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raft_store.go
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/
raft_store.go
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package gossipCluster
import (
"bytes"
"encoding/binary"
"github.com/dgraph-io/badger/v3"
"github.com/hashicorp/go-msgpack/codec"
"github.com/hashicorp/raft"
"github.com/pkg/errors"
"github.com/ronaksoft/rony/store"
)
/*
Creation Time: 2021 - Feb - 10
Created by: (ehsan)
Maintainers:
1. Ehsan N. Moosa (E2)
Auditor: Ehsan N. Moosa (E2)
Copyright Ronak Software Group 2020
*/
var (
// Prefix names to distinguish between logs and conf
prefixLogs = []byte{0x0}
prefixConf = []byte{0x1}
// ErrKeyNotFound is an error indicating a given key does not exist
ErrKeyNotFound = errors.New("not found")
)
// BadgerStore provides access to Badger for Raft to store and retrieve
// log entries. It also provides key/value storage, and can be used as
// a LogStore and StableStore.
type BadgerStore struct{}
// FirstIndex returns the first known index from the Raft log.
func (b *BadgerStore) FirstIndex() (uint64, error) {
var value uint64
err := store.View(func(txn *badger.Txn) error {
it := txn.NewIterator(badger.IteratorOptions{
PrefetchValues: false,
Reverse: false,
})
defer it.Close()
it.Seek(prefixLogs)
if it.ValidForPrefix(prefixLogs) {
value = bytesToUint64(it.Item().Key()[1:])
}
return nil
})
if err != nil {
return 0, err
}
return value, nil
}
// LastIndex returns the last known index from the Raft log.
func (b *BadgerStore) LastIndex() (uint64, error) {
var value uint64
err := store.View(func(txn *badger.Txn) error {
it := txn.NewIterator(badger.IteratorOptions{
PrefetchValues: false,
Reverse: true,
})
defer it.Close()
it.Seek(append(prefixLogs, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff))
if it.ValidForPrefix(prefixLogs) {
value = bytesToUint64(it.Item().Key()[1:])
}
return nil
})
if err != nil {
return 0, err
}
return value, nil
}
// GetLog gets a log entry from Badger at a given index.
func (b *BadgerStore) GetLog(index uint64, log *raft.Log) error {
return store.View(func(txn *badger.Txn) error {
item, err := txn.Get(append(prefixLogs, uint64ToBytes(index)...))
if err != nil {
switch err {
case badger.ErrKeyNotFound:
return raft.ErrLogNotFound
default:
return err
}
}
val, err := item.ValueCopy(nil)
if err != nil {
return err
}
return decodeMsgPack(val, log)
})
}
// StoreLog stores a single raft log.
func (b *BadgerStore) StoreLog(log *raft.Log) error {
val, err := encodeMsgPack(log)
if err != nil {
return err
}
return store.Update(func(txn *badger.Txn) error {
return txn.Set(append(prefixLogs, uint64ToBytes(log.Index)...), val.Bytes())
})
}
// StoreLogs stores a set of raft logs.
func (b *BadgerStore) StoreLogs(logs []*raft.Log) error {
return store.Update(func(txn *badger.Txn) error {
for _, log := range logs {
key := append(prefixLogs, uint64ToBytes(log.Index)...)
val, err := encodeMsgPack(log)
if err != nil {
return err
}
if err := txn.Set(key, val.Bytes()); err != nil {
return err
}
}
return nil
})
}
// DeleteRange deletes logs within a given range inclusively.
func (b *BadgerStore) DeleteRange(min, max uint64) error {
// we manage the transaction manually in order to avoid ErrTxnTooBig errors
txn := store.DB().NewTransaction(true)
it := txn.NewIterator(badger.IteratorOptions{
PrefetchValues: false,
Reverse: false,
})
start := append(prefixLogs, uint64ToBytes(min)...)
for it.Seek(start); it.Valid(); it.Next() {
key := make([]byte, 16)
it.Item().KeyCopy(key)
// Handle out-of-range log index
if bytesToUint64(key[8:]) > max {
break
}
// Delete in-range log index
if err := txn.Delete(key); err != nil {
if err == badger.ErrTxnTooBig {
it.Close()
err = txn.Commit()
if err != nil {
return err
}
return b.DeleteRange(bytesToUint64(key[1:]), max)
}
return err
}
}
it.Close()
err := txn.Commit()
if err != nil {
return err
}
return nil
}
// Set is used to set a key/value set outside of the raft log.
func (b *BadgerStore) Set(key []byte, val []byte) error {
return store.Update(func(txn *badger.Txn) error {
return txn.Set(append(prefixConf, key...), val)
})
}
// Get is used to retrieve a value from the k/v store by key
func (b *BadgerStore) Get(key []byte) ([]byte, error) {
var value []byte
err := store.View(func(txn *badger.Txn) error {
item, err := txn.Get(append(prefixConf, key...))
if err != nil {
switch err {
case badger.ErrKeyNotFound:
return ErrKeyNotFound
default:
return err
}
}
value, err = item.ValueCopy(value)
if err != nil {
return err
}
return nil
})
if err != nil {
return nil, err
}
return value, nil
}
// SetUint64 is like Set, but handles uint64 values
func (b *BadgerStore) SetUint64(key []byte, val uint64) error {
return b.Set(key, uint64ToBytes(val))
}
// GetUint64 is like Get, but handles uint64 values
func (b *BadgerStore) GetUint64(key []byte) (uint64, error) {
val, err := b.Get(key)
if err != nil {
return 0, err
}
return bytesToUint64(val), nil
}
// Decode reverses the encode operation on a byte slice input
func decodeMsgPack(buf []byte, out interface{}) error {
r := bytes.NewBuffer(buf)
hd := codec.MsgpackHandle{}
dec := codec.NewDecoder(r, &hd)
return dec.Decode(out)
}
// Encode writes an encoded object to a new bytes buffer
func encodeMsgPack(in interface{}) (*bytes.Buffer, error) {
buf := bytes.NewBuffer(nil)
hd := codec.MsgpackHandle{}
enc := codec.NewEncoder(buf, &hd)
err := enc.Encode(in)
return buf, err
}
// Converts bytes to an integer
func bytesToUint64(b []byte) uint64 {
return binary.BigEndian.Uint64(b)
}
// Converts a uint to a byte slice
func uint64ToBytes(u uint64) []byte {
buf := make([]byte, 8)
binary.BigEndian.PutUint64(buf, u)
return buf
}