seaweedfs/weed/messaging/broker/broker_grpc_server_subscribe.go

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2020-04-18 08:12:01 +00:00
package broker
import (
"io"
"sync"
"time"
"github.com/golang/protobuf/proto"
"github.com/chrislusf/seaweedfs/weed/glog"
"github.com/chrislusf/seaweedfs/weed/pb/messaging_pb"
"github.com/chrislusf/seaweedfs/weed/util"
)
func (broker *MessageBroker) Subscribe(stream messaging_pb.SeaweedMessaging_SubscribeServer) error {
// process initial request
in, err := stream.Recv()
if err == io.EOF {
return nil
}
if err != nil {
return err
}
subscriberId := in.Init.SubscriberId
// get lock
tp := TopicPartition{
Namespace: in.Init.Namespace,
Topic: in.Init.Topic,
Partition: in.Init.Partition,
}
lock := broker.topicLocks.RequestSubscriberLock(tp)
defer broker.topicLocks.ReleaseLock(tp, false)
cond := sync.NewCond(&lock.Mutex)
lastReadTime := time.Now()
switch in.Init.StartPosition {
case messaging_pb.SubscriberMessage_InitMessage_TIMESTAMP:
lastReadTime = time.Unix(0, in.Init.TimestampNs)
case messaging_pb.SubscriberMessage_InitMessage_LATEST:
case messaging_pb.SubscriberMessage_InitMessage_EARLIEST:
}
// how to process each message
// an error returned will end the subscription
eachMessageFn := func(m *messaging_pb.Message) error {
err := stream.Send(&messaging_pb.BrokerMessage{
Data: m,
})
if err != nil {
glog.V(0).Infof("=> subscriber %v: %+v", subscriberId, err)
}
return err
}
// loop through all messages
for {
_, buf := lock.logBuffer.ReadFromBuffer(lastReadTime)
for pos := 0; pos+4 < len(buf); {
size := util.BytesToUint32(buf[pos : pos+4])
entryData := buf[pos+4 : pos+4+int(size)]
m := &messaging_pb.Message{}
if err = proto.Unmarshal(entryData, m); err != nil {
glog.Errorf("unexpected unmarshal messaging_pb.Message: %v", err)
pos += 4 + int(size)
continue
}
if err = eachMessageFn(m); err != nil {
return err
}
lastReadTime = time.Unix(0, m.Timestamp)
pos += 4 + int(size)
}
lock.Mutex.Lock()
cond.Wait()
lock.Mutex.Unlock()
}
}