container: query the actual private working set (#2585)

Signed-off-by: Jan-Otto Kröpke <mail@jkroepke.de>

internal/headers/kernel32/types.go

@@ -56,7 +56,9 @@ type JobObjectBasicProcessIDList struct {
 	ProcessIdList             [1]uintptr
 }
 
-type PROCESS_VM_COUNTERS struct {
+// VM_COUNTERS_EX2 is the ProcessVmCounters layout used by NtQueryInformationProcess.
+// PrivateUsage is private commit; PrivateWorkingSetSize is resident private memory.
+type VM_COUNTERS_EX2 struct {
 	PeakVirtualSize            uintptr
 	VirtualSize                uintptr
 	PageFaultCount             uint32
@@ -68,5 +70,7 @@ type PROCESS_VM_COUNTERS struct {
 	QuotaNonPagedPoolUsage     uintptr
 	PagefileUsage              uintptr
 	PeakPagefileUsage          uintptr
+	PrivateUsage               uintptr
 	PrivateWorkingSetSize      uintptr
+	SharedCommitUsage          uintptr
 }

internal/headers/kernel32/vm_counters_test.go

@@ -0,0 +1,60 @@
+// SPDX-License-Identifier: Apache-2.0
+//
+// Copyright The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build windows
+
+package kernel32_test
+
+import (
+	"testing"
+	"unsafe"
+
+	"github.com/prometheus-community/windows_exporter/internal/headers/kernel32"
+	"github.com/stretchr/testify/require"
+	"golang.org/x/sys/windows"
+)
+
+func TestVMCountersEX2Layout(t *testing.T) {
+	t.Parallel()
+
+	var counters kernel32.VM_COUNTERS_EX2
+	require.Equal(t, uintptr(112), unsafe.Sizeof(counters))
+	require.Equal(t, uintptr(88), unsafe.Offsetof(counters.PrivateUsage))
+	require.Equal(t, uintptr(96), unsafe.Offsetof(counters.PrivateWorkingSetSize))
+	require.Equal(t, uintptr(104), unsafe.Offsetof(counters.SharedCommitUsage))
+}
+
+func TestVMCountersPrivateWorkingSet(t *testing.T) {
+	t.Parallel()
+
+	const allocation = 64 << 20
+
+	address, err := windows.VirtualAlloc(0, allocation, windows.MEM_RESERVE|windows.MEM_COMMIT, windows.PAGE_READWRITE)
+	require.NoError(t, err)
+	t.Cleanup(func() { require.NoError(t, windows.VirtualFree(address, 0, windows.MEM_RELEASE)) })
+
+	// Leave the committed pages untouched so they need not be resident.
+	var (
+		counters kernel32.VM_COUNTERS_EX2
+		returned uint32
+	)
+
+	err = windows.NtQueryInformationProcess(windows.CurrentProcess(), windows.ProcessVmCounters,
+		unsafe.Pointer(&counters), uint32(unsafe.Sizeof(counters)), &returned)
+	require.NoError(t, err)
+	require.Equal(t, uint32(unsafe.Sizeof(counters)), returned)
+	require.Greater(t, counters.PrivateWorkingSetSize, uintptr(0))
+	require.Greater(t, counters.PrivateUsage, counters.PrivateWorkingSetSize+allocation/2)
+}