database: init engine interface for ffldb

database/engine/engine.go

@@ -0,0 +1,25 @@
+package engine
+
+type Engine interface {
+	Transaction() (Transaction, error)
+	Snapshot() (Snapshot, error)
+	Close() error
+}
+
+type Transaction interface {
+	Put(key, value []byte) error
+	Delete(key []byte) error
+	Commit() error
+	Discard()
+}
+
+type Snapshot interface {
+	Get(key []byte) ([]byte, error)
+	Has(key []byte) (bool, error)
+	NewIterator(*Range) Iterator
+	Releaser
+}
+
+type Releaser interface {
+	Release()
+}

database/engine/iterator.go

@@ -0,0 +1,430 @@
+package engine
+
+import (
+	"bytes"
+
+	"github.com/syndtr/goleveldb/leveldb/errors"
+	"github.com/syndtr/goleveldb/leveldb/util"
+)
+
+type Iterator interface {
+	// First moves the iterator to the first key/value pair. If the iterator
+	// only contains one key/value pair then First and Last would moves
+	// to the same key/value pair.
+	// It returns whether such pair exist.
+	First() bool
+
+	// Last moves the iterator to the last key/value pair. If the iterator
+	// only contains one key/value pair then First and Last would moves
+	// to the same key/value pair.
+	// It returns whether such pair exist.
+	Last() bool
+
+	// Seek moves the iterator to the first key/value pair whose key is greater
+	// than or equal to the given key.
+	// It returns whether such pair exist.
+	//
+	// It is safe to modify the contents of the argument after Seek returns.
+	Seek(key []byte) bool
+
+	// Next moves the iterator to the next key/value pair.
+	// It returns false if the iterator is exhausted.
+	Next() bool
+
+	// Prev moves the iterator to the previous key/value pair.
+	// It returns false if the iterator is exhausted.
+	Prev() bool
+
+	// TODO: Remove this when ready.
+	Valid() bool
+
+	// Error returns any accumulated error. Exhausting all the key/value pairs
+	// is not considered to be an error.
+	Error() error
+
+	// Key returns the key of the current key/value pair, or nil if done.
+	// The caller should not modify the contents of the returned slice, and
+	// its contents may change on the next call to any 'seeks method'.
+	Key() []byte
+
+	// Value returns the value of the current key/value pair, or nil if done.
+	// The caller should not modify the contents of the returned slice, and
+	// its contents may change on the next call to any 'seeks method'.
+	Value() []byte
+
+	Releaser
+}
+
+var (
+	ErrIterReleased = errors.New("iterator: iterator released")
+)
+
+type dir int
+
+const (
+	dirReleased dir = iota - 1
+	dirSOI
+	dirEOI
+	dirBackward
+	dirForward
+)
+
+var _ Iterator = (*mergedIterator)(nil)
+
+type mergedIterator struct {
+	cmp    Comparer
+	iters  []Iterator
+	strict bool
+
+	keys     [][]byte
+	index    int
+	dir      dir
+	err      error
+	errf     func(err error)
+	releaser util.Releaser
+}
+
+func assertKey(key []byte) []byte {
+	if key == nil {
+		panic("leveldb/iterator: nil key")
+	}
+	return key
+}
+
+func (i *mergedIterator) iterErr(iter Iterator) bool {
+	if err := iter.Error(); err != nil {
+		if i.errf != nil {
+			i.errf(err)
+		}
+		if i.strict || !errors.IsCorrupted(err) {
+			i.err = err
+			return true
+		}
+	}
+	return false
+}
+
+func (i *mergedIterator) Valid() bool {
+	return i.err == nil && i.dir > dirEOI
+}
+
+func (i *mergedIterator) First() bool {
+	if i.err != nil {
+		return false
+	} else if i.dir == dirReleased {
+		i.err = ErrIterReleased
+		return false
+	}
+
+	for x, iter := range i.iters {
+		switch {
+		case iter.First():
+			i.keys[x] = assertKey(iter.Key())
+		case i.iterErr(iter):
+			return false
+		default:
+			i.keys[x] = nil
+		}
+	}
+	i.dir = dirSOI
+	return i.next()
+}
+
+func (i *mergedIterator) Last() bool {
+	if i.err != nil {
+		return false
+	} else if i.dir == dirReleased {
+		i.err = ErrIterReleased
+		return false
+	}
+
+	for x, iter := range i.iters {
+		switch {
+		case iter.Last():
+			i.keys[x] = assertKey(iter.Key())
+		case i.iterErr(iter):
+			return false
+		default:
+			i.keys[x] = nil
+		}
+	}
+	i.dir = dirEOI
+	return i.prev()
+}
+
+func (i *mergedIterator) Seek(key []byte) bool {
+	if i.err != nil {
+		return false
+	} else if i.dir == dirReleased {
+		i.err = ErrIterReleased
+		return false
+	}
+
+	for x, iter := range i.iters {
+		switch {
+		case iter.Seek(key):
+			i.keys[x] = assertKey(iter.Key())
+		case i.iterErr(iter):
+			return false
+		default:
+			i.keys[x] = nil
+		}
+	}
+	i.dir = dirSOI
+	return i.next()
+}
+
+func (i *mergedIterator) next() bool {
+	var key []byte
+	if i.dir == dirForward {
+		key = i.keys[i.index]
+	}
+	for x, tkey := range i.keys {
+		if tkey != nil && (key == nil || i.cmp.Compare(tkey, key) < 0) {
+			key = tkey
+			i.index = x
+		}
+	}
+	if key == nil {
+		i.dir = dirEOI
+		return false
+	}
+	i.dir = dirForward
+	return true
+}
+
+func (i *mergedIterator) Next() bool {
+	if i.dir == dirEOI || i.err != nil {
+		return false
+	} else if i.dir == dirReleased {
+		i.err = ErrIterReleased
+		return false
+	}
+
+	switch i.dir {
+	case dirSOI:
+		return i.First()
+	case dirBackward:
+		key := append([]byte{}, i.keys[i.index]...)
+		if !i.Seek(key) {
+			return false
+		}
+		return i.Next()
+	}
+
+	x := i.index
+	iter := i.iters[x]
+	switch {
+	case iter.Next():
+		i.keys[x] = assertKey(iter.Key())
+	case i.iterErr(iter):
+		return false
+	default:
+		i.keys[x] = nil
+	}
+	return i.next()
+}
+
+func (i *mergedIterator) prev() bool {
+	var key []byte
+	if i.dir == dirBackward {
+		key = i.keys[i.index]
+	}
+	for x, tkey := range i.keys {
+		if tkey != nil && (key == nil || i.cmp.Compare(tkey, key) > 0) {
+			key = tkey
+			i.index = x
+		}
+	}
+	if key == nil {
+		i.dir = dirSOI
+		return false
+	}
+	i.dir = dirBackward
+	return true
+}
+
+func (i *mergedIterator) Prev() bool {
+	if i.dir == dirSOI || i.err != nil {
+		return false
+	} else if i.dir == dirReleased {
+		i.err = ErrIterReleased
+		return false
+	}
+
+	switch i.dir {
+	case dirEOI:
+		return i.Last()
+	case dirForward:
+		key := append([]byte{}, i.keys[i.index]...)
+		for x, iter := range i.iters {
+			if x == i.index {
+				continue
+			}
+			seek := iter.Seek(key)
+			switch {
+			case seek && iter.Prev(), !seek && iter.Last():
+				i.keys[x] = assertKey(iter.Key())
+			case i.iterErr(iter):
+				return false
+			default:
+				i.keys[x] = nil
+			}
+		}
+	}
+
+	x := i.index
+	iter := i.iters[x]
+	switch {
+	case iter.Prev():
+		i.keys[x] = assertKey(iter.Key())
+	case i.iterErr(iter):
+		return false
+	default:
+		i.keys[x] = nil
+	}
+	return i.prev()
+}
+
+func (i *mergedIterator) Key() []byte {
+	if i.err != nil || i.dir <= dirEOI {
+		return nil
+	}
+	return i.keys[i.index]
+}
+
+func (i *mergedIterator) Value() []byte {
+	if i.err != nil || i.dir <= dirEOI {
+		return nil
+	}
+	return i.iters[i.index].Value()
+}
+
+func (i *mergedIterator) Release() {
+	if i.dir != dirReleased {
+		i.dir = dirReleased
+		for _, iter := range i.iters {
+			iter.Release()
+		}
+		i.iters = nil
+		i.keys = nil
+		if i.releaser != nil {
+			i.releaser.Release()
+			i.releaser = nil
+		}
+	}
+}
+
+func (i *mergedIterator) SetReleaser(releaser util.Releaser) {
+	if i.dir == dirReleased {
+		panic(util.ErrReleased)
+	}
+	if i.releaser != nil && releaser != nil {
+		panic(util.ErrHasReleaser)
+	}
+	i.releaser = releaser
+}
+
+func (i *mergedIterator) Error() error {
+	return i.err
+}
+
+func (i *mergedIterator) SetErrorCallback(f func(err error)) {
+	i.errf = f
+}
+
+// NewMergedIterator returns an iterator that merges its input. Walking the
+// resultant iterator will return all key/value pairs of all input iterators
+// in strictly increasing key order, as defined by cmp.
+// The input's key ranges may overlap, but there are assumed to be no duplicate
+// keys: if iters[i] contains a key k then iters[j] will not contain that key k.
+// None of the iters may be nil.
+//
+// If strict is true the any 'corruption errors' (i.e errors.IsCorrupted(err) == true)
+// won't be ignored and will halt 'merged iterator', otherwise the iterator will
+// continue to the next 'input iterator'.
+func NewMergedIterator(iters []Iterator, cmp Comparer, strict bool) Iterator {
+	return &mergedIterator{
+		iters:  iters,
+		cmp:    cmp,
+		strict: strict,
+		keys:   make([][]byte, len(iters)),
+	}
+}
+
+type Comparer interface {
+	Compare(a, b []byte) int
+
+	Name() string
+
+	Separator(dst, a, b []byte) []byte
+
+	Successor(dst, b []byte) []byte
+}
+
+type bytesComparer struct{}
+
+func (bytesComparer) Compare(a, b []byte) int {
+	return bytes.Compare(a, b)
+}
+
+func (bytesComparer) Name() string {
+	return "leveldb.BytewiseComparator"
+}
+
+func (bytesComparer) Separator(dst, a, b []byte) []byte {
+	i, n := 0, len(a)
+	if n > len(b) {
+		n = len(b)
+	}
+	for ; i < n && a[i] == b[i]; i++ {
+	}
+	if i >= n {
+		// Do not shorten if one string is a prefix of the other
+	} else if c := a[i]; c < 0xff && c+1 < b[i] {
+		dst = append(dst, a[:i+1]...)
+		dst[len(dst)-1]++
+		return dst
+	}
+	return nil
+}
+
+func (bytesComparer) Successor(dst, b []byte) []byte {
+	for i, c := range b {
+		if c != 0xff {
+			dst = append(dst, b[:i+1]...)
+			dst[len(dst)-1]++
+			return dst
+		}
+	}
+	return nil
+}
+
+// DefaultComparer are default implementation of the Comparer interface.
+// It uses the natural ordering, consistent with bytes.Compare.
+var DefaultComparer = bytesComparer{}
+
+// Range is a key range.
+type Range struct {
+	// Start of the key range, include in the range.
+	Start []byte
+
+	// Limit of the key range, not include in the range.
+	Limit []byte
+}
+
+// BytesPrefix returns key range that satisfy the given prefix.
+// This only applicable for the standard 'bytes comparer'.
+func BytesPrefix(prefix []byte) *Range {
+	var limit []byte
+	for i := len(prefix) - 1; i >= 0; i-- {
+		c := prefix[i]
+		if c < 0xff {
+			limit = make([]byte, i+1)
+			copy(limit, prefix)
+			limit[i] = c + 1
+			break
+		}
+	}
+	return &Range{prefix, limit}
+}

database/engine/leveldb/leveldb.go

@@ -0,0 +1,46 @@
+package leveldb
+
+import (
+	"github.com/btcsuite/btcd/database/engine"
+	"github.com/syndtr/goleveldb/leveldb"
+	"github.com/syndtr/goleveldb/leveldb/filter"
+	"github.com/syndtr/goleveldb/leveldb/opt"
+)
+
+func NewDB(dbPath string, create bool) (engine.Engine, error) {
+	opts := opt.Options{
+		ErrorIfExist: create,
+		Strict:       opt.DefaultStrict,
+		Compression:  opt.NoCompression,
+		Filter:       filter.NewBloomFilter(10),
+	}
+	ldb, err := leveldb.OpenFile(dbPath, &opts)
+	if err != nil {
+		return nil, err
+	}
+	return &DB{DB: ldb}, nil
+}
+
+type DB struct {
+	*leveldb.DB
+}
+
+func (d *DB) Transaction() (engine.Transaction, error) {
+	tx, err := d.DB.OpenTransaction()
+	if err != nil {
+		return nil, err
+	}
+	return NewTransaction(tx), nil
+}
+
+func (d *DB) Snapshot() (engine.Snapshot, error) {
+	snapshot, err := d.DB.GetSnapshot()
+	if err != nil {
+		return nil, err
+	}
+	return NewSnapshot(snapshot), nil
+}
+
+func (d *DB) Close() error {
+	return d.DB.Close()
+}

database/engine/leveldb/snapshot.go

@@ -0,0 +1,34 @@
+package leveldb
+
+import (
+	"github.com/btcsuite/btcd/database/engine"
+	"github.com/syndtr/goleveldb/leveldb"
+	"github.com/syndtr/goleveldb/leveldb/util"
+)
+
+func NewSnapshot(snapshot *leveldb.Snapshot) engine.Snapshot {
+	return &Snapshot{Snapshot: snapshot}
+}
+
+type Snapshot struct {
+	*leveldb.Snapshot
+}
+
+func (s *Snapshot) Has(key []byte) (bool, error) {
+	return s.Snapshot.Has(key, nil)
+}
+
+func (s *Snapshot) Get(key []byte) (val []byte, err error) {
+	return s.Snapshot.Get(key, nil)
+}
+
+func (s *Snapshot) Release() {
+	s.Snapshot.Release()
+}
+
+func (s *Snapshot) NewIterator(slice *engine.Range) engine.Iterator {
+	return s.Snapshot.NewIterator(&util.Range{
+		Start: slice.Start,
+		Limit: slice.Limit,
+	}, nil)
+}

database/engine/leveldb/transaction.go

@@ -0,0 +1,30 @@
+package leveldb
+
+import (
+	"github.com/btcsuite/btcd/database/engine"
+	"github.com/syndtr/goleveldb/leveldb"
+)
+
+func NewTransaction(tx *leveldb.Transaction) engine.Transaction {
+	return &Transaction{Transaction: tx}
+}
+
+type Transaction struct {
+	*leveldb.Transaction
+}
+
+func (t *Transaction) Put(key, value []byte) error {
+	return t.Transaction.Put(key, value, nil)
+}
+
+func (t *Transaction) Delete(key []byte) error {
+	return t.Transaction.Delete(key, nil)
+}
+
+func (t *Transaction) Discard() {
+	t.Transaction.Discard()
+}
+
+func (t *Transaction) Commit() error {
+	return t.Transaction.Commit()
+}