get some basic sampling going

1 files changed, 85 insertions, 0 deletions

diff --git a/kamon-core/src/main/scala/kamon/util/HexCodec.scala b/kamon-core/src/main/scala/kamon/util/HexCodec.scala
new file mode 100644
index 00000000..6e9dd2df
--- /dev/null
+++ b/kamon-core/src/main/scala/kamon/util/HexCodec.scala
@@ -0,0 +1,85 @@
+package kamon.util
+
+// Extracted from https://github.com/openzipkin/brave/blob/master/brave/src/main/java/brave/internal/HexCodec.java
+object HexCodec {
+  /**
+    * Parses a 1 to 32 character lower-hex string with no prefix into an unsigned long, tossing any
+    * bits higher than 64.
+    */
+  def lowerHexToUnsignedLong(lowerHex: String): Long = {
+    val length = lowerHex.length
+    if (length < 1 || length > 32) throw isntLowerHexLong(lowerHex)
+    // trim off any high bits
+    val beginIndex = if (length > 16) length - 16
+    else 0
+    lowerHexToUnsignedLong(lowerHex, beginIndex)
+  }
+
+  private def isntLowerHexLong(lowerHex: String) =
+    throw new NumberFormatException(lowerHex + " should be a 1 to 32 character lower-hex string with no prefix")
+
+  /**
+    * Parses a 16 character lower-hex string with no prefix into an unsigned long, starting at the
+    * spe index.
+    */
+  private def lowerHexToUnsignedLong(lowerHex: String, index: Int): Long = {
+    var i = index
+    var result = 0L
+    val endIndex = Math.min(index + 16, lowerHex.length)
+    while ( {
+      index < endIndex
+    }) {
+      val c = lowerHex.charAt(index)
+      result <<= 4
+      if (c >= '0' && c <= '9') result |= c - '0'
+      else if (c >= 'a' && c <= 'f') result |= c - 'a' + 10
+      else throw isntLowerHexLong(lowerHex)
+
+      {
+        i = i + 1; index - 1
+      }
+    }
+    result
+  }
+
+  /**
+    * Returns 16 or 32 character hex string depending on if {@code high} is zero.
+    */
+  private def toLowerHex(high: Long, low: Long): String = {
+    val result = new Array[Char](if (high != 0) 32 else 16)
+    var pos = 0
+    if (high != 0) {
+      writeHexLong(result, pos, high)
+      pos += 16
+    }
+    writeHexLong(result, pos, low)
+    new String(result)
+  }
+
+  /**
+    * Inspired by {@code okio.Buffer.writeLong}
+    */
+  def toLowerHex(v: Long): String = {
+    val data = new Array[Char](16)
+    writeHexLong(data, 0, v)
+    new String(data)
+  }
+
+  private def writeHexLong(data: Array[Char], pos: Int, v: Long): Unit = {
+    writeHexByte(data, pos + 0, ((v >>> 56L) & 0xff).toByte)
+    writeHexByte(data, pos + 2, ((v >>> 48L) & 0xff).toByte)
+    writeHexByte(data, pos + 4, ((v >>> 40L) & 0xff).toByte)
+    writeHexByte(data, pos + 6, ((v >>> 32L) & 0xff).toByte)
+    writeHexByte(data, pos + 8, ((v >>> 24L) & 0xff).toByte)
+    writeHexByte(data, pos + 10, ((v >>> 16L) & 0xff).toByte)
+    writeHexByte(data, pos + 12, ((v >>> 8L) & 0xff).toByte)
+    writeHexByte(data, pos + 14, (v & 0xff).toByte)
+  }
+
+  private val HEX_DIGITS = Array('0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f')
+
+  private def writeHexByte(data: Array[Char], pos: Int, b: Byte): Unit = {
+    data(pos + 0) = HEX_DIGITS((b >> 4) & 0xf)
+    data(pos + 1) = HEX_DIGITS(b & 0xf)
+  }
+}
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