add cmd/walreader

cmd/walreader/main.go

@@ -0,0 +1,102 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"io"
+	"os"
+
+	"github.com/prometheus/prometheus/pkg/labels"
+	"github.com/prometheus/prometheus/tsdb/record"
+	"github.com/prometheus/prometheus/tsdb/wal"
+)
+
+var (
+	path     string
+	matchers string
+	help     bool
+)
+
+func init() {
+	flag.BoolVar(&help, "help", false, "Show help")
+	flag.StringVar(&matchers, "matchers", "{__name__=~\".+\"", "Label matchers")
+}
+
+func main() {
+	flag.Parse()
+
+	if help {
+		fmt.Fprintln(os.Stderr, "Analyzes a WAL directory or file")
+		flag.PrintDefaults()
+		return
+	}
+
+	args := flag.Args()
+	if len(args) != 1 {
+		fmt.Fprintln(os.Stderr, "expecting one argument")
+		os.Exit(1)
+	}
+
+	path := args[0]
+
+	fi, err := os.Stat(path)
+	if err != nil {
+		panic(err)
+	}
+
+	var rc io.ReadCloser
+	if fi.IsDir() {
+		rc, err = wal.NewSegmentsReader(path)
+	} else {
+		rc, err = wal.OpenReadSegment(path)
+	}
+
+	if err != nil {
+		panic(err)
+	}
+
+	r := wal.NewReader(rc)
+
+	var (
+		dec     record.Decoder
+		series  []record.RefSeries
+		samples []record.RefSample
+		lbls    = make(map[uint64]labels.Labels)
+	)
+
+	for r.Next() {
+		rec := r.Record()
+		switch dec.Type(rec) {
+		case record.Series:
+			series, err = dec.Series(rec, series)
+			if err != nil {
+				fmt.Printf("error while decoding series: %v\n", err)
+				break
+			}
+			for _, s := range series {
+				lbls[s.Ref] = s.Labels
+				//fmt.Printf("series 0x%X (%d): %v\n", s.Ref, s.Ref, s.Labels.String())
+			}
+			series = series[:0]
+		case record.Samples:
+			samples, err = dec.Samples(rec, samples)
+			if err != nil {
+				fmt.Printf("error while decoding samples: %v\n", err)
+				break
+			}
+			for _, s := range samples {
+				lbl, found := lbls[s.Ref]
+				if !found {
+					continue
+				}
+				fmt.Printf("%s (ref: 0x%X): %f@%d\n", lbl.String(), s.Ref, s.V, s.T)
+			}
+			samples = samples[:0]
+
+		}
+	}
+
+	if r.Err() != nil {
+		fmt.Printf("error while reading WAL: %v\n", r.Err())
+	}
+}