Imported Upstream version 1.0.1

database/leveldb.go

@@ -0,0 +1,261 @@
+// Package database provides KV database for meta-information
+package database
+
+import (
+	"bytes"
+	"errors"
+	"io/ioutil"
+	"os"
+
+	"github.com/syndtr/goleveldb/leveldb"
+	"github.com/syndtr/goleveldb/leveldb/filter"
+	"github.com/syndtr/goleveldb/leveldb/opt"
+	"github.com/syndtr/goleveldb/leveldb/storage"
+	"github.com/syndtr/goleveldb/leveldb/util"
+)
+
+// Errors for Storage
+var (
+	ErrNotFound = errors.New("key not found")
+)
+
+// StorageProcessor is a function to process one single storage entry
+type StorageProcessor func(key []byte, value []byte) error
+
+// Storage is an interface to KV storage
+type Storage interface {
+	CreateTemporary() (Storage, error)
+	Get(key []byte) ([]byte, error)
+	Put(key []byte, value []byte) error
+	Delete(key []byte) error
+	HasPrefix(prefix []byte) bool
+	ProcessByPrefix(prefix []byte, proc StorageProcessor) error
+	KeysByPrefix(prefix []byte) [][]byte
+	FetchByPrefix(prefix []byte) [][]byte
+	Close() error
+	ReOpen() error
+	StartBatch()
+	FinishBatch() error
+	CompactDB() error
+	Drop() error
+}
+
+type levelDB struct {
+	path  string
+	db    *leveldb.DB
+	batch *leveldb.Batch
+}
+
+// Check interface
+var (
+	_ Storage = &levelDB{}
+)
+
+func internalOpen(path string, throttleCompaction bool) (*leveldb.DB, error) {
+	o := &opt.Options{
+		Filter:                 filter.NewBloomFilter(10),
+		OpenFilesCacheCapacity: 256,
+	}
+
+	if throttleCompaction {
+		o.CompactionL0Trigger = 32
+		o.WriteL0PauseTrigger = 96
+		o.WriteL0SlowdownTrigger = 64
+	}
+
+	return leveldb.OpenFile(path, o)
+}
+
+// OpenDB opens (creates) LevelDB database
+func OpenDB(path string) (Storage, error) {
+	db, err := internalOpen(path, false)
+	if err != nil {
+		return nil, err
+	}
+	return &levelDB{db: db, path: path}, nil
+}
+
+// RecoverDB recovers LevelDB database from corruption
+func RecoverDB(path string) error {
+	stor, err := storage.OpenFile(path, false)
+	if err != nil {
+		return err
+	}
+
+	db, err := leveldb.Recover(stor, nil)
+	if err != nil {
+		return err
+	}
+
+	db.Close()
+	stor.Close()
+
+	return nil
+}
+
+// CreateTemporary creates new DB of the same type in temp dir
+func (l *levelDB) CreateTemporary() (Storage, error) {
+	tempdir, err := ioutil.TempDir("", "aptly")
+	if err != nil {
+		return nil, err
+	}
+
+	db, err := internalOpen(tempdir, true)
+	if err != nil {
+		return nil, err
+	}
+	return &levelDB{db: db, path: tempdir}, nil
+}
+
+// Get key value from database
+func (l *levelDB) Get(key []byte) ([]byte, error) {
+	value, err := l.db.Get(key, nil)
+	if err != nil {
+		if err == leveldb.ErrNotFound {
+			return nil, ErrNotFound
+		}
+		return nil, err
+	}
+
+	return value, nil
+}
+
+// Put saves key to database, if key has the same value in DB already, it is not saved
+func (l *levelDB) Put(key []byte, value []byte) error {
+	if l.batch != nil {
+		l.batch.Put(key, value)
+		return nil
+	}
+	old, err := l.db.Get(key, nil)
+	if err != nil {
+		if err != leveldb.ErrNotFound {
+			return err
+		}
+	} else {
+		if bytes.Equal(old, value) {
+			return nil
+		}
+	}
+	return l.db.Put(key, value, nil)
+}
+
+// Delete removes key from DB
+func (l *levelDB) Delete(key []byte) error {
+	if l.batch != nil {
+		l.batch.Delete(key)
+		return nil
+	}
+	return l.db.Delete(key, nil)
+}
+
+// KeysByPrefix returns all keys that start with prefix
+func (l *levelDB) KeysByPrefix(prefix []byte) [][]byte {
+	result := make([][]byte, 0, 20)
+
+	iterator := l.db.NewIterator(nil, nil)
+	defer iterator.Release()
+
+	for ok := iterator.Seek(prefix); ok && bytes.HasPrefix(iterator.Key(), prefix); ok = iterator.Next() {
+		key := iterator.Key()
+		keyc := make([]byte, len(key))
+		copy(keyc, key)
+		result = append(result, keyc)
+	}
+
+	return result
+}
+
+// FetchByPrefix returns all values with keys that start with prefix
+func (l *levelDB) FetchByPrefix(prefix []byte) [][]byte {
+	result := make([][]byte, 0, 20)
+
+	iterator := l.db.NewIterator(nil, nil)
+	defer iterator.Release()
+
+	for ok := iterator.Seek(prefix); ok && bytes.HasPrefix(iterator.Key(), prefix); ok = iterator.Next() {
+		val := iterator.Value()
+		valc := make([]byte, len(val))
+		copy(valc, val)
+		result = append(result, valc)
+	}
+
+	return result
+}
+
+// HasPrefix checks whether it can find any key with given prefix and returns true if one exists
+func (l *levelDB) HasPrefix(prefix []byte) bool {
+	iterator := l.db.NewIterator(nil, nil)
+	defer iterator.Release()
+	return iterator.Seek(prefix) && bytes.HasPrefix(iterator.Key(), prefix)
+}
+
+// ProcessByPrefix iterates through all entries where key starts with prefix and calls
+// StorageProcessor on key value pair
+func (l *levelDB) ProcessByPrefix(prefix []byte, proc StorageProcessor) error {
+	iterator := l.db.NewIterator(nil, nil)
+	defer iterator.Release()
+
+	for ok := iterator.Seek(prefix); ok && bytes.HasPrefix(iterator.Key(), prefix); ok = iterator.Next() {
+		err := proc(iterator.Key(), iterator.Value())
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+// Close finishes DB work
+func (l *levelDB) Close() error {
+	if l.db == nil {
+		return nil
+	}
+	err := l.db.Close()
+	l.db = nil
+	return err
+}
+
+// Reopen tries to re-open the database
+func (l *levelDB) ReOpen() error {
+	if l.db != nil {
+		return nil
+	}
+
+	var err error
+	l.db, err = internalOpen(l.path, false)
+	return err
+}
+
+// StartBatch starts batch processing of keys
+//
+// All subsequent Get, Put and Delete would work on batch
+func (l *levelDB) StartBatch() {
+	if l.batch != nil {
+		panic("batch already started")
+	}
+	l.batch = new(leveldb.Batch)
+}
+
+// FinishBatch finalizes the batch, saving operations
+func (l *levelDB) FinishBatch() error {
+	if l.batch == nil {
+		panic("no batch")
+	}
+	err := l.db.Write(l.batch, nil)
+	l.batch = nil
+	return err
+}
+
+// CompactDB compacts database by merging layers
+func (l *levelDB) CompactDB() error {
+	return l.db.CompactRange(util.Range{})
+}
+
+// Drop removes all the DB files (DANGEROUS!)
+func (l *levelDB) Drop() error {
+	if l.db != nil {
+		return errors.New("DB is still open")
+	}
+
+	return os.RemoveAll(l.path)
+}