Question

Talking Java Servlets here… I’m working on creating my own “Per Request Context” and I was looking to tie the “Per Request Context” object to the Thread.currentThread().getId() value.

Instead of passing around this context object everywhere I was planning on checking the current threadid when a user calls a function that is Per Request based and automatically getting the Context object out of a hashtable for that threadId.

I would use the code this like..

public void doPost(HttpServletRequest request, HttpServletResponse response) 
throws ServletException, IOException
{
    MyFramework.EnterContext();
    try {
        // do stuff here that leads to other classes on the same thread
        // Access current context via static MyFramework.getCurrentContext()
    }
    finally { MyFramework.ExitContext(); }
}

However I would like to protect my application automatically from any potential user that does not call ExitContext(). In C# there is an event handler on the thread object for onexit…(think I wrong on this) is there some way to detect or poll when a thread exits? I’m currently storing only the threadId (long).

Any ideas?

Answer 1

unfortunatelly, there is no such feature built in for threads in Java. Besides, thread id is only guaranteed to be unique at any one time, but may be reused eventually when the thread dies (from the docs). however, the servlet framework that you are using may be implementing such feature (just a speculation).

i would recommend you implement a servlet filter, and tell your users to include it in their web.xml. with this you can be sure the client code always gets correctly wraped in your thread context.