python abort / script timeout


Author: Dave
Date: 09.28.23 - 9:02am



working with python embedding, I wanted a way to guaranteed abort a script on command, or trigger a script timeout. Googling didnt provide any simple ways so I ended up hacking the main opcode processing loop in ceval.c.

The following brief patch seems to be working allowing for normal script returns.

//-------------- dzzie
typedef int(__stdcall* vbCallback)(int, char*);

int opCounter = 0; 
int g_AbortScript = 0;
vbCallback vbTimeOutHandler = 0;

void __declspec(dllexport) __stdcall SetTimeoutCallBack(void* lpfnTimeoutHandler) {vbTimeOutHandler = (vbCallback)lpfnTimeoutHandler;}
void __declspec(dllexport) __stdcall SetGlobalAbort(int gAbort) { g_AbortScript = gAbort; }

int dz_timeoutHandler(void) {

    int timedOut = 0;

    if (g_AbortScript == 1) return 1; //is it better to still receive the heartbeat for ui refresh? should be ending very soon...

    if (vbTimeOutHandler != NULL && opCounter != 0 && (opCounter % 1000) == 0) {
        opCounter = 0;
        timedOut = vbTimeOutHandler(0, 0);
        if (timedOut == 1) g_AbortScript = 1;
    }
    opCounter++;

    return timedOut;
}

//--------------- dzzie

/* Do interpreter dispatch accounting for tracing and instrumentation */
#define DISPATCH() 
    { 
        NEXTOPARG(); 
        PRE_DISPATCH_GOTO(); 
        assert(cframe.use_tracing == 0 || cframe.use_tracing == 255); 
        opcode |= cframe.use_tracing OR_DTRACE_LINE; 
        if(dz_timeoutHandler()==1) goto exit_unwind; 
        DISPATCH_GOTO(); 
    }

...

start_frame:

    if(g_AbortScript == 1) goto exit_unwind; //dzzie 

...

resume_frame:
    if (g_AbortScript == 1) goto exit_unwind; //dzzie


Public Function cb_TimeoutHandler(ByVal t As Long, ByVal lpMsg As Long) As Long
    'return 1 to halt execution, 0 to continue
    
    DoEvents 'allow our timer and UI to breath in case its a dead loop
    
    If ABORT_SCRIPT Then
        cb_TimeoutHandler = 1
        Debug.Print "Aborting!"
    Else
        cb_TimeoutHandler = 0
    End If
    
End Function

Function UseTimeoutHandler() As Boolean
    
    Dim h As Long, p As Long
    h = LoadLibrary("python311.dll")
    If h = 0 Then Exit Function
    
    p = GetProcAddress(h, "_SetTimeoutCallBack@4")
    If p = 0 Then Exit Function
    
    SetTimeoutCallBack AddressOf cb_TimeoutHandler
    UseTimeoutHandler = True
    
End Function





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