/
db.go
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/
db.go
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// (c) 2019-2020, Ava Labs, Inc. All rights reserved.
// See the file LICENSE for licensing terms.
package leveldb
import (
"bytes"
"github.com/ava-labs/gecko/database"
"github.com/syndtr/goleveldb/leveldb"
"github.com/syndtr/goleveldb/leveldb/errors"
"github.com/syndtr/goleveldb/leveldb/filter"
"github.com/syndtr/goleveldb/leveldb/iterator"
"github.com/syndtr/goleveldb/leveldb/opt"
"github.com/syndtr/goleveldb/leveldb/util"
)
const (
// minBlockCacheSize is the minimum number of bytes to use for block caching
// in leveldb.
minBlockCacheSize = 8 * opt.MiB
// minWriteBufferSize is the minimum number of bytes to use for buffers in
// leveldb.
minWriteBufferSize = 8 * opt.MiB
// minHandleCap is the minimum number of files descriptors to cap levelDB to
// use
minHandleCap = 16
)
// Database is a persistent key-value store. Apart from basic data storage
// functionality it also supports batch writes and iterating over the keyspace
// in binary-alphabetical order.
type Database struct{ *leveldb.DB }
// New returns a wrapped LevelDB object.
func New(file string, blockCacheSize, writeBufferSize, handleCap int) (*Database, error) {
// Enforce minimums
if blockCacheSize < minBlockCacheSize {
blockCacheSize = minBlockCacheSize
}
if writeBufferSize < minWriteBufferSize {
writeBufferSize = minWriteBufferSize
}
if handleCap < minHandleCap {
handleCap = minHandleCap
}
// Open the db and recover any potential corruptions
db, err := leveldb.OpenFile(file, &opt.Options{
OpenFilesCacheCapacity: handleCap,
BlockCacheCapacity: blockCacheSize,
// There are two buffers of size WriteBuffer used.
WriteBuffer: writeBufferSize / 2,
Filter: filter.NewBloomFilter(10),
})
if _, corrupted := err.(*errors.ErrCorrupted); corrupted {
db, err = leveldb.RecoverFile(file, nil)
}
if err != nil {
return nil, err
}
return &Database{DB: db}, nil
}
// Has returns if the key is set in the database
func (db *Database) Has(key []byte) (bool, error) {
has, err := db.DB.Has(key, nil)
return has, updateError(err)
}
// Get returns the value the key maps to in the database
func (db *Database) Get(key []byte) ([]byte, error) {
value, err := db.DB.Get(key, nil)
return value, updateError(err)
}
// Put sets the value of the provided key to the provided value
func (db *Database) Put(key []byte, value []byte) error {
return updateError(db.DB.Put(key, value, nil))
}
// Delete removes the key from the database
func (db *Database) Delete(key []byte) error { return updateError(db.DB.Delete(key, nil)) }
// NewBatch creates a write/delete-only buffer that is atomically committed to
// the database when write is called
func (db *Database) NewBatch() database.Batch { return &batch{db: db.DB} }
// NewIterator creates a lexicographically ordered iterator over the database
func (db *Database) NewIterator() database.Iterator {
return &iter{db.DB.NewIterator(new(util.Range), nil)}
}
// NewIteratorWithStart creates a lexicographically ordered iterator over the
// database starting at the provided key
func (db *Database) NewIteratorWithStart(start []byte) database.Iterator {
return &iter{db.DB.NewIterator(&util.Range{Start: start}, nil)}
}
// NewIteratorWithPrefix creates a lexicographically ordered iterator over the
// database ignoring keys that do not start with the provided prefix
func (db *Database) NewIteratorWithPrefix(prefix []byte) database.Iterator {
return &iter{db.DB.NewIterator(util.BytesPrefix(prefix), nil)}
}
// NewIteratorWithStartAndPrefix creates a lexicographically ordered iterator
// over the database starting at start and ignoring keys that do not start with
// the provided prefix
func (db *Database) NewIteratorWithStartAndPrefix(start, prefix []byte) database.Iterator {
iterRange := util.BytesPrefix(prefix)
if bytes.Compare(start, prefix) == 1 {
iterRange.Start = start
}
return &iter{db.DB.NewIterator(iterRange, nil)}
}
// Stat returns a particular internal stat of the database.
func (db *Database) Stat(property string) (string, error) {
stat, err := db.DB.GetProperty(property)
return stat, updateError(err)
}
// This comment is basically copy pasted from the underlying levelDB library:
// Compact the underlying DB for the given key range.
// Specifically, deleted and overwritten versions are discarded,
// and the data is rearranged to reduce the cost of operations
// needed to access the data. This operation should typically only
// be invoked by users who understand the underlying implementation.
//
// A nil start is treated as a key before all keys in the DB.
// And a nil limit is treated as a key after all keys in the DB.
// Therefore if both are nil then it will compact entire DB.
func (db *Database) Compact(start []byte, limit []byte) error {
return updateError(db.DB.CompactRange(util.Range{Start: start, Limit: limit}))
}
// Close implements the Database interface
func (db *Database) Close() error { return updateError(db.DB.Close()) }
// batch is a wrapper around a levelDB batch to contain sizes.
type batch struct {
leveldb.Batch
db *leveldb.DB
size int
}
// Put the value into the batch for later writing
func (b *batch) Put(key, value []byte) error {
b.Batch.Put(key, value)
b.size += len(value)
return nil
}
// Delete the key during writing
func (b *batch) Delete(key []byte) error {
b.Batch.Delete(key)
b.size++
return nil
}
// ValueSize retrieves the amount of data queued up for writing.
func (b *batch) ValueSize() int { return b.size }
// Write flushes any accumulated data to disk.
func (b *batch) Write() error { return updateError(b.db.Write(&b.Batch, nil)) }
// Reset resets the batch for reuse.
func (b *batch) Reset() {
b.Batch.Reset()
b.size = 0
}
// Replay the batch contents.
func (b *batch) Replay(w database.KeyValueWriter) error {
replay := &replayer{writer: w}
if err := b.Batch.Replay(replay); err != nil {
// Never actually returns an error, because Replay just returns nil
return updateError(err)
}
return updateError(replay.err)
}
// Inner returns itself
func (b *batch) Inner() database.Batch { return b }
type replayer struct {
writer database.KeyValueWriter
err error
}
func (r *replayer) Put(key, value []byte) {
if r.err != nil {
return
}
r.err = r.writer.Put(key, value)
}
func (r *replayer) Delete(key []byte) {
if r.err != nil {
return
}
r.err = r.writer.Delete(key)
}
type iter struct{ iterator.Iterator }
func (i *iter) Error() error { return updateError(i.Iterator.Error()) }
func updateError(err error) error {
switch err {
case leveldb.ErrClosed:
return database.ErrClosed
case leveldb.ErrNotFound:
return database.ErrNotFound
default:
return err
}
}