suneet-s commented on a change in pull request #10685:
URL: https://github.com/apache/druid/pull/10685#discussion_r551655397
##########
File path:
processing/src/main/java/org/apache/druid/query/groupby/epinephelinae/ByteBufferMinMaxOffsetHeap.java
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@@ -59,6 +60,35 @@ public ByteBufferMinMaxOffsetHeap(
this.heapIndexUpdater = heapIndexUpdater;
}
+ public ByteBufferMinMaxOffsetHeap copy()
+ {
+ LimitedBufferHashGrouper.BufferGrouperOffsetHeapIndexUpdater updater =
+ Optional
+ .ofNullable(heapIndexUpdater)
+
.map(LimitedBufferHashGrouper.BufferGrouperOffsetHeapIndexUpdater::copy)
+ .orElse(null);
+
+ // deep copy buf
+ ByteBuffer buffer = ByteBuffer.allocateDirect(buf.capacity());
+
+ int bufPosition = buf.position();
+ int bufLimit = buf.limit();
+ buf.rewind();
+
+ buffer.put(buf);
+ buffer.position(bufPosition);
+ buffer.limit(bufLimit);
+
+ buf.position(bufPosition);
+ buf.limit(bufLimit);
Review comment:
nit: It seems like this should be moved in to a separate function since
it's used in 2 places. I tried a little googling, and didn't find any libraries
that implement deep copying of ByteBuffers which I thought was surprising.
Looking at an implementation I found in
http://www.java2s.com/example/java/java.nio/performs-a-deep-copy-on-a-byte-buffer.html,
it looks like this implementation does not copy the order of the original
ByteBuffer. I can't tell if this is important or not. What do you think?
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