I have a process function defined with these interfaces

public class MyProcessFunction<IN> extends ProcessFunction<IN, OUT> 
    implements CheckpointedFunction, ProcessingTimeCallback {...}

In snapshotState() method, I want to close files and emit the metadata about the closed files to downstream operator. it doesn't seem possible with snapshotState(FunctionSnapshotContext context) interface.

I can keep metadata in snapshot and restore them during recovery. but if there is no input record coming for a long time,  processElement(T value, Context ctx, Collector<DataFile> out) won't be called. Then I can't forward the restored data to downstream operator with guaranteed latency.

I can add a timer. but it doesn't seem that onProcessingTime(long timestamp) allows me to forward output to downstream operator either.

Thanks,
Steven