fix: tcp, udp sample the IPv4 and IPv6 counters in one PDH query (#2684)

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

internal/pdh/query.go

@@ -0,0 +1,85 @@
+// 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 pdh
+
+import (
+	"fmt"
+	"sync"
+)
+
+// Query is a PDH query that several collectors share, so one
+// PdhCollectQueryData samples all of them. Windows serves counter samples of
+// a process one at a time, so every query waits for the others during a
+// scrape; collectors that are always read together, such as the IPv4 and IPv6
+// objects of a protocol, wait only once in one query.
+//
+// Create the collectors with [NewQueryCollector]. [Query.Collect] takes the
+// sample; [Collector.Collect] of a collector in the query reads the latest
+// sample without taking a new one.
+type Query struct {
+	mu     sync.Mutex
+	handle pdhQueryHandle
+}
+
+// NewQuery opens a query for [NewQueryCollector]. The caller must Close it
+// after the collectors in it.
+func NewQuery() (*Query, error) {
+	var handle pdhQueryHandle
+
+	if ret := OpenQuery(0, 0, &handle); ret != ErrorSuccess {
+		return nil, NewPdhError(ret)
+	}
+
+	return &Query{handle: handle}, nil
+}
+
+// Collect takes one sample of all counters in the query.
+func (q *Query) Collect() error {
+	if q == nil {
+		return ErrPerformanceCounterNotInitialized
+	}
+
+	q.mu.Lock()
+	defer q.mu.Unlock()
+
+	if q.handle == 0 {
+		return ErrPerformanceCounterNotInitialized
+	}
+
+	if ret := CollectQueryData(q.handle); ret != ErrorSuccess {
+		return fmt.Errorf("failed to collect query data: %w", NewPdhError(ret))
+	}
+
+	return nil
+}
+
+// Close closes the query and all counters in it.
+func (q *Query) Close() {
+	if q == nil {
+		return
+	}
+
+	q.mu.Lock()
+	defer q.mu.Unlock()
+
+	if q.handle != 0 {
+		CloseQuery(q.handle)
+	}
+
+	q.handle = 0
+}