| // |
| // 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" |
| |
| type ReaderMessage struct { |
| Reader |
| Message |
| } |
| |
| type ReaderOptions struct { |
| // Specify the topic this consumer will subscribe on. |
| // This argument is required when constructing the reader. |
| Topic string |
| |
| // Set the reader name. |
| Name string |
| |
| // The 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 |
| |
| // Sets a `MessageChannel` for the consumer |
| // When a message is received, it will be pushed to the channel for consumption |
| MessageChannel chan ReaderMessage |
| |
| // 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 |
| |
| // 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 |
| } |
| |
| // A Reader can be used to scan through all the messages currently available in a topic. |
| type Reader interface { |
| // The topic from which this reader is reading from |
| Topic() string |
| |
| // Read the next message in the topic, blocking until a message is available |
| Next(context.Context) (Message, error) |
| |
| // Check if there is any message available to read from the current position |
| HasNext() (bool, error) |
| |
| // Close the reader and stop the broker to push more messages |
| Close() error |
| |
| Schema() Schema |
| } |