Philip O'Toole
10 months ago
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GitHub
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@ -0,0 +1,201 @@
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Apache License
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@ -0,0 +1,147 @@
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||||
package wal
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import (
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"errors"
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"io"
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"sort"
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)
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var (
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// ErrOpenTransaction is returned when the final frame in the WAL file is not a committing frame.
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ErrOpenTransaction = errors.New("open transaction at end of WAL file")
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)
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type cFrame struct {
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Pgno uint32
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Commit uint32
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Offset int64
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}
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type cFrames []*cFrame
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// make cFrames sortable by offset.
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func (c cFrames) Len() int { return len(c) }
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func (c cFrames) Less(i, j int) bool { return c[uint32(i)].Offset < c[uint32(j)].Offset }
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func (c cFrames) Swap(i, j int) { c[uint32(i)], c[uint32(j)] = c[uint32(j)], c[uint32(i)] }
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// CompactingWALScanner implements WALIterator to iterate over frames in a WAL file.
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||||
// It also compacts the WAL file, with Next() returning the last frame for each page.
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||||
// This Scanner requires that the final frame in the WAL file is a committing frame.
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||||
// It will return an error at creation time if this is not the case.
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type CompactingScanner struct {
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readSeeker io.ReadSeeker
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walReader *Reader
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header *WALHeader
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cIdx int
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frames cFrames
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}
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// NewCompactingScanner creates a new CompactingScanner with the given io.ReadSeeker.
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||||
func NewCompactingScanner(r io.ReadSeeker) (*CompactingScanner, error) {
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||||
walReader := NewReader(r)
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err := walReader.ReadHeader()
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if err != nil {
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||||
return nil, err
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}
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hdr := &WALHeader{
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Magic: walReader.magic,
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Version: WALSupportedVersion,
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PageSize: walReader.PageSize(),
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Seq: walReader.seq,
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Salt1: walReader.salt1,
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Salt2: walReader.salt2,
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Checksum1: walReader.chksum1,
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Checksum2: walReader.chksum2,
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}
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s := &CompactingScanner{
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readSeeker: r,
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walReader: walReader,
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header: hdr,
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}
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||||
if err := s.scan(); err != nil {
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return nil, err
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}
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return s, nil
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||||
}
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||||
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||||
// Header returns the header of the WAL file.
|
||||
func (c *CompactingScanner) Header() (*WALHeader, error) {
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||||
return c.header, nil
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||||
}
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// Next reads the next frame from the WAL file.
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||||
func (c *CompactingScanner) Next() (*Frame, error) {
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||||
if c.cIdx >= len(c.frames) {
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return nil, io.EOF
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}
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frame := &Frame{
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Pgno: c.frames[c.cIdx].Pgno,
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Commit: c.frames[c.cIdx].Commit,
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Data: make([]byte, c.header.PageSize),
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}
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if _, err := c.readSeeker.Seek(c.frames[c.cIdx].Offset+WALFrameHeaderSize, io.SeekStart); err != nil {
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return nil, err
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}
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if _, err := io.ReadFull(c.readSeeker, frame.Data); err != nil {
|
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return nil, err
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}
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c.cIdx++
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return frame, nil
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}
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func (c *CompactingScanner) scan() error {
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waitingForCommit := false
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txFrames := make(map[uint32]*cFrame)
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frames := make(map[uint32]*cFrame)
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buf := make([]byte, c.header.PageSize)
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for {
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pgno, commit, err := c.walReader.ReadFrame(buf)
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||||
if err == io.EOF {
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break
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} else if err != nil {
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return err
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}
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frame := &cFrame{
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Pgno: pgno,
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Commit: commit,
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Offset: c.walReader.Offset(),
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}
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// Save latest frame information for each page.
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txFrames[pgno] = frame
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// If this is not a committing frame, continue to next frame.
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if commit == 0 {
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waitingForCommit = true
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continue
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}
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waitingForCommit = false
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// At the end of each transaction, copy frame information to main map.
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for k, v := range txFrames {
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frames[k] = v
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}
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txFrames = make(map[uint32]*cFrame)
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}
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if waitingForCommit {
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return ErrOpenTransaction
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}
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// Now we have the latest version of each frame. Next we need to sort
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// them by offset so we return them in the correct order.
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c.frames = make(cFrames, 0, len(frames))
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for _, frame := range frames {
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c.frames = append(c.frames, frame)
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}
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sort.Sort(c.frames)
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return nil
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}
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@ -0,0 +1,96 @@
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package wal
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import (
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"bytes"
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"io"
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"os"
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"testing"
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)
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func Test_CompactingScanner_Scan(t *testing.T) {
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b, err := os.ReadFile("testdata/wal-reader/ok/wal")
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if err != nil {
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t.Fatal(err)
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}
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s, err := NewCompactingScanner(bytes.NewReader(b))
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||||
if err != nil {
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t.Fatal(err)
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}
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for i, expF := range []struct {
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pgno uint32
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commit uint32
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dataLowIdx int
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dataHighIdx int
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}{
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{1, 0, 56, 4152},
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//{2, 2, 4176, 8272}, skipped by the Compactor.
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||||
{2, 2, 8296, 12392},
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||||
} {
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||||
f, err := s.Next()
|
||||
if err != nil {
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||||
t.Fatal(err)
|
||||
}
|
||||
if f.Pgno != expF.pgno {
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||||
t.Fatalf("expected pgno %d, got %d", expF.pgno, f.Pgno)
|
||||
}
|
||||
if f.Commit != expF.commit {
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||||
t.Fatalf("expected commit %d, got %d", expF.commit, f.Commit)
|
||||
}
|
||||
if len(f.Data) != 4096 {
|
||||
t.Fatalf("expected data length 4096, got %d", len(f.Data))
|
||||
}
|
||||
if !bytes.Equal(f.Data, b[expF.dataLowIdx:expF.dataHighIdx]) {
|
||||
t.Fatalf("page data mismatch on test %d", i)
|
||||
}
|
||||
}
|
||||
|
||||
_, err = s.Next()
|
||||
if err != io.EOF {
|
||||
t.Fatalf("expected EOF, got %v", err)
|
||||
}
|
||||
}
|
||||
|
||||
func Test_CompactingScanner_Scan_Commit0(t *testing.T) {
|
||||
b, err := os.ReadFile("testdata/compacting-scanner/commit-0/wal")
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
|
||||
s, err := NewCompactingScanner(bytes.NewReader(b))
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
|
||||
for _, expF := range []struct {
|
||||
pgno uint32
|
||||
commit uint32
|
||||
}{
|
||||
// {1,0}, skipped by the Compactor.
|
||||
// {2,2}, skipped by the Compactor.
|
||||
{1, 0},
|
||||
{2, 0},
|
||||
{3, 0},
|
||||
{4, 0},
|
||||
{5, 0},
|
||||
// {6,6}, skipped by the Compactor.
|
||||
{6, 6},
|
||||
} {
|
||||
f, err := s.Next()
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
if f.Pgno != expF.pgno {
|
||||
t.Fatalf("expected pgno %d, got %d", expF.pgno, f.Pgno)
|
||||
}
|
||||
if f.Commit != expF.commit {
|
||||
t.Fatalf("expected commit %d, got %d", expF.commit, f.Commit)
|
||||
}
|
||||
}
|
||||
|
||||
_, err = s.Next()
|
||||
if err != io.EOF {
|
||||
t.Fatalf("expected EOF, got %v", err)
|
||||
}
|
||||
}
|
||||
@ -0,0 +1,57 @@
|
||||
package wal
|
||||
|
||||
import (
|
||||
"io"
|
||||
)
|
||||
|
||||
// FullScanner implements WALIterator to iterate over all frames in a WAL file.
|
||||
type FullScanner struct {
|
||||
reader *Reader
|
||||
header *WALHeader
|
||||
}
|
||||
|
||||
// NewFullScanner creates a new FullScanner with the given io.Reader.
|
||||
func NewFullScanner(r io.Reader) (*FullScanner, error) {
|
||||
wr := NewReader(r)
|
||||
err := wr.ReadHeader()
|
||||
if err != nil {
|
||||
return nil, err
|
||||
}
|
||||
|
||||
hdr := &WALHeader{
|
||||
Magic: wr.magic,
|
||||
Version: WALSupportedVersion,
|
||||
PageSize: wr.PageSize(),
|
||||
Seq: wr.seq,
|
||||
Salt1: wr.salt1,
|
||||
Salt2: wr.salt2,
|
||||
Checksum1: wr.chksum1,
|
||||
Checksum2: wr.chksum2,
|
||||
}
|
||||
|
||||
return &FullScanner{
|
||||
reader: wr,
|
||||
header: hdr,
|
||||
}, nil
|
||||
}
|
||||
|
||||
// Header returns the header of the WAL file.
|
||||
func (f *FullScanner) Header() (*WALHeader, error) {
|
||||
return f.header, nil
|
||||
}
|
||||
|
||||
// Next reads the next frame from the WAL file.
|
||||
func (f *FullScanner) Next() (*Frame, error) {
|
||||
data := make([]byte, f.reader.PageSize())
|
||||
pgno, commit, err := f.reader.ReadFrame(data)
|
||||
if err != nil {
|
||||
return nil, err
|
||||
}
|
||||
|
||||
frame := &Frame{
|
||||
Pgno: pgno,
|
||||
Commit: commit,
|
||||
Data: data,
|
||||
}
|
||||
return frame, nil
|
||||
}
|
||||
@ -0,0 +1,53 @@
|
||||
package wal
|
||||
|
||||
import (
|
||||
"bytes"
|
||||
"io"
|
||||
"os"
|
||||
"testing"
|
||||
)
|
||||
|
||||
func Test_FullScanner_Scan(t *testing.T) {
|
||||
b, err := os.ReadFile("testdata/wal-reader/ok/wal")
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
|
||||
s, err := NewFullScanner(bytes.NewReader(b))
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
|
||||
for i, expF := range []struct {
|
||||
pgno uint32
|
||||
commit uint32
|
||||
dataLowIdx int
|
||||
dataHighIdx int
|
||||
}{
|
||||
{1, 0, 56, 4152},
|
||||
{2, 2, 4176, 8272},
|
||||
{2, 2, 8296, 12392},
|
||||
} {
|
||||
f, err := s.Next()
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
if f.Pgno != expF.pgno {
|
||||
t.Fatalf("expected pgno %d, got %d", expF.pgno, f.Pgno)
|
||||
}
|
||||
if f.Commit != expF.commit {
|
||||
t.Fatalf("expected commit %d, got %d", expF.commit, f.Commit)
|
||||
}
|
||||
if len(f.Data) != 4096 {
|
||||
t.Fatalf("expected data length 4096, got %d", len(f.Data))
|
||||
}
|
||||
if !bytes.Equal(f.Data, b[expF.dataLowIdx:expF.dataHighIdx]) {
|
||||
t.Fatalf("page data mismatch on test %d", i)
|
||||
}
|
||||
}
|
||||
|
||||
_, err = s.Next()
|
||||
if err != io.EOF {
|
||||
t.Fatalf("expected EOF, got %v", err)
|
||||
}
|
||||
}
|
||||
@ -0,0 +1,161 @@
|
||||
package wal
|
||||
|
||||
import (
|
||||
"encoding/binary"
|
||||
"fmt"
|
||||
"io"
|
||||
)
|
||||
|
||||
// SQLite constants
|
||||
const (
|
||||
WALHeaderSize = 32
|
||||
WALFrameHeaderSize = 24
|
||||
|
||||
WALSupportedVersion = 3007000
|
||||
)
|
||||
|
||||
// Reader wraps an io.Reader and parses SQLite WAL frames.
|
||||
//
|
||||
// This reader verifies the salt & checksum integrity while it reads. It does
|
||||
// not enforce transaction boundaries (i.e. it may return uncommitted frames).
|
||||
// It is the responsibility of the caller to handle this.
|
||||
//
|
||||
// Reader has been copied from the litefs source code. Many thanks to the
|
||||
// authors of that software. See https://github.com/superfly/litefs for more
|
||||
// details.
|
||||
type Reader struct {
|
||||
r io.Reader
|
||||
frameN int
|
||||
|
||||
magic uint32
|
||||
bo binary.ByteOrder
|
||||
pageSize uint32
|
||||
seq uint32
|
||||
|
||||
salt1, salt2 uint32
|
||||
chksum1, chksum2 uint32
|
||||
}
|
||||
|
||||
// NewReader returns a new instance of Reader.
|
||||
func NewReader(r io.Reader) *Reader {
|
||||
return &Reader{r: r}
|
||||
}
|
||||
|
||||
// PageSize returns the page size from the header. Must call ReadHeader() first.
|
||||
func (r *Reader) PageSize() uint32 { return r.pageSize }
|
||||
|
||||
// Offset returns the file offset of the last read frame.
|
||||
// Returns zero if no frames have been read.
|
||||
func (r *Reader) Offset() int64 {
|
||||
if r.frameN == 0 {
|
||||
return 0
|
||||
}
|
||||
return WALHeaderSize + ((int64(r.frameN) - 1) * (WALFrameHeaderSize + int64(r.pageSize)))
|
||||
}
|
||||
|
||||
// ReadHeader reads the WAL header into the reader. Returns io.EOF if WAL is invalid.
|
||||
func (r *Reader) ReadHeader() error {
|
||||
// If we have a partial WAL, then mark WAL as done.
|
||||
hdr := make([]byte, WALHeaderSize)
|
||||
if _, err := io.ReadFull(r.r, hdr); err == io.ErrUnexpectedEOF {
|
||||
return io.EOF
|
||||
} else if err != nil {
|
||||
return err
|
||||
}
|
||||
|
||||
// Determine byte order of checksums.
|
||||
r.magic = binary.BigEndian.Uint32(hdr[0:])
|
||||
switch r.magic {
|
||||
case 0x377f0682:
|
||||
r.bo = binary.LittleEndian
|
||||
case 0x377f0683:
|
||||
r.bo = binary.BigEndian
|
||||
default:
|
||||
return fmt.Errorf("invalid wal header magic: %x", r.magic)
|
||||
}
|
||||
|
||||
// If the header checksum doesn't match then we may have failed with
|
||||
// a partial WAL header write during checkpointing.
|
||||
chksum1 := binary.BigEndian.Uint32(hdr[24:])
|
||||
chksum2 := binary.BigEndian.Uint32(hdr[28:])
|
||||
if v0, v1 := WALChecksum(r.bo, 0, 0, hdr[:24]); v0 != chksum1 || v1 != chksum2 {
|
||||
return io.EOF
|
||||
}
|
||||
|
||||
// Verify version is correct.
|
||||
if version := binary.BigEndian.Uint32(hdr[4:]); version != WALSupportedVersion {
|
||||
return fmt.Errorf("unsupported wal version: %d", version)
|
||||
}
|
||||
|
||||
r.pageSize = binary.BigEndian.Uint32(hdr[8:])
|
||||
r.seq = binary.BigEndian.Uint32(hdr[12:])
|
||||
r.salt1 = binary.BigEndian.Uint32(hdr[16:])
|
||||
r.salt2 = binary.BigEndian.Uint32(hdr[20:])
|
||||
r.chksum1, r.chksum2 = chksum1, chksum2
|
||||
|
||||
return nil
|
||||
}
|
||||
|
||||
// ReadFrame reads the next frame from the WAL and returns the page number.
|
||||
// Returns io.EOF at the end of the valid WAL.
|
||||
func (r *Reader) ReadFrame(data []byte) (pgno, commit uint32, err error) {
|
||||
if len(data) != int(r.pageSize) {
|
||||
return 0, 0, fmt.Errorf("WALReader.ReadFrame(): buffer size (%d) must match page size (%d)", len(data), r.pageSize)
|
||||
}
|
||||
|
||||
// Read WAL frame header.
|
||||
hdr := make([]byte, WALFrameHeaderSize)
|
||||
if _, err := io.ReadFull(r.r, hdr); err == io.ErrUnexpectedEOF {
|
||||
return 0, 0, io.EOF
|
||||
} else if err != nil {
|
||||
return 0, 0, err
|
||||
}
|
||||
|
||||
// Read WAL page data.
|
||||
if _, err := io.ReadFull(r.r, data); err == io.ErrUnexpectedEOF {
|
||||
return 0, 0, io.EOF
|
||||
} else if err != nil {
|
||||
return 0, 0, err
|
||||
}
|
||||
|
||||
// Verify salt matches the salt in the header.
|
||||
salt1 := binary.BigEndian.Uint32(hdr[8:])
|
||||
salt2 := binary.BigEndian.Uint32(hdr[12:])
|
||||
if r.salt1 != salt1 || r.salt2 != salt2 {
|
||||
return 0, 0, io.EOF
|
||||
}
|
||||
|
||||
// Verify the checksum is valid.
|
||||
chksum1 := binary.BigEndian.Uint32(hdr[16:])
|
||||
chksum2 := binary.BigEndian.Uint32(hdr[20:])
|
||||
r.chksum1, r.chksum2 = WALChecksum(r.bo, r.chksum1, r.chksum2, hdr[:8]) // frame header
|
||||
r.chksum1, r.chksum2 = WALChecksum(r.bo, r.chksum1, r.chksum2, data) // frame data
|
||||
if r.chksum1 != chksum1 || r.chksum2 != chksum2 {
|
||||
return 0, 0, io.EOF
|
||||
}
|
||||
|
||||
pgno = binary.BigEndian.Uint32(hdr[0:])
|
||||
commit = binary.BigEndian.Uint32(hdr[4:])
|
||||
|
||||
r.frameN++
|
||||
|
||||
return pgno, commit, nil
|
||||
}
|
||||
|
||||
// WALChecksum computes a running SQLite WAL checksum over a byte slice.
|
||||
func WALChecksum(bo binary.ByteOrder, s0, s1 uint32, b []byte) (uint32, uint32) {
|
||||
assert(len(b)%8 == 0, "misaligned checksum byte slice")
|
||||
|
||||
// Iterate over 8-byte units and compute checksum.
|
||||
for i := 0; i < len(b); i += 8 {
|
||||
s0 += bo.Uint32(b[i:]) + s1
|
||||
s1 += bo.Uint32(b[i+4:]) + s0
|
||||
}
|
||||
return s0, s1
|
||||
}
|
||||
|
||||
func assert(condition bool, msg string) {
|
||||
if !condition {
|
||||
panic("assertion failed: " + msg)
|
||||
}
|
||||
}
|
||||
@ -0,0 +1,242 @@
|
||||
package wal
|
||||
|
||||
import (
|
||||
"bytes"
|
||||
"io"
|
||||
"os"
|
||||
"testing"
|
||||
)
|
||||
|
||||
func TestReader(t *testing.T) {
|
||||
t.Run("OK", func(t *testing.T) {
|
||||
buf := make([]byte, 4096)
|
||||
b, err := os.ReadFile("testdata/wal-reader/ok/wal")
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
|
||||
// Initialize reader with header info.
|
||||
r := NewReader(bytes.NewReader(b))
|
||||
if err := r.ReadHeader(); err != nil {
|
||||
t.Fatal(err)
|
||||
} else if got, want := r.PageSize(), uint32(4096); got != want {
|
||||
t.Fatalf("PageSize()=%d, want %d", got, want)
|
||||
} else if got, want := r.Offset(), int64(0); got != want {
|
||||
t.Fatalf("Offset()=%d, want %d", got, want)
|
||||
}
|
||||
|
||||
// Read first frame.
|
||||
if pgno, commit, err := r.ReadFrame(buf); err != nil {
|
||||
t.Fatal(err)
|
||||
} else if got, want := pgno, uint32(1); got != want {
|
||||
t.Fatalf("pgno=%d, want %d", got, want)
|
||||
} else if got, want := commit, uint32(0); got != want {
|
||||
t.Fatalf("commit=%d, want %d", got, want)
|
||||
} else if !bytes.Equal(buf, b[56:4152]) {
|
||||
t.Fatal("page data mismatch")
|
||||
} else if got, want := r.Offset(), int64(32); got != want {
|
||||
t.Fatalf("Offset()=%d, want %d", got, want)
|
||||
}
|
||||
|
||||
// Read second frame. End of transaction.
|
||||
if pgno, commit, err := r.ReadFrame(buf); err != nil {
|
||||
t.Fatal(err)
|
||||
} else if got, want := pgno, uint32(2); got != want {
|
||||
t.Fatalf("pgno=%d, want %d", got, want)
|
||||
} else if got, want := commit, uint32(2); got != want {
|
||||
t.Fatalf("commit=%d, want %d", got, want)
|
||||
} else if !bytes.Equal(buf, b[4176:8272]) {
|
||||
t.Fatal("page data mismatch")
|
||||
} else if got, want := r.Offset(), int64(4152); got != want {
|
||||
t.Fatalf("Offset()=%d, want %d", got, want)
|
||||
}
|
||||
|
||||
// Read third frame.
|
||||
if pgno, commit, err := r.ReadFrame(buf); err != nil {
|
||||
t.Fatal(err)
|
||||
} else if got, want := pgno, uint32(2); got != want {
|
||||
t.Fatalf("pgno=%d, want %d", got, want)
|
||||
} else if got, want := commit, uint32(2); got != want {
|
||||
t.Fatalf("commit=%d, want %d", got, want)
|
||||
} else if !bytes.Equal(buf, b[8296:12392]) {
|
||||
t.Fatal("page data mismatch")
|
||||
} else if got, want := r.Offset(), int64(8272); got != want {
|
||||
t.Fatalf("Offset()=%d, want %d", got, want)
|
||||
}
|
||||
|
||||
if _, _, err := r.ReadFrame(buf); err != io.EOF {
|
||||
t.Fatalf("unexpected error: %s", err)
|
||||
}
|
||||
})
|
||||
|
||||
t.Run("SaltMismatch", func(t *testing.T) {
|
||||
buf := make([]byte, 4096)
|
||||
b, err := os.ReadFile("testdata/wal-reader/salt-mismatch/wal")
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
|
||||
// Initialize reader with header info.
|
||||
r := NewReader(bytes.NewReader(b))
|
||||
if err := r.ReadHeader(); err != nil {
|
||||
t.Fatal(err)
|
||||
} else if got, want := r.PageSize(), uint32(4096); got != want {
|
||||
t.Fatalf("PageSize()=%d, want %d", got, want)
|
||||
} else if got, want := r.Offset(), int64(0); got != want {
|
||||
t.Fatalf("Offset()=%d, want %d", got, want)
|
||||
}
|
||||
|
||||
// Read first frame.
|
||||
if pgno, commit, err := r.ReadFrame(buf); err != nil {
|
||||
t.Fatal(err)
|
||||
} else if got, want := pgno, uint32(1); got != want {
|
||||
t.Fatalf("pgno=%d, want %d", got, want)
|
||||
} else if got, want := commit, uint32(0); got != want {
|
||||
t.Fatalf("commit=%d, want %d", got, want)
|
||||
} else if !bytes.Equal(buf, b[56:4152]) {
|
||||
t.Fatal("page data mismatch")
|
||||
}
|
||||
|
||||
// Read second frame. Salt has been altered so it doesn't match header.
|
||||
if _, _, err := r.ReadFrame(buf); err != io.EOF {
|
||||
t.Fatalf("unexpected error: %s", err)
|
||||
}
|
||||
})
|
||||
|
||||
t.Run("FrameChecksumMismatch", func(t *testing.T) {
|
||||
buf := make([]byte, 4096)
|
||||
b, err := os.ReadFile("testdata/wal-reader/frame-checksum-mismatch/wal")
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
|
||||
// Initialize reader with header info.
|
||||
r := NewReader(bytes.NewReader(b))
|
||||
if err := r.ReadHeader(); err != nil {
|
||||
t.Fatal(err)
|
||||
} else if got, want := r.PageSize(), uint32(4096); got != want {
|
||||
t.Fatalf("PageSize()=%d, want %d", got, want)
|
||||
} else if got, want := r.Offset(), int64(0); got != want {
|
||||
t.Fatalf("Offset()=%d, want %d", got, want)
|
||||
}
|
||||
|
||||
// Read first frame.
|
||||
if pgno, commit, err := r.ReadFrame(buf); err != nil {
|
||||
t.Fatal(err)
|
||||
} else if got, want := pgno, uint32(1); got != want {
|
||||
t.Fatalf("pgno=%d, want %d", got, want)
|
||||
} else if got, want := commit, uint32(0); got != want {
|
||||
t.Fatalf("commit=%d, want %d", got, want)
|
||||
} else if !bytes.Equal(buf, b[56:4152]) {
|
||||
t.Fatal("page data mismatch")
|
||||
}
|
||||
|
||||
// Read second frame. Checksum has been altered so it doesn't match.
|
||||
if _, _, err := r.ReadFrame(buf); err != io.EOF {
|
||||
t.Fatalf("unexpected error: %s", err)
|
||||
}
|
||||
})
|
||||
|
||||
t.Run("ZeroLength", func(t *testing.T) {
|
||||
r := NewReader(bytes.NewReader(nil))
|
||||
if err := r.ReadHeader(); err != io.EOF {
|
||||
t.Fatalf("unexpected error: %#v", err)
|
||||
}
|
||||
})
|
||||
|
||||
t.Run("PartialHeader", func(t *testing.T) {
|
||||
r := NewReader(bytes.NewReader(make([]byte, 10)))
|
||||
if err := r.ReadHeader(); err != io.EOF {
|
||||
t.Fatalf("unexpected error: %#v", err)
|
||||
}
|
||||
})
|
||||
|
||||
t.Run("BadMagic", func(t *testing.T) {
|
||||
r := NewReader(bytes.NewReader(make([]byte, 32)))
|
||||
if err := r.ReadHeader(); err == nil || err.Error() != `invalid wal header magic: 0` {
|
||||
t.Fatalf("unexpected error: %#v", err)
|
||||
}
|
||||
})
|
||||
|
||||
t.Run("BadHeaderChecksum", func(t *testing.T) {
|
||||
data := []byte{
|
||||
0x37, 0x7f, 0x06, 0x83, 0x00, 0x00, 0x00, 0x00,
|
||||
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
|
||||
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
|
||||
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}
|
||||
r := NewReader(bytes.NewReader(data))
|
||||
if err := r.ReadHeader(); err != io.EOF {
|
||||
t.Fatalf("unexpected error: %#v", err)
|
||||
}
|
||||
})
|
||||
|
||||
t.Run("BadHeaderVersion", func(t *testing.T) {
|
||||
data := []byte{
|
||||
0x37, 0x7f, 0x06, 0x83, 0x00, 0x00, 0x00, 0x01,
|
||||
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
|
||||
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
|
||||
0x15, 0x7b, 0x20, 0x92, 0xbb, 0xf8, 0x34, 0x1d}
|
||||
r := NewReader(bytes.NewReader(data))
|
||||
if err := r.ReadHeader(); err == nil || err.Error() != `unsupported wal version: 1` {
|
||||
t.Fatalf("unexpected error: %#v", err)
|
||||
}
|
||||
})
|
||||
|
||||
t.Run("ErrBufferSize", func(t *testing.T) {
|
||||
b, err := os.ReadFile("testdata/wal-reader/ok/wal")
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
|
||||
// Initialize reader with header info.
|
||||
r := NewReader(bytes.NewReader(b))
|
||||
if err := r.ReadHeader(); err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
if _, _, err := r.ReadFrame(make([]byte, 512)); err == nil || err.Error() != `WALReader.ReadFrame(): buffer size (512) must match page size (4096)` {
|
||||
t.Fatalf("unexpected error: %#v", err)
|
||||
}
|
||||
})
|
||||
|
||||
t.Run("ErrPartialFrameHeader", func(t *testing.T) {
|
||||
b, err := os.ReadFile("testdata/wal-reader/ok/wal")
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
|
||||
r := NewReader(bytes.NewReader(b[:40]))
|
||||
if err := r.ReadHeader(); err != nil {
|
||||
t.Fatal(err)
|
||||
} else if _, _, err := r.ReadFrame(make([]byte, 4096)); err != io.EOF {
|
||||
t.Fatalf("unexpected error: %#v", err)
|
||||
}
|
||||
})
|
||||
|
||||
t.Run("ErrFrameHeaderOnly", func(t *testing.T) {
|
||||
b, err := os.ReadFile("testdata/wal-reader/ok/wal")
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
|
||||
r := NewReader(bytes.NewReader(b[:56]))
|
||||
if err := r.ReadHeader(); err != nil {
|
||||
t.Fatal(err)
|
||||
} else if _, _, err := r.ReadFrame(make([]byte, 4096)); err != io.EOF {
|
||||
t.Fatalf("unexpected error: %#v", err)
|
||||
}
|
||||
})
|
||||
|
||||
t.Run("ErrPartialFrameData", func(t *testing.T) {
|
||||
b, err := os.ReadFile("testdata/wal-reader/ok/wal")
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
|
||||
r := NewReader(bytes.NewReader(b[:1000]))
|
||||
if err := r.ReadHeader(); err != nil {
|
||||
t.Fatal(err)
|
||||
} else if _, _, err := r.ReadFrame(make([]byte, 4096)); err != io.EOF {
|
||||
t.Fatalf("unexpected error: %#v", err)
|
||||
}
|
||||
})
|
||||
}
|
||||
Binary file not shown.
Binary file not shown.
Binary file not shown.
Binary file not shown.
@ -0,0 +1,68 @@
|
||||
package main
|
||||
|
||||
import (
|
||||
"flag"
|
||||
"fmt"
|
||||
"io"
|
||||
"os"
|
||||
|
||||
"github.com/rqlite/rqlite/db/wal"
|
||||
)
|
||||
|
||||
const name = `walr`
|
||||
const desc = `walr is a tool for displaying information about WAL files.`
|
||||
|
||||
func init() {
|
||||
flag.Usage = func() {
|
||||
fmt.Fprintf(os.Stderr, "\n%s\n\n", desc)
|
||||
fmt.Fprintf(os.Stderr, "Usage: %s <Path to WAL file>\n", name)
|
||||
flag.PrintDefaults()
|
||||
}
|
||||
}
|
||||
|
||||
func main() {
|
||||
flag.Parse()
|
||||
|
||||
if flag.NArg() == 0 {
|
||||
flag.Usage()
|
||||
os.Exit(1)
|
||||
}
|
||||
walPath := flag.Args()[0]
|
||||
|
||||
walFD, err := os.Open(walPath)
|
||||
if err != nil {
|
||||
fmt.Println("failed to open WAL file:", err)
|
||||
os.Exit(1)
|
||||
}
|
||||
|
||||
r := wal.NewReader(walFD)
|
||||
if err := r.ReadHeader(); err != nil {
|
||||
fmt.Println("failed to read WAL header:", err)
|
||||
os.Exit(1)
|
||||
}
|
||||
fmt.Println("WAL page size:", r.PageSize())
|
||||
|
||||
nFrames := 0
|
||||
nCommits := 0
|
||||
uniquePgs := make(map[uint32]struct{})
|
||||
buf := make([]byte, r.PageSize())
|
||||
for {
|
||||
pgno, commit, err := r.ReadFrame(buf)
|
||||
if err == io.EOF {
|
||||
break
|
||||
} else if err != nil {
|
||||
fmt.Println("failed to read WAL frame:", err)
|
||||
os.Exit(1)
|
||||
}
|
||||
fmt.Println("pgno:", pgno, "commit:", commit)
|
||||
|
||||
uniquePgs[pgno] = struct{}{}
|
||||
nFrames++
|
||||
|
||||
if commit != 0 {
|
||||
nCommits++
|
||||
}
|
||||
}
|
||||
|
||||
fmt.Printf("Found %d WAL frames, %d unique pages, %d commit frames\n", nFrames, len(uniquePgs), nCommits)
|
||||
}
|
||||
@ -0,0 +1,147 @@
|
||||
package wal
|
||||
|
||||
import (
|
||||
"encoding/binary"
|
||||
"fmt"
|
||||
"io"
|
||||
)
|
||||
|
||||
// WALHeader represents the header of a WAL file.
|
||||
type WALHeader struct {
|
||||
Magic uint32
|
||||
Version uint32
|
||||
PageSize uint32
|
||||
Seq uint32
|
||||
Salt1 uint32
|
||||
Salt2 uint32
|
||||
Checksum1 uint32
|
||||
Checksum2 uint32
|
||||
}
|
||||
|
||||
// Frame points to a single WAL frame in a WAL file.
|
||||
type Frame struct {
|
||||
Pgno uint32
|
||||
Commit uint32
|
||||
Data []byte
|
||||
}
|
||||
|
||||
// WALIterator defines the interface for WAL frame iteration.
|
||||
type WALIterator interface {
|
||||
Header() (*WALHeader, error)
|
||||
Next() (*Frame, error)
|
||||
}
|
||||
|
||||
// Writer is used to write a WAL file.
|
||||
type Writer struct {
|
||||
r WALIterator
|
||||
rHeader *WALHeader
|
||||
chksum1, chksum2 uint32
|
||||
bo binary.ByteOrder
|
||||
}
|
||||
|
||||
// NewWriter returns a new Writer.
|
||||
func NewWriter(r WALIterator) (*Writer, error) {
|
||||
w := &Writer{
|
||||
r: r,
|
||||
}
|
||||
rh, err := w.r.Header()
|
||||
if err != nil {
|
||||
return nil, err
|
||||
}
|
||||
w.rHeader = rh
|
||||
w.chksum1, w.chksum2 = w.rHeader.Checksum1, w.rHeader.Checksum2
|
||||
switch magic := w.rHeader.Magic; magic {
|
||||
case 0x377f0682:
|
||||
w.bo = binary.LittleEndian
|
||||
case 0x377f0683:
|
||||
w.bo = binary.BigEndian
|
||||
default:
|
||||
return nil, fmt.Errorf("invalid wal header magic: %x", magic)
|
||||
}
|
||||
|
||||
return w, nil
|
||||
}
|
||||
|
||||
// WriteTo writes the frames from the WALIterator to the given io.Writer.
|
||||
func (w *Writer) WriteTo(ww io.Writer) (n int64, retErr error) {
|
||||
nn, err := w.writeWALHeader(ww)
|
||||
if err != nil {
|
||||
return nn, err
|
||||
}
|
||||
n += nn
|
||||
|
||||
for {
|
||||
frame, err := w.r.Next()
|
||||
if err != nil {
|
||||
if err == io.EOF {
|
||||
break // No more frames!
|
||||
}
|
||||
return n, err
|
||||
}
|
||||
|
||||
if nn, err = w.writeFrame(ww, frame); err != nil {
|
||||
return n + nn, err
|
||||
}
|
||||
n += nn
|
||||
}
|
||||
|
||||
return n, nil
|
||||
}
|
||||
|
||||
func (w *Writer) writeWALHeader(ww io.Writer) (n int64, err error) {
|
||||
rHeader, err := w.r.Header()
|
||||
if err != nil {
|
||||
return 0, err
|
||||
}
|
||||
wHeader := make([]byte, WALHeaderSize)
|
||||
|
||||
binary.BigEndian.PutUint32(wHeader[0:], rHeader.Magic)
|
||||
binary.BigEndian.PutUint32(wHeader[4:], rHeader.Version)
|
||||
|
||||
// Database page size
|
||||
binary.BigEndian.PutUint32(wHeader[8:], rHeader.PageSize)
|
||||
|
||||
// Checkpoint sequence number
|
||||
binary.BigEndian.PutUint32(wHeader[12:], rHeader.Seq)
|
||||
|
||||
// Salt values, reusing the original salt values.
|
||||
binary.BigEndian.PutUint32(wHeader[16:], rHeader.Salt1)
|
||||
binary.BigEndian.PutUint32(wHeader[20:], rHeader.Salt2)
|
||||
|
||||
// Checksum of header
|
||||
w.chksum1, w.chksum2 = rHeader.Checksum1, rHeader.Checksum2
|
||||
binary.BigEndian.PutUint32(wHeader[24:], w.chksum1)
|
||||
binary.BigEndian.PutUint32(wHeader[28:], w.chksum2)
|
||||
|
||||
// Write the header to the new WAL file.
|
||||
nn, err := ww.Write(wHeader)
|
||||
return int64(nn), err
|
||||
}
|
||||
|
||||
func (w *Writer) writeFrame(ww io.Writer, frame *Frame) (n int64, err error) {
|
||||
frmHdr := make([]byte, WALFrameHeaderSize)
|
||||
|
||||
// Calculate the frame header.
|
||||
binary.BigEndian.PutUint32(frmHdr[0:], frame.Pgno)
|
||||
binary.BigEndian.PutUint32(frmHdr[4:], frame.Commit)
|
||||
binary.BigEndian.PutUint32(frmHdr[8:], w.rHeader.Salt1)
|
||||
binary.BigEndian.PutUint32(frmHdr[12:], w.rHeader.Salt2)
|
||||
|
||||
// Checksum of frame header: "...the first 8 bytes..."
|
||||
w.chksum1, w.chksum2 = WALChecksum(w.bo, w.chksum1, w.chksum2, frmHdr[:8])
|
||||
|
||||
// Update checksum using frame data: "..the content of all frames up to and including the current frame."
|
||||
w.chksum1, w.chksum2 = WALChecksum(w.bo, w.chksum1, w.chksum2, frame.Data)
|
||||
binary.BigEndian.PutUint32(frmHdr[16:], w.chksum1)
|
||||
binary.BigEndian.PutUint32(frmHdr[20:], w.chksum2)
|
||||
|
||||
// Write the frame header and data.
|
||||
nn, err := ww.Write(frmHdr)
|
||||
if err != nil {
|
||||
return n + int64(nn), err
|
||||
}
|
||||
n += int64(nn)
|
||||
|
||||
nn, err = ww.Write(frame.Data)
|
||||
return n + int64(nn), err
|
||||
}
|
||||
@ -0,0 +1,230 @@
|
||||
package wal
|
||||
|
||||
import (
|
||||
"bytes"
|
||||
"database/sql"
|
||||
"fmt"
|
||||
"io"
|
||||
"os"
|
||||
"testing"
|
||||
|
||||
_ "github.com/rqlite/go-sqlite3"
|
||||
"github.com/rqlite/rqlite/random"
|
||||
)
|
||||
|
||||
func Test_Writer_FullScanner(t *testing.T) {
|
||||
b, err := os.ReadFile("testdata/wal-reader/ok/wal")
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
|
||||
s, err := NewFullScanner(bytes.NewReader(b))
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
|
||||
// Simply reading every frame and writing it back to a buffer should
|
||||
// result in the same bytes as the original WAL file.
|
||||
var buf bytes.Buffer
|
||||
w, err := NewWriter(s)
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
n, err := w.WriteTo(&buf)
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
if n != int64(len(b)) {
|
||||
t.Fatalf("expected to write %d bytes, wrote %d", len(b), n)
|
||||
}
|
||||
|
||||
if !bytes.Equal(b, buf.Bytes()) {
|
||||
t.Fatal("writer did not write the same bytes as the reader")
|
||||
}
|
||||
}
|
||||
|
||||
func Test_Writer_FullScanner_LargeWAL(t *testing.T) {
|
||||
conn, path := mustCreateWAL(t, 128*1024)
|
||||
defer conn.Close()
|
||||
b, err := os.ReadFile(path)
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
t.Log("WAL size:", len(b))
|
||||
|
||||
s, err := NewFullScanner(bytes.NewReader(b))
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
|
||||
// Simply reading every frame and writing it back to a buffer should
|
||||
// result in the same bytes as the original WAL file.
|
||||
var buf bytes.Buffer
|
||||
w, err := NewWriter(s)
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
n, err := w.WriteTo(&buf)
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
if n != int64(len(b)) {
|
||||
t.Fatalf("expected to write %d bytes, wrote %d", len(b), n)
|
||||
}
|
||||
|
||||
if !bytes.Equal(b, buf.Bytes()) {
|
||||
t.Fatal("writer did not write the same bytes as the reader")
|
||||
}
|
||||
}
|
||||
|
||||
// Test_Writer_CompactingScanner tests The CompactingScanner by continuously
|
||||
// using it to copy a WAL file, and using that WAL file to apply changes to a
|
||||
// second database. The second database should be identical to the first in
|
||||
// terms of SQL queries.
|
||||
func Test_Writer_CompactingScanner(t *testing.T) {
|
||||
srcDir := t.TempDir()
|
||||
srcDSN := fmt.Sprintf("file:%s", srcDir+"/src.db?_journal_mode=WAL&_synchronous=OFF")
|
||||
srcDB := srcDir + "/src.db"
|
||||
srcWAL := srcDir + "/src.db-wal"
|
||||
srcConn, err := sql.Open("sqlite3", srcDSN)
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
defer srcConn.Close()
|
||||
mustExec(srcConn, "PRAGMA wal_autocheckpoint=0")
|
||||
|
||||
destDir := t.TempDir()
|
||||
destDSN := fmt.Sprintf("file:%s", destDir+"/dest.db")
|
||||
destDB := destDir + "/dest.db"
|
||||
destWAL := destDir + "/dest.db-wal"
|
||||
|
||||
mustExec(srcConn, "CREATE TABLE foo (id INTEGER PRIMARY KEY, name TEXT)")
|
||||
|
||||
// Copy the src database to the dest database to seed the process.
|
||||
mustCopyFile(destDB, srcDB)
|
||||
|
||||
writeRows := func(db *sql.DB, n int) {
|
||||
// Write 1000 random rows to the src database, this data will appear in the WAL.
|
||||
for i := 0; i < 1000; i++ {
|
||||
mustExec(srcConn, fmt.Sprintf(`INSERT INTO foo (name) VALUES ('%s')`, random.String()))
|
||||
}
|
||||
mustExec(srcConn, "PRAGMA wal_checkpoint(FULL)")
|
||||
}
|
||||
|
||||
copyAndCompactWAL := func(sWAL, dWAL string) {
|
||||
// Copy the src WAL to the dest WAL using the CompactingScanner.
|
||||
srcF, err := os.Open(sWAL)
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
defer srcF.Close()
|
||||
destF, err := os.Create(dWAL)
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
defer destF.Close()
|
||||
s, err := NewCompactingScanner(srcF)
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
w, err := NewWriter(s)
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
_, err = w.WriteTo(destF)
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
}
|
||||
|
||||
checkRowCount := func(dsn string, n int) {
|
||||
db, err := sql.Open("sqlite3", destDSN)
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
defer db.Close()
|
||||
rows, err := db.Query("SELECT COUNT(*) FROM foo")
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
defer rows.Close()
|
||||
var count int
|
||||
for rows.Next() {
|
||||
if err := rows.Scan(&count); err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
}
|
||||
if count != n {
|
||||
t.Fatalf("expected %d rows, got %d", n, count)
|
||||
}
|
||||
}
|
||||
|
||||
writeRows(srcConn, 1000)
|
||||
copyAndCompactWAL(srcWAL, destWAL)
|
||||
checkRowCount(srcDSN, 1000)
|
||||
checkRowCount(destDSN, 1000)
|
||||
|
||||
writeRows(srcConn, 1000)
|
||||
copyAndCompactWAL(srcWAL, destWAL)
|
||||
checkRowCount(srcDSN, 2000)
|
||||
|
||||
checkRowCount(destDSN, 2000)
|
||||
|
||||
writeRows(srcConn, 1000)
|
||||
copyAndCompactWAL(srcWAL, destWAL)
|
||||
checkRowCount(srcDSN, 3000)
|
||||
checkRowCount(destDSN, 3000)
|
||||
}
|
||||
|
||||
func mustExec(db *sql.DB, query string) {
|
||||
if _, err := db.Exec(query); err != nil {
|
||||
panic(err)
|
||||
}
|
||||
}
|
||||
|
||||
func mustCreateWAL(t *testing.T, size int) (*sql.DB, string) {
|
||||
dir := t.TempDir()
|
||||
rwDSN := fmt.Sprintf("file:%s", dir+"/test.db")
|
||||
rwDB, err := sql.Open("sqlite3", rwDSN)
|
||||
if err != nil {
|
||||
panic(err)
|
||||
}
|
||||
|
||||
mustExec(rwDB, "PRAGMA journal_mode=WAL")
|
||||
mustExec(rwDB, "PRAGMA wal_autocheckpoint=0")
|
||||
mustExec(rwDB, "PRAGMA synchronous=OFF")
|
||||
mustExec(rwDB, "CREATE TABLE test (id INTEGER PRIMARY KEY, name TEXT)")
|
||||
for {
|
||||
for i := 0; i < 10; i++ {
|
||||
mustExec(rwDB, "INSERT INTO test (name) VALUES ('name')")
|
||||
}
|
||||
// break if dir+test.db-wal is bigger than size
|
||||
if fi, err := os.Stat(dir + "/test.db-wal"); err != nil {
|
||||
continue
|
||||
} else {
|
||||
if fi.Size() >= int64(size) {
|
||||
break
|
||||
}
|
||||
}
|
||||
}
|
||||
return rwDB, dir + "/test.db-wal"
|
||||
}
|
||||
|
||||
func mustCopyFile(dst, src string) {
|
||||
srcF, err := os.Open(src)
|
||||
if err != nil {
|
||||
panic(err)
|
||||
}
|
||||
defer srcF.Close()
|
||||
|
||||
dstF, err := os.Create(dst)
|
||||
if err != nil {
|
||||
panic(err)
|
||||
}
|
||||
defer dstF.Close()
|
||||
|
||||
_, err = io.Copy(dstF, srcF)
|
||||
if err != nil {
|
||||
panic(err)
|
||||
}
|
||||
}
|
||||
Loading…
Reference in New Issue