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subscription.go
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subscription.go
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package opcua
import (
"context"
"log"
"sync/atomic"
"time"
"github.com/skilld-labs/opcua/debug"
"github.com/skilld-labs/opcua/errors"
"github.com/skilld-labs/opcua/id"
"github.com/skilld-labs/opcua/ua"
"github.com/skilld-labs/opcua/uasc"
)
const (
DefaultSubscriptionMaxNotificationsPerPublish = 10000
DefaultSubscriptionLifetimeCount = 10000
DefaultSubscriptionMaxKeepAliveCount = 3000
DefaultSubscriptionInterval = 100 * time.Millisecond
DefaultSubscriptionPriority = 0
)
const terminatedSubscriptionID uint32 = 0xC0CAC01B
type Subscription struct {
SubscriptionID uint32
RevisedPublishingInterval time.Duration
RevisedLifetimeCount uint32
RevisedMaxKeepAliveCount uint32
Notifs chan *PublishNotificationData
params *SubscriptionParameters
items []*monitoredItem
lastSequenceNumber uint32
pausech chan struct{}
resumech chan struct{}
stopch chan struct{}
c *Client
}
type SubscriptionParameters struct {
Interval time.Duration
LifetimeCount uint32
MaxKeepAliveCount uint32
MaxNotificationsPerPublish uint32
Priority uint8
}
type monitoredItem struct {
ItemToMonitor *ua.ReadValueID
MonitoringParameters *ua.MonitoringParameters
MonitoringMode ua.MonitoringMode
TimestampsToReturn ua.TimestampsToReturn
createResult *ua.MonitoredItemCreateResult
}
func NewMonitoredItemCreateRequestWithDefaults(nodeID *ua.NodeID, attributeID ua.AttributeID, clientHandle uint32) *ua.MonitoredItemCreateRequest {
if attributeID == 0 {
attributeID = ua.AttributeIDValue
}
return &ua.MonitoredItemCreateRequest{
ItemToMonitor: &ua.ReadValueID{
NodeID: nodeID,
AttributeID: attributeID,
DataEncoding: &ua.QualifiedName{},
},
MonitoringMode: ua.MonitoringModeReporting,
RequestedParameters: &ua.MonitoringParameters{
ClientHandle: clientHandle,
DiscardOldest: true,
Filter: nil,
QueueSize: 10,
SamplingInterval: 0.0,
},
}
}
type PublishNotificationData struct {
SubscriptionID uint32
Error error
Value interface{}
}
// Cancel stops the subscription and removes it
// from the client and the server.
func (s *Subscription) Cancel() error {
s.c.forgetSubscription(s.SubscriptionID)
close(s.stopch)
return s.delete()
}
// delete removes the subscription from the server.
func (s *Subscription) delete() error {
req := &ua.DeleteSubscriptionsRequest{
SubscriptionIDs: []uint32{s.SubscriptionID},
}
var res *ua.DeleteSubscriptionsResponse
err := s.c.Send(req, func(v interface{}) error {
return safeAssign(v, &res)
})
switch {
case err != nil:
return err
case res.ResponseHeader.ServiceResult != ua.StatusOK:
return res.ResponseHeader.ServiceResult
default:
return nil
}
}
func (s *Subscription) Monitor(ts ua.TimestampsToReturn, items ...*ua.MonitoredItemCreateRequest) (*ua.CreateMonitoredItemsResponse, error) {
// Part 4, 5.12.2.2 CreateMonitoredItems Service Parameters
req := &ua.CreateMonitoredItemsRequest{
SubscriptionID: s.SubscriptionID,
TimestampsToReturn: ts,
ItemsToCreate: items,
}
var res *ua.CreateMonitoredItemsResponse
err := s.c.Send(req, func(v interface{}) error {
return safeAssign(v, &res)
})
if err != nil {
return nil, err
}
for _, result := range res.Results {
if status := result.StatusCode; status != ua.StatusOK {
return nil, status
}
}
// store monitored items
for i, item := range items {
result := res.Results[i]
mi := &monitoredItem{
ItemToMonitor: item.ItemToMonitor,
MonitoringParameters: item.RequestedParameters,
MonitoringMode: item.MonitoringMode,
TimestampsToReturn: ts,
createResult: result,
}
s.items = append(s.items, mi)
}
return res, err
}
func (s *Subscription) Unmonitor(monitoredItemIDs ...uint32) (*ua.DeleteMonitoredItemsResponse, error) {
req := &ua.DeleteMonitoredItemsRequest{
MonitoredItemIDs: monitoredItemIDs,
SubscriptionID: s.SubscriptionID,
}
var res *ua.DeleteMonitoredItemsResponse
err := s.c.Send(req, func(v interface{}) error {
return safeAssign(v, &res)
})
return res, err
}
// SetTriggering sends a request to the server to add and/or remove triggering links from a triggering item.
// To add links from a triggering item to an item to report provide the server assigned ID(s) in the `add` argument.
// To remove links from a triggering item to an item to report provide the server assigned ID(s) in the `remove` argument.
func (s *Subscription) SetTriggering(triggeringItemID uint32, add, remove []uint32) (*ua.SetTriggeringResponse, error) {
// Part 4, 5.12.5.2 SetTriggering Service Parameters
req := &ua.SetTriggeringRequest{
SubscriptionID: s.SubscriptionID,
TriggeringItemID: triggeringItemID,
LinksToAdd: add,
LinksToRemove: remove,
}
var res *ua.SetTriggeringResponse
err := s.c.Send(req, func(v interface{}) error {
return safeAssign(v, &res)
})
return res, err
}
// republish executes a synchronous republish request.
func (s *Subscription) republish(req *ua.RepublishRequest) (*ua.RepublishResponse, error) {
var res *ua.RepublishResponse
err := s.c.sechan.SendRequest(req, s.c.Session().resp.AuthenticationToken, func(v interface{}) error {
return safeAssign(v, &res)
})
return res, err
}
func (s *Subscription) publish(acks []*ua.SubscriptionAcknowledgement) (*ua.PublishResponse, error) {
if acks == nil {
acks = []*ua.SubscriptionAcknowledgement{}
}
req := &ua.PublishRequest{
SubscriptionAcknowledgements: acks,
}
var res *ua.PublishResponse
err := s.c.sendWithTimeout(req, s.publishTimeout(), func(v interface{}) error {
return safeAssign(v, &res)
})
return res, err
}
func (s *Subscription) publishTimeout() time.Duration {
timeout := time.Duration(s.RevisedMaxKeepAliveCount) * s.RevisedPublishingInterval // expected keepalive interval
if timeout > uasc.MaxTimeout {
return uasc.MaxTimeout
}
if timeout < s.c.cfg.RequestTimeout {
return s.c.cfg.RequestTimeout
}
return timeout
}
// pause suspends the run loop by signalling the pausech.
// Since the channel is unbuffered we wait until the
// run loop has completed the current publish message.
func (s *Subscription) pause(ctx context.Context) {
select {
case <-ctx.Done():
case <-s.stopch:
case s.pausech <- struct{}{}:
}
}
// resume restarts the run loop by signalling the resumech.
// It has no effect if the run loop isn't paused.
func (s *Subscription) resume(ctx context.Context) {
select {
case <-ctx.Done():
case <-s.stopch:
case s.resumech <- struct{}{}:
}
}
// Run starts an infinite loop which sends PublishRequests and delivers received
// notifications to registered subcribers.
//
// It is the responsibility of the caller to stop the run loops by
// cancelling the context.
//
// Note that Run may return before the context is cancelled
// in case of an irrecoverable communication error.
func (s *Subscription) Run(ctx context.Context) {
cctx, cancel := context.WithCancel(ctx)
defer cancel()
defer log.Print("sub: done")
publish:
for {
log.Print("sub: select")
select {
case <-ctx.Done():
log.Println("sub: ctx.Done()")
cancel()
return
case <-s.stopch:
log.Println("sub: stop")
cancel()
return
case <-s.pausech:
log.Print("sub: pause")
paused:
for {
select {
case <-ctx.Done():
log.Print("sub: pause: ctx.Done()")
cancel()
return
case <-s.stopch:
log.Print("sub: pause: stop")
cancel()
return
case <-s.pausech:
log.Print("sub: pause: pause")
// ignore since already paused
continue paused
case <-s.resumech:
log.Print("sub: pause: resume")
continue publish
}
}
case <-s.resumech:
log.Print("sub: resume")
// ignore since not paused
continue
default:
log.Print("sub: publish")
s.run(cctx)
}
}
}
func (s *Subscription) run(ctx context.Context) {
defer log.Print("publish: done")
var acks []*ua.SubscriptionAcknowledgement
for {
log.Print("publish: select")
select {
case <-ctx.Done():
log.Print("publish: ctx.Done()")
return
case <-s.stopch:
log.Printf("publish: stop")
return
default:
log.Printf("publish: default")
// send the next publish request
// note that res contains data even if an error was returned
res, err := s.publish(acks)
switch {
case err == ua.StatusBadSequenceNumberUnknown:
// At least one ack has been submitted repeatedly
// Ignore the error. Acks will be cleared below
case err == ua.StatusBadTimeout:
// ignore and continue the loop
case err == ua.StatusBadNoSubscription:
// All subscriptions have been deleted, but the publishing loop is still running
// The user will stop the loop or create subscriptions at his discretion
case err != nil:
// irrecoverable error
s.c.notifySubscriptionsOfError(ctx, res, err)
debug.Printf("subscription %v Run loop stopped", s.SubscriptionID)
log.Print("publish: notify error")
return
}
if res != nil {
// Prepare SubscriptionAcknowledgement for next PublishRequest
acks = make([]*ua.SubscriptionAcknowledgement, 0)
if res.AvailableSequenceNumbers != nil {
for _, i := range res.AvailableSequenceNumbers {
ack := &ua.SubscriptionAcknowledgement{
SubscriptionID: res.SubscriptionID,
SequenceNumber: i,
}
if i > atomic.LoadUint32(&s.lastSequenceNumber) {
atomic.StoreUint32(&s.lastSequenceNumber, i)
}
acks = append(acks, ack)
}
}
}
if err == nil {
s.c.notifySubscription(ctx, res)
log.Print("publish: notify")
}
}
}
}
func (s *Subscription) notify(ctx context.Context, data *PublishNotificationData) {
select {
case <-ctx.Done():
return
case s.Notifs <- data:
}
}
// Stats returns a diagnostic struct with metadata about the current subscription
func (s *Subscription) Stats() (*ua.SubscriptionDiagnosticsDataType, error) {
// TODO(kung-foo): once browsing feature is merged, attempt to get direct access to the
// diagnostics node. for example, Prosys lists them like:
// i=2290/ns=1;g=918ee6f4-2d25-4506-980d-e659441c166d
// maybe cache the nodeid to speed up future stats queries
node := s.c.Node(ua.NewNumericNodeID(0, id.Server_ServerDiagnostics_SubscriptionDiagnosticsArray))
v, err := node.Value()
if err != nil {
return nil, err
}
for _, eo := range v.Value().([]*ua.ExtensionObject) {
stat := eo.Value.(*ua.SubscriptionDiagnosticsDataType)
if stat.SubscriptionID == s.SubscriptionID {
return stat, nil
}
}
return nil, errors.Errorf("unable to find SubscriptionDiagnostics for sub=%d", s.SubscriptionID)
}
func (p *SubscriptionParameters) setDefaults() {
if p.MaxNotificationsPerPublish == 0 {
p.MaxNotificationsPerPublish = DefaultSubscriptionMaxNotificationsPerPublish
}
if p.LifetimeCount == 0 {
p.LifetimeCount = DefaultSubscriptionLifetimeCount
}
if p.MaxKeepAliveCount == 0 {
p.MaxKeepAliveCount = DefaultSubscriptionMaxKeepAliveCount
}
if p.Interval == 0 {
p.Interval = DefaultSubscriptionInterval
}
if p.Priority == 0 {
// DefaultSubscriptionPriority is 0 at the time of writing, so this redundant assignment is
// made only to allow for a one-liner change of default priority should a need arise
// and to explicitly expose the default priority as a constant
p.Priority = DefaultSubscriptionPriority
}
}
// restore creates a new subscription based on the previous subscription
// parameters and monitored items.
func (s *Subscription) restore() error {
if s.SubscriptionID == terminatedSubscriptionID {
debug.Printf("Subscription is not in a valid state")
return nil
}
params := s.params
{
req := &ua.DeleteSubscriptionsRequest{
SubscriptionIDs: []uint32{s.SubscriptionID},
}
var res *ua.DeleteSubscriptionsResponse
_ = s.c.Send(req, func(v interface{}) error {
return safeAssign(v, &res)
})
}
s.c.forgetSubscription(s.SubscriptionID)
req := &ua.CreateSubscriptionRequest{
RequestedPublishingInterval: float64(params.Interval / time.Millisecond),
RequestedLifetimeCount: params.LifetimeCount,
RequestedMaxKeepAliveCount: params.MaxKeepAliveCount,
PublishingEnabled: true,
MaxNotificationsPerPublish: params.MaxNotificationsPerPublish,
Priority: params.Priority,
}
var res *ua.CreateSubscriptionResponse
err := s.c.Send(req, func(v interface{}) error {
return safeAssign(v, &res)
})
if err != nil {
return err
}
// todo (unknownet): check if necessary
if status := res.ResponseHeader.ServiceResult; status != ua.StatusOK {
return status
}
s.SubscriptionID = res.SubscriptionID
s.RevisedPublishingInterval = time.Duration(res.RevisedPublishingInterval) * time.Millisecond
s.RevisedLifetimeCount = res.RevisedLifetimeCount
s.RevisedMaxKeepAliveCount = res.RevisedMaxKeepAliveCount
atomic.StoreUint32(&s.lastSequenceNumber, 0)
if err := s.c.registerSubscription(s); err != nil {
return err
}
// Sort by timestamp to return
itemsByTs := make(map[ua.TimestampsToReturn][]*ua.MonitoredItemCreateRequest)
for _, m := range s.items {
cr := &ua.MonitoredItemCreateRequest{
ItemToMonitor: m.ItemToMonitor,
MonitoringMode: m.MonitoringMode,
RequestedParameters: m.MonitoringParameters,
}
itemsByTs[m.TimestampsToReturn] = append(itemsByTs[m.TimestampsToReturn], cr)
}
for ts, items := range itemsByTs {
req := &ua.CreateMonitoredItemsRequest{
SubscriptionID: s.SubscriptionID,
TimestampsToReturn: ts,
ItemsToCreate: items,
}
var res *ua.CreateMonitoredItemsResponse
err := s.c.Send(req, func(v interface{}) error {
return safeAssign(v, &res)
})
if err != nil {
return err
}
for _, result := range res.Results {
if status := result.StatusCode; status != ua.StatusOK {
return status
}
}
for i, m := range s.items {
m.createResult = res.Results[i]
}
}
return nil
}