waveterm/pkg/wps/wps.go

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// Copyright 2024, Command Line Inc.
// SPDX-License-Identifier: Apache-2.0
// wave pubsub system
package wps
import (
"sync"
"github.com/wavetermdev/thenextwave/pkg/util/utilfn"
)
// this broker interface is mostly generic
// strong typing and event types can be defined elsewhere
type WaveEvent struct {
Event string `json:"event"`
Scopes []string `json:"scopes,omitempty"`
Sender string `json:"sender,omitempty"`
Data any `json:"data,omitempty"`
}
type SubscriptionRequest struct {
Event string `json:"event"`
Scopes []string `json:"scopes,omitempty"`
AllScopes bool `json:"allscopes,omitempty"`
}
type Client interface {
ClientId() string
SendEvent(event WaveEvent)
}
type BrokerSubscription struct {
AllSubs []string // clientids of client subscribed to "all" events
ScopeSubs map[string][]string // clientids of client subscribed to specific scopes
}
type Broker struct {
Lock *sync.Mutex
ClientMap map[string]Client
SubMap map[string]*BrokerSubscription
}
func (b *Broker) Subscribe(subscriber Client, sub SubscriptionRequest) {
b.Lock.Lock()
defer b.Lock.Unlock()
clientId := subscriber.ClientId()
bs := b.SubMap[sub.Event]
if bs == nil {
bs = &BrokerSubscription{
AllSubs: []string{},
ScopeSubs: make(map[string][]string),
}
b.SubMap[sub.Event] = bs
}
if sub.AllScopes {
bs.AllSubs = utilfn.AddElemToSliceUniq(bs.AllSubs, clientId)
}
for _, scope := range sub.Scopes {
scopeSubs := bs.ScopeSubs[scope]
scopeSubs = utilfn.AddElemToSliceUniq(scopeSubs, clientId)
bs.ScopeSubs[scope] = scopeSubs
}
}
func (bs *BrokerSubscription) IsEmpty() bool {
return len(bs.AllSubs) == 0 && len(bs.ScopeSubs) == 0
}
func (b *Broker) Unsubscribe(subscriber Client, sub SubscriptionRequest) {
b.Lock.Lock()
defer b.Lock.Unlock()
clientId := subscriber.ClientId()
bs := b.SubMap[sub.Event]
if bs == nil {
return
}
if sub.AllScopes {
bs.AllSubs = utilfn.RemoveElemFromSlice(bs.AllSubs, clientId)
}
for _, scope := range sub.Scopes {
scopeSubs := bs.ScopeSubs[scope]
scopeSubs = utilfn.RemoveElemFromSlice(scopeSubs, clientId)
if len(scopeSubs) == 0 {
delete(bs.ScopeSubs, scope)
} else {
bs.ScopeSubs[scope] = scopeSubs
}
}
if bs.IsEmpty() {
delete(b.SubMap, sub.Event)
}
}
func (b *Broker) UnsubscribeAll(subscriber Client) {
b.Lock.Lock()
defer b.Lock.Unlock()
clientId := subscriber.ClientId()
delete(b.ClientMap, clientId)
for eventType, bs := range b.SubMap {
bs.AllSubs = utilfn.RemoveElemFromSlice(bs.AllSubs, clientId)
for scope, scopeSubs := range bs.ScopeSubs {
scopeSubs = utilfn.RemoveElemFromSlice(scopeSubs, clientId)
if len(scopeSubs) == 0 {
delete(bs.ScopeSubs, scope)
} else {
bs.ScopeSubs[scope] = scopeSubs
}
}
if bs.IsEmpty() {
delete(b.SubMap, eventType)
}
}
}
func (b *Broker) Publish(subscriber Client, event WaveEvent) {
clientIds := b.getMatchingClientIds(event)
for _, clientId := range clientIds {
client := b.ClientMap[clientId]
if client != nil {
client.SendEvent(event)
}
}
}
func (b *Broker) getMatchingClientIds(event WaveEvent) []string {
b.Lock.Lock()
defer b.Lock.Unlock()
bs := b.SubMap[event.Event]
if bs == nil {
return nil
}
clientIds := make(map[string]bool)
for _, clientId := range bs.AllSubs {
clientIds[clientId] = true
}
for _, scope := range event.Scopes {
for _, clientId := range bs.ScopeSubs[scope] {
clientIds[clientId] = true
}
}
var rtn []string
for clientId := range clientIds {
rtn = append(rtn, clientId)
}
return rtn
}