gianm commented on code in PR #18909:
URL: https://github.com/apache/druid/pull/18909#discussion_r2688246415
##########
processing/src/main/java/org/apache/druid/frame/channel/ReadableFrameChannel.java:
##########
@@ -20,54 +20,80 @@
package org.apache.druid.frame.channel;
import com.google.common.util.concurrent.ListenableFuture;
+import org.apache.druid.error.DruidException;
import org.apache.druid.frame.Frame;
+import org.apache.druid.query.rowsandcols.RowsAndColumns;
import java.io.Closeable;
+import java.util.NoSuchElementException;
/**
- * Interface for reading a sequence of frames. Supports nonblocking reads
through the {@link #canRead()} and
+ * Interface for reading a sequence of batches of data. Supports nonblocking
reads through the {@link #canRead()} and
* {@link #readabilityFuture()} methods.
*
* May be implemented using an in-memory queue, disk file, stream, etc.
*
* Channels implementing this interface are used by a single reader; they do
not support concurrent reads.
+ *
+ * Despite its name, instances of this class can typically return any {@link
RowsAndColumns} through the
+ * {@link #readRAC()} method.
*/
public interface ReadableFrameChannel extends Closeable
{
/**
- * Returns whether this channel is finished. Finished channels will not
generate any further frames or errors.
+ * Returns whether this channel is finished. Finished channels will not
generate any further data batches or errors.
*
* Generally, once you discover that a channel is finished, you should call
{@link #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 {@link
#readabilityFuture()} for details.
+ * Note that it is possible for a channel to be unfinished and also have no
available data batches or errors.
+ * This happens when it is not in a ready-for-reading state. See {@link
#readabilityFuture()} for details.
*/
boolean isFinished();
/**
- * Returns whether this channel has a frame or error condition currently
available. If this method returns true, then
- * you can call {@link #read()} to retrieve the frame or error.
+ * Returns whether this channel has a batch of data or error condition
currently available. If this method returns
+ * true, then you can call {@link #read()} or {@link #readRAC()} to retrieve
the batch or error.
*
- * Note that it is possible for a channel to be unfinished and also have no
available frames or errors. This happens
+ * Note that it is possible for a channel to be unfinished and also have no
available batches or errors. This happens
* when it is not in a ready-for-reading state. See {@link
#readabilityFuture()} for details.
*/
boolean canRead();
/**
- * Returns the next available frame from this channel.
+ * Returns the next available batch of data from this channel as a {@link
Frame}.
+ *
+ * Before calling this method, you should check {@link #canRead()} to ensure
there is a batch of data or
+ * error available.
+ *
+ * @throws NoSuchElementException if there is no batch currently available
+ * @throws DruidException if the available batch was not available
as a {@link Frame}
+ */
+ default Frame read()
+ {
+ final RowsAndColumns rac = readRAC();
+ final Frame frame = rac.as(Frame.class);
+ if (frame != null) {
+ return frame;
+ } else {
+ throw DruidException.defensive("Got RAC[%s] which is not a frame", rac);
+ }
+ }
+
+ /**
+ * Returns the next available batch of data from this channel as a {@link
RowsAndColumns}.
*
- * Before calling this method, you should check {@link #canRead()} to ensure
there is a frame or
+ * Before calling this method, you should check {@link #canRead()} to ensure
there is a batch of data or
* error available.
*
- * @throws java.util.NoSuchElementException if there is no frame currently
available
+ * @throws NoSuchElementException if there is no batch currently available
*/
- Frame read();
+ RowsAndColumns readRAC();
Review Comment:
Hmm, I'll just change it now.
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