编年史队列大小确定

Question

如果我们需要将编年史队列的总大小限制为 1GB 或 10GB。最好的方法是什么？

我们将缓冲区存储为字节，因此我试图通过对缓冲区大小求和来计算总大小，但看起来没有简单的方法将其与队列的实际大小相关联。一种方法是每 5 分钟左右使用文件实用程序计算总目录大小，但如果间隔中有大量数据并且可能溢出，这将容易出错

Answer 1

您必须将每个 cq4 文件的大小相加

writePosition 以字节为单位为您提供每个 cq4 文件的长度

public class Example {

    public static void main(String[] args) throws FileNotFoundException {
        SingleChronicleQueue q = SingleChronicleQueueBuilder.builder().path("tmp").build();

        ExcerptAppender appender = q.createAppender();

        try (DocumentContext dc = appender.writingDocument()) {
            long l = dc.wire().bytes().writePosition();
            dc.wire().write().text("lastx");
        }

       DumpQueueMain.dump(q.fileAbsolutePath());

    }
}

输出如下

--- !!meta-data #binary
header: !SCQStore {
  writePosition: [
    131328,
    564049465049088
  ],
  indexing: !SCQSIndexing {
    indexCount: !short 8192,
    indexSpacing: 64,
    index2Index: 184,
    lastIndex: 64
  }
}

# position: 184, header: -1
--- !!meta-data #binary
index2index: [
  # length: 8192, used: 1
  65760 # truncated trailing zeros
]
# position: 65760, header: -1
--- !!meta-data #binary
index: [
  # length: 8192, used: 1
  131328 # truncated trailing zeros
]
# position: 131328, header: 0
--- !!data #binary
"": lastx

...
# 83754737 bytes remaining

--- !!meta-data #binary
header: !STStore {
  wireType: !WireType BINARY_LIGHT,
  recovery: !TimedStoreRecovery {
    timeStamp: 0
  },
  metadata: !SCQMeta {
    roll: !SCQSRoll { length: !int 86400000, format: yyyyMMdd, epoch: 0 },
    deltaCheckpointInterval: 64,
    sourceId: 0
  }
}

# position: 225, header: 0
--- !!data #binary
listing.highestCycle: 17780

# position: 264, header: 1
--- !!data #binary
listing.lowestCycle: 17780

# position: 304, header: 2
--- !!data #binary
listing.modCount: 1

# position: 336, header: 3
--- !!data #binary
chronicle.write.lock: -9223372036854775808

# position: 376, header: 4
--- !!data #binary
chronicle.lastIndexReplicated: -1

# position: 432, header: 5
--- !!data #binary
chronicle.lastAcknowledgedIndexReplicated: -1

...
# 65044 bytes remaining

当.cq4文件的长度定义为

writePosition: [
    131328,
     ....
  ],

换句话说，131328 字节