prometheus/wal_test.go

package tsdb

import (
	"encoding/binary"
	"fmt"
	"io/ioutil"
	"os"
	"testing"

	"github.com/coreos/etcd/pkg/fileutil"
	"github.com/stretchr/testify/require"
)

func TestWAL_initSegments(t *testing.T) {
	tmpdir, err := ioutil.TempDir("", "test_wal_open")
	require.NoError(t, err)
	defer os.RemoveAll(tmpdir)

	df, err := fileutil.OpenDir(tmpdir)
	require.NoError(t, err)

	w := &WAL{dirFile: df}

	// Create segment files with an appropriate header.
	for i := 1; i <= 5; i++ {
		metab := make([]byte, 8)
		binary.BigEndian.PutUint32(metab[:4], WALMagic)
		metab[4] = WALFormatDefault

		f, err := os.Create(fmt.Sprintf("%s/000%d", tmpdir, i))
		require.NoError(t, err)
		_, err = f.Write(metab)
		require.NoError(t, err)
		require.NoError(t, f.Close())
	}

	// Initialize 5 correct segment files.
	require.NoError(t, w.initSegments())

	require.Equal(t, 5, len(w.files), "unexpected number of segments loaded")

	// Validate that files are locked properly.
	for _, of := range w.files {
		f, err := os.Open(of.Name())
		require.NoError(t, err, "open locked segment %s", f.Name())

		_, err = f.Read([]byte{0})
		require.NoError(t, err, "read locked segment %s", f.Name())

		_, err = f.Write([]byte{0})
		require.Error(t, err, "write to tail segment file %s", f.Name())

		require.NoError(t, f.Close())
	}

	for _, f := range w.files {
		require.NoError(t, f.Close())
	}

	// Make initialization fail by corrupting the header of one file.
	f, err := os.OpenFile(w.files[3].Name(), os.O_WRONLY, 0666)
	require.NoError(t, err)

	_, err = f.WriteAt([]byte{0}, 4)
	require.NoError(t, err)

	w = &WAL{dirFile: df}
	require.Error(t, w.initSegments(), "init corrupted segments")

	for _, f := range w.files {
		require.NoError(t, f.Close())
	}
}

func TestWAL_cut(t *testing.T) {
	tmpdir, err := ioutil.TempDir("", "test_wal_cut")
	require.NoError(t, err)
	defer os.RemoveAll(tmpdir)

	// This calls cut() implicitly the first time without a previous tail.
	w, err := OpenWAL(tmpdir, nil, 0)
	require.NoError(t, err)

	require.NoError(t, w.entry(WALEntrySeries, 1, []byte("Hello World!!")))

	require.NoError(t, w.cut(), "cut failed")

	// Cutting creates a new file and close the previous tail file.
	require.Equal(t, 2, len(w.files))
	require.Equal(t, os.ErrInvalid.Error(), w.files[0].Close().Error())

	require.NoError(t, w.entry(WALEntrySeries, 1, []byte("Hello World!!")))

	require.NoError(t, w.Close())

	for _, of := range w.files {
		f, err := os.Open(of.Name())
		require.NoError(t, err)

		// Verify header data.
		metab := make([]byte, 8)
		_, err = f.Read(metab)
		require.NoError(t, err, "read meta data %s", f.Name())
		require.Equal(t, WALMagic, binary.BigEndian.Uint32(metab[:4]), "verify magic")
		require.Equal(t, WALFormatDefault, metab[4], "verify format flag")

		// We cannot actually check for correct pre-allocation as it is
		// optional per filesystem and handled transparently.
		et, flag, b, err := newWALDecoder(f, nil).entry()
		require.NoError(t, err)
		require.Equal(t, WALEntrySeries, et)
		require.Equal(t, flag, byte(walSeriesSimple))
		require.Equal(t, []byte("Hello World!!"), b)
	}
}