1 files changed, 101 insertions, 0 deletions
diff --git a/kamon-core/src/legacy-main/scala/kamon/trace/Sampler.scala b/kamon-core/src/legacy-main/scala/kamon/trace/Sampler.scala
new file mode 100644
index 00000000..234c67bb
--- /dev/null
+++ b/kamon-core/src/legacy-main/scala/kamon/trace/Sampler.scala
@@ -0,0 +1,101 @@
+/*
+ * =========================================================================================
+ * Copyright © 2013-2014 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.InetAddress
+import java.util.concurrent.atomic.AtomicLong
+import kamon.util.{NanoTimestamp, NanoInterval, Sequencer}
+import scala.concurrent.forkjoin.ThreadLocalRandom
+
+import scala.util.Try
+
+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 {
+  import OrderedSampler._
+
+  require(interval > 0, "kamon.trace.ordered-sampler.sample-interval cannot be <= 0")
+  assume(interval isPowerOfTwo, "kamon.trace.ordered-sampler.sample-interval must be power of two")
+
+  private val sequencer = Sequencer()
+
+  def shouldTrace: Boolean = (sequencer.next() fastMod interval) == 0
+  def shouldReport(traceElapsedTime: NanoInterval): Boolean = true
+}
+
+object OrderedSampler {
+  implicit class EnhancedInt(i: Int) {
+    def isPowerOfTwo = (i & (i - 1)) == 0
+  }
+
+  implicit class EnhancedLong(dividend: Long) {
+    def fastMod(divisor: Int) = dividend & (divisor - 1)
+  }
+}
+
+class ThresholdSampler(thresholdInNanoseconds: NanoInterval) extends Sampler {
+  require(thresholdInNanoseconds.nanos > 0, "kamon.trace.threshold-sampler.minimum-elapsed-time cannot be <= 0")
+
+  def shouldTrace: Boolean = true
+  def shouldReport(traceElapsedTime: NanoInterval): Boolean = traceElapsedTime >= thresholdInNanoseconds
+}
+
+class ClockSampler(pauseInNanoseconds: NanoInterval) extends Sampler {
+  require(pauseInNanoseconds.nanos > 0, "kamon.trace.clock-sampler.pause cannot be <= 0")
+
+  private val timer: AtomicLong = new AtomicLong(0L)
+
+  def shouldTrace: Boolean = {
+    val now = NanoTimestamp.now.nanos
+    val lastTimer = timer.get()
+    if ((lastTimer + pauseInNanoseconds.nanos) < now)
+      timer.compareAndSet(lastTimer, now)
+    else
+      false
+  }
+  def shouldReport(traceElapsedTime: NanoInterval): Boolean = true
+}
+
+class DefaultTokenGenerator extends Function0[String] {
+  private val _hostnamePrefix = Try(InetAddress.getLocalHost.getHostName).getOrElse("unknown-localhost")
+  private val _tokenCounter = new AtomicLong
+
+  def apply(): String = {
+    _hostnamePrefix + "-" + String.valueOf(_tokenCounter.incrementAndGet())
+  }
+}
+\ No newline at end of file