[HBASE-14120] ByteBufferUtils#compareTo small optimization

• Type: Sub-task
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 2.0.0
• Component/s: regionserver, Scanners
• Hadoop Flags: Reviewed
• Assignee: Anoop Sam John
• Reporter: Anoop Sam John
• Created: 18/Jul/15 14:35
• Updated: 17/Jun/22 05:25
• Resolved: 20/Jul/15 11:22

Description

We have it like

if (UnsafeAccess.isAvailable()) {
  long offset1Adj, offset2Adj;
  Object refObj1 = null, refObj2 = null;
  if (buf1.hasArray()) {
	offset1Adj = o1 + buf1.arrayOffset() + UnsafeAccess.BYTE_ARRAY_BASE_OFFSET;
	refObj1 = buf1.array();
  } else {
	offset1Adj = o1 + ((DirectBuffer) buf1).address();
  }
  if (buf2.hasArray()) {

Instead of hasArray() check we can have isDirect() check and reverse the if else block. Because we will be making BB backed cells when it is offheap BB. So when code reaches here for comparison, it will be direct BB.

Doing JMH test proves it.

Benchmark                            Mode  Cnt         Score         Error  Units
OnHeapVsOffHeapComparer.offheap     thrpt    4  50516432.643 ±  651828.103  ops/s
OnHeapVsOffHeapComparer.offheapOld  thrpt    4  37696698.093 ± 1121685.293  ops/s