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Re: Trying to clear a dead-lock of some type
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Re: Trying to clear a dead-lock of some type


  • Subject: Re: Trying to clear a dead-lock of some type
  • From: Chuck Hill <email@hidden>
  • Date: Thu, 19 May 2005 13:49:42 -0700

In addition to all the other good advice...

public void SearchForSixAMTasks() {

        TimeZone tz = TimeZone.getTimeZone("Etc/GMT");
        NSTimestamp SixAM = new NSTimestamp(1899, 12, 30, 14, 2, 0, tz);
        NSMutableArray args = new NSMutableArray();
        args.addObject(SixAM);
        args.addObject("0");
        EOQualifier qualifier =
            EOQualifier.qualifierWithQualifierFormat("starttime = %@ AND
            taskcompletedindicator = %@", args);
        EOFetchSpecification spec = new EOFetchSpecification("Tbltasks",
            qualifier, null);
        spec.setRefreshesRefetchedObjects(true);  // Use fresh data

        EOEditingContext ec = new EOEditingContext();
        ec.lock();

        try {
            NSArray array = ec.objectsWithFetchSpecification(spec);
            NSMutableArray foundTasks = new NSMutableArray(array);

Enumeration e = foundTasks.objectEnumerator();
while(e.hasMoreElements()) {
Tbltasks currentTask = (Tbltasks)e.nextElement();
// TaskReview is a process, not an EO - right?
TaskReview review = new TaskReview();
System.out.println(currentTask.taskcomment() + " - before
change.");


review.GetRepsData(currentTask); //data is read,modified,etc. in this method
System.out.println(currentTask.taskcompletedindicator());
System.out.println(currentTask.alarmindicator());
}


ec.saveChanges();
} catch (Exception e) {
// - Definite potential for locking issues with TPE, but only when intentionally trying to break it
System.out.println("RepeatingTask: exception in SearchForSixAMTasks()");
}
finally {
ec.unlock();
ec.dispose();
}
}



On May 19, 2005, at 12:22 PM, WebObjects wrote:

The following function works consistently, unless there is some contention
(I'm sharing a datasource with other applications). There is the expected
issue of saving to a locked row - but even if I trap the exception, then
repeat this function some time later (after I'm certain the other apps are
not locking the same rows) I still get the same contention.


First, do you see anything in this method that is out of place or sequence?
(it occurs in a TimerTask within Application) I'm not 100% certain that my
ec.refreshAllObjects is place in the proper place.


Advice is greatly appreciated!

-Bill


public void SearchForSixAMTasks() {

        try{

TimeZone tz = TimeZone.getTimeZone("Etc/GMT");
NSTimestamp SixAM = new NSTimestamp(1899, 12, 30, 14, 2, 0, tz);
NSMutableArray args = new NSMutableArray();
args.addObject(SixAM);
args.addObject("0");
EOQualifier qualifier =
EOQualifier.qualifierWithQualifierFormat("starttime = %@ AND
taskcompletedindicator = %@", args);



EOFetchSpecification spec = new EOFetchSpecification("Tbltasks",
qualifier, null);



EOEditingContext ec = new EOEditingContext(); ec.refreshAllObjects();

        //lock EC
        ec.lock();

        //Fetch
        NSArray array = ec.objectsWithFetchSpecification(spec);
        NSMutableArray foundTasks = new NSMutableArray(array);


Enumeration e = foundTasks.objectEnumerator();

            while(e.hasMoreElements()) {

                Tbltasks currentTask = (Tbltasks)e.nextElement();
                TaskReview review = new TaskReview();

System.out.println(currentTask.taskcomment() + " - before
change.");


                review.GetRepsData(currentTask); //data is
read,modified,etc. in this method

System.out.println(currentTask.taskcompletedindicator());

                System.out.println(currentTask.alarmindicator());

                }

            ec.saveChanges();

            //-- unlock EC
            ec.unlock();
            ec.refreshAllObjects();


} catch (Exception e) {

// - Definite potential for locking issues with TPE, but
only when intentionally trying to break it
System.out.println("RepeatingTask: exception in
SearchForSixAMTasks()");


                }

            }


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