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server.go
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server.go
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package main
import (
"encoding/json"
"fmt"
"log"
"time"
"github.com/streadway/amqp"
)
var bpm = 145
func msgListener(ch *amqp.Channel) {
q, err := ch.QueueDeclare(
"", // name
false, // durable
false, // delete when usused
true, // exclusive
false, // no-wait
nil, // arguments
)
failOnError(err, "Failed to declare a queue")
err = ch.QueueBind(
q.Name, // queue name
"", // routing key
"updateMsgs", // exchange
false,
nil)
failOnError(err, "Failed to bind a queue")
msgs, err := ch.Consume(
q.Name, // queue
"", // consumer
true, // auto-ack
false, // exclusive
false, // no-local
false, // no-wait
nil, // args
)
failOnError(err, "Failed to register a consumer")
for d := range msgs {
var m UpdateMsg
err := json.Unmarshal(d.Body, &m)
if err != nil {
fmt.Println("blah", err)
}
if m.Name == "bpm" {
fmt.Println("Setting BPM to", m.Value)
bpm = m.Value
}
}
}
func serverMain(ch *amqp.Channel) {
go msgListener(ch)
tickCounter := 1
tickLength := (60000 / bpm) / 4 // 1min divided by bpm divided by 4 microticks
for {
if bpm != 0 {
tickLength = (60000 / bpm) / 4
}
timer := time.NewTimer(time.Duration(tickLength) * time.Millisecond)
beatTick := tickCounter % 32
beat := (beatTick + 3) / 4
microTick := tickCounter % 4
if microTick == 0 {
microTick = 4
}
m := BpmMsg{bpm, microTick, tickLength, beat, tickCounter}
msg, err := json.Marshal(m)
if err != nil {
log.Fatal("Barf!", err)
}
err = ch.Publish(
"bpm", // exchange
"", // routing key
false, // mandatory
false, // immediate
amqp.Publishing{
ContentType: "text/json",
Body: msg,
})
failOnError(err, "Failed to publish a message")
log.Printf("Sending msg -- %s", msg)
tickCounter++
<-timer.C // pause before next iteration - length of bpm
}
}