version_set_test.go

// Copyright 2020 The LevelDB-Go and Pebble Authors. All rights reserved. Use
// of this source code is governed by a BSD-style license that can be found in
// the LICENSE file.

package pebble

import (
	"io"
	"testing"

	"github.com/cockroachdb/pebble/internal/base"
	"github.com/cockroachdb/pebble/record"
	"github.com/cockroachdb/pebble/sstable"
	"github.com/cockroachdb/pebble/vfs"
	"github.com/stretchr/testify/require"
)

func writeAndIngest(t *testing.T, mem vfs.FS, d *DB, k InternalKey, v []byte, filename string) {
	path := mem.PathJoin("ext", filename)
	f, err := mem.Create(path)
	require.NoError(t, err)
	w := sstable.NewWriter(f, sstable.WriterOptions{})
	require.NoError(t, w.Add(k, v))
	require.NoError(t, w.Close())
	require.NoError(t, d.Ingest([]string{path}))
}

func TestVersionSetCheckpoint(t *testing.T) {
	mem := vfs.NewMem()
	require.NoError(t, mem.MkdirAll("ext", 0755))

	opts := &Options{
		FS:                  mem,
		MaxManifestFileSize: 1,
	}
	d, err := Open("", opts)
	require.NoError(t, err)

	// Multiple manifest files are created such that the latest one must have a correct snapshot
	// of the preceding state for the DB to be opened correctly and see the written data.
	// Snapshot has no files, so first edit will cause manifest rotation.
	writeAndIngest(t, mem, d, base.MakeInternalKey([]byte("a"), 0, InternalKeyKindSet), []byte("b"), "a")
	// Snapshot has no files, and manifest has an edit from the previous ingest,
	// so this second ingest will cause manifest rotation.
	writeAndIngest(t, mem, d, base.MakeInternalKey([]byte("c"), 0, InternalKeyKindSet), []byte("d"), "c")
	require.NoError(t, d.Close())
	d, err = Open("", opts)
	require.NoError(t, err)
	checkValue := func(k string, expected string) {
		v, closer, err := d.Get([]byte(k))
		require.NoError(t, err)
		require.Equal(t, expected, string(v))
		closer.Close()
	}
	checkValue("a", "b")
	checkValue("c", "d")
	require.NoError(t, d.Close())
}

func TestVersionSetSeqNums(t *testing.T) {
	mem := vfs.NewMem()
	require.NoError(t, mem.MkdirAll("ext", 0755))

	opts := &Options{
		FS:                  mem,
		MaxManifestFileSize: 1,
	}
	d, err := Open("", opts)
	require.NoError(t, err)

	// Snapshot has no files, so first edit will cause manifest rotation.
	writeAndIngest(t, mem, d, base.MakeInternalKey([]byte("a"), 0, InternalKeyKindSet), []byte("b"), "a")
	// Snapshot has no files, and manifest has an edit from the previous ingest,
	// so this second ingest will cause manifest rotation.
	writeAndIngest(t, mem, d, base.MakeInternalKey([]byte("c"), 0, InternalKeyKindSet), []byte("d"), "c")
	require.NoError(t, d.Close())
	d, err = Open("", opts)
	require.NoError(t, err)
	defer d.Close()

	// Check that the manifest has the correct LastSeqNum, equalling the highest
	// observed SeqNum.
	filenames, err := mem.List("")
	require.NoError(t, err)
	var manifest vfs.File
	for _, filename := range filenames {
		fileType, _, ok := base.ParseFilename(mem, filename)
		if ok && fileType == fileTypeManifest {
			manifest, err = mem.Open(filename)
			require.NoError(t, err)
		}
	}
	require.NotNil(t, manifest)
	defer manifest.Close()
	rr := record.NewReader(manifest, 0 /* logNum */)
	lastSeqNum := uint64(0)
	for {
		r, err := rr.Next()
		if err == io.EOF {
			break
		}
		require.NoError(t, err)
		var ve versionEdit
		err = ve.Decode(r)
		require.NoError(t, err)
		if ve.LastSeqNum != 0 {
			lastSeqNum = ve.LastSeqNum
		}
	}
	// 2 ingestions happened, so LastSeqNum should equal 2.
	require.Equal(t, uint64(2), lastSeqNum)
	// logSeqNum is always one greater than the last assigned sequence number.
	require.Equal(t, d.mu.versions.atomic.logSeqNum, lastSeqNum+1)
}