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/*
* SPDX-FileCopyrightText: © Hypermode Inc. <hello@hypermode.com>
* SPDX-License-Identifier: Apache-2.0
*/
package y
import (
"bytes"
"encoding/binary"
)
// ValueStruct represents the value info that can be associated with a key, but also the internal
// Meta field.
type ValueStruct struct {
Meta byte
UserMeta byte
ExpiresAt uint64
Value []byte
Version uint64 // This field is not serialized. Only for internal usage.
}
func sizeVarint(x uint64) (n int) {
for {
n++
x >>= 7
if x == 0 {
break
}
}
return n
}
// EncodedSize is the size of the ValueStruct when encoded
func (v *ValueStruct) EncodedSize() uint32 {
sz := len(v.Value) + 2 // meta, usermeta.
enc := sizeVarint(v.ExpiresAt)
return uint32(sz + enc)
}
// Decode uses the length of the slice to infer the length of the Value field.
func (v *ValueStruct) Decode(b []byte) {
v.Meta = b[0]
v.UserMeta = b[1]
var sz int
v.ExpiresAt, sz = binary.Uvarint(b[2:])
v.Value = b[2+sz:]
}
// Encode expects a slice of length at least v.EncodedSize().
func (v *ValueStruct) Encode(b []byte) uint32 {
b[0] = v.Meta
b[1] = v.UserMeta
sz := binary.PutUvarint(b[2:], v.ExpiresAt)
n := copy(b[2+sz:], v.Value)
return uint32(2 + sz + n)
}
// EncodeTo should be kept in sync with the Encode function above. The reason
// this function exists is to avoid creating byte arrays per key-value pair in
// table/builder.go.
func (v *ValueStruct) EncodeTo(buf *bytes.Buffer) {
buf.WriteByte(v.Meta)
buf.WriteByte(v.UserMeta)
var enc [binary.MaxVarintLen64]byte
sz := binary.PutUvarint(enc[:], v.ExpiresAt)
buf.Write(enc[:sz])
buf.Write(v.Value)
}
// Iterator is an interface for a basic iterator.
type Iterator interface {
Next()
Rewind()
Seek(key []byte)
Key() []byte
Value() ValueStruct
Valid() bool
// All iterators should be closed so that file garbage collection works.
Close() error
}
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