fix: performance issue caused by the render calls

mactop has high CPU usage. Running it with cpuprofiling shows that the
top CPU time is spent in the termui.Render calls (to be specific, in the
ioctl syscalls there).

I removed a bunch of unnecessary Render calls (there were some
duplicates) and replaced all the other calls with a throttled version: I
call Render in the main process but not more often than twice in the
single "update interval" period.

This should address issue #13.

Author: Md-Cake

main.go

@@ -48,6 +48,35 @@ type MemoryMetrics struct {
 	Total, Used, Available, SwapTotal, SwapUsed uint64
 }
 
+type EventThrottler struct {
+	timer       *time.Timer
+	gracePeriod time.Duration
+
+	C chan struct{}
+}
+
+func NewEventThrottler(gracePeriod time.Duration) *EventThrottler {
+	return &EventThrottler{
+		timer:       nil,
+		gracePeriod: gracePeriod,
+		C:           make(chan struct{}, 1),
+	}
+}
+
+func (e *EventThrottler) Notify() {
+	if e.timer != nil {
+		return
+	}
+
+	e.timer = time.AfterFunc(e.gracePeriod, func() {
+		e.timer = nil
+		select {
+		case e.C <- struct{}{}:
+		default:
+		}
+	})
+}
+
 var (
 	cpu1Gauge, cpu2Gauge, gpuGauge, aneGauge        *w.Gauge
 	TotalPowerChart                                 *w.BarChart
@@ -173,7 +202,6 @@ func setupGrid() {
 
 func switchGridLayout() {
 	if currentGridLayout == "default" {
-		ui.Clear()
 		newGrid := ui.NewGrid()
 		newGrid.Set(
 			ui.NewRow(1.0/2, // This row now takes half the height of the grid
@@ -196,9 +224,7 @@ func switchGridLayout() {
 		newGrid.SetRect(0, 0, termWidth, termHeight)
 		grid = newGrid
 		currentGridLayout = "alternative"
-		ui.Render(grid)
 	} else {
-		ui.Clear()
 		newGrid := ui.NewGrid()
 		newGrid.Set(
 			ui.NewRow(1.0/2,
@@ -219,7 +245,6 @@ func switchGridLayout() {
 		newGrid.SetRect(0, 0, termWidth, termHeight)
 		grid = newGrid
 		currentGridLayout = "default"
-		ui.Render(grid)
 	}
 }
 
@@ -352,21 +377,24 @@ func main() {
 	appleSiliconModel := getSOCInfo()
 	go collectMetrics(done, cpuMetricsChan, gpuMetricsChan, netdiskMetricsChan, processMetricsChan, appleSiliconModel["name"].(string))
 	lastUpdateTime = time.Now()
+	needRender := NewEventThrottler(time.Duration(updateInterval/2) * time.Millisecond)
 	go func() {
 		for {
 			select {
 			case cpuMetrics := <-cpuMetricsChan:
 				updateCPUUI(cpuMetrics)
 				updateTotalPowerChart(cpuMetrics.PackageW)
-				ui.Render(grid)
+				needRender.Notify()
 			case gpuMetrics := <-gpuMetricsChan:
 				updateGPUUI(gpuMetrics)
-				ui.Render(grid)
+				needRender.Notify()
 			case netdiskMetrics := <-netdiskMetricsChan:
 				updateNetDiskUI(netdiskMetrics)
-				ui.Render(grid)
+				needRender.Notify()
 			case processMetrics := <-processMetricsChan:
 				updateProcessUI(processMetrics)
+				needRender.Notify()
+			case <-needRender.C:
 				ui.Render(grid)
 			case <-quit:
 				close(done)
@@ -489,7 +517,6 @@ func updateTotalPowerChart(newPowerValue float64) {
 		}
 		powerValues = nil
 		lastUpdateTime = currentTime
-		ui.Render(TotalPowerChart)
 	}
 }
 
@@ -507,8 +534,6 @@ func updateCPUUI(cpuMetrics CPUMetrics) {
 	memoryMetrics := getMemoryMetrics()
 	memoryGauge.Title = fmt.Sprintf("Memory Usage: %.2f GB / %.2f GB (Swap: %.2f/%.2f GB)", float64(memoryMetrics.Used)/1024/1024/1024, float64(memoryMetrics.Total)/1024/1024/1024, float64(memoryMetrics.SwapUsed)/1024/1024/1024, float64(memoryMetrics.SwapTotal)/1024/1024/1024)
 	memoryGauge.Percent = int((float64(memoryMetrics.Used) / float64(memoryMetrics.Total)) * 100)
-	ui.Render(grid)
-	ui.Render(cpu1Gauge, cpu2Gauge, gpuGauge, aneGauge, memoryGauge, modelText, PowerChart)
 }
 
 func updateGPUUI(gpuMetrics GPUMetrics) {
@@ -532,7 +557,6 @@ func updateProcessUI(processMetrics []ProcessMetrics) {
 	for _, pm := range processMetrics {
 		ProcessInfo.Text += fmt.Sprintf("%d - %s: %.2f ms/s\n", pm.ID, pm.Name, pm.CPUUsage)
 	}
-	ui.Render(ProcessInfo)
 }
 
 func parseProcessMetrics(powermetricsOutput string, processMetrics []ProcessMetrics) []ProcessMetrics {