presistent-queue

Persistent message queue. Messages are stored in the disk. Messages by cursor are supported

What this is

persistent-message-queue is a queue SDK that stores messages on disk.

Function point

• Messages are stored in the disk to ensure that the service will not stackoverflow in memory due to too many messages;
  • 消息存储在磁盘中，可以保证服务不会因消息过多导致内存溢出;
• Messages are not one-time consumption. Messages can be subscribed again by cursor;
  • 消息不是一次性消费，消息可以按 cursor 再次订阅;
• Service restart will not lose messages;
  • 服务重新启动不会丢失消息;
• After the service is restarted, it can automatically continue to execute from the last address written or read;
  • 服务重新启动后可以自动从上次写入或读取的地址继续执行;
• Thanks to Kafka logsegment;
  • 致谢 Kafka LogSegment;

Quick-start

Maven:

<dependency>
    <groupId>io.github.kubrickLiu</groupId>
    <artifactId>persistent-queue</artifactId>
    <version>1.0.1</version>
</dependency>

Example Code :

1. Single file queue ;

produce message:

File file = new File("${file path}");

// create a single file persistent file -- FileRecords
FileRecords fileRecords = new FileRecords(file);

// mock id and message
int id = idGenerator.getAndIncrement();
String message = "msg-" + id;

// build a Record 
Record record = new Record(id, message.getBytes());

// append message to persistent queue
fileRecords.appendOne(record);

consume message:

// get iterator from FileRecords
Iterator<Record> iterator = fileRecords.iterator();

// consume record from persistent queue
while (iterator.hasNext()) {
    Record result = iterator.next();
    System.out.println(result.getId() + " : " + new String(result.getBytes()));
}