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/*
* PESessionLocker.java
*
* Created on January 18, 2006, 4:46 PM
*/
package com.sun.enterprise.web;
import org.apache.catalina.Context;
import org.apache.catalina.Manager;
import org.apache.catalina.Session;
import org.apache.catalina.SessionLocker;
import org.apache.catalina.session.BaseSessionLocker;
import org.apache.catalina.session.StandardSession;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
/**
*
* @author lwhite
*/
public class PESessionLocker extends BaseSessionLocker implements SessionLocker {
/** Creates a new instance of PESessionLocker */
public PESessionLocker() {
}
/** Creates a new instance of PESessionLocker */
public PESessionLocker(Context ctx) {
this();
_context = ctx;
}
/**
* lock the session associated with this request
* this will be a foreground lock
* checks for background lock to clear
* and does a decay poll loop to wait until
* it is clear; after 5 times it takes control for
* the foreground
* @param request
*/
public boolean lockSession(ServletRequest request) throws ServletException {
boolean result = false;
Session sess = this.getSession(request);
//now lock the session
if(sess != null) {
long pollTime = 200L;
int maxNumberOfRetries = 7;
int tryNumber = 0;
boolean keepTrying = true;
boolean lockResult = false;
//try to lock up to maxNumberOfRetries times
//poll and wait starting with 200 ms
while(keepTrying) {
lockResult = sess.lockForeground();
if(lockResult) {
keepTrying = false;
result = true;
break;
}
tryNumber++;
if(tryNumber < maxNumberOfRetries) {
pollTime = pollTime * 2L;
threadSleep(pollTime);
} else {
//tried to wait and lock maxNumberOfRetries times; throw an exception
//throw new ServletException("unable to acquire session lock");
//instead of above; unlock the background so we can take over
if (sess instanceof StandardSession) {
((StandardSession)sess).unlockBackground();
}
}
}
}
return result;
}
private Session getSession(ServletRequest request) {
javax.servlet.http.HttpServletRequest httpReq =
(javax.servlet.http.HttpServletRequest) request;
javax.servlet.http.HttpSession httpSess = httpReq.getSession(false);
if(httpSess == null) {
return null;
}
String id = httpSess.getId();
Manager mgr = _context.getManager();
Session sess = null;
try {
sess = mgr.findSession(id);
} catch (java.io.IOException ex) {}
return sess;
}
protected void threadSleep(long sleepTime) {
try {
Thread.sleep(sleepTime);
} catch (InterruptedException e) {
;
}
}
/**
* unlock the session associated with this request
* @param request
*/
public void unlockSession(ServletRequest request) {
Session sess = this.getSession(request);
//now unlock the session
if(sess != null) {
sess.unlockForeground();
}
}
}