CPU History, CPU Utilization

util/sys/sys_windows.go

@@ -5,6 +5,9 @@ package sys
 
 import (
 	"errors"
+	"sync"
+	"syscall"
+	"unsafe"
 
 	"github.com/shirou/gopsutil/v4/net"
 )
@@ -28,3 +31,81 @@ func GetTCPCount() (int, error) {
 func GetUDPCount() (int, error) {
 	return GetConnectionCount("udp")
 }
+
+// --- CPU Utilization (Windows native) ---
+
+var (
+	modKernel32        = syscall.NewLazyDLL("kernel32.dll")
+	procGetSystemTimes = modKernel32.NewProc("GetSystemTimes")
+
+	cpuMu      sync.Mutex
+	lastIdle   uint64
+	lastKernel uint64
+	lastUser   uint64
+	hasLast    bool
+)
+
+type filetime struct {
+	LowDateTime  uint32
+	HighDateTime uint32
+}
+
+func ftToUint64(ft filetime) uint64 {
+	return (uint64(ft.HighDateTime) << 32) | uint64(ft.LowDateTime)
+}
+
+// CPUPercentRaw returns the instantaneous total CPU utilization percentage using
+// Windows GetSystemTimes across all logical processors. The first call returns 0
+// as it initializes the baseline. Subsequent calls compute deltas.
+func CPUPercentRaw() (float64, error) {
+	var idleFT, kernelFT, userFT filetime
+	r1, _, e1 := procGetSystemTimes.Call(
+		uintptr(unsafe.Pointer(&idleFT)),
+		uintptr(unsafe.Pointer(&kernelFT)),
+		uintptr(unsafe.Pointer(&userFT)),
+	)
+	if r1 == 0 { // failure
+		if e1 != nil {
+			return 0, e1
+		}
+		return 0, syscall.GetLastError()
+	}
+
+	idle := ftToUint64(idleFT)
+	kernel := ftToUint64(kernelFT)
+	user := ftToUint64(userFT)
+
+	cpuMu.Lock()
+	defer cpuMu.Unlock()
+
+	if !hasLast {
+		lastIdle = idle
+		lastKernel = kernel
+		lastUser = user
+		hasLast = true
+		return 0, nil
+	}
+
+	idleDelta := idle - lastIdle
+	kernelDelta := kernel - lastKernel
+	userDelta := user - lastUser
+
+	// Update for next call
+	lastIdle = idle
+	lastKernel = kernel
+	lastUser = user
+
+	total := kernelDelta + userDelta
+	if total == 0 {
+		return 0, nil
+	}
+	// On Windows, kernel time includes idle time; busy = total - idle
+	busy := total - idleDelta
+
+	pct := float64(busy) / float64(total) * 100.0
+	// lower bound not needed; ratios of uint64 are non-negative
+	if pct > 100 {
+		pct = 100
+	}
+	return pct, nil
+}