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package consensus
import (
"bytes"
"encoding/binary"
"fmt"
"hash/crc32"
"io"
"path/filepath"
"time"
"github.com/pkg/errors"
wire "github.com/tendermint/go-wire"
"github.com/tendermint/tendermint/types"
auto "github.com/tendermint/tmlibs/autofile"
cmn "github.com/tendermint/tmlibs/common"
)
//--------------------------------------------------------
// types and functions for savings consensus messages
var (
walSeparator = []byte{55, 127, 6, 130} // 0x377f0682 - magic number
)
type TimedWALMessage struct {
Time time.Time `json:"time"` // for debugging purposes
Msg WALMessage `json:"msg"`
}
// EndHeightMessage marks the end of the given height inside WAL.
// @internal used by scripts/cutWALUntil util.
type EndHeightMessage struct {
Height int64 `json:"height"`
}
type WALMessage interface{}
var _ = wire.RegisterInterface(
struct{ WALMessage }{},
wire.ConcreteType{types.EventDataRoundState{}, 0x01},
wire.ConcreteType{msgInfo{}, 0x02},
wire.ConcreteType{timeoutInfo{}, 0x03},
wire.ConcreteType{EndHeightMessage{}, 0x04},
)
//--------------------------------------------------------
// Simple write-ahead logger
// WAL is an interface for any write-ahead logger.
type WAL interface {
Save(WALMessage)
Group() *auto.Group
SearchForEndHeight(height int64) (gr *auto.GroupReader, found bool, err error)
Start() error
Stop() error
Wait()
}
// Write ahead logger writes msgs to disk before they are processed.
// Can be used for crash-recovery and deterministic replay
// TODO: currently the wal is overwritten during replay catchup
// give it a mode so it's either reading or appending - must read to end to start appending again
type baseWAL struct {
cmn.BaseService
group *auto.Group
light bool // ignore block parts
enc *WALEncoder
}
func NewWAL(walFile string, light bool) (*baseWAL, error) {
err := cmn.EnsureDir(filepath.Dir(walFile), 0700)
if err != nil {
return nil, errors.Wrap(err, "failed to ensure WAL directory is in place")
}
group, err := auto.OpenGroup(walFile)
if err != nil {
return nil, err
}
wal := &baseWAL{
group: group,
light: light,
enc: NewWALEncoder(group),
}
wal.BaseService = *cmn.NewBaseService(nil, "baseWAL", wal)
return wal, nil
}
func (wal *baseWAL) Group() *auto.Group {
return wal.group
}
func (wal *baseWAL) OnStart() error {
size, err := wal.group.Head.Size()
if err != nil {
return err
} else if size == 0 {
wal.Save(EndHeightMessage{0})
}
err = wal.group.Start()
return err
}
func (wal *baseWAL) OnStop() {
wal.BaseService.OnStop()
wal.group.Stop()
}
// called in newStep and for each pass in receiveRoutine
func (wal *baseWAL) Save(msg WALMessage) {
if wal == nil {
return
}
if wal.light {
// in light mode we only write new steps, timeouts, and our own votes (no proposals, block parts)
if mi, ok := msg.(msgInfo); ok {
if mi.PeerKey != "" {
return
}
}
}
// Write the wal message
if err := wal.enc.Encode(&TimedWALMessage{time.Now(), msg}); err != nil {
cmn.PanicQ(cmn.Fmt("Error writing msg to consensus wal: %v \n\nMessage: %v", err, msg))
}
// TODO: only flush when necessary
if err := wal.group.Flush(); err != nil {
cmn.PanicQ(cmn.Fmt("Error flushing consensus wal buf to file. Error: %v \n", err))
}
}
// SearchForEndHeight searches for the EndHeightMessage with the height and
// returns an auto.GroupReader, whenever it was found or not and an error.
// Group reader will be nil if found equals false.
//
// CONTRACT: caller must close group reader.
func (wal *baseWAL) SearchForEndHeight(height int64) (gr *auto.GroupReader, found bool, err error) {
var msg *TimedWALMessage
// NOTE: starting from the last file in the group because we're usually
// searching for the last height. See replay.go
min, max := wal.group.MinIndex(), wal.group.MaxIndex()
wal.Logger.Debug("Searching for height", "height", height, "min", min, "max", max)
for index := max; index >= min; index-- {
gr, err = wal.group.NewReader(index)
if err != nil {
return nil, false, err
}
dec := NewWALDecoder(gr)
for {
msg, err = dec.Decode()
if err == io.EOF {
// check next file
break
}
if err != nil {
gr.Close()
return nil, false, err
}
if m, ok := msg.Msg.(EndHeightMessage); ok {
if m.Height == height { // found
wal.Logger.Debug("Found", "height", height, "index", index)
return gr, true, nil
}
}
}
gr.Close()
}
return nil, false, nil
}
///////////////////////////////////////////////////////////////////////////////
// A WALEncoder writes custom-encoded WAL messages to an output stream.
//
// Format: 4 bytes CRC sum + 4 bytes length + arbitrary-length value (go-wire encoded)
type WALEncoder struct {
wr io.Writer
}
// NewWALEncoder returns a new encoder that writes to wr.
func NewWALEncoder(wr io.Writer) *WALEncoder {
return &WALEncoder{wr}
}
// Encode writes the custom encoding of v to the stream.
func (enc *WALEncoder) Encode(v interface{}) error {
data := wire.BinaryBytes(v)
crc := crc32.Checksum(data, crc32c)
length := uint32(len(data))
totalLength := 8 + int(length)
msg := make([]byte, totalLength)
binary.BigEndian.PutUint32(msg[0:4], crc)
binary.BigEndian.PutUint32(msg[4:8], length)
copy(msg[8:], data)
_, err := enc.wr.Write(msg)
if err == nil {
// TODO [Anton Kaliaev 23 Oct 2017]: remove separator
_, err = enc.wr.Write(walSeparator)
}
return err
}
///////////////////////////////////////////////////////////////////////////////
// A WALDecoder reads and decodes custom-encoded WAL messages from an input
// stream. See WALEncoder for the format used.
//
// It will also compare the checksums and make sure data size is equal to the
// length from the header. If that is not the case, error will be returned.
type WALDecoder struct {
rd io.Reader
}
// NewWALDecoder returns a new decoder that reads from rd.
func NewWALDecoder(rd io.Reader) *WALDecoder {
return &WALDecoder{rd}
}
// Decode reads the next custom-encoded value from its reader and returns it.
func (dec *WALDecoder) Decode() (*TimedWALMessage, error) {
b := make([]byte, 4)
n, err := dec.rd.Read(b)
if err == io.EOF {
return nil, err
}
if err != nil {
return nil, fmt.Errorf("failed to read checksum: %v", err)
}
crc := binary.BigEndian.Uint32(b)
b = make([]byte, 4)
n, err = dec.rd.Read(b)
if err == io.EOF {
return nil, err
}
if err != nil {
return nil, fmt.Errorf("failed to read length: %v", err)
}
length := binary.BigEndian.Uint32(b)
data := make([]byte, length)
n, err = dec.rd.Read(data)
if err == io.EOF {
return nil, err
}
if err != nil {
return nil, fmt.Errorf("not enough bytes for data: %v (want: %d, read: %v)", err, length, n)
}
// check checksum before decoding data
actualCRC := crc32.Checksum(data, crc32c)
if actualCRC != crc {
return nil, fmt.Errorf("checksums do not match: (read: %v, actual: %v)", crc, actualCRC)
}
var nn int
var res *TimedWALMessage // nolint: gosimple
res = wire.ReadBinary(&TimedWALMessage{}, bytes.NewBuffer(data), int(length), &nn, &err).(*TimedWALMessage)
if err != nil {
return nil, fmt.Errorf("failed to decode data: %v", err)
}
// TODO [Anton Kaliaev 23 Oct 2017]: remove separator
if err = readSeparator(dec.rd); err != nil {
return nil, err
}
return res, err
}
// readSeparator reads a separator from r. It returns any error from underlying
// reader or if it's not a separator.
func readSeparator(r io.Reader) error {
b := make([]byte, len(walSeparator))
_, err := r.Read(b)
if err != nil {
return fmt.Errorf("failed to read separator: %v", err)
}
if !bytes.Equal(b, walSeparator) {
return fmt.Errorf("not a separator: %v", b)
}
return nil
}
type nilWAL struct{}
func (nilWAL) Save(m WALMessage) {}
func (nilWAL) Group() *auto.Group { return nil }
func (nilWAL) SearchForEndHeight(height int64) (gr *auto.GroupReader, found bool, err error) {
return nil, false, nil
}
func (nilWAL) Start() error { return nil }
func (nilWAL) Stop() error { return nil }
func (nilWAL) Wait() {}