1 files changed, 46 insertions, 0 deletions
diff --git a/kamon-core/src/main/scala/kamon/trace/Sampler.scala b/kamon-core/src/main/scala/kamon/trace/Sampler.scala
new file mode 100644
index 00000000..650592a5
--- /dev/null
+++ b/kamon-core/src/main/scala/kamon/trace/Sampler.scala
@@ -0,0 +1,46 @@
+package kamon.trace
+
+import java.util.concurrent.atomic.AtomicLong
+
+import kamon.NanoInterval
+import scala.concurrent.forkjoin.ThreadLocalRandom
+
+trait Sampler {
+  def shouldTrace: Boolean
+  def shouldReport(traceElapsedTime: NanoInterval): Boolean
+}
+
+object NoSampling extends Sampler {
+  def shouldTrace: Boolean = false
+  def shouldReport(traceElapsedTime: NanoInterval): Boolean = false
+}
+
+object SampleAll extends Sampler {
+  def shouldTrace: Boolean = true
+  def shouldReport(traceElapsedTime: NanoInterval): Boolean = true
+}
+
+class RandomSampler(chance: Int) extends Sampler {
+  require(chance > 0, "kamon.trace.random-sampler.chance cannot be <= 0")
+  require(chance <= 100, "kamon.trace.random-sampler.chance cannot be > 100")
+
+  def shouldTrace: Boolean = ThreadLocalRandom.current().nextInt(100) <= chance
+  def shouldReport(traceElapsedTime: NanoInterval): Boolean = true
+}
+
+class OrderedSampler(interval: Int) extends Sampler {
+  require(interval > 0, "kamon.trace.ordered-sampler.interval cannot be <= 0")
+
+  private val counter = new AtomicLong(0L)
+  def shouldTrace: Boolean = counter.incrementAndGet() % interval == 0
+  // TODO: find a more efficient way to do this, protect from long overflow.
+  def shouldReport(traceElapsedTime: NanoInterval): Boolean = true
+}
+
+class ThresholdSampler(thresholdInNanoseconds: Long) extends Sampler {
+  require(thresholdInNanoseconds > 0, "kamon.trace.threshold-sampler.minimum-elapsed-time cannot be <= 0")
+
+  def shouldTrace: Boolean = true
+  def shouldReport(traceElapsedTime: NanoInterval): Boolean = traceElapsedTime.nanos >= thresholdInNanoseconds
+}
+