blob: 8fe99f8e0dcc50d95a3fb7d6f73feaed7cb0f21a [file] [log] [blame]
// 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
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// KIND, either express or implied. See the License for the
// specific language governing permissions and limitations
// under the License.
package pulsar
import "context"
// ReaderMessage package Reader and Message as a struct to use
type ReaderMessage struct {
// ReaderOptions abstraction Reader options to use.
type ReaderOptions struct {
// Topic specify the topic this consumer will subscribe on.
// This argument is required when constructing the reader.
Topic string
// Name set the reader name.
Name string
// Attach a set of application defined properties to the reader
// This properties will be visible in the topic stats
Properties map[string]string
// StartMessageID initial reader positioning is done by specifying a message id. The options are:
// * `pulsar.EarliestMessage` : Start reading from the earliest message available in the topic
// * `pulsar.LatestMessage` : Start reading from the end topic, only getting messages published after the
// reader was created
// * `MessageID` : Start reading from a particular message id, the reader will position itself on that
// specific position. The first message to be read will be the message next to the specified
// messageID
StartMessageID MessageID
// If true, the reader will start at the `StartMessageID`, included.
// Default is `false` and the reader will start from the "next" message
StartMessageIDInclusive bool
// MessageChannel sets a `MessageChannel` for the consumer
// When a message is received, it will be pushed to the channel for consumption
MessageChannel chan ReaderMessage
// ReceiverQueueSize sets the size of the consumer receive queue.
// The consumer receive queue controls how many messages can be accumulated by the Reader before the
// application calls Reader.readNext(). Using a higher value could potentially increase the consumer
// throughput at the expense of bigger memory utilization.
// Default value is {@code 1000} messages and should be good for most use cases.
ReceiverQueueSize int
// SubscriptionRolePrefix set the subscription role prefix. The default prefix is "reader".
SubscriptionRolePrefix string
// If enabled, the reader will read messages from the compacted topic rather than reading the full message backlog
// of the topic. This means that, if the topic has been compacted, the reader will only see the latest value for
// each key in the topic, up until the point in the topic message backlog that has been compacted. Beyond that
// point, the messages will be sent as normal.
// ReadCompacted can only be enabled when reading from a persistent topic. Attempting to enable it on non-persistent
// topics will lead to the reader create call throwing a PulsarClientException.
ReadCompacted bool
// Reader can be used to scan through all the messages currently available in a topic.
type Reader interface {
// Topic from which this reader is reading from
Topic() string
// Next read the next message in the topic, blocking until a message is available
Next(context.Context) (Message, error)
// HasNext check if there is any message available to read from the current position
HasNext() bool
// Close the reader and stop the broker to push more messages