------------------ */
        public long getContentLength()
        {
            if (_buffer==null)
                return -1;
            return _buffer.length();
        }

        /* ------------------------------------------------------------ */
        public InputStream getInputStream() throws IOException
        {
            return _resource.getInputStream();
        }
        
    }

}