cachedresource.java

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// CachedResource.java
// $Id: CachedResource.java,v 1.78 2003/01/24 14:39:59 ylafon Exp $
// (c) COPYRIGHT MIT, INRIA and Keio, 1999.
// Please first read the full copyright statement in file COPYRIGHT.html

package org.w3c.www.protocol.http.cache;

import java.io.File;

import org.w3c.util.ArrayDictionary;
import org.w3c.util.LRUAble;

import org.w3c.tools.resources.Attribute;
import org.w3c.tools.resources.AttributeHolder;
import org.w3c.tools.resources.AttributeRegistry;
import org.w3c.tools.resources.DateAttribute;
import org.w3c.tools.resources.FileAttribute;
import org.w3c.tools.resources.IntegerAttribute;
import org.w3c.tools.resources.PropertiesAttribute;
import org.w3c.tools.resources.StringArrayAttribute;
import org.w3c.tools.resources.StringAttribute;

import org.w3c.www.http.HttpEntityTag;

import org.w3c.www.protocol.http.HttpException;
import org.w3c.www.protocol.http.Reply;
import org.w3c.www.protocol.http.Request;

import org.w3c.www.mime.MimeType;

import org.w3c.jigsaw.frames.MimeTypeAttribute;

public abstract class CachedResource extends AttributeHolder 
    implements TeeMonitor, LRUAble {

    /**
     * Condition check return code - Condition existed but failed.
     */
    public static final int COND_FAILED = 1;
    /**
     * Condition check return code - Condition existed and succeeded.
     */
    public static final int COND_OK = 2;

    /**
     * The download state of the resource, currently not loaded
     */
    public static final int STATE_NOT_LOADED = 0;

    /**
     * The download state of the resource, complete content
     */
    public static final int STATE_LOAD_COMPLETE = 1;

    /**
     * The download state of the resource, partial content
     */
    public static final int STATE_LOAD_PARTIAL = 2;

    /**
     * The download state of the resource, unknown, probably an HTTP/1.0
     * reply without the Content-Length.
     */
    public static final int STATE_LOAD_UNKNOWN = 3;
    /**
     * The download state of the resource, erroneous, something weird 
     * happened! but at least we know that :)
     */
    public static final int STATE_LOAD_ERROR = 4;

    /**
     * Attribute index - The identifier
     */
    protected static int ATTR_IDENTIFIER = -1;    
    /**
     * Attribute index - The resource content length.
     */
    protected static int ATTR_CONTENT_LENGTH = -1;
    /**
     * Attribute index - The resource current length.
     */
    protected static int ATTR_CURRENT_LENGTH = -1;
    /**
     * Attribute index - The file
     */
    protected static int ATTR_FILE = -1;

    /**
     * Attribute name - The resource content length.
     */
    protected static final String NAME_CONTENT_LENGTH = "content-length";

    /**
     * Attribute name -  The resource current length
     */
    protected static final String NAME_CURRENT_LENGTH = "current-length";

    /**
     * Attribute name - The identifier
     */
    protected static final String NAME_IDENTIFIER     = "id";

    /**
     * Attribute name - The identifier
     */
    protected static final String NAME_FILE           = "file";

    /**
     * Attribute index - The download state
     */
    protected static int ATTR_LOAD_STATE = -1;  
    /**
     * Attribute index - The entity tag (if any) associated with the resource.
     */
    protected static int ATTR_ETAG = -1;
    /**
     * Attribute index - The reply status.
     */
    protected static int ATTR_STATUS = -1;
    /**
     * Attribute index - The Last modified of this resource
     */
    protected static int ATTR_REPLY_LAST_MODIFIED = -1;
    /**
     * Attribute index - The Date of the resource
     */
    protected static int ATTR_DATE = -1;
    /**
     * Attribute index - The Content MD5 of the resource
     */
    protected static int ATTR_CONTENT_MD5 = -1;
    /**
     * Attribute index - The Content Encoding of the resource
     */
    protected static int ATTR_CONTENT_ENCODING = -1;
    /**
     * Attribute index - The Content Language of the resource
     */
    protected static int ATTR_CONTENT_LANGUAGE = -1;
    /**
     * Attribute index - The Location of this resource
     */
    protected static int ATTR_LOCATION = -1;
    /**
     * Attribute index - The Vary of this resource
     */
    protected static int ATTR_VARY = -1;
    /**
     * Attribute index - The extra headers attribute.
     */
    protected static int ATTR_EXTRA_HEADERS = -1;
    /**
     * Attribute index - The request headers used for content negotiation
     *                   as set by the reply Vary header.
     */
    protected static int ATTR_CONNEG_HEADERS = -1;

    static {
	Attribute a = null;
	Class     c = null;
	try {
	    c = Class.forName(
		"org.w3c.www.protocol.http.cache.CachedResource");
	} catch (Exception ex) {
	    ex.printStackTrace();
	    System.exit(1);
	}    
	// This resource ntity tag:
	a = new StringAttribute(NAME_IDENTIFIER
				, null
				, Attribute.COMPUTED);
	ATTR_IDENTIFIER = AttributeRegistry.registerAttribute(c, a);
	// Declare the content length attribuite:
	a = new IntegerAttribute(NAME_CONTENT_LENGTH
				 , null
				 , Attribute.COMPUTED);
	ATTR_CONTENT_LENGTH = AttributeRegistry.registerAttribute(c, a);
	// Declare the currentlength attribuite:
	a = new IntegerAttribute(NAME_CURRENT_LENGTH
				 , null
				 , Attribute.COMPUTED);
	ATTR_CURRENT_LENGTH = AttributeRegistry.registerAttribute(c, a);
	// Declare the file attribute
	a = new FileAttribute(NAME_FILE
			      , null
			      , Attribute.COMPUTED);
	ATTR_FILE = AttributeRegistry.registerAttribute(c, a);
	// Declare the download state value
	a = new IntegerAttribute("load-state"
				 , null
				 , Attribute.COMPUTED);
	ATTR_LOAD_STATE = AttributeRegistry.registerAttribute(c, a);
	// This resource entity tag:
	a = new StringAttribute("etag"
				, null
				, Attribute.COMPUTED);
	ATTR_ETAG = AttributeRegistry.registerAttribute(c, a);
	// Declare the status attribute:
	a = new IntegerAttribute("status"
				 , null
				 , Attribute.COMPUTED);
	ATTR_STATUS = AttributeRegistry.registerAttribute(c, a);
	// The last modified attribute:
	a = new DateAttribute("reply-last-modified",
			      null,
			      Attribute.COMPUTED|Attribute.EDITABLE) ;
	ATTR_REPLY_LAST_MODIFIED = AttributeRegistry.registerAttribute(c,a);
	// The last modified attribute:
	a = new DateAttribute("reply-date",
			      null,
			      Attribute.COMPUTED|Attribute.EDITABLE) ;
	ATTR_DATE = AttributeRegistry.registerAttribute(c,a);
	// This resource content-md5
	a = new StringAttribute("content-md5"
				, null
				, Attribute.COMPUTED);
	ATTR_CONTENT_MD5 = AttributeRegistry.registerAttribute(c, a);
	// This resource content encoding
	a = new StringArrayAttribute("content-encoding"
				     , null
				     , Attribute.COMPUTED);
	ATTR_CONTENT_ENCODING = AttributeRegistry.registerAttribute(c, a);
	// This resource content-language
	a = new StringArrayAttribute("content-language"
				     , null
				     , Attribute.COMPUTED);
	ATTR_CONTENT_LANGUAGE = AttributeRegistry.registerAttribute(c, a);
	// This resource location
	a = new StringAttribute("location"
				, null
				, Attribute.COMPUTED);
	ATTR_LOCATION = AttributeRegistry.registerAttribute(c, a);
	// This resource location
	a = new StringArrayAttribute("vary"
				     , null
				     , Attribute.COMPUTED);
	ATTR_VARY = AttributeRegistry.registerAttribute(c, a);
	// The extra headers attribute:
	a = new PropertiesAttribute("headers"
				    , null
				    , Attribute.COMPUTED);
	ATTR_EXTRA_HEADERS = AttributeRegistry.registerAttribute(c, a);
	// The extra headers attribute:
	a = new PropertiesAttribute("conneg"
				    , null
				    , Attribute.COMPUTED);
	ATTR_CONNEG_HEADERS = AttributeRegistry.registerAttribute(c, a);
    }

    /**
     * The minimal attribute set used to describe a cachedresource without
     * loading it entirely.
     */
    protected static String ATTR_DESCR[] = { 
	NAME_IDENTIFIER, 
	NAME_CURRENT_LENGTH,
	NAME_FILE
    };

    // should we revalidate next time?
    protected boolean invalidated = false;
    // our generation
    protected CacheGeneration generation = null;
    // Cached Entity tag HTTP list value for this resource.
    HttpEntityTag etags[] = null;
    // the extra headers
    protected ArrayDictionary a = null;
    // are we uploading or not?
    protected boolean uploading = false;

    public void notifyTeeFailure(int size) {};
    public void notifyTeeSuccess(int size) {};

    // the filter that is using this resource
    protected CacheFilter filter;
    /**
     * LRU management - previous entry.
     */
    protected LRUAble prev = null;
    /**
     * LRU management - next entry.
     */
    protected LRUAble next = null;

    /**
     * LRU management - Get next node.
     * @return A CvsDirectory instance.
     */

    public LRUAble getNext() {
	return next;
    }

    /**
     * LRU management - Get previous node.
     * @return A CvsDirectory instance.
     */

    public LRUAble getPrev() {
	return prev;
    }

    /**
     * LRU management - Set next node.
     * @return A CvsDirectory instance.
     */

    public synchronized void setNext(LRUAble next) {
	this.next = next;
    }

    /**
     * LRU management - Set previous node.
     * @return A CvsDirectory instance.
     */

    public synchronized void setPrev(LRUAble prev) {
	this.prev = prev;
    }

    /**
     * overrides the default setValue to invalidate the ETag
     */
    public void setValue(int idx, Object value) {
	super.setValue(idx, value);
	if ( idx == ATTR_ETAG )
	    etags = null;
    }

    /**
     * returns the current age of this cached resource
     * @return an integer, the current age in seconds
     */
    public abstract int getCurrentAge();