open62541/src/server/ua_subscription.c

#include "ua_subscription.h"
#include "ua_server_internal.h"
#include "ua_nodestore.h"

/****************/
/* Subscription */
/****************/

UA_Subscription *UA_Subscription_new(UA_Int32 subscriptionID) {
    UA_Subscription *new = UA_malloc(sizeof(UA_Subscription));
    if(!new)
        return UA_NULL;
    new->subscriptionID = subscriptionID;
    new->lastPublished  = 0;
    new->sequenceNumber = 1;
    memset(&new->timedUpdateJobGuid, 0, sizeof(UA_Guid));
    new->timedUpdateJob          = UA_NULL;
    new->timedUpdateIsRegistered = UA_FALSE;
    LIST_INIT(&new->MonitoredItems);
    LIST_INIT(&new->unpublishedNotifications);
    return new;
}

void UA_Subscription_deleteMembers(UA_Subscription *subscription, UA_Server *server) {
    UA_unpublishedNotification *not, *tmp_not;
    UA_MonitoredItem *mon, *tmp_mon;
    
    // Just in case any parallel process attempts to access this subscription
    // while we are deleting it... make it vanish.
    subscription->subscriptionID = 0;
    
    // Delete monitored Items
    LIST_FOREACH_SAFE(mon, &subscription->MonitoredItems, listEntry, tmp_mon) {
        LIST_REMOVE(mon, listEntry);
        MonitoredItem_delete(mon);
    }
    
    // Delete unpublished Notifications
    LIST_FOREACH_SAFE(not, &subscription->unpublishedNotifications, listEntry, tmp_not) {
        Subscription_deleteUnpublishedNotification(not->notification->sequenceNumber, subscription);
    }
    
    // Unhook/Unregister any timed work assiociated with this subscription
    if(subscription->timedUpdateJob != UA_NULL){
        Subscription_unregisterUpdateJob(server, subscription);
        UA_free(subscription->timedUpdateJob);
    }
}

UA_UInt32 Subscription_queuedNotifications(UA_Subscription *subscription) {
    if(!subscription)
        return 0;

    UA_UInt32 j = 0;
    UA_unpublishedNotification *i;
    LIST_FOREACH(i, &subscription->unpublishedNotifications, listEntry)
        j++;
    return j;
}

void Subscription_generateKeepAlive(UA_Subscription *subscription) {
    if(subscription->keepAliveCount.currentValue > subscription->keepAliveCount.minValue &&
       subscription->keepAliveCount.currentValue <= subscription->keepAliveCount.maxValue)
        return;

    UA_unpublishedNotification *msg = UA_malloc(sizeof(UA_unpublishedNotification));
    if(!msg)
        return;
    msg->notification = UA_NULL;
    msg->notification = UA_malloc(sizeof(UA_NotificationMessage));
    msg->notification->notificationData = UA_NULL;
    // KeepAlive uses next message, but does not increment counter
    msg->notification->sequenceNumber = subscription->sequenceNumber + 1;
    msg->notification->publishTime    = UA_DateTime_now();
    msg->notification->notificationDataSize = 0;
    LIST_INSERT_HEAD(&subscription->unpublishedNotifications, msg, listEntry);
    subscription->keepAliveCount.currentValue = subscription->keepAliveCount.maxValue;
}

void Subscription_updateNotifications(UA_Subscription *subscription) {
    UA_MonitoredItem *mon;
    //MonitoredItem_queuedValue *queuedValue;
    UA_unpublishedNotification *msg = NULL, *tempmsg;
    UA_UInt32 monItemsChangeT = 0, monItemsStatusT = 0, monItemsEventT = 0;
    UA_DataChangeNotification *changeNotification;
    size_t notificationOffset;
    
    if(!subscription || subscription->lastPublished + subscription->publishingInterval > UA_DateTime_now())
        return;
    
    // Make sure there is data to be published and establish which message types
    // will need to be generated
    LIST_FOREACH(mon, &subscription->MonitoredItems, listEntry) {
        // Check if this MonitoredItems Queue holds data and how much data is held in total
        if(!TAILQ_FIRST(&mon->queue))
            continue;
        if((mon->monitoredItemType & MONITOREDITEM_TYPE_CHANGENOTIFY) != 0)
            monItemsChangeT+=mon->queueSize.currentValue;
	    else if((mon->monitoredItemType & MONITOREDITEM_TYPE_STATUSNOTIFY) != 0)
            monItemsStatusT+=mon->queueSize.currentValue;
	    else if((mon->monitoredItemType & MONITOREDITEM_TYPE_EVENTNOTIFY)  != 0)
            monItemsEventT+=mon->queueSize.currentValue;
    }
    
    // FIXME: This is hardcoded to 100 because it is not covered by the spec but we need to protect the server!
    if(Subscription_queuedNotifications(subscription) >= 10) {
        // Remove last entry
        LIST_FOREACH_SAFE(msg, &subscription->unpublishedNotifications, listEntry, tempmsg)
            Subscription_deleteUnpublishedNotification(msg->notification->sequenceNumber, subscription);
    }
    
    if(monItemsChangeT == 0 && monItemsEventT == 0 && monItemsStatusT == 0) {
        // Decrement KeepAlive
        subscription->keepAliveCount.currentValue--;
        // +- Generate KeepAlive msg if counter overruns
        if (subscription->keepAliveCount.currentValue < subscription->keepAliveCount.minValue)
          Subscription_generateKeepAlive(subscription);
        
        return;
    }
    
    msg = (UA_unpublishedNotification *) UA_malloc(sizeof(UA_unpublishedNotification));
    msg->notification = UA_malloc(sizeof(UA_NotificationMessage));
    INITPOINTER(msg->notification->notificationData);
    msg->notification->sequenceNumber = subscription->sequenceNumber++;
    msg->notification->publishTime    = UA_DateTime_now();
    
    // NotificationData is an array of Change, Status and Event messages, each containing the appropriate
    // list of Queued values from all monitoredItems of that type
    msg->notification->notificationDataSize = ISNOTZERO(monItemsChangeT);
    // + ISNOTZERO(monItemsEventT) + ISNOTZERO(monItemsStatusT);
    msg->notification->notificationData = UA_Array_new(&UA_TYPES[UA_TYPES_EXTENSIONOBJECT], 
                                                       msg->notification->notificationDataSize);
    
    for(int notmsgn=0; notmsgn < msg->notification->notificationDataSize; notmsgn++) {
        // Set the notification message type and encoding for each of 
        //   the three possible NotificationData Types
        msg->notification->notificationData[notmsgn].encoding = 1; // Encoding is always binary
        msg->notification->notificationData[notmsgn].typeId = UA_NODEID_NUMERIC(0, 811);
      
        if(notmsgn == 0) {
            // Construct a DataChangeNotification
            changeNotification = UA_malloc(sizeof(UA_DataChangeNotification));
	
            // Create one DataChangeNotification for each queue item held in each monitoredItems queue:
            changeNotification->monitoredItems = UA_Array_new(&UA_TYPES[UA_TYPES_MONITOREDITEMNOTIFICATION],
                                                              monItemsChangeT);
	
            // Scan all monitoredItems in this subscription and have their queue transformed into an Array of
            // the propper NotificationMessageType (Status, Change, Event)
            monItemsChangeT = 0;
            LIST_FOREACH(mon, &subscription->MonitoredItems, listEntry) {
                if(mon->monitoredItemType != MONITOREDITEM_TYPE_CHANGENOTIFY || !TAILQ_FIRST(&mon->queue))
                    continue;
                // Note: Monitored Items might not return a queuedValue if there is a problem encoding it.
                monItemsChangeT += MonitoredItem_QueueToDataChangeNotifications(&changeNotification->monitoredItems[monItemsChangeT], mon);
                MonitoredItem_ClearQueue(mon);
            }
            
            changeNotification->monitoredItemsSize  = monItemsChangeT;
            changeNotification->diagnosticInfosSize = 0;
            changeNotification->diagnosticInfos     = UA_NULL;
        
            msg->notification->notificationData[notmsgn].body.length =
                UA_calcSizeBinary(changeNotification, &UA_TYPES[UA_TYPES_DATACHANGENOTIFICATION]);
            msg->notification->notificationData[notmsgn].body.data   =
                UA_calloc(msg->notification->notificationData[notmsgn].body.length, sizeof(UA_Byte));
        
            notificationOffset = 0;
            UA_encodeBinary(changeNotification, &UA_TYPES[UA_TYPES_DATACHANGENOTIFICATION],
                            &msg->notification->notificationData[notmsgn].body, &notificationOffset);
	
            // FIXME: Not properly freed!
            for(unsigned int i=0; i<monItemsChangeT; i++) {
                UA_MonitoredItemNotification *thisNotification = &(changeNotification->monitoredItems[i]);
                UA_DataValue_deleteMembers(&(thisNotification->value));
            }
            UA_free(changeNotification->monitoredItems);
            UA_free(changeNotification);
        } else if(notmsgn == 1) {
            // FIXME: Constructing a StatusChangeNotification is not implemented
        } else if(notmsgn == 2) {
            // FIXME: Constructing a EventListNotification is not implemented
        }
    }
    LIST_INSERT_HEAD(&subscription->unpublishedNotifications, msg, listEntry);
}

UA_UInt32 *Subscription_getAvailableSequenceNumbers(UA_Subscription *sub) {
    UA_UInt32 *seqArray = UA_malloc(sizeof(UA_UInt32) * Subscription_queuedNotifications(sub));
    if(!seqArray)
        return UA_NULL;
  
    int i = 0;
    UA_unpublishedNotification *not;
    LIST_FOREACH(not, &sub->unpublishedNotifications, listEntry) {
        seqArray[i] = not->notification->sequenceNumber;
        i++;
    }
    return seqArray;
}

void Subscription_copyTopNotificationMessage(UA_NotificationMessage *dst, UA_Subscription *sub) {
    if(!dst)
        return;
    
    if(Subscription_queuedNotifications(sub) == 0) {
      dst->notificationDataSize = 0;
      dst->publishTime = UA_DateTime_now();
      dst->sequenceNumber = 0;
      return;
    }
    
    UA_NotificationMessage *latest = LIST_FIRST(&sub->unpublishedNotifications)->notification;
    dst->notificationDataSize = latest->notificationDataSize;
    dst->publishTime = latest->publishTime;
    dst->sequenceNumber = latest->sequenceNumber;
    
    if(latest->notificationDataSize == 0)
        return;
    
    dst->notificationData = (UA_ExtensionObject *) UA_malloc(sizeof(UA_ExtensionObject));
    dst->notificationData->encoding = latest->notificationData->encoding;
    dst->notificationData->typeId   = latest->notificationData->typeId;
    UA_ByteString_copy(&latest->notificationData->body,
                       &dst->notificationData->body);
}

UA_UInt32 Subscription_deleteUnpublishedNotification(UA_UInt32 seqNo, UA_Subscription *sub) {
    UA_UInt32 deletedItems = 0;
    UA_unpublishedNotification *not, *tmp;
    LIST_FOREACH_SAFE(not, &sub->unpublishedNotifications, listEntry, tmp) {
        if(not->notification->sequenceNumber != seqNo)
            continue;
        LIST_REMOVE(not, listEntry);
        if(not->notification) {
            if(not->notification->notificationData) {
                if(not->notification->notificationData->body.data)
                    UA_free(not->notification->notificationData->body.data);
                UA_free(not->notification->notificationData);
            }
            UA_free(not->notification);
        }
        UA_free(not);
        deletedItems++;
    }
    return deletedItems;
}


static void Subscription_timedUpdateNotificationsJob(UA_Server *server, void *data) {
    // Timed-Worker/Job Version of updateNotifications
    UA_Subscription *sub = (UA_Subscription *) data;
    UA_MonitoredItem *mon;
    
    if(!data || !server)
        return;
    
    // This is set by the Subscription_delete function to detere us from fiddling with
    // this subscription if it is being deleted (not technically thread save, but better
    // then nothing at all)
    if(sub->subscriptionID == 0)
        return;
    
    // FIXME: This should be done by the event system
    LIST_FOREACH(mon, &sub->MonitoredItems, listEntry)
        MonitoredItem_QueuePushDataValue(server, mon);
    
    Subscription_updateNotifications(sub);
}


UA_StatusCode Subscription_createdUpdateJob(UA_Server *server, UA_Guid jobId, UA_Subscription *sub) {
    if(server == UA_NULL || sub == UA_NULL)
        return UA_STATUSCODE_BADSERVERINDEXINVALID;
        
    UA_Job *theWork;
    theWork = (UA_Job *) UA_malloc(sizeof(UA_Job));
    if(!theWork)
        return UA_STATUSCODE_BADOUTOFMEMORY;
    
   *theWork = (UA_Job) {.type = UA_JOBTYPE_METHODCALL,
                        .job.methodCall = {.method = Subscription_timedUpdateNotificationsJob, .data = sub} };
   
   sub->timedUpdateJobGuid = jobId;
   sub->timedUpdateJob     = theWork;
   
   return UA_STATUSCODE_GOOD;
}

UA_StatusCode Subscription_registerUpdateJob(UA_Server *server, UA_Subscription *sub) {
    if(server == UA_NULL || sub == UA_NULL)
        return UA_STATUSCODE_BADSERVERINDEXINVALID;
    
    if(sub->publishingInterval <= 5 ) 
        return UA_STATUSCODE_BADNOTSUPPORTED;
    
    // Practically enough, the client sends a uint32 in ms, which we store as datetime, which here is required in as uint32 in ms as the interval
    UA_StatusCode retval = UA_Server_addRepeatedJob(server, *sub->timedUpdateJob, sub->publishingInterval,
                                                    &sub->timedUpdateJobGuid);
    if(!retval)
        sub->timedUpdateIsRegistered = UA_TRUE;
    return retval;
}

UA_StatusCode Subscription_unregisterUpdateJob(UA_Server *server, UA_Subscription *sub) {
    if(server == UA_NULL || sub == UA_NULL)
        return UA_STATUSCODE_BADSERVERINDEXINVALID;
    UA_Int32 retval = UA_Server_removeRepeatedJob(server, sub->timedUpdateJobGuid);
    sub->timedUpdateIsRegistered = UA_FALSE;
    return retval;
}

/*****************/
/* MonitoredItem */
/*****************/

UA_MonitoredItem *UA_MonitoredItem_new() {
    UA_MonitoredItem *new = (UA_MonitoredItem *) UA_malloc(sizeof(UA_MonitoredItem));
    new->queueSize   = (UA_UInt32_BoundedValue) { .minValue = 0, .maxValue = 0, .currentValue = 0};
    new->lastSampled = 0;
    // FIXME: This is currently hardcoded;
    new->monitoredItemType = MONITOREDITEM_TYPE_CHANGENOTIFY;
    TAILQ_INIT(&new->queue);
    UA_NodeId_init(&new->monitoredNodeId);
    INITPOINTER(new->lastSampledValue.data );
    return new;
}

void MonitoredItem_delete(UA_MonitoredItem *monitoredItem) {
    // Delete Queued Data
    MonitoredItem_ClearQueue(monitoredItem);
    // Remove from subscription list
    LIST_REMOVE(monitoredItem, listEntry);
    // Release comparison sample
    if(monitoredItem->lastSampledValue.data != NULL) { 
      UA_free(monitoredItem->lastSampledValue.data);
    }
    
    UA_NodeId_deleteMembers(&(monitoredItem->monitoredNodeId));
    UA_free(monitoredItem);
}

int MonitoredItem_QueueToDataChangeNotifications(UA_MonitoredItemNotification *dst,
                                                 UA_MonitoredItem *monitoredItem) {
    int queueSize = 0;
    MonitoredItem_queuedValue *queueItem;
  
    // Count instead of relying on the items currentValue
    TAILQ_FOREACH(queueItem, &monitoredItem->queue, listEntry) {
        dst[queueSize].clientHandle = monitoredItem->clientHandle;
        dst[queueSize].value.hasServerPicoseconds = UA_FALSE;
        dst[queueSize].value.hasServerTimestamp   = UA_TRUE;
        dst[queueSize].value.serverTimestamp      = UA_DateTime_now();
        dst[queueSize].value.hasSourcePicoseconds = UA_FALSE;
        dst[queueSize].value.hasSourceTimestamp   = UA_TRUE;
        dst[queueSize].value.sourceTimestamp      = UA_DateTime_now();
        dst[queueSize].value.hasValue             = UA_TRUE;
        dst[queueSize].value.status = UA_STATUSCODE_GOOD;
    
        UA_Variant_copy(&(queueItem->value), &(dst[queueSize].value.value));
    
        // Do not create variants with no type -> will make calcSizeBinary() segfault.
        if(dst[queueSize].value.value.type)
            queueSize++;
    }
    return queueSize;
}

void MonitoredItem_ClearQueue(UA_MonitoredItem *monitoredItem) {
    MonitoredItem_queuedValue *val, *val_tmp;
    TAILQ_FOREACH_SAFE(val, &monitoredItem->queue, listEntry, val_tmp) {
        TAILQ_REMOVE(&monitoredItem->queue, val, listEntry);
        UA_Variant_deleteMembers(&val->value);
        UA_free(val);
    }
    monitoredItem->queueSize.currentValue = 0;
}

UA_Boolean MonitoredItem_CopyMonitoredValueToVariant(UA_UInt32 attributeID, const UA_Node *src,
                                                     UA_Variant *dst) {
    UA_Boolean samplingError = UA_TRUE; 
    UA_DataValue sourceDataValue;
    UA_DataValue_init(&sourceDataValue);
    const UA_VariableNode *srcAsVariableNode = (const UA_VariableNode*)src;
  
    // FIXME: Not all attributeIDs can be monitored yet
    switch(attributeID) {
    case UA_ATTRIBUTEID_NODEID:
        UA_Variant_setScalarCopy(dst, (const UA_NodeId*)&src->nodeId, &UA_TYPES[UA_TYPES_NODEID]);
        samplingError = UA_FALSE;
        break;
    case UA_ATTRIBUTEID_NODECLASS:
        UA_Variant_setScalarCopy(dst, (const UA_Int32*)&src->nodeClass, &UA_TYPES[UA_TYPES_INT32]);
        samplingError = UA_FALSE;
        break;
    case UA_ATTRIBUTEID_BROWSENAME:
        UA_Variant_setScalarCopy(dst, (const UA_String*)&src->browseName, &UA_TYPES[UA_TYPES_QUALIFIEDNAME]);
        samplingError = UA_FALSE;
        break;
    case UA_ATTRIBUTEID_DISPLAYNAME:
        UA_Variant_setScalarCopy(dst, (const UA_String*)&src->displayName, &UA_TYPES[UA_TYPES_LOCALIZEDTEXT]);
        samplingError = UA_FALSE;
        break;
    case UA_ATTRIBUTEID_DESCRIPTION:
        UA_Variant_setScalarCopy(dst, (const UA_String*)&src->displayName, &UA_TYPES[UA_TYPES_LOCALIZEDTEXT]);
        samplingError = UA_FALSE;
        break;
    case UA_ATTRIBUTEID_WRITEMASK:
        UA_Variant_setScalarCopy(dst, (const UA_String*)&src->writeMask, &UA_TYPES[UA_TYPES_UINT32]);
        samplingError = UA_FALSE;
        break;
    case UA_ATTRIBUTEID_USERWRITEMASK:
        UA_Variant_setScalarCopy(dst, (const UA_String*)&src->writeMask, &UA_TYPES[UA_TYPES_UINT32]);
        samplingError = UA_FALSE;
        break;
    case UA_ATTRIBUTEID_ISABSTRACT:
        break;
    case UA_ATTRIBUTEID_SYMMETRIC:
        break;
    case UA_ATTRIBUTEID_INVERSENAME:
        break;
    case UA_ATTRIBUTEID_CONTAINSNOLOOPS:
        break;
    case UA_ATTRIBUTEID_EVENTNOTIFIER:
        break;
    case UA_ATTRIBUTEID_VALUE: 
        if(src->nodeClass == UA_NODECLASS_VARIABLE) {
            const UA_VariableNode *vsrc = (const UA_VariableNode*)src;
            if(srcAsVariableNode->valueSource == UA_VALUESOURCE_VARIANT) {
                UA_Variant_copy(&vsrc->value.variant.value, dst);
                //no onRead callback here since triggered by a subscription
                samplingError = UA_FALSE;
            } else {
                if(srcAsVariableNode->valueSource != UA_VALUESOURCE_DATASOURCE)
                    break;
                // todo: handle numeric ranges
                if(srcAsVariableNode->value.dataSource.read(vsrc->value.dataSource.handle, vsrc->nodeId, UA_TRUE, UA_NULL,
                                                            &sourceDataValue) != UA_STATUSCODE_GOOD)
                    break;
                UA_Variant_copy(&sourceDataValue.value, dst);
                if(sourceDataValue.value.data) {
                    UA_deleteMembers(sourceDataValue.value.data, sourceDataValue.value.type);
                    UA_free(sourceDataValue.value.data);
                    sourceDataValue.value.data = UA_NULL;
                }
                UA_DataValue_deleteMembers(&sourceDataValue);
                samplingError = UA_FALSE;
            }
        }
        break;
    case UA_ATTRIBUTEID_DATATYPE:
        break;
    case UA_ATTRIBUTEID_VALUERANK:
        break;
    case UA_ATTRIBUTEID_ARRAYDIMENSIONS:
        break;
    case UA_ATTRIBUTEID_ACCESSLEVEL:
        break;
    case UA_ATTRIBUTEID_USERACCESSLEVEL:
        break;
    case UA_ATTRIBUTEID_MINIMUMSAMPLINGINTERVAL:
        break;
    case UA_ATTRIBUTEID_HISTORIZING:
        break;
    case UA_ATTRIBUTEID_EXECUTABLE:
        break;
    case UA_ATTRIBUTEID_USEREXECUTABLE:
        break;
    default:
        break;
    }
  
    return samplingError;
}

void MonitoredItem_QueuePushDataValue(UA_Server *server, UA_MonitoredItem *monitoredItem) {
    UA_ByteString newValueAsByteString = { .length=0, .data=NULL };
    size_t encodingOffset = 0;
  
    if(!monitoredItem || monitoredItem->lastSampled + monitoredItem->samplingInterval > UA_DateTime_now())
        return;
  
    // FIXME: Actively suppress non change value based monitoring. There should be
    // another function to handle status and events.
    if(monitoredItem->monitoredItemType != MONITOREDITEM_TYPE_CHANGENOTIFY)
        return;

    MonitoredItem_queuedValue *newvalue = UA_malloc(sizeof(MonitoredItem_queuedValue));
    if(!newvalue)
        return;

    newvalue->listEntry.tqe_next = UA_NULL;
    newvalue->listEntry.tqe_prev = UA_NULL;
    UA_Variant_init(&newvalue->value);

    // Verify that the *Node being monitored is still valid
    // Looking up the in the nodestore is only necessary if we suspect that it is changed during writes
    // e.g. in multithreaded applications
    const UA_Node *target = UA_NodeStore_get(server->nodestore, &monitoredItem->monitoredNodeId);
    if(!target) {
        UA_free(newvalue);
        return;
    }
  
    UA_Boolean samplingError = MonitoredItem_CopyMonitoredValueToVariant(monitoredItem->attributeID, target,
                                                                         &newvalue->value);
    UA_NodeStore_release(target);
    if(samplingError != UA_FALSE || !newvalue->value.type) {
        UA_Variant_deleteMembers(&newvalue->value);
        UA_free(newvalue);
        return;
    }
  
    if(monitoredItem->queueSize.currentValue >= monitoredItem->queueSize.maxValue) {
        if(monitoredItem->discardOldest != UA_TRUE) {
            // We cannot remove the oldest value and theres no queue space left. We're done here.
            UA_free(newvalue);
            return;
        }
        MonitoredItem_queuedValue *queueItem = TAILQ_LAST(&monitoredItem->queue, QueueOfQueueDataValues);
        TAILQ_REMOVE(&monitoredItem->queue, queueItem, listEntry);
        UA_free(queueItem);
        monitoredItem->queueSize.currentValue--;
    }
  
    // encode the data to find if its different to the previous
    newValueAsByteString.length = UA_calcSizeBinary(&newvalue->value, &UA_TYPES[UA_TYPES_VARIANT]);
    newValueAsByteString.data   = UA_malloc(newValueAsByteString.length);
    UA_encodeBinary(&newvalue->value, &UA_TYPES[UA_TYPES_VARIANT], &newValueAsByteString, &encodingOffset);
  
    if(!monitoredItem->lastSampledValue.data) { 
        UA_ByteString_copy(&newValueAsByteString, &monitoredItem->lastSampledValue);
        TAILQ_INSERT_HEAD(&monitoredItem->queue, newvalue, listEntry);
        monitoredItem->queueSize.currentValue++;
        monitoredItem->lastSampled = UA_DateTime_now();
        UA_free(newValueAsByteString.data);
    } else {
        if(UA_String_equal(&newValueAsByteString, &monitoredItem->lastSampledValue) == UA_TRUE) {
            UA_Variant_deleteMembers(&newvalue->value);
            UA_free(newvalue);
            UA_String_deleteMembers(&newValueAsByteString);
            return;
        }
        UA_ByteString_deleteMembers(&monitoredItem->lastSampledValue);
        monitoredItem->lastSampledValue = newValueAsByteString;
        TAILQ_INSERT_HEAD(&monitoredItem->queue, newvalue, listEntry);
        monitoredItem->queueSize.currentValue++;
        monitoredItem->lastSampled = UA_DateTime_now();
    }
}