/
bootstrap.go
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/
bootstrap.go
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/*
Copyright 2022 The Numaproj Authors.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package wal
import (
"encoding/binary"
"errors"
"fmt"
"io"
"os"
"time"
"github.com/numaproj/numaflow/pkg/isb"
"github.com/numaproj/numaflow/pkg/reduce/pbq/partition"
)
var location *time.Location
func init() {
var err error
location, err = time.LoadLocation("UTC")
if err != nil {
panic(fmt.Sprint("cannot load UTC", err))
}
}
// IsCorrupted checks whether the file is corrupt
func (w *WAL) IsCorrupted() bool {
return w.corrupted
}
func (w *WAL) readWALHeader() (*partition.ID, error) {
if w.openMode == os.O_WRONLY {
return nil, fmt.Errorf("opened using O_WRONLY")
}
if w.rOffset > 0 {
return nil, fmt.Errorf("header has already been read, current readoffset is at %d", w.rOffset)
}
id, err := decodeWALHeader(w.fp)
if err != nil {
return nil, err
}
seek, err := w.fp.Seek(0, io.SeekCurrent)
if err != nil {
return nil, err
}
w.rOffset += seek
return id, err
}
func (w *WAL) isEnd() bool {
// TODO: If we are done reading, check that we got the expected
// number of entries and return EOF.
return w.rOffset >= w.readUpTo
}
// decodeWALHeader decodes the header which is encoded by encodeWALHeader.
func decodeWALHeader(buf io.Reader) (*partition.ID, error) {
var err error
// read the fixed vals
var hp = new(walHeaderPreamble)
err = binary.Read(buf, binary.LittleEndian, hp)
if err != nil {
return nil, err
}
// read the variadic key
var key = make([]rune, hp.SLen)
err = binary.Read(buf, binary.LittleEndian, key)
if err != nil {
return nil, err
}
return &partition.ID{
Start: time.UnixMilli(hp.S).In(location),
End: time.UnixMilli(hp.E).In(location),
Slot: string(key),
}, nil
}
func (w *WAL) Read(size int64) ([]*isb.ReadMessage, bool, error) {
if w.openMode == os.O_WRONLY {
return nil, false, fmt.Errorf("opened using O_WRONLY")
}
if w.rOffset < w.wOffset {
return nil, false, fmt.Errorf("read can only happen at startup not after any new writes")
}
messages := make([]*isb.ReadMessage, 0)
// if size is greater than the number of messages in the store
// we will assign size with the number of messages in the store
start := w.rOffset
for size > w.rOffset-start && !w.isEnd() {
message, sizeRead, err := decodeReadMessage(w.fp)
if err != nil {
if errors.Is(err, errChecksumMismatch) {
w.corrupted = true
}
return nil, false, err
}
w.rOffset += sizeRead
messages = append(messages, message)
}
currentTime := time.Now()
if w.isEnd() {
w.wOffset = w.rOffset
w.prevSyncedWOffset = w.wOffset
w.prevSyncedTime = currentTime
w.numOfUnsyncedMsgs = 0
return messages, true, nil
}
return messages, false, nil
}
// decodeReadMessage decodes the WALMessage which is encoded by encodeWALMessage.
func decodeReadMessage(buf io.Reader) (*isb.ReadMessage, int64, error) {
entryHeader, err := decodeWALMessageHeader(buf)
if err != nil {
return nil, 0, err
}
entryBody, err := decodeWALBody(buf, entryHeader)
if err != nil {
return nil, 0, err
}
size := EntryHeaderSize + entryHeader.MessageLen
return &isb.ReadMessage{
Message: *entryBody,
Watermark: time.UnixMilli(entryHeader.WaterMark).In(location),
ReadOffset: isb.SimpleIntOffset(func() int64 { return entryHeader.Offset }),
}, size, nil
}
// decodeWALMessageHeader decodes the WALMessage header which is encoded by encodeWALMessageHeader.
func decodeWALMessageHeader(buf io.Reader) (*readMessageHeaderPreamble, error) {
// read the fixed vals
var entryHeader = new(readMessageHeaderPreamble)
err := binary.Read(buf, binary.LittleEndian, entryHeader)
if err != nil {
return nil, err
}
return entryHeader, nil
}
// decodeWALBody decodes the WALMessage body which is encoded by encodeWALMessageBody.
// Returns errChecksumMismatch to indicate if corrupted entry is found.
func decodeWALBody(buf io.Reader, entryHeader *readMessageHeaderPreamble) (*isb.Message, error) {
var err error
body := make([]byte, entryHeader.MessageLen)
size, err := buf.Read(body)
if err != nil {
return nil, err
}
if int64(size) != entryHeader.MessageLen {
return nil, fmt.Errorf("expected to read length of %d, but wrote only %d", entryHeader.MessageLen, size)
}
// verify the checksum
checksum := calculateChecksum(body)
if checksum != entryHeader.Checksum {
return nil, errChecksumMismatch
}
var message = new(isb.Message)
err = message.UnmarshalBinary(body)
if err != nil {
return nil, err
}
return message, nil
}