聊聊flink的ListCheckpointed

最新推荐文章于 2024-04-28 22:55:07 发布

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最新推荐文章于 2024-04-28 22:55:07 发布 · 854 阅读

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CC 4.0 BY-SA版权

本文深入探讨Flink中ListCheckpointed接口的实现原理，通过具体示例CounterSource，展示了如何通过该接口实现状态保存与恢复，确保Exactly-once语义。并详细解释了snapshotState和restoreState方法的作用。

本文主要研究一下flink的ListCheckpointed

实例

public static class CounterSource
        extends RichParallelSourceFunction<Long>
        implements ListCheckpointed<Long> {

    /**  current offset for exactly once semantics */
    private Long offset;

    /** flag for job cancellation */
    private volatile boolean isRunning = true;

    @Override
    public void run(SourceContext<Long> ctx) {
        final Object lock = ctx.getCheckpointLock();

        while (isRunning) {
            // output and state update are atomic
            synchronized (lock) {
                ctx.collect(offset);
                offset += 1;
            }
        }
    }

    @Override
    public void cancel() {
        isRunning = false;
    }

    @Override
    public List<Long> snapshotState(long checkpointId, long checkpointTimestamp) {
        return Collections.singletonList(offset);
    }

    @Override
    public