package consensus import ( "encoding/binary" "fmt" "hash/crc32" "io" "path/filepath" "time" "github.com/pkg/errors" amino "github.com/tendermint/go-amino" auto "github.com/tendermint/tendermint/libs/autofile" cmn "github.com/tendermint/tendermint/libs/common" "github.com/tendermint/tendermint/libs/log" "github.com/tendermint/tendermint/types" tmtime "github.com/tendermint/tendermint/types/time" ) const ( // amino overhead + time.Time + max consensus msg size // TODO: Can we clarify better where 24 comes from precisely? maxMsgSizeBytes = maxMsgSize + 24 // how often the WAL should be sync'd during period sync'ing walDefaultFlushInterval = 2 * time.Second ) //-------------------------------------------------------- // types and functions for savings consensus messages // TimedWALMessage wraps WALMessage and adds Time for debugging purposes. type TimedWALMessage struct { Time time.Time `json:"time"` Msg WALMessage `json:"msg"` } // EndHeightMessage marks the end of the given height inside WAL. // @internal used by scripts/wal2json util. type EndHeightMessage struct { Height int64 `json:"height"` } type WALMessage interface{} func RegisterWALMessages(cdc *amino.Codec) { cdc.RegisterInterface((*WALMessage)(nil), nil) cdc.RegisterConcrete(types.EventDataRoundState{}, "tendermint/wal/EventDataRoundState", nil) cdc.RegisterConcrete(msgInfo{}, "tendermint/wal/MsgInfo", nil) cdc.RegisterConcrete(timeoutInfo{}, "tendermint/wal/TimeoutInfo", nil) cdc.RegisterConcrete(EndHeightMessage{}, "tendermint/wal/EndHeightMessage", nil) } //-------------------------------------------------------- // Simple write-ahead logger // WAL is an interface for any write-ahead logger. type WAL interface { Write(WALMessage) error WriteSync(WALMessage) error FlushAndSync() error SearchForEndHeight(height int64, options *WALSearchOptions) (rd io.ReadCloser, found bool, err error) // service methods 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 enc *WALEncoder flushTicker *time.Ticker flushInterval time.Duration } var _ WAL = &baseWAL{} // NewWAL returns a new write-ahead logger based on `baseWAL`, which implements // WAL. It's flushed and synced to disk every 2s and once when stopped. func NewWAL(walFile string, groupOptions ...func(*auto.Group)) (*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, groupOptions...) if err != nil { return nil, err } wal := &baseWAL{ group: group, enc: NewWALEncoder(group), flushInterval: walDefaultFlushInterval, } wal.BaseService = *cmn.NewBaseService(nil, "baseWAL", wal) return wal, nil } // SetFlushInterval allows us to override the periodic flush interval for the WAL. func (wal *baseWAL) SetFlushInterval(i time.Duration) { wal.flushInterval = i } func (wal *baseWAL) Group() *auto.Group { return wal.group } func (wal *baseWAL) SetLogger(l log.Logger) { wal.BaseService.Logger = l wal.group.SetLogger(l) } func (wal *baseWAL) OnStart() error { size, err := wal.group.Head.Size() if err != nil { return err } else if size == 0 { wal.WriteSync(EndHeightMessage{0}) } err = wal.group.Start() if err != nil { return err } wal.flushTicker = time.NewTicker(wal.flushInterval) go wal.processFlushTicks() return nil } func (wal *baseWAL) processFlushTicks() { for { select { case <-wal.flushTicker.C: if err := wal.FlushAndSync(); err != nil { wal.Logger.Error("Periodic WAL flush failed", "err", err) } case <-wal.Quit(): return } } } // FlushAndSync flushes and fsync's the underlying group's data to disk. // See auto#FlushAndSync func (wal *baseWAL) FlushAndSync() error { return wal.group.FlushAndSync() } // Stop the underlying autofile group. // Use Wait() to ensure it's finished shutting down // before cleaning up files. func (wal *baseWAL) OnStop() { wal.flushTicker.Stop() wal.FlushAndSync() wal.group.Stop() wal.group.Close() } // Wait for the underlying autofile group to finish shutting down // so it's safe to cleanup files. func (wal *baseWAL) Wait() { wal.group.Wait() } // Write is called in newStep and for each receive on the // peerMsgQueue and the timeoutTicker. // NOTE: does not call fsync() func (wal *baseWAL) Write(msg WALMessage) error { if wal == nil { return nil } if err := wal.enc.Encode(&TimedWALMessage{tmtime.Now(), msg}); err != nil { wal.Logger.Error("Error writing msg to consensus wal. WARNING: recover may not be possible for the current height", "err", err, "msg", msg) return err } return nil } // WriteSync is called when we receive a msg from ourselves // so that we write to disk before sending signed messages. // NOTE: calls fsync() func (wal *baseWAL) WriteSync(msg WALMessage) error { if wal == nil { return nil } if err := wal.Write(msg); err != nil { return err } if err := wal.FlushAndSync(); err != nil { wal.Logger.Error("WriteSync failed to flush consensus wal. WARNING: may result in creating alternative proposals / votes for the current height iff the node restarted", "err", err) return err } return nil } // WALSearchOptions are optional arguments to SearchForEndHeight. type WALSearchOptions struct { // IgnoreDataCorruptionErrors set to true will result in skipping data corruption errors. IgnoreDataCorruptionErrors bool } // SearchForEndHeight searches for the EndHeightMessage with the given 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, options *WALSearchOptions) (rd io.ReadCloser, found bool, err error) { var ( msg *TimedWALMessage gr *auto.GroupReader ) lastHeightFound := int64(-1) // 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.Info("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 { // OPTIMISATION: no need to look for height in older files if we've seen h < height if lastHeightFound > 0 && lastHeightFound < height { gr.Close() return nil, false, nil } // check next file break } if options.IgnoreDataCorruptionErrors && IsDataCorruptionError(err) { wal.Logger.Error("Corrupted entry. Skipping...", "err", err) // do nothing continue } else if err != nil { gr.Close() return nil, false, err } if m, ok := msg.Msg.(EndHeightMessage); ok { lastHeightFound = m.Height if m.Height == height { // found wal.Logger.Info("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-amino 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. It returns an error if // the amino-encoded size of v is greater than 1MB. Any error encountered // during the write is also returned. func (enc *WALEncoder) Encode(v *TimedWALMessage) error { data := cdc.MustMarshalBinaryBare(v) crc := crc32.Checksum(data, crc32c) length := uint32(len(data)) if length > maxMsgSizeBytes { return fmt.Errorf("msg is too big: %d bytes, max: %d bytes", length, maxMsgSizeBytes) } 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) return err } /////////////////////////////////////////////////////////////////////////////// // IsDataCorruptionError returns true if data has been corrupted inside WAL. func IsDataCorruptionError(err error) bool { _, ok := err.(DataCorruptionError) return ok } // DataCorruptionError is an error that occures if data on disk was corrupted. type DataCorruptionError struct { cause error } func (e DataCorruptionError) Error() string { return fmt.Sprintf("DataCorruptionError[%v]", e.cause) } func (e DataCorruptionError) Cause() error { return e.cause } // 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) _, err := dec.rd.Read(b) if err == io.EOF { return nil, err } if err != nil { return nil, DataCorruptionError{fmt.Errorf("failed to read checksum: %v", err)} } crc := binary.BigEndian.Uint32(b) b = make([]byte, 4) _, err = dec.rd.Read(b) if err != nil { return nil, DataCorruptionError{fmt.Errorf("failed to read length: %v", err)} } length := binary.BigEndian.Uint32(b) if length > maxMsgSizeBytes { return nil, DataCorruptionError{fmt.Errorf( "length %d exceeded maximum possible value of %d bytes", length, maxMsgSizeBytes)} } data := make([]byte, length) n, err := dec.rd.Read(data) if err != nil { return nil, DataCorruptionError{fmt.Errorf("failed to read data: %v (read: %d, wanted: %d)", err, n, length)} } // check checksum before decoding data actualCRC := crc32.Checksum(data, crc32c) if actualCRC != crc { return nil, DataCorruptionError{fmt.Errorf("checksums do not match: read: %v, actual: %v", crc, actualCRC)} } var res = new(TimedWALMessage) // nolint: gosimple err = cdc.UnmarshalBinaryBare(data, res) if err != nil { return nil, DataCorruptionError{fmt.Errorf("failed to decode data: %v", err)} } return res, err } type nilWAL struct{} var _ WAL = nilWAL{} func (nilWAL) Write(m WALMessage) error { return nil } func (nilWAL) WriteSync(m WALMessage) error { return nil } func (nilWAL) FlushAndSync() error { return nil } func (nilWAL) SearchForEndHeight(height int64, options *WALSearchOptions) (rd io.ReadCloser, found bool, err error) { return nil, false, nil } func (nilWAL) Start() error { return nil } func (nilWAL) Stop() error { return nil } func (nilWAL) Wait() {}