Peter Stuifzand
83956b4d9f
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New endpoint action "action=events" opens an SSE channel. Implementation based on https://thoughtbot.com/blog/writing-a-server-sent-events-server-in-go
75 lines
1.9 KiB
Go
75 lines
1.9 KiB
Go
package server
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import (
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"log"
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)
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// A MessageChan is a channel of channels
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// Each connection sends a channel of bytes to a global MessageChan
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// The main broker listen() loop listens on new connections on MessageChan
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// New event messages are broadcast to all registered connection channels
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type MessageChan chan Message
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type Message struct {
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Event string
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Object interface{}
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}
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// A Broker holds open client connections,
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// listens for incoming events on its Notifier channel
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// and broadcast event data to all registered connections
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type Broker struct {
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// Events are pushed to this channel by the main UDP daemon
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Notifier chan Message
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// New client connections
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newClients chan MessageChan
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// Closed client connections
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closingClients chan MessageChan
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// Client connections registry
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clients map[MessageChan]bool
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}
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// Listen on different channels and act accordingly
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func (broker *Broker) listen() {
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for {
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select {
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case s := <-broker.newClients:
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// A new client has connected.
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// Register their message channel
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broker.clients[s] = true
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log.Printf("Client added. %d registered clients", len(broker.clients))
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case s := <-broker.closingClients:
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// A client has detached and we want to
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// stop sending them messages.
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delete(broker.clients, s)
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log.Printf("Removed client. %d registered clients", len(broker.clients))
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case event := <-broker.Notifier:
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// We got a new event from the outside!
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// Send event to all connected clients
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for clientMessageChan := range broker.clients {
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clientMessageChan <- event
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}
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}
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}
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}
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// Broker factory
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func NewServer() (broker *Broker) {
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// Instantiate a broker
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broker = &Broker{
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Notifier: make(chan Message, 1),
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newClients: make(chan MessageChan),
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closingClients: make(chan MessageChan),
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clients: make(map[MessageChan]bool),
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}
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// Set it running - listening and broadcasting events
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go broker.listen()
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return
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}
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