Package org.apache.druid.frame.processor

Class FrameChannelBatcher

java.lang.Object

org.apache.druid.frame.processor.FrameChannelBatcher

All Implemented Interfaces:

FrameProcessor<Pair<List<Frame>,it.unimi.dsi.fastutil.ints.IntSet>>

public class FrameChannelBatcher
extends Object
implements FrameProcessor<Pair<List<Frame>,it.unimi.dsi.fastutil.ints.IntSet>>

Processor that reads up to "maxFrames" frames from some input channels and combines them into a batch. There may be frames left over in the channels when the worker is done. Returns the batch and the set of channels that have more left to read. This processor does not close its input channels. The caller should do that after all input channels are finished.

Constructor Summary

Constructors

Constructor	Description
FrameChannelBatcher(List<ReadableFrameChannel> channels, int maxFrames)

Method Summary

Modifier and Type	Method	Description
void	cleanup()	Closes resources used by this worker.
List<ReadableFrameChannel>	inputChannels()	List of input channels.
List<WritableFrameChannel>	outputChannels()	List of output channels.
ReturnOrAwait<Pair<List<Frame>,it.unimi.dsi.fastutil.ints.IntSet>>	runIncrementally(it.unimi.dsi.fastutil.ints.IntSet readableInputs)	Runs some of the algorithm, without blocking, and either returns a value or a set of input channels to wait for.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

FrameChannelBatcher

public FrameChannelBatcher(List<ReadableFrameChannel> channels,
                           int maxFrames)

Method Detail

inputChannels

public List<ReadableFrameChannel> inputChannels()

Description copied from interface: FrameProcessor

List of input channels. The positions of channels in this list are used to build the readableInputs set provided to FrameProcessor.runIncrementally(it.unimi.dsi.fastutil.ints.IntSet).

Specified by:

inputChannels in interface FrameProcessor<Pair<List<Frame>,it.unimi.dsi.fastutil.ints.IntSet>>

outputChannels

public List<WritableFrameChannel> outputChannels()

Description copied from interface: FrameProcessor

List of output channels.

Specified by:

outputChannels in interface FrameProcessor<Pair<List<Frame>,it.unimi.dsi.fastutil.ints.IntSet>>

runIncrementally

public ReturnOrAwait<Pair<List<Frame>,it.unimi.dsi.fastutil.ints.IntSet>> runIncrementally(it.unimi.dsi.fastutil.ints.IntSet readableInputs)

Description copied from interface: FrameProcessor

Runs some of the algorithm, without blocking, and either returns a value or a set of input channels to wait for. This method is called by FrameProcessorExecutor.runFully(org.apache.druid.frame.processor.FrameProcessor<T>, java.lang.String) when all output channels are writable. Therefore, it is guaranteed that each output channel can accept at least one frame. This method must not read more than one frame from each readable input channel, and must not write more than one frame to each output channel.

Specified by:

runIncrementally in interface FrameProcessor<Pair<List<Frame>,it.unimi.dsi.fastutil.ints.IntSet>>

Parameters:

readableInputs - channels from FrameProcessor.inputChannels() that are either finished or ready to read. That is: either ReadableFrameChannel.isFinished() or ReadableFrameChannel.canRead() are true.

Returns:

either a final return value or a set of input channels to wait for. Must be nonnull.

cleanup

public void cleanup()

Description copied from interface: FrameProcessor

Closes resources used by this worker. Exact same concept as Closeable.close(). This interface does not extend Closeable, in order to make it easier to find all places where cleanup happens. (Static analysis tools can lose the thread when Closeables are closed in generic ways.) Implementations typically call ReadableFrameChannel.close() and WritableFrameChannel.close() on all input and output channels, as well as releasing any additional resources that may be held, such as FrameWriter. In cases of cancellation, this method may be called even if FrameProcessor.runIncrementally(it.unimi.dsi.fastutil.ints.IntSet) has not yet returned a result via ReturnOrAwait.returnObject(T).

Specified by:

cleanup in interface FrameProcessor<Pair<List<Frame>,it.unimi.dsi.fastutil.ints.IntSet>>