Stop redrawing charts gracefully

.gitignore

@@ -4,6 +4,7 @@
 *.dll
 *.so
 *.dylib
+ali
 
 # Test binary, built with `go test -c`
 *.test

attacker/attacker.go

@@ -5,8 +5,6 @@ import (
 	"net/http"
 	"time"
 
-	"github.com/k0kubun/pp"
-
 	vegeta "github.com/tsenart/vegeta/v12/lib"
 )
 
@@ -34,6 +32,8 @@ type Options struct {
 // Result contains the results of a single HTTP request.
 type Result struct {
 	Latency time.Duration
+	// Indicates if the last result in the entire attack.
+	End bool
 }
 
 // Attack keeps the request running for the specified period of time.
@@ -76,7 +76,6 @@ func Attack(ctx context.Context, target string, resCh chan *Result, opts Options
 		}
 	}
 	metrics.Close()
-	pp.Println("vegeta metrics", metrics)
 
 	return newMetrics(&metrics)
 }

gui/drawer.go

@@ -4,10 +4,9 @@ import (
 	"context"
 	"time"
 
-	"github.com/mum4k/termdash/widgets/text"
-
 	"github.com/mum4k/termdash/cell"
 	"github.com/mum4k/termdash/widgets/linechart"
+	"github.com/mum4k/termdash/widgets/text"
 
 	"github.com/nakabonne/ali/attacker"
 )
@@ -16,16 +15,26 @@ type drawer struct {
 	widgets  *widgets
 	chartsCh chan *attacker.Result
 	reportCh chan string
+
+	// Indicates if charts are drawing.
+	chartDrawing bool
 }
 
+// redrawChart appends entities as soon as a result arrives.
+// Given maxSize, then it can be pre-allocated.
 // TODO: In the future, multiple charts including bytes-in/out etc will be re-drawn.
 func (d *drawer) redrawChart(ctx context.Context, maxSize int) {
 	values := make([]float64, 0, maxSize)
+	d.chartDrawing = true
+L:
 	for {
 		select {
 		case <-ctx.Done():
-			return
+			break L
 		case res := <-d.chartsCh:
+			if res.End {
+				break L
+			}
 			values = append(values, float64(res.Latency/time.Millisecond))
 			d.widgets.latencyChart.Series("latency", values,
 				linechart.SeriesCellOpts(cell.FgColor(cell.ColorNumber(87))),
@@ -35,6 +44,7 @@ func (d *drawer) redrawChart(ctx context.Context, maxSize int) {
 			)
 		}
 	}
+	d.chartDrawing = false
 }
 
 func (d *drawer) redrawReport(ctx context.Context) {

gui/gui.go

@@ -57,15 +57,19 @@ func Run() error {
 		case keyboard.KeyEsc, keyboard.KeyCtrlC:
 			cancel()
 		case keyboard.KeySpace:
+			if d.chartDrawing {
+				return
+			}
 			// TODO: Enalble to poplulate from input
-			rate := 50
+			rate := 10
 			duration, _ := time.ParseDuration("2s")
 			requestNum := rate * int(duration/time.Second)
+			// To pre-allocate, run redrawChart on a per-attack basis.
 			go d.redrawChart(ctx, requestNum)
 			go func(ctx context.Context, d *drawer, r int, du time.Duration) {
 				metrics := attacker.Attack(ctx, "http://34.84.111.163:9898", d.chartsCh, attacker.Options{Rate: r, Duration: du})
-				//close(ch) TODO: Gracefully stop redrawChart goroutine.
 				d.reportCh <- metrics.String()
+				d.chartsCh <- &attacker.Result{End: true}
 			}(ctx, d, rate, duration)
 		}
 	}