Add memory.CPUTimesPercent()

This new method returns a TimesStat that holds CPU usage
percentages for different work loads (e.g. user, system and so on).

cpu/cpu.go

@@ -14,8 +14,8 @@ import (
 )
 
 // TimesStat contains the amounts of time the CPU has spent performing different
-// kinds of work. Time units are in USER_HZ or Jiffies (typically hundredths of
-// a second). It is based on linux /proc/stat file.
+// kinds of work. Time units are in USER_HZ, Jiffies (typically hundredths of
+// a second) or percentages. It is based on linux /proc/stat file.
 type TimesStat struct {
 	CPU       string  `json:"cpu"`
 	User      float64 `json:"user"`
@@ -132,39 +132,124 @@ func calculateAllBusy(t1, t2 []TimesStat) ([]float64, error) {
 	return ret, nil
 }
 
+func calculateItem(v1, v2, duration float64) float64 {
+	if v2 <= v1 {
+		return 0
+	}
+	if duration <= 0 {
+		return 0
+	}
+
+	return math.Min(100, math.Max(0, (v2-v1)/(duration)*100))
+}
+
+func calculateItems(t1, t2 TimesStat) TimesStat {
+	duration := t2.Total() - t1.Total()
+
+	items := TimesStat{
+		CPU:       t1.CPU,
+		User:      calculateItem(t1.User, t2.User, duration),
+		System:    calculateItem(t1.System, t2.System, duration),
+		Idle:      calculateItem(t1.Idle, t2.Idle, duration),
+		Nice:      calculateItem(t1.Nice, t2.Nice, duration),
+		Iowait:    calculateItem(t1.Iowait, t2.Iowait, duration),
+		Irq:       calculateItem(t1.Irq, t2.Irq, duration),
+		Softirq:   calculateItem(t1.Softirq, t2.Softirq, duration),
+		Steal:     calculateItem(t1.Steal, t2.Steal, duration),
+		Guest:     calculateItem(t1.Guest, t2.Guest, duration),
+		GuestNice: calculateItem(t1.GuestNice, t2.GuestNice, duration),
+	}
+
+	return items
+}
+
+func calculateAllItems(t1, t2 []TimesStat) ([]TimesStat, error) {
+	// Make sure the CPU measurements have the same length.
+	if len(t1) != len(t2) {
+		return nil, fmt.Errorf(
+			"received two CPU counts: %d != %d",
+			len(t1), len(t2),
+		)
+	}
+
+	ret := make([]TimesStat, len(t1))
+	for i, t := range t2 {
+		if t1[i].CPU != t.CPU {
+			return nil, fmt.Errorf(
+				"CPU number mismatch at %d: %s != %s",
+				i, t1[i].CPU, t.CPU,
+			)
+		}
+		ret[i] = calculateItems(t1[i], t)
+	}
+	return ret, nil
+}
+
 // Percent calculates the percentage of cpu used either per CPU or combined.
 // If an interval of 0 is given it will compare the current cpu times against the last call.
 // Returns one value per cpu, or a single value if percpu is set to false.
 func Percent(interval time.Duration, percpu bool) ([]float64, error) {
 	return PercentWithContext(context.Background(), interval, percpu)
 }
 
+// CPUTimesPercent calculates the percentage of CPU time used for different type of work
+// either per CPU or combined.
+// If an interval of 0 is given it will compare the current cpu times against the last call.
+// Returns one value per cpu, or a single value if percpu is set to false.
+// When interval is too small, returned values can be all zero.
+func CPUTimesPercent(interval time.Duration, percpu bool) ([]TimesStat, error) {
+	return CPUTimesPercentWithContext(context.Background(), interval, percpu)
+}
+
 func PercentWithContext(ctx context.Context, interval time.Duration, percpu bool) ([]float64, error) {
+	t1, t2, err := sample(ctx, interval, percpu)
+	if err != nil {
+		return nil, err
+	}
+
+	return calculateAllBusy(t1, t2)
+}
+
+func CPUTimesPercentWithContext(ctx context.Context, interval time.Duration, percpu bool) ([]TimesStat, error) {
+	t1, t2, err := sample(ctx, interval, percpu)
+	if err != nil {
+		return nil, err
+	}
+
+	return calculateAllItems(t1, t2)
+}
+
+func sample(ctx context.Context, interval time.Duration, percpu bool) (t1, t2 []TimesStat, err error) {
 	if interval <= 0 {
-		return percentUsedFromLastCall(percpu)
+		return sampleAndSaveAsLast(ctx, percpu)
 	}
 
 	// Get CPU usage at the start of the interval.
-	cpuTimes1, err := Times(percpu)
+	t1, err = TimesWithContext(ctx, percpu)
 	if err != nil {
-		return nil, err
+		return
 	}
 
-	time.Sleep(interval)
+	select {
+	case <-time.After(interval):
+	case <-ctx.Done():
+		err = ctx.Err()
+		return
+	}
 
 	// And at the end of the interval.
-	cpuTimes2, err := Times(percpu)
+	t2, err = TimesWithContext(ctx, percpu)
 	if err != nil {
-		return nil, err
+		return
 	}
 
-	return calculateAllBusy(cpuTimes1, cpuTimes2)
+	return
 }
 
-func percentUsedFromLastCall(percpu bool) ([]float64, error) {
-	cpuTimes, err := Times(percpu)
+func sampleAndSaveAsLast(ctx context.Context, percpu bool) ([]TimesStat, []TimesStat, error) {
+	cpuTimes, err := TimesWithContext(ctx, percpu)
 	if err != nil {
-		return nil, err
+		return nil, nil, err
 	}
 	lastCPUPercent.Lock()
 	defer lastCPUPercent.Unlock()
@@ -178,7 +263,7 @@ func percentUsedFromLastCall(percpu bool) ([]float64, error) {
 	}
 
 	if lastTimes == nil {
-		return nil, fmt.Errorf("error getting times for cpu percent. lastTimes was nil")
+		return nil, nil, fmt.Errorf("error getting times for cpu percent. lastTimes was nil")
 	}
-	return calculateAllBusy(lastTimes, cpuTimes)
+	return lastTimes, cpuTimes, nil
 }

cpu/cpu_test.go

@@ -2,6 +2,7 @@ package cpu
 
 import (
 	"fmt"
+	"math"
 	"os"
 	"runtime"
 	"testing"
@@ -125,7 +126,6 @@ func testCPUPercent(t *testing.T, percpu bool) {
 }
 
 func testCPUPercentLastUsed(t *testing.T, percpu bool) {
-
 	numcpu := runtime.NumCPU()
 	testCount := 10
 
@@ -158,6 +158,107 @@ func testCPUPercentLastUsed(t *testing.T, percpu bool) {
 
 }
 
+func checkTimesStatPercentages(t *testing.T, ps TimesStat, numcpu int) {
+	t.Helper()
+
+	// Check for slightly greater then 100% to account for any rounding issues.
+	if ps.User < 0.0 || ps.User > 100.0001*float64(numcpu) {
+		t.Fatalf("CPUPercent value User is invalid: %f", ps.User)
+	}
+	if ps.System < 0.0 || ps.System > 100.0001*float64(numcpu) {
+		t.Fatalf("CPUPercent value System is invalid: %f", ps.System)
+	}
+	if ps.Idle < 0.0 || ps.Idle > 100.0001*float64(numcpu) {
+		t.Fatalf("CPUPercent value Idle is invalid: %f", ps.Idle)
+	}
+	if ps.Nice < 0.0 || ps.Nice > 100.0001*float64(numcpu) {
+		t.Fatalf("CPUPercent value Nice is invalid: %f", ps.Nice)
+	}
+	if ps.Iowait < 0.0 || ps.Iowait > 100.0001*float64(numcpu) {
+		t.Fatalf("CPUPercent value Iowait is invalid: %f", ps.Iowait)
+	}
+	if ps.Irq < 0.0 || ps.Irq > 100.0001*float64(numcpu) {
+		t.Fatalf("CPUPercent value Irq is invalid: %f", ps.Irq)
+	}
+	if ps.Softirq < 0.0 || ps.Softirq > 100.0001*float64(numcpu) {
+		t.Fatalf("CPUPercent value Softirq is invalid: %f", ps.Softirq)
+	}
+	if ps.Steal < 0.0 || ps.Steal > 100.0001*float64(numcpu) {
+		t.Fatalf("CPUPercent value Steal is invalid: %f", ps.Steal)
+	}
+
+	total := ps.User + ps.System + ps.Idle + ps.Nice + ps.Iowait +
+		ps.Irq + ps.Softirq + ps.Steal
+	if math.Round(total) != 100 {
+		t.Fatalf("CPUPercent total is invalid: %f", total)
+	}
+
+	if ps.Guest < 0.0 || ps.Guest > 100.0001*float64(numcpu) {
+		t.Fatalf("CPUPercent value Guest is invalid: %f", ps.Guest)
+	}
+	if ps.GuestNice < 0.0 || ps.GuestNice > 100.0001*float64(numcpu) {
+		t.Fatalf("CPUPercent value GuestNice is invalid: %f", ps.GuestNice)
+	}
+}
+
+func testCPUTimesPercent(t *testing.T, percpu bool) {
+	numcpu := runtime.NumCPU()
+	testCount := 10
+
+	if runtime.GOOS != "windows" {
+		testCount = 2
+		v, err := CPUTimesPercent(time.Millisecond, percpu)
+		if err != nil {
+			t.Errorf("error %v", err)
+		}
+		// Skip CircleCI which CPU num is different
+		if os.Getenv("CIRCLECI") != "true" {
+			if (percpu && len(v) != numcpu) || (!percpu && len(v) != 1) {
+				t.Fatalf("wrong number of entries from CPUPercent: %v", v)
+			}
+		}
+	}
+	for i := 0; i < testCount; i++ {
+		duration := time.Duration(100) * time.Millisecond
+		v, err := CPUTimesPercent(duration, percpu)
+		if err != nil {
+			t.Errorf("error %v", err)
+		}
+		for _, ps := range v {
+			checkTimesStatPercentages(t, ps, numcpu)
+		}
+	}
+}
+
+func testCPUTimesPercentLastUsed(t *testing.T, percpu bool) {
+	numcpu := runtime.NumCPU()
+	testCount := 10
+
+	if runtime.GOOS != "windows" {
+		testCount = 2
+		v, err := CPUTimesPercent(time.Millisecond, percpu)
+		if err != nil {
+			t.Errorf("error %v", err)
+		}
+		// Skip CircleCI which CPU num is different
+		if os.Getenv("CIRCLECI") != "true" {
+			if (percpu && len(v) != numcpu) || (!percpu && len(v) != 1) {
+				t.Fatalf("wrong number of entries from CPUPercent: %v", v)
+			}
+		}
+	}
+	for i := 0; i < testCount; i++ {
+		v, err := CPUTimesPercent(0, percpu)
+		if err != nil {
+			t.Errorf("error %v", err)
+		}
+		time.Sleep(100 * time.Millisecond)
+		for _, ps := range v {
+			checkTimesStatPercentages(t, ps, numcpu)
+		}
+	}
+}
+
 func TestCPUPercent(t *testing.T) {
 	testCPUPercent(t, false)
 }
@@ -173,3 +274,19 @@ func TestCPUPercentIntervalZero(t *testing.T) {
 func TestCPUPercentIntervalZeroPerCPU(t *testing.T) {
 	testCPUPercentLastUsed(t, true)
 }
+
+func TestCPUTimesPercent(t *testing.T) {
+	testCPUTimesPercent(t, false)
+}
+
+func TestCPUTimesPercentPerCpu(t *testing.T) {
+	testCPUTimesPercent(t, true)
+}
+
+func TestCPUTimesPercentIntervalZero(t *testing.T) {
+	testCPUTimesPercentLastUsed(t, false)
+}
+
+func TestCPUTimesPercentIntervalZeroPerCPU(t *testing.T) {
+	testCPUTimesPercentLastUsed(t, true)
+}