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