io.fsq.twitter.ostrich.stats.Metric.scala Maven / Gradle / Ivy

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Light fork of com.twitter.ostrich Stats module, for use in Foursquare's Fsq.io.

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/*
 * Copyright 2009 Twitter, Inc.
 *
 * 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 io.fsq.twitter.ostrich.stats

import com.twitter.logging.Logger

/**
  * A Metric collates data points and can report a Distribution.
  */
class Metric {
  val log = Logger.get(getClass.getName)

  private var histogram = new Histogram()

  /**
    * Resets the state of this Metric. Clears all data points collected so far.
    */
  def clear() {
    histogram.clear()
  }

  /**
    * Adds a data point.
    */
  def add(n: Int): Long = {
    if (n > -1) {
      histogram.add(n)
    } else {
      log.debug("Tried to add a negative data point.")
      histogram.count
    }
  }

  /**
    * Add a summarized set of data points.
    */
  def add(distribution: Distribution): Long = synchronized {
    histogram.merge(distribution.histogram)
    histogram.count
  }

  override def clone(): Metric = {
    val rv = new Metric
    rv.histogram = histogram.clone()
    rv
  }

  /**
    * Returns a Distribution for this Metric.
    */
  def apply(): Distribution = synchronized { histogram() }
}