/*   
 *  Copyright 1997-2004 The Apache Sofware Foundation.
 *
 *  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.apache.tomcat.util.depend;


/** How it works:
    - A DependManager gets loaded with a number of Dependency
    - each Dependency includes a File and a timestamp.
    - If any of the Files is changed after timestamp this DependManager
    will set "expired" to true
    - One check at a time, but without sync
    - if a check was done recently ( delay property ) - assume nothing changed

    It is also possible to do the checks in background, but for big
    servers ( with many contexts) it have scalability problems.
 */
public class DependManager {
    static org.apache.commons.logging.Log logger =
	org.apache.commons.logging.LogFactory.getLog(DependManager.class);

    int delay=4000;
    Dependency deps[];
    int depsCount=0;
    long lastCheck=0;
    boolean checking=false;
    long checkTime=0;
    int checkCount=0;

    private boolean expired=false;

    static final int INITIAL_DEP_SIZE=32;
    
    public DependManager() {
	this( INITIAL_DEP_SIZE );
    }

    public DependManager(int initial_size) {
	deps=new Dependency[initial_size];
    }

    /** Reset the depend manager - all dependencies are reset too.
	This will be called after a reload
    */
    public void reset() {
	expired=false;
	for( int i=0; i= deps.length ) {
	    Dependency deps1[]=new Dependency[ deps.length *2 ];
	    System.arraycopy( deps, 0, deps1, 0 , depsCount );
	    deps=deps1;
	}
	deps[depsCount++]= dep ;
	if( logger.isDebugEnabled() )
	    logger.debug( "Added " + dep.getOrigin() + " " + dep.getTarget());
    }

    // -------------------- Private 

    private int debug=0;

    public void setDebug( int i ) {
	debug=i;
    }

}