*: Implement collector interface for registry perfdata (#1670)

internal/perfdata/v1/nametable.go

@@ -0,0 +1,85 @@
+package v1
+
+import (
+	"bytes"
+	"fmt"
+	"strconv"
+	"sync"
+)
+
+// Initialize global name tables
+// TODO: profiling, add option to disable name tables if necessary
+// Not sure if we should resolve the names at all or just have the caller do it on demand
+// (for many use cases the index is sufficient)
+
+var CounterNameTable = *QueryNameTable("Counter 009")
+
+func (p *perfObjectType) LookupName() string {
+	return CounterNameTable.LookupString(p.ObjectNameTitleIndex)
+}
+
+type NameTable struct {
+	once sync.Once
+
+	name string
+
+	table struct {
+		index  map[uint32]string
+		string map[string]uint32
+	}
+}
+
+func (t *NameTable) LookupString(index uint32) string {
+	t.initialize()
+
+	return t.table.index[index]
+}
+
+func (t *NameTable) LookupIndex(str string) uint32 {
+	t.initialize()
+
+	return t.table.string[str]
+}
+
+// QueryNameTable Query a perflib name table from the v1. Specify the type and the language
+// code (i.e. "Counter 009" or "Help 009") for English language.
+func QueryNameTable(tableName string) *NameTable {
+	return &NameTable{
+		name: tableName,
+	}
+}
+
+func (t *NameTable) initialize() {
+	t.once.Do(func() {
+		t.table.index = make(map[uint32]string)
+		t.table.string = make(map[string]uint32)
+
+		buffer, err := queryRawData(t.name)
+		if err != nil {
+			panic(err)
+		}
+
+		r := bytes.NewReader(buffer)
+
+		for {
+			index, err := readUTF16String(r)
+			if err != nil {
+				break
+			}
+
+			desc, err := readUTF16String(r)
+			if err != nil {
+				break
+			}
+
+			if err != nil {
+				panic(fmt.Sprint("Invalid index ", index))
+			}
+
+			indexInt, _ := strconv.Atoi(index)
+
+			t.table.index[uint32(indexInt)] = desc
+			t.table.string[desc] = uint32(indexInt)
+		}
+	})
+}