85 lines
2.3 KiB
Go
85 lines
2.3 KiB
Go
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package sse
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import (
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"fmt"
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"log"
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"sync"
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)
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var eventBusLock = &sync.Mutex{}
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var singletonEventBusInstance *EventBus
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// New event messages are broadcast to all registered client connection channels
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// TODO: change this to be use specific channels.
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type ClientChan chan string
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// Get a reference to the EventBus singleton Start procnteessing requests
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// this should be a singleton, to ensure that we're always broadcasting to the same clients
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// see: https://refactoring.guru/design-patterns/singleton/go/example
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func GetEventBusServer() (bus *EventBus) {
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if singletonEventBusInstance == nil {
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eventBusLock.Lock()
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defer eventBusLock.Unlock()
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if singletonEventBusInstance == nil {
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fmt.Println("Creating single instance now.")
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singletonEventBusInstance = &EventBus{
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Message: make(chan string),
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NewClients: make(chan chan string),
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ClosedClients: make(chan chan string),
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TotalClients: make(map[chan string]bool),
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}
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// Start processing requests
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go bus.listen()
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} else {
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fmt.Println("Single instance already created.")
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}
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} else {
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fmt.Println("Single instance already created.")
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}
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return singletonEventBusInstance
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}
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// It keeps a list of clients those are currently attached
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// and broadcasting events to those clients.
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type EventBus struct {
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// Events are pushed to this channel by the main events-gathering routine
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Message chan string
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// New client connections
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NewClients chan chan string
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// Closed client connections
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ClosedClients chan chan string
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// Total client connections
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TotalClients map[chan string]bool
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}
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// It Listens all incoming requests from clients.
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// Handles addition and removal of clients and broadcast messages to clients.
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func (bus *EventBus) listen() {
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for {
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select {
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// Add new available client
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case client := <-bus.NewClients:
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bus.TotalClients[client] = true
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log.Printf("Client added. %d registered clients", len(bus.TotalClients))
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// Remove closed client
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case client := <-bus.ClosedClients:
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delete(bus.TotalClients, client)
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close(client)
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log.Printf("Removed client. %d registered clients", len(bus.TotalClients))
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// Broadcast message to client
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case eventMsg := <-bus.Message:
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for clientMessageChan := range bus.TotalClients {
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clientMessageChan <- eventMsg
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}
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}
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}
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}
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