com.metamx.tranquility.finagle.DruidTaskResolver.scala Maven / Gradle / Ivy

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/*
 * Licensed to Metamarkets Group Inc. (Metamarkets) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  Metamarkets licenses this file
 * to you 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 com.metamx.tranquility.finagle

import com.google.common.util.concurrent.ThreadFactoryBuilder
import com.metamx.common.scala.Logging
import com.metamx.common.scala.timekeeper.Timekeeper
import com.metamx.tranquility.druid.IndexService
import com.twitter.finagle.Addr
import com.twitter.finagle.Resolver
import com.twitter.util.Await
import com.twitter.util.Closable
import com.twitter.util.Future
import com.twitter.util.Time
import com.twitter.util.Updatable
import com.twitter.util.Var
import java.util.concurrent.Executors
import java.util.concurrent.atomic.AtomicBoolean
import java.util.concurrent.atomic.AtomicLong
import java.util.concurrent.atomic.AtomicReference
import org.scala_tools.time.Imports._
import scala.util.Random
import scala.util.control.NonFatal

class DruidTaskResolver(
  indexService: IndexService,
  timekeeper: Timekeeper,
  pollPeriod: Period
) extends Resolver with Logging
{
  private val pollExecutor = Executors.newSingleThreadExecutor(
    new ThreadFactoryBuilder().setNameFormat(s"DruidTaskResolver[$indexService]").setDaemon(true).build()
  )

  private val started      = new AtomicBoolean
  private val taskNumberer = new AtomicLong

  private val lock     = new AnyRef
  private var nextPoll = 0L
  private var tasks    = Map[Long, (String, AtomicReference[Addr], Updatable[Addr])]()

  private def ensureStarted() {
    if (started.compareAndSet(false, true)) {
      log.info(s"Starting poll thread for indexService[$indexService], pollPeriod[$pollPeriod].")
      pollExecutor.submit(
        new Runnable
        {
          override def run(): Unit = {
            while (!Thread.currentThread().isInterrupted) {
              try {
                val tasksSnapshot: Map[Long, (String, AtomicReference[Addr], Updatable[Addr])] = lock.synchronized {
                  while (timekeeper.now.millis < nextPoll) {
                    val waitMillis = nextPoll - timekeeper.now.millis
                    if (waitMillis > 0) {
                      lock.wait(waitMillis)
                    }
                  }
                  tasks
                }

                val now = timekeeper.now
                val baseWait = now.plus(pollPeriod).millis - now.millis
                val fuzzyWait = (math.max(1 + 0.25 * Random.nextGaussian, 0) * baseWait).toLong
                nextPoll = now.millis + fuzzyWait

                val running = Await.result(indexService.runningTasks())

                log.debug(s"Polled[$indexServiceKey] and found ${running.size} tasks " +
                  s"(${running.count(_._2.isBound)} bound).")

                for ((taskNumber, (taskId, addr, updatable)) <- tasksSnapshot) {
                  val runningHostPort = running.get(taskId)
                  val runningAddr: Addr = runningHostPort.map(_.toAddr).getOrElse(Addr.Neg)
                  if (addr.get() != runningAddr) {
                    log.info(s"Updating location for task[$taskId] (#$taskNumber) to[$runningAddr].")
                    addr.set(runningAddr)
                    updatable.update(runningAddr)
                  }
                }
              }
              catch {
                case NonFatal(e) =>
                  log.warn(e, s"Poll failed, trying again at[${new DateTime(nextPoll)}].")
              }
            }
          }
        }
      )
    }
  }

  override val scheme = DruidTaskResolver.mkscheme(indexService.key)

  override def bind(taskId: String) = {
    val taskNumber = taskNumberer.incrementAndGet()

    Var.async[Addr](Addr.Pending) {
      updatable =>
        log.info(s"Started monitoring task[$taskId] (#$taskNumber).")

        lock.synchronized {
          nextPoll = 0L
          tasks = tasks + (taskNumber ->(taskId, new AtomicReference[Addr], updatable))
          lock.notifyAll()
        }

        ensureStarted()
        new Closable
        {
          override def close(deadline: Time): Future[Unit] = {
            lock.synchronized {
              log.info(s"Stopped monitoring task[$taskId] (#$taskNumber).")
              tasks = tasks - taskNumber
              Future.Done
            }
          }
        }
    }
  }

  def indexServiceKey: String = indexService.key
}

object DruidTaskResolver
{
  def mkscheme(indexServiceKey: String) = s"druidTask!$indexServiceKey"
}