org.apache.druid.frame.channel

Interface WritableFrameChannel

All Superinterfaces:

AutoCloseable, Closeable

All Known Implementing Classes:

WritableFrameFileChannel

public interface WritableFrameChannel
extends Closeable

Interface for writing a sequence of frames. Supports nonblocking writes through the writabilityFuture() method. May be implemented using an in-memory queue, disk file, stream, etc. Channels implementing this interface are used by a single writer; they do not support concurrent writes.

Method Summary

Modifier and Type	Method and Description
void	close() Finish writing to this channel.
void	fail(Throwable cause) Called prior to close() if the writer has failed.
com.google.common.util.concurrent.ListenableFuture<?>	writabilityFuture() Returns a future that resolves when write(org.apache.druid.frame.channel.FrameWithPartition) is able to receive a new frame without blocking or throwing an exception.
default void	write(Frame frame) Writes a frame without an attached partition number.
void	write(FrameWithPartition frameWithPartition) Writes a frame with an attached partition number.

Method Detail

write

void write(FrameWithPartition frameWithPartition)
    throws IOException

Writes a frame with an attached partition number. May throw an exception if writabilityFuture() is unresolved.

Throws:

IOException

write

default void write(Frame frame)
            throws IOException

Writes a frame without an attached partition number. May throw an exception if writabilityFuture() is unresolved.

Throws:

IOException

fail

void fail(@Nullable
          Throwable cause)
   throws IOException

Called prior to close() if the writer has failed. Must be followed by a call to close().

Parameters:

cause - optional cause of failure. Used by the in-memory channel BlockingQueueFrameChannel.Writable to propagate exeptions to downstream processors. Most other channels ignore the provided cause.

Throws:

IOException

close

void close()
    throws IOException

Finish writing to this channel. When this method is called without fail(Throwable) having previously been called, the writer is understood to have completed successfully. After calling this method, no additional calls to write(org.apache.druid.frame.channel.FrameWithPartition), fail(Throwable), or this method are permitted.

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Throws:

IOException

writabilityFuture

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

Returns a future that resolves when write(org.apache.druid.frame.channel.FrameWithPartition) is able to receive a new frame without blocking or throwing an exception. The future never resolves to an exception.