basic ring buffer search/retrieval procedure

package com.fnordmetric.enterprise

import scala.collection.mutable.ListBuffer

case class MetricKey(key: String, mode: String, flush_interval: Long)

class Metric(key: MetricKey) {

  def flush_rbuf = this.synchronized {

    val flush_range = rbuf.size - rbuf_seek_pos

    // FIXPAUL: wrong order!

    for (sample <- rbuf.tail(flush_range))

      swap.put(sample._1, sample._2)

  // returns all aggregated values for this metric in the specified time

  // range. if time1 is 0 then only the first value at time0 is returned

  // note that time0 > time1! this method is threadsafe

  def values_in(time0: Long, time1: Long) : List[(Long, Double)] = {

    val lst = List[(Long, Double)]()

    val lst = ListBuffer[(Long, Double)]()

    var found_start : Long = 0

    // FIXPAUL: skip!

    val rbuf_snap = rbuf.tail(rbuf.size)

    var rbuf_last : Long = java.lang.Long.MAX_VALUE

    var rbuf_pos = 0

    // search our rbuf snapshot backwards

    while (rbuf_pos > 0 && rbuf_pos < rbuf_snap.size) {

      val cur = rbuf_snap(rbuf_pos)

      // since the snapshot is not atomic, we need to check if we hit

      // rbuf wrap and exit if so

      if (cur._1 < rbuf_last)

        rbuf_last = cur._1

      else

        rbuf_pos = -1

      // if we are already beyond time1 we can exit

      if (time1 != 0 && (cur._1 < time1))

        rbuf_pos = -1

      // if we are only looking for a single value and already beyond time0

      // plus flush_interval and didnt find a value yet, we can exit

      if (time1 == 0 && (cur._1 < (time0 + key.flush_interval)))

        rbuf_pos = -1

      // continues only if we didn't hit the buffer wrap

      if (rbuf_pos > 0) {

        // check if we found the start of the range yet

        if (cur._1 <= time0 && ((cur._1 >= time1) || time1 == 0)) {

          // collect all matching items

          lst += cur

          if (found_start == 0)

            found_start = cur._1

          // if we are looking only for a single value we can exit now

          if (time1 == 0)

            rbuf_pos = -1

        }

      }

    }

    // exit if we have already seen the whole time range and don't need to

    // search the swapfile anymore

    if (rbuf_last <= time1)

      return lst.toList

    // here be dragons

    // FIXPAUL: here be dragons -> search in swapfile

    println("SEARCH_SWPFILE")

    lst

    lst.toList

  }

}