Network update problem with timer

[Marc Vanzegbroeck]

Hi,

I have a strange network problem. I use in my program a nummeric field with contain a number.
Each time something is update in the program I increase this value.
In my program I have a timer that check the value. If it has been change, something must be done.

The problem is now that only the program that increase the value see the value-change. The other PC still show the old value.

I have make a sample-code so you can test this. I show every 10seconds the value + time() in the title of the dialog.
You can see the timer is executed, because the time change. The only thing that is not changing is the value...

To test this, hou have to run it on a network on 2 PC's. If you press 'Add' the value is changed, but only on that PC, not on the other.
What can be the problem? I do a commit after increasing the value.

Code: Select all  Expand view

#INCLUDE "FiveWin.ch"
static sDlg
FUNCTION test()
   local  oWnd
   local vstruct:={}
   IF !file('refresh.dbf')
      aadd(vstruct,{'NR','N',10,0})
      dbcreate('refresh',vstruct)
   ENDIF
   use refresh new shared
   IF reccount()= 0
      appe blank
      unlock
   ENDIF

   DEFINE WINDOW oWnd FROM 1, 1 TO 22, 75 TITLE "Test"

   ACTIVATE WINDOW oWnd MAXIMIZED on init test_()
RETURN nil

FUNCTION test_()
   local  oBtn ,oTim
   Define Timer oTim Interval 10000 Action chkrefresh()
   activate timer oTim

   DEFINE DIALOG sDlg FROM 5, 5 TO 15, 40 TITLE "Test"

   @ 3,  4 BUTTON "&Add" OF sDlg SIZE 40, 12 ACTION telop()

   @ 3, 12 BUTTON "&Exit" OF sDlg SIZE 40, 12  ACTION sDlg:End()

   ACTIVATE DIALOG sDlg
   release timer oTim
RETURN nil

FUNCTION telop()
   sele refresh
   IF rlock()
      repl nr with nr+1
      unlock
   ENDIF
   dbcommit()
RETURN nil

FUNCTION chkrefresh()
   sDlg:Settext(str(refresh->nr)+' '+time())
RETURN nil


Thanks,
Marc

[Marc Vanzegbroeck]

Any suggestions?

BTW You can also try it on one PC with VMWare

Regards,
Marc

[Enrico Maria Giordano]

A workaroud:

Code: Select all  Expand view

FUNCTION chkrefresh()
   use refresh shared
   sDlg:Settext(str(refresh->nr)+' '+time())
RETURN nil

EMG

[Otto]

Hello Marc,

First I thought maybe „refresh“ is a non allowed word.
I changed all to re_fresh. But this didn’t help.

But if you position before reading the data to record 1 for me it is working perfectly.



Best regards,
Otto



FUNCTION chkre_fresh()
local nCounter
select re_fresh
goto 1
nCounter:= re_fresh->nr

sDlg:Settext(str(nCounter)+' '+time())
RETURN nil

[Marc Vanzegbroeck]

Thanks Otto, I will try it this evening. I'm at the moment with a client...

Enrico, I prefer using the 'goto 1' suggestion of Otto, then opening the database again.

It's very strange that the program doen't see the change, only when he's changing it himself.

Regards,
Marc

[Enrico Maria Giordano]

Enrico, I prefer using the 'goto 1' suggestion of Otto, then opening the database again.

I agree, it's definitely a better workaround than mine.

It's very strange that the program doen't see the change, only when he's changing it himself.

I'm going to report this strange behavior to the Harbour and xHarbour developers lists.

EMG

[Enrico Maria Giordano]

Done. In the meanwhile, you can use an even better workaround: Skip 0.

EMG

[Enrico Maria Giordano]

This is the answer of a Harbour developer:

> Is it expected?

Hi,

yes, of cause. The whole record buffer is written to file after record
cursor is "touched". This helps to avoid multiple disk access on:
FIELD1 := value1
FIELD2 := value2
...
FIELDn := valuen

Use DBCOMMIT() (or move record pointer DBSKIP(), DBGOTO(), etc.) to
force write of record buffer.

EMG

[Marc Vanzegbroeck]

Enrico,

As you can see I use dbcommit() in function telop() after changing the value.
Do they mean to use it also before reading?

Regards,
Marc

[Otto]

Hello Marc, hello Enrico,

I have the same result as Marc. If I watch with WDBU I see the changes.
I think the problem is reading without explicit positioning the record.

Regards,
Otto

[Enrico Maria Giordano]

Enrico,

As you can see I use dbcommit() in function telop() after changing the value.
Do they mean to use it also before reading?

Regards,
Marc

Yes. But Skip 0 is enough.

EMG