feat: native cross-platform total memory detection

go.mod

@@ -12,6 +12,7 @@ require (
 	github.com/prometheus/client_golang v1.23.2
 	github.com/stretchr/testify v1.11.1
 	golang.org/x/net v0.56.0
+	golang.org/x/sys v0.46.0
 )
 
 require (
@@ -61,7 +62,6 @@ require (
 	go.opentelemetry.io/otel/trace v1.44.0 // indirect
 	go.yaml.in/yaml/v3 v3.0.4 // indirect
 	golang.org/x/crypto v0.53.0 // indirect
-	golang.org/x/sys v0.46.0 // indirect
 	golang.org/x/text v0.38.0 // indirect
 	google.golang.org/protobuf v1.36.11 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect

internal/memory/memory_darwin.go

@@ -0,0 +1,13 @@
+package memory
+
+import "golang.org/x/sys/unix"
+
+// TotalSysMemory returns the total physical memory in bytes via sysctl hw.memsize
+func TotalSysMemory() uint64 {
+	memsize, err := unix.SysctlUint64("hw.memsize")
+	if err != nil {
+		return 0
+	}
+
+	return memsize
+}

internal/memory/memory_others.go

@@ -1,4 +1,4 @@
-//go:build !linux
+//go:build !linux && !darwin && !windows
 
 package memory
 

internal/memory/memory_windows.go

@@ -0,0 +1,36 @@
+package memory
+
+import (
+	"unsafe"
+
+	"golang.org/x/sys/windows"
+)
+
+// memoryStatusEx mirrors the Win32 MEMORYSTATUSEX structure.
+// https://learn.microsoft.com/en-us/windows/win32/api/sysinfoapi/ns-sysinfoapi-memorystatusex
+type memoryStatusEx struct {
+	length               uint32
+	memoryLoad           uint32
+	totalPhys            uint64
+	availPhys            uint64
+	totalPageFile        uint64
+	availPageFile        uint64
+	totalVirtual         uint64
+	availVirtual         uint64
+	availExtendedVirtual uint64
+}
+
+var procGlobalMemoryStatusEx = windows.NewLazySystemDLL("kernel32.dll").NewProc("GlobalMemoryStatusEx")
+
+// TotalSysMemory returns the total physical memory in bytes via GlobalMemoryStatusEx
+func TotalSysMemory() uint64 {
+	memStatus := memoryStatusEx{}
+	memStatus.length = uint32(unsafe.Sizeof(memStatus))
+
+	ret, _, _ := procGlobalMemoryStatusEx.Call(uintptr(unsafe.Pointer(&memStatus)))
+	if ret == 0 {
+		return 0
+	}
+
+	return memStatus.totalPhys
+}