forked from apache/pulsar-client-go
/
reader_impl.go
152 lines (127 loc) · 3.95 KB
/
reader_impl.go
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// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements. See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership. The ASF licenses this file
// to you 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, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied. See the License for the
// specific language governing permissions and limitations
// under the License.
package pulsar
import (
"context"
log "github.com/sirupsen/logrus"
)
const (
defaultReceiverQueueSize = 1000
)
type reader struct {
pc *partitionConsumer
messageCh chan ConsumerMessage
lastMessageInBroker *messageID
log *log.Entry
}
func newReader(client *client, options ReaderOptions) (Reader, error) {
if options.Topic == "" {
return nil, newError(ResultInvalidConfiguration, "Topic is required")
}
if options.StartMessageID == nil {
return nil, newError(ResultInvalidConfiguration, "StartMessageID is required")
}
subscriptionName := options.SubscriptionRolePrefix
if subscriptionName == "" {
subscriptionName = "reader"
}
subscriptionName += "-" + generateRandomName()
receiverQueueSize := options.ReceiverQueueSize
if receiverQueueSize == 0 {
receiverQueueSize = defaultReceiverQueueSize
}
consumerOptions := &partitionConsumerOpts{
topic: options.Topic,
consumerName: options.Name,
subscription: subscriptionName,
subscriptionType: Exclusive,
receiverQueueSize: receiverQueueSize,
startMessageID: options.StartMessageID.(*messageID),
startMessageIDInclusive: options.StartMessageIDInclusive,
subscriptionMode: nonDurable,
readCompacted: options.ReadCompacted,
metadata: options.Properties,
nackRedeliveryDelay: defaultNackRedeliveryDelay,
replicateSubscriptionState: false,
}
reader := &reader{
messageCh: make(chan ConsumerMessage),
log: log.WithField("topic", options.Topic),
}
// Provide dummy dlq router with not dlq policy
dlq, err := newDlqRouter(client, nil)
if err != nil {
return nil, err
}
pc, err := newPartitionConsumer(nil, client, consumerOptions, reader.messageCh, dlq)
if err != nil {
close(reader.messageCh)
return nil, err
}
reader.pc = pc
return reader, nil
}
func (r *reader) Topic() string {
return r.pc.topic
}
func (r *reader) Next(ctx context.Context) (Message, error) {
for {
select {
case cm, ok := <-r.messageCh:
if !ok {
return nil, ErrConsumerClosed
}
// Acknowledge message immediately because the reader is based on non-durable subscription. When it reconnects,
// it will specify the subscription position anyway
msgID := cm.Message.ID().(*messageID)
r.pc.lastDequeuedMsg = msgID
r.pc.AckID(msgID)
return cm.Message, nil
case <-ctx.Done():
return nil, ctx.Err()
}
}
}
func (r *reader) HasNext() bool {
if r.lastMessageInBroker != nil && r.hasMoreMessages() {
return true
}
for {
lastMsgID, err := r.pc.getLastMessageID()
if err != nil {
r.log.WithError(err).Error("Failed to get last message id from broker")
continue
} else {
r.lastMessageInBroker = lastMsgID
break
}
}
return r.hasMoreMessages()
}
func (r *reader) hasMoreMessages() bool {
if r.pc.lastDequeuedMsg != nil {
return r.lastMessageInBroker.greater(r.pc.lastDequeuedMsg)
}
if r.pc.options.startMessageIDInclusive {
return r.lastMessageInBroker.greaterEqual(r.pc.startMessageID)
}
// Non-inclusive
return r.lastMessageInBroker.greater(r.pc.startMessageID)
}
func (r *reader) Close() {
r.pc.Close()
}