Delete Method

[Tom Henricksen]

I am working on B&S and my deleteRecord method is not working. I have a unit test that I run and it doesn't seem to delete the record. It seems to delete the record in cache only. The file valid record indicator is always true. I suspect it may be my seek distance.

  
public void deleteRecord(long recNo, long lockCookie)
throws RecordNotFoundException, SecurityException {
Long recordNo = new Long(recNo);
Long lockLongCookie = new Long(lockCookie);
if (locks.containsKey(recordNo) && locks.containsValue(lockLongCookie)) {
synchronized (contractors) {
 
RandomAccessFile raf;
long seekDistance = 0;
                                // header plus record distance
seekDistance = 55 + (recNo * 183);
try {
//Delete in file
raf = new RandomAccessFile("C:/tmp/scjd/db-2x3.db", "rw");
raf.seek(seekDistance);
raf.writeBoolean(false);
unlock(recNo, lockCookie);
raf.close();
//Delete in cache
Contractor contrator = getByRecNo(recNo);
contractors.remove(contrator);
contrator.setValidFlag(false);
contractors.add(contrator);
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
} else {
throw new SecurityException("Lock not found on: " + recNo);
}
}

Thanks,
Tom

[Thomas Paul Bigbee]

There are a couple of things, that stand out, like not using constants and opening and closing the file for each delete, also it looks like the record is not being locked before the update, however, I believe you may be right is assuming the seek is wrong

try this...

databaseFile.seek(HEADER_OFFSET + (RECORD_LENGTH *
(recordNumber - 1)));

Therefore, if you wanted to delete record #1, you are just positioning the file pointer to the byte at the end of the HEADER_OFFSET + (0)

I believe that you are deleting the next record after the one you really want to delete.

[Alex Sharkoff]

Thomas Paul Bigbee wrote
databaseFile.seek(HEADER_OFFSET + (RECORD_LENGTH * (recordNumber - 1)));

Very nice, Tom

Thomas Paul Bigbee wrote
also it looks like the record is not being locked before the update

I guess the client would lock it before calling delete method

[I]db client[/I]
asks database layer to lock record1
asks database layer to delete record1
asks database layer to unlock record1

[Tom Henricksen]

Thanks for your advice I will try that out.
Tom

[Jesse Xie Y.S.]

if (locks.containsKey(recordNo) && locks.containsValue(lockLongCookie)) {

If recordNo=1 locked cookie=001
and recordNo=2 locked cookie=002
when invoke deleteRecord(1,002); then...

unlock(recNo, lockCookie);

I don't think it's a good way that invoke unlock in the deleteRecord method.

} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}

catch IOException and then just print the message, is it really OK?