139 lines
3.4 KiB
Go
139 lines
3.4 KiB
Go
// Copyright 2022-present PingCAP, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package stream
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import (
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"encoding/binary"
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"math"
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"github.com/pingcap/errors"
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berrors "github.com/pingcap/tidb/br/pkg/errors"
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)
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// Iterator specifies a read iterator Interface.
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type Iterator interface {
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Next()
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Valid() bool
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Key() []byte
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Value() []byte
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GetError() error
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}
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// EventIterator is used for reading kv-event from buffer by iterator.
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type EventIterator struct {
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buff []byte
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pos uint32
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k []byte
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v []byte
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err error
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}
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// NewEventIterator creates a Iterator to read kv-event.
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func NewEventIterator(buff []byte) Iterator {
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return &EventIterator{buff: buff}
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}
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// Next specifies the next iterative element.
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func (ei *EventIterator) Next() {
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if !ei.Valid() {
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return
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}
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k, v, pos, err := DecodeKVEntry(ei.buff[ei.pos:])
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if err != nil {
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ei.err = err
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return
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}
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ei.k = k
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ei.v = v
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ei.pos += pos
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}
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// Valid checks whether the iterator is valid.
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func (ei *EventIterator) Valid() bool {
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if ei.err != nil {
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return false
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}
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buffLen := len(ei.buff)
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// Check if buffer length exceeds uint32 range
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// This prevents truncation when comparing with ei.pos (uint32)
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if buffLen > math.MaxUint32 {
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ei.err = errors.Annotatef(berrors.ErrInvalidArgument,
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"buffer too large: %d bytes exceeds uint32 limit (%d bytes)", buffLen, math.MaxUint32)
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return false
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}
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return ei.pos < uint32(buffLen)
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}
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// Key gets the key in kv-event if valid() == true
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func (ei *EventIterator) Key() []byte {
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return ei.k
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}
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// Value gets the value in kv-event if valid() == true
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func (ei *EventIterator) Value() []byte {
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return ei.v
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}
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// GetError gets the error in iterator.
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// it returns nil if it has nothing mistaken happened
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func (ei *EventIterator) GetError() error {
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return ei.err
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}
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// EncodeKVEntry gets a entry-event from input: k, v.
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func EncodeKVEntry(k, v []byte) []byte {
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entry := make([]byte, 0, 4+len(k)+4+len(v))
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length := make([]byte, 4)
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binary.LittleEndian.PutUint32(length, uint32(len(k)))
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entry = append(entry, length...)
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entry = append(entry, k...)
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binary.LittleEndian.PutUint32(length, uint32(len(v)))
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entry = append(entry, length...)
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entry = append(entry, v...)
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return entry
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}
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// DecodeKVEntry decodes kv-entry from buff.
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// If error returned is nil, it can get key/value and the length occupied in buff.
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func DecodeKVEntry(buff []byte) (k, v []byte, length uint32, err error) {
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if len(buff) < 8 {
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return nil, nil, 0, errors.Annotate(berrors.ErrInvalidArgument, "invalid buff")
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}
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var pos uint32 = 0
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kLen := binary.LittleEndian.Uint32(buff)
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pos += 4
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if uint32(len(buff)) < 8+kLen {
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return nil, nil, 0, errors.Annotate(berrors.ErrInvalidArgument, "invalid buff")
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}
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k = buff[pos : pos+kLen]
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pos += kLen
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vLen := binary.LittleEndian.Uint32(buff[pos:])
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pos += 4
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if uint32(len(buff)) < 8+kLen+vLen {
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return nil, nil, 0, errors.Annotate(berrors.ErrInvalidArgument, "invalid buff")
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}
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v = buff[pos : pos+vLen]
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pos += vLen
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return k, v, pos, nil
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}
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