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reader.go
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/
reader.go
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// Copyright 2018 PingCAP, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
package reader
import (
"github.com/Shopify/sarama"
"github.com/pingcap/errors"
pb "github.com/pingcap/tidb-tools/tidb-binlog/slave_binlog_proto/go-binlog"
log "github.com/sirupsen/logrus"
)
func init() {
// log.SetLevel(log.LOG_LEVEL_NONE)
sarama.MaxResponseSize = 1 << 30
}
// Config for Reader
type Config struct {
KafkaAddr []string
// the CommitTs of binlog return by reader will bigger than the config CommitTs
CommitTS int64
Offset int64 // start at kafka offset
// if Topic is empty, use the default name in drainer <ClusterID>_obinlog
Topic string
ClusterID string
}
func (c *Config) valid() error {
if len(c.Topic) == 0 && len(c.ClusterID) == 0 {
return errors.New("Topic or ClusterID must be set")
}
return nil
}
// Message read from reader
type Message struct {
Binlog *pb.Binlog
Offset int64 // kafka offset
}
// Reader to read binlog from kafka
type Reader struct {
cfg *Config
client sarama.Client
msgs chan *Message
stop chan struct{}
clusterID string
}
func (r *Reader) getTopic() (string, int32) {
if r.cfg.Topic != "" {
return r.cfg.Topic, 0
}
return r.cfg.ClusterID + "_obinlog", 0
}
// NewReader creates an instance of Reader
func NewReader(cfg *Config) (r *Reader, err error) {
err = cfg.valid()
if err != nil {
errors.Trace(err)
}
r = &Reader{
cfg: cfg,
stop: make(chan struct{}),
msgs: make(chan *Message, 1024),
clusterID: cfg.ClusterID,
}
r.client, err = sarama.NewClient(r.cfg.KafkaAddr, nil)
if err != nil {
err = errors.Trace(err)
r = nil
return
}
if r.cfg.CommitTS > 0 {
r.cfg.Offset, err = r.getOffsetByTS(r.cfg.CommitTS)
if err != nil {
err = errors.Trace(err)
r = nil
return
}
log.Debug("set offset to: ", r.cfg.Offset)
}
go r.run()
return
}
// Close shuts down the reader
func (r *Reader) Close() {
close(r.stop)
r.client.Close()
}
// Messages returns a chan that contains unread buffered message
func (r *Reader) Messages() (msgs <-chan *Message) {
return r.msgs
}
func (r *Reader) getOffsetByTS(ts int64) (offset int64, err error) {
seeker, err := NewKafkaSeeker(r.cfg.KafkaAddr, nil)
if err != nil {
err = errors.Trace(err)
return
}
topic, partition := r.getTopic()
offsets, err := seeker.Seek(topic, ts, []int32{partition})
if err != nil {
err = errors.Trace(err)
return
}
offset = offsets[0]
return
}
func (r *Reader) run() {
offset := r.cfg.Offset
log.Debug("start at offset: ", offset)
consumer, err := sarama.NewConsumerFromClient(r.client)
if err != nil {
log.Fatal(err)
}
defer consumer.Close()
topic, partition := r.getTopic()
partitionConsumer, err := consumer.ConsumePartition(topic, partition, offset)
if err != nil {
log.Fatal(err)
}
defer partitionConsumer.Close()
for {
select {
case <-r.stop:
partitionConsumer.Close()
close(r.msgs)
log.Info("reader stop to run")
return
case kmsg := <-partitionConsumer.Messages():
log.Debug("get kmsg offset: ", kmsg.Offset)
binlog := new(pb.Binlog)
err := binlog.Unmarshal(kmsg.Value)
if err != nil {
log.Warn(err)
continue
}
if r.cfg.CommitTS > 0 && binlog.CommitTs <= r.cfg.CommitTS {
log.Warn("skip binlog CommitTs: ", binlog.CommitTs)
continue
}
r.msgs <- &Message{
Binlog: binlog,
Offset: kmsg.Offset,
}
}
}
}