COL.IMap2 and HashTableFactory cause frequent Access Violation

2025-09-11T06:27:20.131000Z

Good morning,

I’ve been using the Collection library for a long time, mostly with Stack, LinkedList, and List.
From your examples I was able to manage the different factories, even for custom elements.

Now I need a hashtable, but with this object I’m running into a lot of random access violations.

If I append something inside FB_Init after constructing the hashtable, it crashes, even though the list was already created.

If I only create the hashtable in FB_Init and append afterwards, it usually works.

I don’t understand the meaning of the dispose call in this code:

pSlave := ADR(slave);
uSlave := TO_ULINT(pSlave);
iKey := fKey.Create(uSlave);

IF hash.CountKeys() = 0 THEN
    Service.logger.appendLog('Filling hashtable', 'HashManager', AdvLogType.AdvDebugMsg);
    ok := FALSE;
ELSE
    eError := hash.ContainsKey(iKey, xResult => ok);
END_IF

IF NOT ok THEN
    pI := __NEW(UINT);
    iVal := fKey.Create(TO_ULINT(pI));
    Service.logger.appendLog(CONCAT('New slave', TO_STRING(uSlave)), 'HashManager', AdvLogType.AdvDebugMsg);
    hash.AddKeyValuePair(iKey, iVal);
    appendNewSlave := pI;
ELSE
    eError := hash.GetElementByKey(iKey, itfValue => iElem);
    xResult := __QUERYINTERFACE(iKey, itfIInstance);
    IF xResult THEN
        itfIInstance.Dispose();
    END_IF
    IF eError <> COL.COLLECTION_ERROR.NO_ERROR THEN
        Service.logger.appendLog(CONCAT('ERROR ', TO_STRING(eError)), 'HashManager', AdvLogType.AdvCriticalMsg);
        appendNewSlave := nullptr;
        RETURN;
    END_IF
    __QUERYINTERFACE(iElem, iVal);
    {warning disable C0033}
    pI := TO___UXINT(iVal.UlintValue);
    {warning restore C0033}
    appendNewSlave := pI;
END_IF

Without the dispose call, every second cold reset crashes immediately when I try to access iVal, even if eError doesn’t report any error.

With the dispose call, the cold reset issue disappears, but I get other problems:

a) If I start the runtime using systemctl start codesyscontrol, it crashes at
IF hash.CountKeys() = 0 THEN

b) If I delete the files in PlcLogic and download again, it works and survives multiple cold resets.
But as soon as I run systemctl restart codesyscontrol, everything gets corrupted again and it starts crashing at that point.

FUNCTION_BLOCK SlaveMapCounter
VAR
    hash : COL.IMap2;
    eError : COL.COLLECTION_ERROR;
END_VAR

In its FB_Init I create it:

METHOD FB_Init: BOOL
VAR_INPUT
    bInitRetains: BOOL; // TRUE: retain variables are initialized (reset warm / reset cold)
    bInCopyCode: BOOL;  // TRUE: the instance will be copied to the copy code afterward (online change)   
END_VAR
VAR
    hF : COL.HashTableFactory;
END_VAR

hash := hF.Create(256);

In another FB I instantiate it statically:

FUNCTION_BLOCK ABSTRACT AbstractServoEthercatController EXTENDS AbstractServoController
VAR_STAT    
    hashSlaves : SlaveMapCounter;
END_VAR
VAR
    field : REFERENCE TO ADVAbstractFieldUnitEthercatCia402;
    initCnt : REFERENCE TO UINT;
END_VAR

The append method is the one shown above, and I call it after the runtime has started.

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COL.IMap2 and HashTableFactory cause frequent Access Violation