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129 lines
3.5 KiB
Go
129 lines
3.5 KiB
Go
// Licensed to the LF AI & Data foundation under one
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// or more contributor license agreements. See the NOTICE file
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// distributed with this work for additional information
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// regarding copyright ownership. The ASF licenses this file
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// to you under the Apache License, Version 2.0 (the
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// "License"); you may not use this file except in compliance
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// with the License. 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 storage
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import (
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"bytes"
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"encoding/binary"
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"errors"
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"fmt"
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"io"
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"github.com/milvus-io/milvus/internal/common"
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)
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// BinlogReader is an object to read binlog file. Binlog file's format can be
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// found in design docs.
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type BinlogReader struct {
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magicNumber int32
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descriptorEvent
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buffer *bytes.Buffer
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eventReader *EventReader
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isClose bool
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}
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// NextEventReader iters all events reader to read the binlog file.
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func (reader *BinlogReader) NextEventReader() (*EventReader, error) {
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if reader.isClose {
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return nil, errors.New("bin log reader is closed")
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}
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if reader.buffer.Len() <= 0 {
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return nil, nil
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}
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// close the previous reader
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if reader.eventReader != nil {
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reader.eventReader.Close()
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}
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var err error
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reader.eventReader, err = newEventReader(reader.descriptorEvent.PayloadDataType, reader.buffer)
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if err != nil {
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return nil, err
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}
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return reader.eventReader, nil
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}
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func (reader *BinlogReader) readMagicNumber() (int32, error) {
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var err error
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reader.magicNumber, err = readMagicNumber(reader.buffer)
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return reader.magicNumber, err
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}
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func (reader *BinlogReader) readDescriptorEvent() (*descriptorEvent, error) {
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event, err := ReadDescriptorEvent(reader.buffer)
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if err != nil {
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return nil, err
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}
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reader.descriptorEvent = *event
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return &reader.descriptorEvent, nil
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}
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func readMagicNumber(buffer io.Reader) (int32, error) {
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var magicNumber int32
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if err := binary.Read(buffer, common.Endian, &magicNumber); err != nil {
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return -1, err
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}
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if magicNumber != MagicNumber {
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return -1, fmt.Errorf("parse magic number failed, expected: %d, actual: %d", MagicNumber, magicNumber)
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}
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return magicNumber, nil
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}
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// ReadDescriptorEvent reads a descriptorEvent from buffer
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func ReadDescriptorEvent(buffer io.Reader) (*descriptorEvent, error) {
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header, err := readDescriptorEventHeader(buffer)
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if err != nil {
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return nil, err
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}
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data, err := readDescriptorEventData(buffer)
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if err != nil {
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return nil, err
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}
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return &descriptorEvent{
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descriptorEventHeader: *header,
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descriptorEventData: *data,
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}, nil
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}
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// Close closes the BinlogReader object.
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// It mainly calls the Close method of the internal events, reclaims resources, and marks itself as closed.
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func (reader *BinlogReader) Close() {
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if reader.isClose {
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return
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}
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if reader.eventReader != nil {
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reader.eventReader.Close()
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}
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reader.isClose = true
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}
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// NewBinlogReader creates binlogReader to read binlog file.
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func NewBinlogReader(data []byte) (*BinlogReader, error) {
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reader := &BinlogReader{
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buffer: bytes.NewBuffer(data),
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isClose: false,
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}
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if _, err := reader.readMagicNumber(); err != nil {
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return nil, err
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}
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if _, err := reader.readDescriptorEvent(); err != nil {
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return nil, err
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}
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return reader, nil
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}
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