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package kamon.newrelic
import java.lang.{ StringBuilder ⇒ JStringBuilder }
import spray.json._
import scala.annotation.tailrec
// We need a special treatment of / that needs to be escaped as \/ for New Relic to work properly with all metrics.
// Without this custom json printer the scoped metrics are not displayed in the site.
// format: OFF
trait NewRelicJsonPrinter extends CompactPrinter {
override def printString(s: String, sb: JStringBuilder) {
import NewRelicJsonPrinter._
@tailrec def firstToBeEncoded(ix: Int = 0): Int =
if (ix == s.length) -1 else if (requiresEncoding(s.charAt(ix))) ix else firstToBeEncoded(ix + 1)
sb.append('"')
firstToBeEncoded() match {
case -1 ⇒ sb.append(s)
case first ⇒
sb.append(s, 0, first)
@tailrec def append(ix: Int): Unit =
if (ix < s.length) {
s.charAt(ix) match {
case c if !requiresEncoding(c) => sb.append(c)
case '"' => sb.append("\\\"")
case '\\' => sb.append("\\\\")
case '/' => sb.append("\\/")
case '\b' => sb.append("\\b")
case '\f' => sb.append("\\f")
case '\n' => sb.append("\\n")
case '\r' => sb.append("\\r")
case '\t' => sb.append("\\t")
case x if x <= 0xF => sb.append("\\u000").append(Integer.toHexString(x))
case x if x <= 0xFF => sb.append("\\u00").append(Integer.toHexString(x))
case x if x <= 0xFFF => sb.append("\\u0").append(Integer.toHexString(x))
case x => sb.append("\\u").append(Integer.toHexString(x))
}
append(ix + 1)
}
append(first)
}
sb.append('"')
}
}
object NewRelicJsonPrinter extends NewRelicJsonPrinter {
def requiresEncoding(c: Char): Boolean =
// from RFC 4627
// unescaped = %x20-21 / %x23-5B / %x5D-10FFFF
c match {
case '"' ⇒ true
case '\\' ⇒ true
case '/' ⇒ true
case c ⇒ c < 0x20
}
}
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