forked from hyperledger/fabric
/
leveldb_provider.go
230 lines (195 loc) · 6.21 KB
/
leveldb_provider.go
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/*
Copyright IBM Corp. All Rights Reserved.
SPDX-License-Identifier: Apache-2.0
*/
package leveldbhelper
import (
"bytes"
"fmt"
"sync"
"github.com/hyperledger/fabric/common/ledger/dataformat"
"github.com/syndtr/goleveldb/leveldb"
"github.com/syndtr/goleveldb/leveldb/iterator"
)
// internalDBName is used to keep track of data related to internals such as data format
// _ is used as name because this is not allowed as a channelname
const internalDBName = "_"
var (
dbNameKeySep = []byte{0x00}
lastKeyIndicator = byte(0x01)
formatVersionKey = []byte{'f'} // a single key in db whose value indicates the version of the data format
)
// Conf configuration for `Provider`
//
// `ExpectedFormatVersion` is the expected value of the format key in the internal database.
// At the time of opening the db, A check is performed that
// either the db is empty (i.e., opening for the first time) or the value
// of the formatVersionKey is equal to `ExpectedFormatVersion`. Otherwise, an error is returned.
// A nil value for ExpectedFormatVersion indicates that the format is never set and hence there is no such record
type Conf struct {
DBPath string
ExpectedFormatVersion string
}
// Provider enables to use a single leveldb as multiple logical leveldbs
type Provider struct {
db *DB
mux sync.Mutex
dbHandles map[string]*DBHandle
}
// NewProvider constructs a Provider
func NewProvider(conf *Conf) (*Provider, error) {
db, err := openDBAndCheckFormat(conf)
if err != nil {
return nil, err
}
return &Provider{
db: db,
dbHandles: make(map[string]*DBHandle),
}, nil
}
func openDBAndCheckFormat(conf *Conf) (d *DB, e error) {
db := CreateDB(conf)
db.Open()
defer func() {
if e != nil {
db.Close()
}
}()
internalDB := &DBHandle{
db: db,
dbName: internalDBName,
}
dbEmpty, err := db.IsEmpty()
if err != nil {
return nil, err
}
if dbEmpty && conf.ExpectedFormatVersion != "" {
logger.Infof("DB is empty Setting db format as %s", conf.ExpectedFormatVersion)
if err := internalDB.Put(formatVersionKey, []byte(conf.ExpectedFormatVersion), true); err != nil {
return nil, err
}
return db, nil
}
formatVersion, err := internalDB.Get(formatVersionKey)
if err != nil {
return nil, err
}
logger.Debugf("Checking for db format at path [%s]", conf.DBPath)
if !bytes.Equal(formatVersion, []byte(conf.ExpectedFormatVersion)) {
logger.Errorf("The db at path [%s] contains data in unexpected format. expected data format = [%s] (%#v), data format = [%s] (%#v).",
conf.DBPath, conf.ExpectedFormatVersion, []byte(conf.ExpectedFormatVersion), formatVersion, formatVersion)
return nil, &dataformat.ErrVersionMismatch{
ExpectedVersion: conf.ExpectedFormatVersion,
Version: string(formatVersion),
DBInfo: fmt.Sprintf("leveldb at [%s]", conf.DBPath),
}
}
logger.Debug("format is latest, nothing to do")
return db, nil
}
// GetDataFormat returns the format of the data
func (p *Provider) GetDataFormat() (string, error) {
f, err := p.GetDBHandle(internalDBName).Get(formatVersionKey)
return string(f), err
}
// GetDBHandle returns a handle to a named db
func (p *Provider) GetDBHandle(dbName string) *DBHandle {
p.mux.Lock()
defer p.mux.Unlock()
dbHandle := p.dbHandles[dbName]
if dbHandle == nil {
dbHandle = &DBHandle{dbName, p.db}
p.dbHandles[dbName] = dbHandle
}
return dbHandle
}
// Close closes the underlying leveldb
func (p *Provider) Close() {
p.db.Close()
}
// DBHandle is an handle to a named db
type DBHandle struct {
dbName string
db *DB
}
// Get returns the value for the given key
func (h *DBHandle) Get(key []byte) ([]byte, error) {
return h.db.Get(constructLevelKey(h.dbName, key))
}
// Put saves the key/value
func (h *DBHandle) Put(key []byte, value []byte, sync bool) error {
return h.db.Put(constructLevelKey(h.dbName, key), value, sync)
}
// Delete deletes the given key
func (h *DBHandle) Delete(key []byte, sync bool) error {
return h.db.Delete(constructLevelKey(h.dbName, key), sync)
}
// WriteBatch writes a batch in an atomic way
func (h *DBHandle) WriteBatch(batch *UpdateBatch, sync bool) error {
if len(batch.KVs) == 0 {
return nil
}
levelBatch := &leveldb.Batch{}
for k, v := range batch.KVs {
key := constructLevelKey(h.dbName, []byte(k))
if v == nil {
levelBatch.Delete(key)
} else {
levelBatch.Put(key, v)
}
}
if err := h.db.WriteBatch(levelBatch, sync); err != nil {
return err
}
return nil
}
// GetIterator gets an handle to iterator. The iterator should be released after the use.
// The resultset contains all the keys that are present in the db between the startKey (inclusive) and the endKey (exclusive).
// A nil startKey represents the first available key and a nil endKey represent a logical key after the last available key
func (h *DBHandle) GetIterator(startKey []byte, endKey []byte) *Iterator {
sKey := constructLevelKey(h.dbName, startKey)
eKey := constructLevelKey(h.dbName, endKey)
if endKey == nil {
// replace the last byte 'dbNameKeySep' by 'lastKeyIndicator'
eKey[len(eKey)-1] = lastKeyIndicator
}
logger.Debugf("Getting iterator for range [%#v] - [%#v]", sKey, eKey)
return &Iterator{h.db.GetIterator(sKey, eKey)}
}
// UpdateBatch encloses the details of multiple `updates`
type UpdateBatch struct {
KVs map[string][]byte
}
// NewUpdateBatch constructs an instance of a Batch
func NewUpdateBatch() *UpdateBatch {
return &UpdateBatch{make(map[string][]byte)}
}
// Put adds a KV
func (batch *UpdateBatch) Put(key []byte, value []byte) {
if value == nil {
panic("Nil value not allowed")
}
batch.KVs[string(key)] = value
}
// Delete deletes a Key and associated value
func (batch *UpdateBatch) Delete(key []byte) {
batch.KVs[string(key)] = nil
}
// Len returns the number of entries in the batch
func (batch *UpdateBatch) Len() int {
return len(batch.KVs)
}
// Iterator extends actual leveldb iterator
type Iterator struct {
iterator.Iterator
}
// Key wraps actual leveldb iterator method
func (itr *Iterator) Key() []byte {
return retrieveAppKey(itr.Iterator.Key())
}
func constructLevelKey(dbName string, key []byte) []byte {
return append(append([]byte(dbName), dbNameKeySep...), key...)
}
func retrieveAppKey(levelKey []byte) []byte {
return bytes.SplitN(levelKey, dbNameKeySep, 2)[1]
}