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<< Click to Display Table of Contents >> Navigation: ThinBASIC Core Language > BuiltIn Functions > Application functions > APP_MutexCreate |
Description
Create a unique mutex returning its handle.
Syntax
Mutex_Handle = APP_MutexCreate(AUniqueMutexName)
Returns
Number
If Zero it can mean either that a mutex with the same name already exists or current user has no enough authorization to create a mutex.
Parameters
Name |
Type |
Optional |
Meaning |
AUniqueMutexName |
String |
No |
A mutex name. |
Remarks
The Mutex object is a synchronization objects. Its basic purpose is to provide a synchronization method. For example if you want to be sure that a script is executed just once, try to create a mutex with a unique name. If you cannot create a mutex with that name (return value is zero), it can mean the same script is already running in your system so stop current one. If instead you can create a mutex, it means the same script is not running.
It is important to store returned handle in order to be able, later, to close it.
It is programmer responsibility to close all created mutex.
If return value is zero it can mean either that a mutex with the same name already exists or current user has no enough authorization to create a mutex.
Restrictions
See also
Examples
Dim hMutex As DWORD
Dim Mutex_Name As String = "AVeryUniqueStringToNameMutex"
'---Better if MutexName has script name inside so it will be specific to this script
Mutex_Name += app_scriptname
hMutex = APP_MutexCreate(Mutex_Name)
If hMutex = 0 Then
MSGBOX 0, _
"I was not able to create a Mutex named: " & Mutex_Name & $crlf & _
"This means that another instance of the same script is already running" & $crlf & _
"or you have not enough user authorization to create a Mutex." & $crlf & _
"In any case script execution is aborted. Sorry", %MB_ICONERROR
STOP
Else
MSGBOX 0, _
"I was able to create a Mutex named: " & Mutex_Name & $crlf & _
"Mutex handle is " & hMutex & "" & $crlf & _
"Script will continue. Perfect", %MB_ICONINFORMATION
End If
'...
'------
'---Here code for script ...
'---
'...
'---At the end close the mutex handle to release it for new script execution
APP_MutexClose(hMutex)