org.apache.druid.frame.channel

Class ReadableByteChunksFrameChannel

java.lang.Object

org.apache.druid.frame.channel.ReadableByteChunksFrameChannel

All Implemented Interfaces:

Closeable, AutoCloseable, ReadableFrameChannel

public class ReadableByteChunksFrameChannel
extends Object
implements ReadableFrameChannel

Channel backed by a byte stream that is continuously streamed in using addChunk(byte[]). The byte stream must be in the format of a FrameFile. This class is used by FrameFileHttpResponseHandler to provide nonblocking reads from a remote http server.

Method Summary

Modifier and Type	Method and Description
com.google.common.util.concurrent.ListenableFuture<?>	addChunk(byte[] chunk) Adds a chunk of bytes.
boolean	canRead() Returns whether this channel has a frame or error condition currently available.
void	close() Releases any resources associated with this readable channel.
static ReadableByteChunksFrameChannel	create(String id) Create a channel that aims to limit its memory footprint to one frame.
void	doneWriting() Call method when caller is done adding chunks.
long	getBytesAdded()
String	getId()
boolean	isErrorOrFinished()
boolean	isFinished() Returns whether this channel is finished.
Frame	read() Returns the next available frame from this channel.
com.google.common.util.concurrent.ListenableFuture<?>	readabilityFuture() Returns a future that will resolve when either ReadableFrameChannel.isFinished() or ReadableFrameChannel.canRead() would return true.
void	setError(Throwable t) Clears the channel and replaces it with the given error.

Methods inherited from class java.lang.Object

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

Method Detail

create

public static ReadableByteChunksFrameChannel create(String id)

Create a channel that aims to limit its memory footprint to one frame. The channel exerts backpressure from addChunk(byte[]) immediately once a full frame has been buffered.

addChunk

@Nullable
public com.google.common.util.concurrent.ListenableFuture<?> addChunk(byte[] chunk)

Adds a chunk of bytes. If this chunk forms a full frame, it will immediately become available for reading. Otherwise, the bytes will be buffered until a full frame is encountered. Returns a backpressure future if the amount of queued bytes is at or above this channel's limit. If the return future is nonnull, callers are politely requested to wait for the future to resolve before adding additional chunks. (This is not enforced; addChunk will continue to accept new chunks even if the channel is over its limit.) When done adding chunks call doneWriting.

setError

public void setError(Throwable t)

Clears the channel and replaces it with the given error. After calling this method, no additional chunks will be accepted.

doneWriting

public void doneWriting()

Call method when caller is done adding chunks.

isFinished

public boolean isFinished()

Description copied from interface: ReadableFrameChannel

Returns whether this channel is finished. Finished channels will not generate any further frames or errors. Generally, once you discover that a channel is finished, you should call ReadableFrameChannel.close() and then discard it. Note that it is possible for a channel to be unfinished and also have no available frames or errors. This happens when it is not in a ready-for-reading state. See ReadableFrameChannel.readabilityFuture() for details.

Specified by:

isFinished in interface ReadableFrameChannel

canRead

public boolean canRead()

Description copied from interface: ReadableFrameChannel

Returns whether this channel has a frame or error condition currently available. If this method returns true, then you can call ReadableFrameChannel.read() to retrieve the frame or error. Note that it is possible for a channel to be unfinished and also have no available frames or errors. This happens when it is not in a ready-for-reading state. See ReadableFrameChannel.readabilityFuture() for details.

Specified by:

canRead in interface ReadableFrameChannel

read

public Frame read()

Description copied from interface: ReadableFrameChannel

Returns the next available frame from this channel. Before calling this method, you should check ReadableFrameChannel.canRead() to ensure there is a frame or error available.

Specified by:

read in interface ReadableFrameChannel

readabilityFuture

public com.google.common.util.concurrent.ListenableFuture<?> readabilityFuture()

Description copied from interface: ReadableFrameChannel

Returns a future that will resolve when either ReadableFrameChannel.isFinished() or ReadableFrameChannel.canRead() would return true. The future will never resolve to an exception. If something exceptional has happened, the exception can be retrieved from ReadableFrameChannel.read().

Specified by:

readabilityFuture in interface ReadableFrameChannel

close

public void close()

Description copied from interface: ReadableFrameChannel

Releases any resources associated with this readable channel. After calling this, you should not call any other methods on the channel.

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Specified by:

close in interface ReadableFrameChannel

getId

public String getId()

getBytesAdded

public long getBytesAdded()

isErrorOrFinished

public boolean isErrorOrFinished()