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[CASSANDRA-21399][trunk] Avoid megamorphic call overhead at org.apache.cassandra.io.util.RandomAccessReader#current #4839

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[CASSANDRA-21399][trunk] Avoid megamorphic call overhead at org.apache.cassandra.io.util.RandomAccessReader#current #4839

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4 changes: 2 additions & 2 deletions src/java/org/apache/cassandra/index/sai/disk/v1/vector/RandomAccessReaderAdapter.java
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Original file line number Diff line number Diff line change
Expand Up @@ -46,7 +46,7 @@ static ReaderSupplier createSupplier(FileHandle fileHandle)
@Override
public void readFully(float[] dest) throws IOException
{
BufferHolder bh = bufferHolder;
BufferHolder bh = getBufferHolder();
long position = getPosition();

FloatBuffer floatBuffer;
Expand Down Expand Up @@ -94,7 +94,7 @@ public void read(int[] dest, int offset, int count) throws IOException
if (count == 0)
return;

BufferHolder bh = bufferHolder;
BufferHolder bh = getBufferHolder();
long position = getPosition();

IntBuffer intBuffer;
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18 changes: 14 additions & 4 deletions src/java/org/apache/cassandra/io/util/RandomAccessReader.java
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Expand Up @@ -38,7 +38,9 @@ public class RandomAccessReader extends RebufferingInputStream implements FileDa
private long markedPointer;

final Rebufferer rebufferer;
protected BufferHolder bufferHolder = Rebufferer.EMPTY;
private BufferHolder bufferHolder = Rebufferer.EMPTY;
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@netudima netudima May 25, 2026

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I've made it private to avoid modifying the value in subclasses without updating the paired bufferHolderOffset value

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@smiklosovic smiklosovic May 26, 2026

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document this in the code explicitly, not just by commenting here


private long bufferHolderOffset = 0;

/**
* Only created through Builder
Expand Down Expand Up @@ -67,7 +69,9 @@ private void reBufferAt(long position)
bufferHolder.release();
bufferHolder = rebufferer.rebuffer(position);
buffer = bufferHolder.buffer();
buffer.position(Ints.checkedCast(position - bufferHolder.offset()));
long newOffset = bufferHolder.offset();
bufferHolderOffset = newOffset;
buffer.position(Ints.checkedCast(position - newOffset));

assert buffer.order() == ByteOrder.BIG_ENDIAN : "Buffer must have BIG ENDIAN byte ordering";
}
Expand All @@ -80,9 +84,14 @@ public long getFilePointer()
return current();
}

protected BufferHolder getBufferHolder()
{
return bufferHolder;
}

protected long current()
{
return bufferHolder.offset() + buffer.position();
return bufferHolderOffset + buffer.position();
}

public String getPath()
Expand Down Expand Up @@ -164,6 +173,7 @@ public void close()
rebufferer.closeReader();
buffer = null;
bufferHolder = null;
bufferHolderOffset = 0;

//For performance reasons we don't keep a reference to the file
//channel so we don't close it
Expand Down Expand Up @@ -197,7 +207,7 @@ public void seek(long newPosition)
if (buffer == null)
throw new IllegalStateException("Attempted to seek in a closed RAR");

long bufferOffset = bufferHolder.offset();
long bufferOffset = bufferHolderOffset;
if (newPosition >= bufferOffset && newPosition < bufferOffset + buffer.limit())
{
buffer.position((int) (newPosition - bufferOffset));
Expand Down