server.go

package main

import (
	"fmt"
	"math/rand"
	"time"
)

var dataBuffer = make(map[string][]StampedReading) // Map to store readings in until they are sent

func main() {
	go dataReadLoop()        // Start our async read loop
	client.wait.Add(1)       // Make sure data and heartbeat loops don't do anything without a valid client
	InitializeClient()       // Get our client in this thread
	go client.readIncoming() // Start our loop to read incoming messages
	go dataSendLoop()        // Start our async send loop
	go heartbeatLoop()       // Start our async heartbeat loop

	select {} // Immortality
}

func dataReadLoop() { // Read data all day every day
	for {
		reading := readData() // TODO: error handling
		for metric, value := range reading { // Put our data in the buffer
			if record, found := dataBuffer[metric]; !found {
				dataBuffer[metric] = []StampedReading{value}
			} else {
				dataBuffer[metric] = append(record, value)
			}
		}
		time.Sleep(time.Second * dataReadPeriod)
	}
}

func dataSendLoop() {
	for {
		time.Sleep(time.Second * dataSendPeriod)
		if len(dataBuffer) == 0 { // Only send if we have data
			fmt.Println("No data to send... check logs (that don't exist yet) for data reading errors (also don't exist)")
			continue
		}
		go client.sendData(dataBuffer)
		dataBuffer = make(map[string][]StampedReading)
	}
}

func heartbeatLoop() {
	for {
		go client.sendHeartbeat()
		time.Sleep(time.Second * heartbeatPeriod)
	}
}

func readData() map[string]StampedReading {
	// TODO: modbus
	return map[string]StampedReading{
		"oil.temp": {
			Timestamp: int(time.Now().Unix()),
			Value:     rand.Intn(150),
		},
		"fuel.temp": {
			Timestamp: int(time.Now().Unix()),
			Value:     rand.Intn(150),
		},
	}
}