143 lines
3.2 KiB
Go
143 lines
3.2 KiB
Go
// Copyright (c) 2012, Suryandaru Triandana <syndtr@gmail.com>
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// All rights reserved.
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//
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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package leveldb
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import (
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"encoding/binary"
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"fmt"
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"github.com/syndtr/goleveldb/leveldb/errors"
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)
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type ErrIkeyCorrupted struct {
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Ikey []byte
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Reason string
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}
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func (e *ErrIkeyCorrupted) Error() string {
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return fmt.Sprintf("leveldb: iKey %q corrupted: %s", e.Ikey, e.Reason)
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}
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func newErrIkeyCorrupted(ikey []byte, reason string) error {
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return errors.NewErrCorrupted(nil, &ErrIkeyCorrupted{append([]byte{}, ikey...), reason})
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}
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type kType int
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func (kt kType) String() string {
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switch kt {
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case ktDel:
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return "d"
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case ktVal:
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return "v"
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}
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return "x"
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}
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// Value types encoded as the last component of internal keys.
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// Don't modify; this value are saved to disk.
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const (
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ktDel kType = iota
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ktVal
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)
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// ktSeek defines the kType that should be passed when constructing an
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// internal key for seeking to a particular sequence number (since we
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// sort sequence numbers in decreasing order and the value type is
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// embedded as the low 8 bits in the sequence number in internal keys,
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// we need to use the highest-numbered ValueType, not the lowest).
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const ktSeek = ktVal
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const (
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// Maximum value possible for sequence number; the 8-bits are
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// used by value type, so its can packed together in single
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// 64-bit integer.
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kMaxSeq uint64 = (uint64(1) << 56) - 1
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// Maximum value possible for packed sequence number and type.
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kMaxNum uint64 = (kMaxSeq << 8) | uint64(ktSeek)
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)
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// Maximum number encoded in bytes.
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var kMaxNumBytes = make([]byte, 8)
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func init() {
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binary.LittleEndian.PutUint64(kMaxNumBytes, kMaxNum)
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}
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type iKey []byte
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func newIkey(ukey []byte, seq uint64, kt kType) iKey {
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if seq > kMaxSeq {
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panic("leveldb: invalid sequence number")
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} else if kt > ktVal {
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panic("leveldb: invalid type")
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}
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ik := make(iKey, len(ukey)+8)
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copy(ik, ukey)
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binary.LittleEndian.PutUint64(ik[len(ukey):], (seq<<8)|uint64(kt))
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return ik
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}
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func parseIkey(ik []byte) (ukey []byte, seq uint64, kt kType, err error) {
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if len(ik) < 8 {
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return nil, 0, 0, newErrIkeyCorrupted(ik, "invalid length")
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}
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num := binary.LittleEndian.Uint64(ik[len(ik)-8:])
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seq, kt = uint64(num>>8), kType(num&0xff)
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if kt > ktVal {
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return nil, 0, 0, newErrIkeyCorrupted(ik, "invalid type")
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}
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ukey = ik[:len(ik)-8]
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return
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}
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func validIkey(ik []byte) bool {
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_, _, _, err := parseIkey(ik)
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return err == nil
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}
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func (ik iKey) assert() {
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if ik == nil {
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panic("leveldb: nil iKey")
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}
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if len(ik) < 8 {
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panic(fmt.Sprintf("leveldb: iKey %q, len=%d: invalid length", []byte(ik), len(ik)))
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}
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}
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func (ik iKey) ukey() []byte {
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ik.assert()
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return ik[:len(ik)-8]
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}
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func (ik iKey) num() uint64 {
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ik.assert()
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return binary.LittleEndian.Uint64(ik[len(ik)-8:])
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}
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func (ik iKey) parseNum() (seq uint64, kt kType) {
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num := ik.num()
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seq, kt = uint64(num>>8), kType(num&0xff)
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if kt > ktVal {
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panic(fmt.Sprintf("leveldb: iKey %q, len=%d: invalid type %#x", []byte(ik), len(ik), kt))
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}
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return
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}
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func (ik iKey) String() string {
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if ik == nil {
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return "<nil>"
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}
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if ukey, seq, kt, err := parseIkey(ik); err == nil {
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return fmt.Sprintf("%s,%s%d", shorten(string(ukey)), kt, seq)
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} else {
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return "<invalid>"
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}
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}
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