org.apache.flink.runtime.io

接口 PullingAsyncDataInput<T>

所有超级接口:

AvailabilityProvider

所有已知实现类:

IndexedInputGate, InputGate, InputGateWithMetrics, SingleInputGate, UnionInputGate

@Internal
public interface PullingAsyncDataInput<T>
extends AvailabilityProvider

Interface defining couple of essential methods for asynchronous and non blocking data polling.

For the most efficient usage, user of this class is supposed to call pollNext() until it returns that no more elements are available. If that happens, he should check if input isFinished(). If not, he should wait for AvailabilityProvider.getAvailableFuture() CompletableFuture to be completed. For example:

 AsyncDataInput<T> input = ...;
 while (!input.isFinished()) {
 	Optional<T> next;

 	while (true) {
 		next = input.pollNext();
 		if (!next.isPresent()) {
 			break;
 		}
 		// do something with next
 	}

 	input.getAvailableFuture().get();
 }
 

嵌套类概要

嵌套类

限定符和类型	接口和说明
static class	PullingAsyncDataInput.EndOfDataStatus Status for describing if we have reached the end of data.

从接口继承的嵌套类/接口 org.apache.flink.runtime.io.AvailabilityProvider

AvailabilityProvider.AvailabilityHelper

字段概要

从接口继承的字段 org.apache.flink.runtime.io.AvailabilityProvider

AVAILABLE

方法概要

限定符和类型	方法和说明
PullingAsyncDataInput.EndOfDataStatus	hasReceivedEndOfData() Tells if we consumed all available data.
boolean	isFinished()
Optional<T>	pollNext() Poll the next element.

从接口继承的方法 org.apache.flink.runtime.io.AvailabilityProvider

and, getAvailableFuture, isApproximatelyAvailable, isAvailable, or

方法详细资料

pollNext

Optional<T> pollNext()
              throws Exception

Poll the next element. This method should be non blocking.

返回:

Optional.empty() will be returned if there is no data to return or if isFinished() returns true. Otherwise Optional.of(element).

抛出:

Exception

isFinished

boolean isFinished()

返回:

true if is finished and for example end of input was reached, false otherwise.

hasReceivedEndOfData

PullingAsyncDataInput.EndOfDataStatus hasReceivedEndOfData()

Tells if we consumed all available data.

Moreover it tells us the reason why there is no more data incoming. If any of the upstream subtasks finished because of the stop-with-savepoint --no-drain, we should not drain the input. See also StopMode.