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8 changes: 4 additions & 4 deletions tail/tail.go
Original file line number Diff line number Diff line change
Expand Up @@ -207,19 +207,19 @@ func (t *Tailer) Read(b []byte) (int, error) {
}
}

// openSegment finds a WAL segment with a name that parses to n. This
// way we do not need to know how wide the segment filename is (i.e.,
// how many zeros to pad with).
func openSegment(dir string, n int) (io.ReadCloser, error) {
files, err := fileutil.ReadDir(dir)
if err != nil {
return nil, err
}
for _, fn := range files {
k, err := strconv.Atoi(fn)
if err != nil || k < n {
if err != nil || k != n {
continue
}
if k > n {
return nil, errors.Errorf("next segment %d too high, expected %d", n, k)
}
return wal.OpenReadSegment(filepath.Join(dir, fn))
}
return nil, tsdb.ErrNotFound
Expand Down
42 changes: 42 additions & 0 deletions tail/tail_test.go
Original file line number Diff line number Diff line change
Expand Up @@ -17,15 +17,57 @@ package tail
import (
"bytes"
"context"
"fmt"
"io/ioutil"
"math/rand"
"os"
"path"
"testing"
"time"

"github.com/prometheus/tsdb/wal"
)

func TestOpenSegment(t *testing.T) {
dir, err := ioutil.TempDir("", "test_open_segment")
if err != nil {
t.Fatal(err)
}
defer os.RemoveAll(dir)

if err := ioutil.WriteFile(path.Join(dir, "000000000000000000000nonsense"), []byte("bad"), 0777); err != nil {
t.Fatal(err)
}

for i := 0; i < 10; i++ {
if err := ioutil.WriteFile(path.Join(dir, fmt.Sprint("000000000000000000000", i)), []byte(fmt.Sprint(i)), 0777); err != nil {
t.Fatal(err)
}
}
for i := 19; i >= 10; i-- {
if err := ioutil.WriteFile(path.Join(dir, fmt.Sprint("000000000000000000000", i)), []byte(fmt.Sprint(i)), 0777); err != nil {
t.Fatal(err)
}
}

for i := 0; i < 20; i++ {
rc, err := openSegment(dir, i)
if err != nil {
t.Fatal(err)
}
body, err := ioutil.ReadAll(rc)
if err != nil {
t.Fatal(err)
}
if want, have := fmt.Sprint(i), string(body); want != have {
t.Fatalf("invalid body read want=%q have=%q", want, have)
}
if err := rc.Close(); err != nil {
t.Fatal(err)
}
}
}

func TestTailFuzz(t *testing.T) {
dir, err := ioutil.TempDir("", "test_tail")
if err != nil {
Expand Down