added load average calculations and moved the testing from main to their own cli commands

internal/load_average/win_loadavg.go

@@ -0,0 +1,99 @@
+//go:build windows
+
+package loadaverage
+
+import (
+	"fmt"
+	"rpi5-health/internal/windows_system"
+	"sync"
+	"syscall"
+	"time"
+	"unsafe"
+)
+
+const (
+	// Formatting flag for PdhGetFormattedCounterValue to return a float64
+	PDH_FMT_DOUBLE = 0x00000200
+	ERROR_SUCCESS  = 0
+)
+
+// PDH_FMT_COUNTERVALUE_DOUBLE maps the C struct _PDH_FMT_COUNTERVALUE for double values.
+// * Note the explicit padding: C++ unions align to 8 bytes on 64-bit systems.
+type PDH_FMT_COUNTERVALUE_DOUBLE struct {
+	CStatus     uint32
+	Pad         uint32  // ! Crucial padding for 64-bit alignment before the float64
+	DoubleValue float64 // Represents the union where the double is stored
+}
+
+var (
+	GlobalLoadAverage LoadAverageInformation
+
+	// 1. A RWMutex protects the struct from concurrent reads/writes
+	loadMu sync.RWMutex
+
+	startWorker = sync.OnceFunc(func() {
+		go loadAverageWorker()
+	})
+)
+
+func loadAverageWorker() {
+	var hQuery syscall.Handle   // PDH_HQUERY
+	var hCounter syscall.Handle // PDH_HCOUNTER
+
+	wintools := windows_system.GetWindowsTools()
+
+	// initialize query
+	ret, _, _ := wintools.ProcPdhOpenQuery.Call(0, 0, uintptr(unsafe.Pointer(&hQuery)))
+	if ret != ERROR_SUCCESS {
+		fmt.Printf("PdhOpenQueryW failed: %x\n", ret)
+		return
+	}
+	defer wintools.ProcPdhCloseQuery.Call(uintptr(hQuery))
+
+	counterPath, _ := syscall.UTF16PtrFromString(`\Processor(_Total)\% Processor Time`)
+	ret, _, _ = wintools.ProcPdhAddCounter.Call(
+		uintptr(hQuery),
+		uintptr(unsafe.Pointer(counterPath)),
+		0,
+		uintptr(unsafe.Pointer(&hCounter)),
+	)
+	if ret != ERROR_SUCCESS {
+		fmt.Printf("PdhAddCounterW failed: %x\n", ret)
+		return
+	}
+
+	// Collect initial data, "priming the counter"
+	wintools.ProcPdhCollectQueryData.Call(uintptr(hQuery))
+
+	// Infinite collection loop
+	for {
+		time.Sleep(SAMPLE_DELAY)
+
+		wintools.ProcPdhCollectQueryData.Call(uintptr(hQuery))
+
+		var counterType uint32
+		var value PDH_FMT_COUNTERVALUE_DOUBLE
+
+		ret, _, _ = wintools.ProcPdhGetFormattedCounterValue.Call(
+			uintptr(hCounter),
+			uintptr(PDH_FMT_DOUBLE),
+			uintptr(unsafe.Pointer(&counterType)),
+			uintptr(unsafe.Pointer(&value)),
+		)
+
+		if ret == ERROR_SUCCESS {
+			loadMu.Lock()
+			GlobalLoadAverage.Update(value.DoubleValue)
+			loadMu.Unlock()
+		} else {
+			fmt.Printf("PdhGetFormattedCounterValue failed: %x\n", ret)
+		}
+	}
+}
+
+func GetLoadAverage() (LoadAverageInformation, error) {
+	startWorker()
+	loadMu.RLock()
+	defer loadMu.RUnlock()
+	return GlobalLoadAverage, nil
+}