UUID.fromString improvements

jsoniter-scala-benchmark/src/main/scala/com/github/plokhotnyuk/jsoniter_scala/benchmark/ArrayOfUUIDsBenchmark.scala

@@ -9,13 +9,17 @@ abstract class ArrayOfUUIDsBenchmark extends CommonParams {
   @Param(Array("1", "10", "100", "1000", "10000", "100000", "1000000"))
   var size: Int = 1000
   var obj: Array[UUID] = _
+  var strings: Array[String] = _
+  var res: Array[UUID] = _
   var jsonString: String = _
   var jsonBytes: Array[Byte] = _
   var preallocatedBuf: Array[Byte] = _
 
   @Setup
   def setup(): Unit = {
     obj = (1 to size).map(i => new UUID(i * 6971258582664805397L, i * 6971258582664805397L)).toArray
+    strings = obj.map(_.toString)
+    res = new Array[UUID](size)
     jsonString = obj.mkString("[\"", "\",\"", "\"]")
     jsonBytes = jsonString.getBytes(UTF_8)
     preallocatedBuf = new Array[Byte](jsonBytes.length + 100/*to avoid possible out of bounds error*/)

jsoniter-scala-benchmark/src/main/scala/com/github/plokhotnyuk/jsoniter_scala/benchmark/ArrayOfUUIDsReading.scala

@@ -49,4 +49,101 @@ class ArrayOfUUIDsReading extends ArrayOfUUIDsBenchmark {
 
   @Benchmark
   def weePickle(): Array[UUID] = FromJson(jsonBytes).transform(ToScala[Array[UUID]])
+
+  @Benchmark
+  def javaCopy(): Array[UUID] = {
+    val len = res.length
+    var i = 0
+    while (i < len) {
+      res(i) = obj(i)
+      i += 1
+    }
+    res
+  }
+
+  @Benchmark
+  def javaOrig(): Array[UUID] = {
+    val len = res.length
+    var i = 0
+    while (i < len) {
+      res(i) = UUID.fromString(strings(i))
+      i += 1
+    }
+    res
+  }
+
+  @Benchmark
+  def javaFast(): Array[UUID] = {
+    val len = res.length
+    var i = 0
+    while (i < len) {
+      res(i) = fromString(strings(i))
+      i += 1
+    }
+    res
+  }
+
+  def fromString(name: String): UUID = {
+    val ns = nibbles
+    var msb, lsb = 0L
+    if (name.length == 36 && {
+      val ch1: Long = name.charAt(8)
+      val ch2: Long = name.charAt(13)
+      val ch3: Long = name.charAt(18)
+      val ch4: Long = name.charAt(23)
+      (ch1 << 48 | ch2 << 32 | ch3 << 16 | ch4) == 0x2D002D002D002DL
+    } && {
+      val msb1 = parse4Nibbles(name, ns, 0)
+      val msb2 = parse4Nibbles(name, ns, 4)
+      val msb3 = parse4Nibbles(name, ns, 9)
+      val msb4 = parse4Nibbles(name, ns, 14)
+      msb = msb1 << 48 | msb2 << 32 | msb3 << 16 | msb4
+      (msb1 | msb2 | msb3 | msb4) >= 0
+    } && {
+      val lsb1 = parse4Nibbles(name, ns, 19)
+      val lsb2 = parse4Nibbles(name, ns, 24)
+      val lsb3 = parse4Nibbles(name, ns, 28)
+      val lsb4 = parse4Nibbles(name, ns, 32)
+      lsb = lsb1 << 48 | lsb2 << 32 | lsb3 << 16 | lsb4
+      (lsb1 | lsb2 | lsb3 | lsb4) >= 0
+    }) new UUID(msb, lsb)
+    else UUID.fromString(name)
+  }
+
+  private[this] def parse4Nibbles(name: String, ns: Array[Byte], pos: Int): Long = {
+    val ch1 = name.charAt(pos)
+    val ch2 = name.charAt(pos + 1)
+    val ch3 = name.charAt(pos + 2)
+    val ch4 = name.charAt(pos + 3)
+    if ((ch1 | ch2 | ch3 | ch4) > 0xFF) -1
+    else ns(ch1) << 12 | ns(ch2) << 8 | ns(ch3) << 4 | ns(ch4)
+  }
+
+  private final val nibbles: Array[Byte] = {
+    val ns = new Array[Byte](256)
+    java.util.Arrays.fill(ns, -1: Byte)
+    ns('0') = 0
+    ns('1') = 1
+    ns('2') = 2
+    ns('3') = 3
+    ns('4') = 4
+    ns('5') = 5
+    ns('6') = 6
+    ns('7') = 7
+    ns('8') = 8
+    ns('9') = 9
+    ns('A') = 10
+    ns('B') = 11
+    ns('C') = 12
+    ns('D') = 13
+    ns('E') = 14
+    ns('F') = 15
+    ns('a') = 10
+    ns('b') = 11
+    ns('c') = 12
+    ns('d') = 13
+    ns('e') = 14
+    ns('f') = 15
+    ns
+  }
 }

jsoniter-scala-benchmark/src/test/scala/com/github/plokhotnyuk/jsoniter_scala/benchmark/ArrayOfUUIDsReadingSpec.scala

@@ -13,6 +13,9 @@ class ArrayOfUUIDsReadingSpec extends BenchmarkSpecBase {
       benchmark.dslJsonScala() shouldBe benchmark.obj
       benchmark.jacksonScala() shouldBe benchmark.obj
       benchmark.jsoniterScala() shouldBe benchmark.obj
+      benchmark.javaCopy() shouldBe benchmark.obj
+      benchmark.javaOrig() shouldBe benchmark.obj
+      benchmark.javaFast() shouldBe benchmark.obj
       benchmark.playJson() shouldBe benchmark.obj
       benchmark.sprayJson() shouldBe benchmark.obj
       benchmark.uPickle() shouldBe benchmark.obj