yaooqinn opened a new pull request, #46952:
URL: https://github.com/apache/spark/pull/46952
### What changes were proposed in this pull request?
This PR optimizes the method of `Hex.hex(num: Long)` via:
- Strip hexing leading zeros
- Avoid array copy
### Why are the changes needed?
<!--
Please clarify why the changes are needed. For instance,
1. If you propose a new API, clarify the use case for a new API.
2. If you fix a bug, you can clarify why it is a bug.
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- Unit tests added
- Did a benchmark locally (30~50% speedup)
```scala
Hex Long Tests: Best Time(ms) Avg Time(ms)
Stdev(ms) Rate(M/s) Per Row(ns) Relative
------------------------------------------------------------------------------------------------------------------------
Legacy 1062 1094
16 9.4 106.2 1.0X
New 739 807
26 13.5 73.9 1.4X
```
```scala
object HexBenchmark extends BenchmarkBase {
override def runBenchmarkSuite(mainArgs: Array[String]): Unit = {
val N = 10_000_000
runBenchmark("Hex") {
val benchmark = new Benchmark("Hex Long Tests", N, 10, output = output)
val range = 1 to 12
benchmark.addCase("Legacy") { _ =>
(1 to N).foreach(x => range.foreach(y => hexLegacy(x - y)))
}
benchmark.addCase("New") { _ =>
(1 to N).foreach(x => range.foreach(y => Hex.hex(x - y)))
}
benchmark.run()
}
}
def hexLegacy(num: Long): UTF8String = {
// Extract the hex digits of num into value[] from right to left
val value = new Array[Byte](16)
var numBuf = num
var len = 0
do {
len += 1
// Hex.hexDigits need to be seen here
value(value.length - len) = Hex.hexDigits((numBuf & 0xF).toInt)
numBuf >>>= 4
} while (numBuf != 0)
UTF8String.fromBytes(java.util.Arrays.copyOfRange(value, value.length -
len, value.length))
}
}
```
### Does this PR introduce _any_ user-facing change?
no
### How was this patch tested?
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### Was this patch authored or co-authored using generative AI tooling?
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