fix: lint fixes (#2138)

* feat: lint fixes for cpu fix

* fix: lint fixes

* fix: lint fixes

Author: ujwalsah

internal/windows/api/pdh_test.go

@@ -172,7 +172,8 @@ func BenchmarkUTF16PtrToString(b *testing.B) {
 // BenchmarkUTF16PtrToString_LongString benchmarks with a longer string.
 func BenchmarkUTF16PtrToString_LongString(b *testing.B) {
 	// Create a longer test string
-	testString := "This is a much longer string to test the performance of the UTF16PtrToString function with more realistic data that might be encountered in real-world scenarios"
+	testString := "This is a much longer string to test the performance of the UTF16PtrToString function " +
+		"with more realistic data that might be encountered in real-world scenarios"
 	utf16Ptr, err := syscall.UTF16PtrFromString(testString)
 	require.NoError(b, err)
 

pkg/metrics/cpu.go

@@ -3,6 +3,7 @@
 package metrics
 
 import (
+	"errors"
 	"fmt"
 	"runtime/debug"
 
@@ -17,6 +18,9 @@ import (
 var (
 	cpuLog = log.WithComponent("CPUMonitor")
 
+	// ErrCPUMonitorPanic is returned when a panic occurs in CPUMonitor.Sample.
+	ErrCPUMonitorPanic = errors.New("panic in CPUMonitor.Sample")
+
 	// defaultCPUSample is a reusable zero-value CPU sample.
 	defaultCPUSample = &CPUSample{
 		CPUPercent:       0,
@@ -53,13 +57,15 @@ func (m *CPUMonitor) Close() error {
 	if m.windowsMonitor != nil {
 		return m.windowsMonitor.close()
 	}
+
 	return nil
 }
 
-func (m *CPUMonitor) Sample() (sample *CPUSample, err error) {
+func (m *CPUMonitor) Sample() (*CPUSample, error) {
+	var err error
 	defer func() {
 		if panicErr := recover(); panicErr != nil {
-			err = fmt.Errorf("panic in CPUMonitor.Sample: %v\nStack: %s", panicErr, debug.Stack())
+			err = fmt.Errorf("%w: %v\nStack: %s", ErrCPUMonitorPanic, panicErr, debug.Stack())
 		}
 	}()
 
@@ -92,7 +98,8 @@ func (m *CPUMonitor) Sample() (sample *CPUSample, err error) {
 	var userPercent, stolenPercent, systemPercent, ioWaitPercent float64
 
 	// Calculate total manually instead of using deprecated Total() method
-	deltaTotal := delta.User + delta.Nice + delta.System + delta.Idle + delta.Iowait + delta.Irq + delta.Softirq + delta.Steal + delta.Guest + delta.GuestNice
+	deltaTotal := delta.User + delta.Nice + delta.System + delta.Idle + delta.Iowait +
+		delta.Irq + delta.Softirq + delta.Steal + delta.Guest + delta.GuestNice
 	if deltaTotal != 0 {
 		userPercent = userDelta / deltaTotal * 100.0
 		stolenPercent = stolenDelta / deltaTotal * 100.0
@@ -101,7 +108,7 @@ func (m *CPUMonitor) Sample() (sample *CPUSample, err error) {
 	}
 	idlePercent := 100 - userPercent - systemPercent - ioWaitPercent - stolenPercent
 
-	sample = &CPUSample{
+	sample := &CPUSample{
 		CPUPercent:       userPercent + systemPercent + ioWaitPercent + stolenPercent,
 		CPUUserPercent:   userPercent,
 		CPUSystemPercent: systemPercent,
@@ -117,7 +124,7 @@ func (m *CPUMonitor) Sample() (sample *CPUSample, err error) {
 
 	m.last = currentTimes
 
-	return
+	return sample, err
 }
 
 func cpuDelta(current, previous *cpu.TimesStat) *cpu.TimesStat {

pkg/metrics/cpu_test.go

@@ -50,8 +50,6 @@ func TestCPUSample(t *testing.T) {
 	assert.LessOrEqual(t, result.CPUSystemPercent, 100.0, "CPU system percent should be <= 100")
 	assert.GreaterOrEqual(t, result.CPUIdlePercent, 0.0, "CPU idle percent should be >= 0")
 	assert.LessOrEqual(t, result.CPUIdlePercent, 100.0, "CPU idle percent should be <= 100")
-
-	// Platform-specific validations would be handled in platform-specific test files
 }
 
 func TestCPUSample_MultipleCalls(t *testing.T) {
@@ -91,6 +89,7 @@ func TestCPUSample_JSON_Marshaling(t *testing.T) {
 
 	// Test JSON unmarshaling
 	var unmarshaledSample CPUSample
+
 	err = json.Unmarshal(jsonData, &unmarshaledSample)
 	require.NoError(t, err)
 	assert.InDelta(t, sample.CPUPercent, unmarshaledSample.CPUPercent, 0.001)

pkg/metrics/cpu_unix.go

@@ -3,6 +3,7 @@
 
 // Copyright 2020 New Relic Corporation. All rights reserved.
 // SPDX-License-Identifier: Apache-2.0
+
 package metrics
 
 import (

pkg/metrics/cpu_windows.go

@@ -7,6 +7,7 @@
 package metrics
 
 import (
+	"errors"
 	"fmt"
 	"time"
 
@@ -17,7 +18,12 @@ import (
 )
 
 //nolint:gochecknoglobals
-var cpuWindowsLog = log.WithComponent("CPUWindows")
+var (
+	cpuWindowsLog = log.WithComponent("CPUWindows")
+
+	// ErrNoUserTimeData indicates no user time data is available.
+	ErrNoUserTimeData = errors.New("no user time data available")
+)
 
 // Windows CPU performance counter paths using wildcard for all cores.
 const (
@@ -49,10 +55,15 @@ type WindowsCPUMonitor struct {
 func NewCPUMonitor(context agent.AgentContext) *CPUMonitor {
 	winMonitor := &WindowsCPUMonitor{
 		context:            context,
+		rawPoll:            nil,
+		started:            false,
 		requiresTwoSamples: true, // PDH requires two samples for rate counters
+		lastSample:         nil,
+		lastTimestamp:      time.Time{},
 	}
 	return &CPUMonitor{
 		context:        context,
+		last:           nil,
 		cpuTimes:       nil,
 		windowsMonitor: winMonitor,
 	}
@@ -79,6 +90,7 @@ func (w *WindowsCPUMonitor) initializeRawPDH() error {
 	}
 
 	w.started = true
+
 	return nil
 }
 
@@ -101,7 +113,7 @@ func (w *WindowsCPUMonitor) sample() (*CPUSample, error) {
 	idleTimeData := rawData[idleTimeAllCores]
 
 	if len(userTimeData) == 0 {
-		return nil, fmt.Errorf("no user time data available")
+		return nil, fmt.Errorf("failed to get CPU user time data: %w", ErrNoUserTimeData) //nolint:wrapcheck
 	}
 
 	// For the first sample, we need two collections to calculate rates
@@ -177,7 +189,7 @@ func (w *WindowsCPUMonitor) sample() (*CPUSample, error) {
 	return sample, nil
 }
 
-// calculateCPUTimeDelta calculates the delta between current and last counter samples
+// calculateCPUTimeDelta calculates the delta between current and last counter samples.
 func (w *WindowsCPUMonitor) calculateCPUTimeDelta(
 	currentData []nrwin.CPUGroupInfo,
 	lastData []nrwin.CPUGroupInfo,
@@ -215,6 +227,7 @@ func (w *WindowsCPUMonitor) calculateCPUTimeDelta(
 				"last":     lastInfo.RawValue.FirstValue,
 				"delta":    delta,
 			}).Debug("Counter wrapped - skipping sample (current < last)")
+
 			continue
 		}
 
@@ -247,6 +260,7 @@ func (w *WindowsCPUMonitor) close() error {
 	if w.started && w.rawPoll != nil {
 		return w.rawPoll.Close()
 	}
+
 	return nil
 }
 

pkg/metrics/cpu_windows_test.go

@@ -260,7 +260,8 @@ func TestCalculatePercent(t *testing.T) {
 			t.Parallel()
 
 			result := calculatePercent(tt.part, tt.total)
-			assert.InDelta(t, tt.expected, result, 0.0001, "calculatePercent(%v, %v) should return %f, got %f", tt.part, tt.total, tt.expected, result)
+			assert.InDelta(t, tt.expected, result, 0.0001,
+				"calculatePercent(%v, %v) should return %f, got %f", tt.part, tt.total, tt.expected, result)
 		})
 	}
 }