Revert "Changed the query Timeout behavior to only purge the Timer qu…

…eue intermittently."

On further inspection, we don't need to call purge() at all. We'll revert this, and remove
the call to purge in a future change.

This reverts commit 576bda7.

src/main/scala/com/twitter/querulous/Timeout.scala

@@ -1,49 +1,38 @@
 package com.twitter.querulous
 
 import java.util.{Timer, TimerTask}
-import java.util.concurrent.atomic.AtomicInteger
 import com.twitter.util.Duration
 import net.lag.logging.Logger
 
 
 class TimeoutException extends Exception
 
 object Timeout {
-  val defaultTimer = new Timer("Timer thread", true)
-  val defaultPurgeInterval = 1000  // TODO(benjy): Set from config?
-}
-
-class Timeout(timer: Timer, val purgeInterval: Int) {
-  def this(timer: Timer) = this(timer, Timeout.defaultPurgeInterval)
-  def this(purgeInterval: Int) = this(Timeout.defaultTimer, purgeInterval)
-  def this() = this(Timeout.defaultTimer, Timeout.defaultPurgeInterval)
-
   private val log = Logger.get(getClass.getName)
 
-  private var numTimeouts = new AtomicInteger(0)
+  val defaultTimer = new Timer("Timer thread", true)
 
-  def apply[T](timeout: Duration)(f: => T)(onTimeout: => Unit): T = {
-    @volatile var timedOut = false
+  def apply[T](timer: Timer, timeout: Duration)(f: => T)(onTimeout: => Unit): T = {
+    @volatile var cancelled = false
     val task = if (timeout.inMillis > 0)
-      Some(schedule(timer, timeout, { timedOut = true; numTimeouts.incrementAndGet(); onTimeout }))
+      Some(schedule(timer, timeout, { cancelled = true; onTimeout }))
     else None
 
     try {
       f
     } finally {
       task map { t =>
-        t.cancel()  // Cancel the timeout (regardless of whether it was reached or not).
-        // We purge intermittently, so that cancelled tasks can get garbage-collected.
-        // We don't want to purge on every cancel, as purge() is linear in the number
-        // of tasks scheduled in the timer, and is synchronized on the timer, so if
-        // many tasks are cancelled we end up with quadratic behavior.
-        if (numTimeouts.get() % purgeInterval == 0)
-          timer.purge()
+        t.cancel()
+        timer.purge()
       }
-      if (timedOut) throw new TimeoutException
+      if (cancelled) throw new TimeoutException
     }
   }
 
+  def apply[T](timeout: Duration)(f: => T)(onTimeout: => Unit): T = {
+    apply(defaultTimer, timeout)(f)(onTimeout)
+  }
+
   private def schedule(timer: Timer, timeout: Duration, f: => Unit) = {
     val task = new TimerTask() {
       override def run() {

src/main/scala/com/twitter/querulous/query/TimingOutQuery.scala

@@ -41,7 +41,6 @@ class PerQueryTimingOutQueryFactory(queryFactory: QueryFactory, val timeouts: Ma
 
 private object QueryCancellation {
   val cancelTimer = new java.util.Timer("global query cancellation timer", true)
-  val queryCanceller = new Timeout(cancelTimer)
 }
 
 /**
@@ -60,7 +59,7 @@ class TimingOutQuery(query: Query, connection: Connection, timeout: Duration, ca
 
   override def delegate[A](f: => A) = {
     try {
-      queryCanceller(timeout)(f) {
+      Timeout(cancelTimer, timeout)(f) {
         if (cancelOnTimeout) cancel()
         destroyConnection(connection)
       }

src/test/scala/com/twitter/querulous/integration/TimeoutSpec.scala

@@ -2,17 +2,16 @@ package com.twitter.querulous.integration
 
 import java.util.concurrent.CountDownLatch
 import org.specs.Specification
-import org.specs.mock.{JMocker, ClassMocker}
 import net.lag.configgy.Configgy
 import com.twitter.util.Time
 import com.twitter.util.TimeConversions._
-import com.twitter.querulous.{TestEvaluator, Timeout, TimeoutException}
+import com.twitter.querulous.TestEvaluator
 import com.twitter.querulous.database.ApachePoolingDatabaseFactory
 import com.twitter.querulous.query.{SqlQueryFactory, TimingOutQueryFactory, SqlQueryTimeoutException}
 import com.twitter.querulous.evaluator.{StandardQueryEvaluatorFactory, QueryEvaluator}
 
 
-class TimeoutSpec extends Specification with JMocker with ClassMocker {
+class TimeoutSpec extends Specification {
   Configgy.configure("config/test.conf")
 
   import TestEvaluator._
@@ -52,35 +51,5 @@ class TimeoutSpec extends Specification with JMocker with ClassMocker {
       thread.interrupt()
       thread.join()
     }
-
-    "purge intermittently" in {
-      val task = capturingParam[java.util.TimerTask]
-
-      class FakeTimer extends java.util.Timer  {
-        var numPurges = 0
-
-        // Ignore the timeout and run the task immediately, to force the appearance of a timeout.
-        override def schedule(task: java.util.TimerTask, timeout: Long) = task.run
-
-        override def purge = { numPurges += 1; 0}
-      }
-
-      val fakeTimer = new FakeTimer()
-      val fakeTimeout = new Timeout(fakeTimer, 3)
-
-      def forceTimeout(shouldPurge: Boolean) {
-        val purgesBefore = fakeTimer.numPurges
-        fakeTimeout(1.second)(1)(()) must throwA[TimeoutException]
-        val purgesAfter = fakeTimer.numPurges
-        shouldPurge == (purgesAfter != purgesBefore) must beTrue
-      }
-
-      forceTimeout(false)
-      forceTimeout(false)
-      forceTimeout(true)
-      forceTimeout(false)
-      forceTimeout(false)
-      forceTimeout(true)
-    }
   }
 }