How to check file lock on .txt file before opening - excel

Question

Long story short... I am using a pc to open a .txt file located on a server... but sometimes the .txt file is not finished (there is still data stored in a buffer of the source computer).
FilePath = "D:\test.txt"
Workbooks.Open(Filename:=FilePath, ReadOnly:=True, IgnoreReadOnlyRecommended:=True)
Someone smarter than I am has identified that the .txt file is "locked" by the operating system until it is finished but I am still able to open it. I would like to wait for the .txt file to be "not locked" before opening it. How do I do this?
Note: The "smarter" person than me explained... the .txt file can be opened by a "dumb" program like "notepad" but if you try to use "Microsoft Word" to open it... you get a message telling you that it is locked...

Answer 1

import time
is_open = False
while not(is_open):
try:
f = open('test.txt','w')
is_open=True
except:
time.sleep(1)

Answer 2

I don't know how well the code below will work for your scenario.
You could change the constants into parameters (if you think their values need to change/be determined dynamically).
You could also change the GetFileOrWait's implementation such that it allows an infinite loop (I chose to avoid this, but maybe you want this).
All in all, the below is basically a function which tries to return the workbook in 120 seconds (or times out with an error) -- which you can hopefully use in a parent subroutine/procedure.
You may be able to specify finer frequencies (seconds may be too coarse) by using Timer instead or other lower level APIs.
Option Explicit
Private Function GetFileOrNothing() As Workbook
Const FILE_PATH As String = "D:\test.txt" ' Could pass this in as argument (if needed).
On Error Resume Next
Set GetFileOrNothing = Workbooks.Open(Filename:=FILE_PATH, ReadOnly:=True, IgnoreReadOnlyRecommended:=True)
On Error GoTo 0
End Function
Private Function GetFileOrWait() As Workbook
' Attempts to open a file. If access fails, waits n seconds before trying again.
' This function raises an error (times out to prevent infinite loop) after N seconds.
Const MAXIMUM_WAIT_IN_SECONDS As Long = 10
Const INTERVAL_WAIT_IN_SECONDS As Long = 1
Dim timeToStopAt As Date
timeToStopAt = DateAdd("s", MAXIMUM_WAIT_IN_SECONDS, Now)
Do While Now < timeToStopAt
Dim outputWorkbook As Workbook
Set outputWorkbook = GetFileOrNothing()
If Not (outputWorkbook Is Nothing) Then Exit Do
Application.Wait DateAdd("s", INTERVAL_WAIT_IN_SECONDS, Now)
DoEvents
Loop
If outputWorkbook Is Nothing Then
Err.Raise vbObjectError + 5, , "Failed to access file within the specified time frame."
End If
Set GetFileOrWait = outputWorkbook
End Function