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/*
* =========================================================================================
* 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())
}
}
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