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event_monitored_item.go
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event_monitored_item.go
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// Copyright 2021 Converter Systems LLC. All rights reserved.
package server
import (
"context"
"sync/atomic"
"time"
"sync"
"github.com/awcullen/opcua/ua"
deque "github.com/gammazero/deque"
)
// EventMonitoredItem specifies a node that is monitored for events.
type EventMonitoredItem struct {
sync.RWMutex
id uint32
itemToMonitor ua.ReadValueID
monitoringMode ua.MonitoringMode
clientHandle uint32
samplingInterval float64
queueSize uint32
discardOldest bool
queue deque.Deque[[]ua.Variant]
node Node
eventFilter ua.EventFilter
sub *Subscription
srv *Server
triggeredItems []MonitoredItem
triggered bool
}
// NewEventMonitoredItem constructs a new EventMonitoredItem.
func NewEventMonitoredItem(ctx context.Context, sub *Subscription, node Node, itemToMonitor ua.ReadValueID, monitoringMode ua.MonitoringMode, parameters ua.MonitoringParameters) *EventMonitoredItem {
mi := &EventMonitoredItem{
sub: sub,
srv: sub.manager.server,
node: node,
id: atomic.AddUint32(&monitoredItemID, 1),
itemToMonitor: itemToMonitor,
monitoringMode: monitoringMode,
clientHandle: parameters.ClientHandle,
discardOldest: parameters.DiscardOldest,
queue: deque.Deque[[]ua.Variant]{},
}
mi.setQueueSize(parameters.QueueSize)
mi.setSamplingInterval(parameters.SamplingInterval)
mi.setFilter(parameters.Filter)
mi.Lock()
mi.startMonitoring(ctx)
mi.Unlock()
return mi
}
// ID returns the identifier of the MonitoredItem.
func (mi *EventMonitoredItem) ID() uint32 {
return mi.id
}
// Node returns the Node of the MonitoredItem.
func (mi *EventMonitoredItem) Node() Node {
return mi.node
}
// ItemToMonitor returns the ReadValueID of the MonitoredItem.
func (mi *EventMonitoredItem) ItemToMonitor() ua.ReadValueID {
return mi.itemToMonitor
}
// SamplingInterval returns the sampling interval in ms of the MonitoredItem.
func (mi *EventMonitoredItem) SamplingInterval() float64 {
mi.RLock()
defer mi.RUnlock()
return mi.samplingInterval
}
// QueueSize returns the queue size of the MonitoredItem.
func (mi *EventMonitoredItem) QueueSize() uint32 {
mi.RLock()
defer mi.RUnlock()
return mi.queueSize
}
// MonitoringMode returns the monitoring mode of the MonitoredItem.
func (mi *EventMonitoredItem) MonitoringMode() ua.MonitoringMode {
mi.RLock()
defer mi.RUnlock()
return mi.monitoringMode
}
// ClientHandle returns the client handle of the MonitoredItem.
func (mi *EventMonitoredItem) ClientHandle() uint32 {
mi.RLock()
defer mi.RUnlock()
return mi.clientHandle
}
// Triggered returns true when the MonitoredItem is triggered.
func (mi *EventMonitoredItem) Triggered() bool {
mi.RLock()
defer mi.RUnlock()
return mi.triggered
}
// SetTriggered sets when the MonitoredItem is triggered.
func (mi *EventMonitoredItem) SetTriggered(val bool) {
mi.Lock()
defer mi.Unlock()
mi.triggered = val
}
// Modify modifies the MonitoredItem.
func (mi *EventMonitoredItem) Modify(ctx context.Context, req ua.MonitoredItemModifyRequest) ua.MonitoredItemModifyResult {
mi.Lock()
defer mi.Unlock()
mi.stopMonitoring()
mi.clientHandle = req.RequestedParameters.ClientHandle
mi.discardOldest = req.RequestedParameters.DiscardOldest
mi.setQueueSize(req.RequestedParameters.QueueSize)
mi.setSamplingInterval(req.RequestedParameters.SamplingInterval)
mi.setFilter(req.RequestedParameters.Filter)
mi.startMonitoring(ctx)
return ua.MonitoredItemModifyResult{RevisedSamplingInterval: mi.samplingInterval, RevisedQueueSize: mi.queueSize}
}
// Delete deletes the DataMonitoredItem.
func (mi *EventMonitoredItem) Delete() {
mi.Lock()
defer mi.Unlock()
mi.stopMonitoring()
mi.queue.Clear()
mi.node = nil
mi.sub = nil
mi.triggeredItems = nil
}
// SetMonitoringMode sets the MonitoringMode of the MonitoredItem.
func (mi *EventMonitoredItem) SetMonitoringMode(ctx context.Context, mode ua.MonitoringMode) {
mi.Lock()
defer mi.Unlock()
if mi.monitoringMode == mode {
return
}
mi.stopMonitoring()
mi.monitoringMode = mode
if mode == ua.MonitoringModeDisabled {
mi.queue.Clear()
mi.sub.disabledMonitoredItemCount++
} else {
mi.sub.disabledMonitoredItemCount--
}
mi.startMonitoring(ctx)
}
func (mi *EventMonitoredItem) setQueueSize(queueSize uint32) {
mi.queueSize = maxQueueSize
// trim to size
if mi.discardOldest {
for mi.queue.Len() > int(mi.queueSize) {
mi.queue.PopFront()
}
} else {
for mi.queue.Len() > int(mi.queueSize) {
mi.queue.PopBack()
}
}
}
func (mi *EventMonitoredItem) setSamplingInterval(samplingInterval float64) {
mi.samplingInterval = 0
}
func (mi *EventMonitoredItem) setFilter(filter any) {
if ef, ok := filter.(ua.EventFilter); ok {
mi.eventFilter = ef
} else {
mi.eventFilter = ua.EventFilter{}
}
}
func (mi *EventMonitoredItem) enqueue(item []ua.Variant) {
overflow := false
if mi.discardOldest {
for mi.queue.Len() >= int(mi.queueSize) {
mi.queue.PopFront() // discard oldest
overflow = true
}
mi.queue.PushBack(item)
if overflow && mi.queueSize > 1 {
mi.sub.monitoringQueueOverflowCount++
}
} else {
for mi.queue.Len() >= int(mi.queueSize) {
mi.queue.PopBack() // discard newest
overflow = true
}
mi.queue.PushBack(item)
if overflow && mi.queueSize > 1 {
mi.sub.monitoringQueueOverflowCount++
}
}
if mi.triggeredItems != nil {
for _, item := range mi.triggeredItems {
item.SetTriggered(true)
// log.Printf("Item %d triggered %d", mi.id, item.id)
}
}
}
func (mi *EventMonitoredItem) OnEvent(evt ua.Event) {
mi.Lock()
if res, ok := mi.whereClause(evt, 0).(bool); ok && res {
mi.enqueue(mi.selectFields(evt))
}
mi.Unlock()
}
var (
attributeOperandEventType = ua.SimpleAttributeOperand{TypeDefinitionID: ua.ObjectTypeIDBaseEventType, BrowsePath: ua.ParseBrowsePath("EventType"), AttributeID: ua.AttributeIDValue}
)
func (mi *EventMonitoredItem) whereClause(evt ua.Event, idx int) any {
if idx >= len(mi.eventFilter.WhereClause.Elements) {
return true
}
element := mi.eventFilter.WhereClause.Elements[idx]
switch element.FilterOperator {
case ua.FilterOperatorEquals:
var a, b ua.Variant
switch c := element.FilterOperands[0].(type) {
case ua.LiteralOperand:
a = c.Value
case ua.SimpleAttributeOperand:
a = evt.GetAttribute(c)
case ua.ElementOperand:
a = mi.whereClause(evt, int(c.Index))
default:
return false
}
switch c := element.FilterOperands[1].(type) {
case ua.LiteralOperand:
b = c.Value
case ua.SimpleAttributeOperand:
b = evt.GetAttribute(c)
case ua.ElementOperand:
b = mi.whereClause(evt, int(c.Index))
default:
return false
}
return a == b
case ua.FilterOperatorOfType:
if a, ok := element.FilterOperands[0].(ua.LiteralOperand); ok {
if b, ok := a.Value.(ua.NodeID); ok {
if c, ok := evt.GetAttribute(attributeOperandEventType).(ua.NodeID); ok {
if c == b || mi.srv.namespaceManager.IsSubtype(c, b) {
return true
}
}
}
}
return false
default:
return false
}
}
func (mi *EventMonitoredItem) selectFields(evt ua.Event) []ua.Variant {
clauses := mi.eventFilter.SelectClauses
ret := make([]ua.Variant, len(clauses))
for i, clause := range clauses {
ret[i] = evt.GetAttribute(clause)
}
return ret
}
func (mi *EventMonitoredItem) startMonitoring(ctx context.Context) {
if mi.monitoringMode == ua.MonitoringModeDisabled {
return
}
if n2, ok := mi.node.(*ObjectNode); ok {
n2.AddEventListener(mi)
}
}
func (mi *EventMonitoredItem) stopMonitoring() {
if n2, ok := mi.node.(*ObjectNode); ok {
n2.RemoveEventListener(mi)
}
}
func (mi *EventMonitoredItem) notifications(max int) (notifications []any, more bool) {
mi.Lock()
defer mi.Unlock()
notifications = make([]any, 0, 4)
for i := 0; i < max; i++ {
if mi.queue.Len() > 0 {
notifications = append(notifications, mi.queue.PopFront())
} else {
break
}
}
more = mi.queue.Len() > 0
if mi.triggered && !more {
mi.triggered = false
// log.Printf("Reset triggered %d", mi.id)
}
return notifications, more
}
func (mi *EventMonitoredItem) notificationsAvailable(tn time.Time, late bool, resend bool) bool {
_ = late
mi.Lock()
defer mi.Unlock()
// if disabled, then report false.
if mi.monitoringMode == ua.MonitoringModeDisabled {
return false
}
return mi.queue.Len() > 0 && (mi.monitoringMode == ua.MonitoringModeReporting || mi.triggered)
}
// AddTriggeredItem adds a item to be triggered by this item.
func (mi *EventMonitoredItem) AddTriggeredItem(item MonitoredItem) bool {
mi.Lock()
mi.triggeredItems = append(mi.triggeredItems, item)
mi.Unlock()
return true
}
// RemoveTriggeredItem removes an item to be triggered by this item.
func (mi *EventMonitoredItem) RemoveTriggeredItem(item MonitoredItem) bool {
mi.Lock()
ret := false
for i, e := range mi.triggeredItems {
if e.ID() == item.ID() {
mi.triggeredItems[i] = mi.triggeredItems[len(mi.triggeredItems)-1]
mi.triggeredItems[len(mi.triggeredItems)-1] = nil
mi.triggeredItems = mi.triggeredItems[:len(mi.triggeredItems)-1]
ret = true
break
}
}
mi.Unlock()
return ret
}