Make scrape interval changeable

diagnoser/diagnoser.go

@@ -1,3 +1,5 @@
+// Package diagnoser mainly provides two components, scraper and GUI
+// for the process diagnosis.
 package diagnoser
 
 import (
@@ -13,21 +15,21 @@ import (
 	"github.com/nakabonne/gosivy/stats"
 )
 
-const defaultRequestInterval = time.Second
-
-func Run(addr *net.TCPAddr) error {
+// Run performs the scraper which periodically scrapes from the agent,
+// and then draws charts to show the stats.
+func Run(addr *net.TCPAddr, scrapeInterval time.Duration) error {
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
 
 	statsCh := make(chan *stats.Stats)
-	meta, err := poll(ctx, addr, statsCh)
+	meta, err := startScraping(ctx, addr, scrapeInterval, statsCh)
 	if err != nil {
 		return err
 	}
 	return gui.Run(meta, statsCh)
 }
 
-func poll(ctx context.Context, addr *net.TCPAddr, statsCh chan<- *stats.Stats) (*stats.Meta, error) {
+func startScraping(ctx context.Context, addr *net.TCPAddr, interval time.Duration, statsCh chan<- *stats.Stats) (*stats.Meta, error) {
 	conn, err := net.DialTCP("tcp", nil, addr)
 	if err != nil {
 		return nil, err
@@ -48,7 +50,7 @@ func poll(ctx context.Context, addr *net.TCPAddr, statsCh chan<- *stats.Stats) (
 	}
 
 	go func(ctx context.Context, ch chan<- *stats.Stats) {
-		tick := time.NewTicker(defaultRequestInterval)
+		tick := time.NewTicker(interval)
 		defer tick.Stop()
 		for {
 			select {
@@ -64,19 +66,19 @@ func poll(ctx context.Context, addr *net.TCPAddr, statsCh chan<- *stats.Stats) (
 
 				buf := []byte{stats.SignalStats}
 				if _, err := conn.Write(buf); err != nil {
-					logrus.Errorf("failed to write: %v", err)
+					logrus.Errorf("failed to write into connection: %v", err)
 					continue
 				}
 				res, err := ioutil.ReadAll(conn)
 				if err != nil {
-					logrus.Errorf("failed to read: %v", err)
+					logrus.Errorf("failed to read the response: %v", err)
 					continue
 				}
 				conn.Close()
 
 				var stats stats.Stats
 				if err := json.Unmarshal(res, &stats); err != nil {
-					logrus.Errorf("failed to unmarshal stats: %v", err)
+					logrus.Errorf("failed to decode stats: %v", err)
 					continue
 				}
 				ch <- &stats

diagnoser/gui/gui.go

@@ -17,8 +17,8 @@ import (
 
 const (
 	// How often termdash redraws the screen.
-	redrawInterval = 250 * time.Millisecond
-	rootID         = "root"
+	defaultRedrawInterval = time.Second
+	rootID                = "root"
 )
 
 type runner func(ctx context.Context, t terminalapi.Terminal, c *container.Container, opts ...termdash.Option) error

main.go

@@ -11,6 +11,7 @@ import (
 	"runtime"
 	"strconv"
 	"strings"
+	"time"
 
 	"github.com/k0kubun/pp"
 	"github.com/sirupsen/logrus"
@@ -20,6 +21,8 @@ import (
 	"github.com/nakabonne/gosivy/pidfile"
 )
 
+const defaultScrapeInterval = time.Second
+
 var (
 	flagSet = flag.NewFlagSet("gosivy", flag.ContinueOnError)
 
@@ -30,11 +33,12 @@ var (
 )
 
 type cli struct {
-	debug   bool
-	version bool
-	list    bool
-	stdout  io.Writer
-	stderr  io.Writer
+	debug          bool
+	version        bool
+	list           bool
+	scrapeInterval time.Duration
+	stdout         io.Writer
+	stderr         io.Writer
 }
 
 func (c *cli) usage() {
@@ -69,21 +73,34 @@ func parseFlags(stdout, stderr io.Writer) (*cli, error) {
 	flagSet.BoolVarP(&c.version, "version", "v", false, "Print the current version.")
 	flagSet.BoolVar(&c.debug, "debug", false, "Run in debug mode.")
 	flagSet.BoolVarP(&c.list, "list-processes", "l", false, "Show processes where gosivy agent runs on.")
+	flagSet.DurationVar(&c.scrapeInterval, "scrape-interval", defaultScrapeInterval, "Interval to scrape from the agent. It must be >= 1s")
 	flagSet.Usage = c.usage
 	if err := flagSet.Parse(os.Args[1:]); err != nil {
 		if !errors.Is(err, flag.ErrHelp) {
 			fmt.Fprintln(c.stderr, err)
 		}
 		return nil, err
 	}
+
 	return c, nil
 }
 
+func (c *cli) validate() error {
+	if c.scrapeInterval < time.Second {
+		return fmt.Errorf(`"--scrape-interval" must be >= 1s`)
+	}
+	return nil
+}
+
 func (c *cli) run(args []string) int {
 	if c.version {
 		fmt.Fprintf(c.stderr, "version=%s, commit=%s, buildDate=%s, os=%s, arch=%s\n", version, commit, date, runtime.GOOS, runtime.GOARCH)
 		return 0
 	}
+	if err := c.validate(); err != nil {
+		fmt.Fprintln(c.stderr, err)
+		return 1
+	}
 	if err := setLogger(nil, c.debug); err != nil {
 		fmt.Fprintf(c.stderr, "failed to prepare for debugging: %v\n", err)
 		return 1
@@ -105,7 +122,7 @@ func (c *cli) run(args []string) int {
 			return 1
 		}
 	}
-	if err := diagnoser.Run(addr); err != nil {
+	if err := diagnoser.Run(addr, c.scrapeInterval); err != nil {
 		fmt.Fprintf(c.stderr, "failed to start diagnoser: %s\n", err.Error())
 		c.usage()
 		return 1