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you started Windows. TimeGetTime resets itself to every 48 days, whereas Timer resets once every day—if you need to time a lengthy operation, timeGetTime provides a mechanism for measuring time spans longer than a single day (and makes it possible to measure time spans that cross midnight). Of course, if you're timing an operation that takes more than a day, you're probably not going to care about millisecond accuracy, but that's what you get! The code in basProfiler calls timeGetTime to retrieve the current "time" whenever you push or pop a value and stores it in the stack array. You can call timeGetTime in any application, once you include this declaration in a global module:

Public Declare Function timeGetTime _

Lib "Kernel32" ( ) As Long

The code in basTestProfiler also uses timeGetTime in the Wait subroutine. This procedure does nothing but wait for the requested number of milliseconds, calling DoEvents inside the loop and giving Windows time to do its work:

Public Sub Wait (intWait As Integer)

Dim lngStart As Long

lngStart = timeGetTime( )

Do While timeGetTime( ) < lngStart + intWait

DoEvents

Loop

End Sub

The code in basProfiler opens and closes the output file each time it needs to write a piece of information. This slows down your application, but it ensures that if your machine crashes for some reason, your log file will always be current. Although you'll never directly call this routine, if you've never used Access to write directly to a text file you may find it interesting to see how it does its work.

The acbProWriteToLog procedure first checks to see if an error has ever occurred in the logging mechanism (that is, if mfLogErrorOccurred has been set to True). If so, it doesn't try to write anything to the file, because something may be wrong with the disk. If not, it gets a free file handle, opens the log file for appending, writes the item to the file, and then closes it. The following is the source code for the acbProWriteToLog routine:

Private Sub acbProWriteToLog (strItem As String)

Dim intFile As Integer

On Error GoTo HandleErr

' If an error has EVER occurred in this session,

' just get out of here.

If mfLogErrorOccurred Then Exit Sub

intFile = FreeFile

Open acbcLogFile For Append As intFile

Print #intFile, strItem

Close #intFile

ExitHere:

Exit Sub

HandleErr:

mfLogErrorOccurred = True

MsgBox Err & ": " & Err.Description, , "Writing to Log"

Resume ExitHere

End Sub

As in the Solution in Recipe 7.2, you'll find that for the procedure stack profiler mechanism to be of any value, you must be conscientious about the placement of your calls to acbProPushStack and acbProPopStack. If you have multiple exit points from routines, this is a good time to try to consolidate them. If you can't, you'll need to make sure that you've placed a call to acbProPopStack before every exit point in each procedure.

If you attempt to decipher the log file, you'll notice that the elapsed time for each procedure must also include any procedures it happens to call, as in the example of A calling B, which calls C, which calls D. The elapsed time for function A was 1,702 ms. That's the time that elapsed between the calls to acbProPushStack and acbProPopStack in function A, including the time it took to run all the calls to B, C, and D. This isn't necessarily a problem, nor is it wrong, but you should be aware that there's no way to "stop the clock" while in subordinate procedures.

The code for the profiler includes another public entry point, acbProLogString. The profiler doesn't actually call this procedure, but your own code can. Pass it a single string, and the profile will send that string to the log file for you. For example, the following code will append "This is a test" to the log file:

acbProLogString "This is a test"

7.4. Multitask Your VBA Code

Problem

If your VBA code includes a loop that runs for more than just a second or two, Access seems to come to a halt. You can't move the windows on the screen, and mouse-clicks inside Access are disregarded until your code has