SystemMonitorDispatcher.go

package main

import "net/http"
import "encoding/json"

import "time"
import "errors"
import "log"

type SystemStateRequest struct {
	BasicRequest
}

type SystemMonitorResponse struct {
	CPUUsage  CPUAverage
	MemSample MemSample
}

type SystemMonitorDispatcher struct {
	lastCPUSample   CPUSample
	lastCPUAverage  CPUAverage
	measureJob      BatchJob
	lastRequestTime time.Time
}

func (serviceStateDispatcher *SystemMonitorDispatcher) getCPUUsage() CPUAverage {
	lastCPUAverage := serviceStateDispatcher.lastCPUAverage
	return lastCPUAverage

}

func (serviceStateDispatcher *SystemMonitorDispatcher) measureCPU() {
	for {
		serviceStateDispatcher.lastCPUAverage = GetCPUAverage(serviceStateDispatcher.lastCPUSample, GetCPUSample())
		serviceStateDispatcher.lastCPUSample = GetCPUSample()
		time.Sleep(500 * time.Millisecond)
		secondLastRequest := time.Now().Sub(serviceStateDispatcher.lastRequestTime)
		if secondLastRequest.Seconds() > 5 {

			log.Println("info: sleep measure cpu job")
			serviceStateDispatcher.measureJob.Stop()

		}
	}
}

func (serviceStateDispatcher *SystemMonitorDispatcher) StartMeasure() error {
	serviceStateDispatcher.measureJob.Job = serviceStateDispatcher.measureCPU
	serviceStateDispatcher.lastRequestTime = time.Now()
	err := serviceStateDispatcher.measureJob.Start()
	if err != nil {
		stErr := "error: Can't start measure job"
		log.Println(stErr)
		return errors.New(stErr)
	}
	return nil
}
func (serviceStateDispatcher *SystemMonitorDispatcher) Stopmeasure() error {
	err := serviceStateDispatcher.measureJob.Stop()
	if err != nil {
		stErr := "error: Can't start measure job"
		log.Println(stErr)
		return errors.New("error: Can't stop measure job\n")
	}
	return nil
}

func (serviceStateDispatcher *SystemMonitorDispatcher) Dispatch(request Request, responseWriter http.ResponseWriter, httpRequest *http.Request) error {
	if !serviceStateDispatcher.measureJob.runJob {
		log.Println("info: start measure cpu job")
		serviceStateDispatcher.measureJob.Start()
	}

	systemInfo := SystemMonitorResponse{CPUUsage: serviceStateDispatcher.getCPUUsage(), MemSample: GetMemSample()}
	js, err := json.Marshal(systemInfo)
	if err != nil {
		http.Error(responseWriter, err.Error(), http.StatusInternalServerError)
		stErr := "error: Can't create system state response"
		log.Println(stErr)
		responseWriter.Write(js)
		return errors.New(stErr)
	}
	responseWriter.Header().Set("Content-Type", "application/json")
	responseWriter.Write(js)
	serviceStateDispatcher.lastRequestTime = time.Now()
	return nil
}