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/* =========================================================================================
* Copyright © 2013-2017 the kamon project <http://kamon.io/>
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file
* except in compliance with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software distributed under the
* License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
* either express or implied. See the License for the specific language governing permissions
* and limitations under the License.
* =========================================================================================
*/
package kamon.trace
import java.net.{URLDecoder, URLEncoder}
import kamon.Kamon
import kamon.context.{Codec, Context, TextMap}
import kamon.trace.SpanContext.SamplingDecision
object SpanCodec {
class B3 extends Codec.ForEntry[TextMap] {
import B3.Headers
override def encode(context: Context): TextMap = {
val span = context.get(Span.ContextKey)
val carrier = TextMap.Default()
if(span.nonEmpty()) {
val spanContext = span.context
carrier.put(Headers.TraceIdentifier, urlEncode(spanContext.traceID.string))
carrier.put(Headers.SpanIdentifier, urlEncode(spanContext.spanID.string))
carrier.put(Headers.ParentSpanIdentifier, urlEncode(spanContext.parentID.string))
encodeSamplingDecision(spanContext.samplingDecision).foreach { samplingDecision =>
carrier.put(Headers.Sampled, samplingDecision)
}
}
carrier
}
override def decode(carrier: TextMap, context: Context): Context = {
val identityProvider = Kamon.tracer.identityProvider
val traceID = carrier.get(Headers.TraceIdentifier)
.map(id => identityProvider.traceIdGenerator().from(urlDecode(id)))
.getOrElse(IdentityProvider.NoIdentifier)
val spanID = carrier.get(Headers.SpanIdentifier)
.map(id => identityProvider.spanIdGenerator().from(urlDecode(id)))
.getOrElse(IdentityProvider.NoIdentifier)
if(traceID != IdentityProvider.NoIdentifier && spanID != IdentityProvider.NoIdentifier) {
val parentID = carrier.get(Headers.ParentSpanIdentifier)
.map(id => identityProvider.spanIdGenerator().from(urlDecode(id)))
.getOrElse(IdentityProvider.NoIdentifier)
val flags = carrier.get(Headers.Flags)
val samplingDecision = flags.orElse(carrier.get(Headers.Sampled)) match {
case Some(sampled) if sampled == "1" => SamplingDecision.Sample
case Some(sampled) if sampled == "0" => SamplingDecision.DoNotSample
case _ => SamplingDecision.Unknown
}
context.withKey(Span.ContextKey, Span.Remote(SpanContext(traceID, spanID, parentID, samplingDecision)))
} else context
}
private def encodeSamplingDecision(samplingDecision: SamplingDecision): Option[String] = samplingDecision match {
case SamplingDecision.Sample => Some("1")
case SamplingDecision.DoNotSample => Some("0")
case SamplingDecision.Unknown => None
}
private def urlEncode(s: String): String = URLEncoder.encode(s, "UTF-8")
private def urlDecode(s: String): String = URLDecoder.decode(s, "UTF-8")
}
object B3 {
def apply(): B3 =
new B3()
object Headers {
val TraceIdentifier = "X-B3-TraceId"
val ParentSpanIdentifier = "X-B3-ParentSpanId"
val SpanIdentifier = "X-B3-SpanId"
val Sampled = "X-B3-Sampled"
val Flags = "X-B3-Flags"
}
}
}
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