Hello everybody,
I am back with a new problem, a real mindcracker for me. As usual, it is
possible that this problem is as easy as cake, then i will feel stupid
again, but as it is now (with my limited knowledge) i cant seem to find a
solution.
The situation is as following:
check the next piece of mapping:
<<<<<<<<<<<<<<<<<<<mapping>>>>>>>>>>>>>>>>
<field name="start" type="date">
<sql name="start" type="timestamp" />
</field>
<field name="stop" type="date">
<sql name="stop" type="timestamp" />
</field>
<<<<<<<<<<<<<<<<<< end of mapping >>>>>>>>>>>
As you can see, i am trying to "convert" java date obj into a timestamp
object.
This piece of mapping tries to map a Performance Object, the code following
here:
*********************** start of code **************************
public class Performance implements TimeStampable {
private int performanceID;
private int userID;
private int activityID;
private Date start;
private Date stop;
private long timestamp = 0;
public long jdoGetTimeStamp(){
return timestamp;
}
public void jdoSetTimeStamp(long timestamp){
this.timestamp = timestamp;
}
public int getUserID() {
return userID;
}
public void setUserID(int userID) {
this.userID = userID;
}
public int getActivityID() {
return activityID;
}
public void setActivityID(int activityID) {
this.activityID = activityID;
}
public Date getStart() {
return start;
}
public void setStart(Date start) {
this.start = start;
}
public Date getStop() {
return stop;
}
public void setStop(Date stop) {
this.stop = stop;
}
public int getPerformanceID() {
return performanceID;
}
public void setPerformanceID(int performanceID) {
this.performanceID = performanceID;
}
}
************************** end of code ***************************
As you all can see, not much about it.
I recently solved the problems i had with caching and long transactions,
everything worked perfectly, until i tried to create and update Performance
objects in long transactions.
The scenario is as following: i create a performance object to track the
start of some activity. Due to database restrictions (mysql), it is
impossible to have a timestamp entry that is null (this might have nothing
to do with the problem but i think its better to just tell everything).
Ofcourse i also need to know when the activity stops, so i perform an update
on the Performance object when the activity stops, and i would then like to
create a new Performance object for the next Activity.
But on the update, i get the following Exception and errormessage:
org.exolab.castor.jdo.ObjectModifiedException: Invalid object timestamp
detected.
Now, to me, this looks very strange. ObjectModifiedException is thrown when
there is a concurrency problem, more accurate, when one transaction is
modifying an entry used by another transaction.
In my case, this is not really possible, because every single operation i
perform on the database is a transaction that has been committed. To prove
this, i ll give the code i use to update.
************** start of code *************
public void update(Object updatedObject) {
try {
db.begin();
db.update(updatedObject);
logger.info("UPDATE COMPLETED");
db.commit();
} catch (PersistenceException e) {
logger.fatal("PersistanceException : " +
e.getMessage());
e.printStackTrace();
}
}
********************* end of code **************
In the application, when i create the currentPerformanceObject, it has no
ID. I let MySql create an auto increasing number for that. So i figured i
might be making my own object a dirty one, because castor isnt aware of the
change in the database. So logically i tried to set the the dirty attribute
in the mappingfile to ingnore, but with no effect (this also means that my
theory about the ID is not correct as well).
I dont have a clue what could be wrong. To complete this post, i ll add the
pieces of code where all this stuff happens.
********************** start of code *********************
activityList.getList().addSelectionListener(new
SelectionListener(){
public void widgetSelected(SelectionEvent event){
MessageBox msgbox = new
MessageBox(site.getShell(),SWT.ICON_INFORMATION|SWT.YES|SWT.NO);
msgbox.setMessage("Are you sure you wish to
start this activity?");
int msg = msgbox.open();
if(msg == SWT.YES){
if(currentPerformance != null){
endCurrentPerformance();
}
currentActivity =
(Activity)activityList.getElementAt(activityList.getList().getSelectionIndex());
status.setText(statusText+currentActivity.getName());
logActivity();
}
}
private void logActivity(){
currentPerformance = new Performance();
currentPerformance.setActivityID(currentActivity.getActivityID());
currentPerformance.setUserID(Application.conn.getCurrentUser());
currentPerformance.setStart(new Date());
currentPerformance.setStop(null);
Application.conn.getAccess().createPerformance(currentPerformance);
System.out.println("THE TIMESTAMP OF THE PERFORMANCE OBJECT:
"+currentPerformance.jdoGetTimeStamp());
}
private void endCurrentPerformance(){
currentPerformance.setStop(new Date());
System.out.println("THE TIMESTAMP OF THE PERFORMANCE OBJECT
WHEN UPDATING:
"+currentPerformance.jdoGetTimeStamp());
Application.conn.getAccess().updatePerformance(currentPerformance);
System.out.println("UPDATE COMPLETED");
}
******************** end of code **********************
As you can see, all the activities are contained in a listviewer. When i
click an activity, i want to make sure that the user didnt accidently
clicked it, so i ask to confirm with a dialogbox. If there is a
currentPerformance, i update it in 'endCurrentPerformance', if not, i just
create a new Performance in 'logActivity'.
In my opinion this is a very strange situation. The errormessage indicates
that there is an invalid object timestamp. I know that when i create a new
object, the timestamp has to be 0, as an indication that the object is a new
one. Castor changes the timestamp, so the object will not be forgotten.
I compare the timestamp value with the original one just before updating,
and they are exactly the same.
In my application i use the same variable name to instantiate a new
Performance. But since instantiating means assigning a new reference to the
variable, it can not be that the new object has the timestamp of the object
that was previously referenced by the same variable.
Any help on this matter would be very much appreciated.
greetings,
Noc2
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