139 lines
3.3 KiB
Go
139 lines
3.3 KiB
Go
package subscription
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//TODO WILDCARD SUBSCRIPTIONS
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import (
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"strings"
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"sync"
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"badat.dev/maeqtt/v2/mqtt/packets"
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)
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var Subscriptions SubscriptionTreeNode = *newSubscriptionTreeNode()
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type SubscriptionChannel chan packets.PublishPacket
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type Subscription struct {
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SubscriptionChannel
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packets.TopicFilter
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}
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type SubscriptionTreeNode struct {
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children map[string]*SubscriptionTreeNode
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Subscriptions []Subscription
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NodeLock sync.RWMutex
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}
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func newSubscriptionTreeNode() *SubscriptionTreeNode {
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s := SubscriptionTreeNode{}
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s.children = make(map[string]*SubscriptionTreeNode)
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return &s
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}
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func (s *SubscriptionTreeNode) findNode(fields []string) *SubscriptionTreeNode {
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if len(fields) == 0 {
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return s
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}
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field := fields[0]
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s.NodeLock.RLock()
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_, exists := s.children[field]
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// Insert a value into the map if one doesn't exist yet
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if !exists {
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// Can't upgrade a read lock so we need to unlock and
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// check again, this time with a write lock
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s.NodeLock.RUnlock()
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s.NodeLock.Lock()
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_, exists = s.children[field]
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if !exists {
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s.children[field] = newSubscriptionTreeNode()
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}
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s.NodeLock.Unlock()
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s.NodeLock.RLock()
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}
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child, _ := s.children[field]
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s.NodeLock.RUnlock()
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return child.findNode(fields[1:])
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}
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func (s *SubscriptionTreeNode) removeSubscription(subChan SubscriptionChannel) {
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for i, sub := range s.Subscriptions {
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if sub.SubscriptionChannel == subChan {
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lst := len(s.Subscriptions) - 1
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s.Subscriptions[i] = s.Subscriptions[lst]
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s.Subscriptions = s.Subscriptions[:lst]
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}
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}
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}
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func (s *SubscriptionTreeNode) Subscribe(topicFilter packets.TopicFilter, subChan SubscriptionChannel) {
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sub := Subscription{subChan, topicFilter}
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node := s.findNode(topicFilter.Topic.Fields)
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node.NodeLock.Lock()
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node.Subscriptions = append(node.Subscriptions, sub)
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node.NodeLock.Unlock()
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}
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func (s *SubscriptionTreeNode) Unsubscribe(topic packets.Topic, subChan SubscriptionChannel) {
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node := s.findNode(topic.Fields)
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node.NodeLock.Lock()
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node.removeSubscription(subChan)
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node.NodeLock.Unlock()
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}
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func (s *SubscriptionTreeNode) RemoveSubsForChannel(subChan SubscriptionChannel) {
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for _, node := range s.children {
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node.NodeLock.Lock()
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node.removeSubscription(subChan)
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node.NodeLock.Unlock()
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node.RemoveSubsForChannel(subChan)
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}
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}
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// Returns the subscriptions whose filters match the given topic name
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func (s *SubscriptionTreeNode) GetSubscriptions(topicName string) []*SubscriptionTreeNode {
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fields := strings.Split(topicName, "/")
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return s.matchSubscriptions(fields)
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}
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// Returns nodes with subscriptions that match the given topic
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func (s *SubscriptionTreeNode) matchSubscriptions(fields []string) []*SubscriptionTreeNode {
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if len(fields) == 0 {
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return []*SubscriptionTreeNode{s}
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}
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sub := make([]*SubscriptionTreeNode, 0)
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s.NodeLock.RLock()
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// Single level wildcard(+)
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if SlWildcard, exists := s.children["+"]; exists {
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sub = append(sub, SlWildcard.matchSubscriptions(fields[1:])...)
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}
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// Multi level wildcard(#)
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if MlWildcard, exists := s.children["#"]; exists {
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sub = append(sub, MlWildcard)
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}
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field := fields[0]
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if field == "#" || field == "+" {
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// TODO handle gracefully
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panic("Wildcard in topic")
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}
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if child, exists := s.children[field]; exists {
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sub = append(sub, child.matchSubscriptions(fields[1:])...)
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}
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s.NodeLock.RUnlock()
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return sub
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}
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