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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.metric.instrument
import kamon.jsr166.LongAdder
trait Counter extends Instrument {
type SnapshotType = Counter.Snapshot
def increment(): Unit
def increment(times: Long): Unit
}
object Counter {
def apply(): Counter = new LongAdderCounter
def create(): Counter = apply()
trait Snapshot extends InstrumentSnapshot {
def count: Long
def merge(that: InstrumentSnapshot, context: CollectionContext): Counter.Snapshot
def scale(from: UnitOfMeasurement, to: UnitOfMeasurement): Counter.Snapshot
}
}
class LongAdderCounter extends Counter {
private val counter = new LongAdder
def increment(): Unit = counter.increment()
def increment(times: Long): Unit = {
if (times < 0)
throw new UnsupportedOperationException("Counters cannot be decremented")
counter.add(times)
}
def collect(context: CollectionContext): Counter.Snapshot = CounterSnapshot(counter.sumAndReset())
def cleanup: Unit = {}
}
case class CounterSnapshot(count: Long) extends Counter.Snapshot {
def merge(that: InstrumentSnapshot, context: CollectionContext): Counter.Snapshot = that match {
case CounterSnapshot(thatCount) ⇒ CounterSnapshot(count + thatCount)
case other ⇒ sys.error(s"Cannot merge a CounterSnapshot with the incompatible [${other.getClass.getName}] type.")
}
override def scale(from: UnitOfMeasurement, to: UnitOfMeasurement): Counter.Snapshot =
CounterSnapshot(from.tryScale(to)(count).toLong)
}
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