prometheus/vendor/github.com/syndtr/goleveldb/leveldb/key.go

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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"
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"github.com/syndtr/goleveldb/leveldb/storage"
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)
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// ErrInternalKeyCorrupted records internal key corruption.
type ErrInternalKeyCorrupted struct {
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Ikey []byte
Reason string
}
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func (e *ErrInternalKeyCorrupted) Error() string {
return fmt.Sprintf("leveldb: internal key %q corrupted: %s", e.Ikey, e.Reason)
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}
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func newErrInternalKeyCorrupted(ikey []byte, reason string) error {
return errors.NewErrCorrupted(storage.FileDesc{}, &ErrInternalKeyCorrupted{append([]byte{}, ikey...), reason})
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}
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type keyType uint
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func (kt keyType) String() string {
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switch kt {
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case keyTypeDel:
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return "d"
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case keyTypeVal:
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return "v"
}
return "x"
}
// Value types encoded as the last component of internal keys.
// Don't modify; this value are saved to disk.
const (
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keyTypeDel keyType = iota
keyTypeVal
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)
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// keyTypeSeek defines the keyType that should be passed when constructing an
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// 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).
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const keyTypeSeek = keyTypeVal
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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.
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keyMaxSeq = (uint64(1) << 56) - 1
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// Maximum value possible for packed sequence number and type.
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keyMaxNum = (keyMaxSeq << 8) | uint64(keyTypeSeek)
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)
// Maximum number encoded in bytes.
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var keyMaxNumBytes = make([]byte, 8)
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func init() {
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binary.LittleEndian.PutUint64(keyMaxNumBytes, keyMaxNum)
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}
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type internalKey []byte
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func makeInternalKey(dst, ukey []byte, seq uint64, kt keyType) internalKey {
if seq > keyMaxSeq {
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panic("leveldb: invalid sequence number")
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} else if kt > keyTypeVal {
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panic("leveldb: invalid type")
}
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if n := len(ukey) + 8; cap(dst) < n {
dst = make([]byte, n)
} else {
dst = dst[:n]
}
copy(dst, ukey)
binary.LittleEndian.PutUint64(dst[len(ukey):], (seq<<8)|uint64(kt))
return internalKey(dst)
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}
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func parseInternalKey(ik []byte) (ukey []byte, seq uint64, kt keyType, err error) {
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if len(ik) < 8 {
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return nil, 0, 0, newErrInternalKeyCorrupted(ik, "invalid length")
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}
num := binary.LittleEndian.Uint64(ik[len(ik)-8:])
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seq, kt = uint64(num>>8), keyType(num&0xff)
if kt > keyTypeVal {
return nil, 0, 0, newErrInternalKeyCorrupted(ik, "invalid type")
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}
ukey = ik[:len(ik)-8]
return
}
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func validInternalKey(ik []byte) bool {
_, _, _, err := parseInternalKey(ik)
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return err == nil
}
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func (ik internalKey) assert() {
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if ik == nil {
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panic("leveldb: nil internalKey")
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}
if len(ik) < 8 {
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panic(fmt.Sprintf("leveldb: internal key %q, len=%d: invalid length", []byte(ik), len(ik)))
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}
}
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func (ik internalKey) ukey() []byte {
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ik.assert()
return ik[:len(ik)-8]
}
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func (ik internalKey) num() uint64 {
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ik.assert()
return binary.LittleEndian.Uint64(ik[len(ik)-8:])
}
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func (ik internalKey) parseNum() (seq uint64, kt keyType) {
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num := ik.num()
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seq, kt = uint64(num>>8), keyType(num&0xff)
if kt > keyTypeVal {
panic(fmt.Sprintf("leveldb: internal key %q, len=%d: invalid type %#x", []byte(ik), len(ik), kt))
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}
return
}
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func (ik internalKey) String() string {
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if ik == nil {
return "<nil>"
}
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if ukey, seq, kt, err := parseInternalKey(ik); err == nil {
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return fmt.Sprintf("%s,%s%d", shorten(string(ukey)), kt, seq)
}
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return "<invalid>"
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}