org.scalatest.concurrent.Timeouts.scala Maven / Gradle / Ivy
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/*
* Copyright 2001-2012 Artima, 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 org.scalatest.concurrent
import java.util.TimerTask
import java.util.Timer
import org.scalatest.exceptions.StackDepthExceptionHelper.getStackDepthFun
import org.scalatest.Resources
import org.scalatest.exceptions.StackDepthException
import java.nio.channels.ClosedByInterruptException
import java.nio.channels.Selector
import java.net.Socket
import org.scalatest.time.Span
import org.scalatest.exceptions.TestFailedDueToTimeoutException
/**
* Trait that provides a failAfter construct, which allows you to specify a time limit for an
* operation passed as a by-name parameter, as well as a way to interrupt it if the operation exceeds its time limit.
*
*
* The time limit is passed as the first parameter, as a Span. The operation is
* passed as the second parameter. And an Interruptor, a strategy for interrupting the operation, is
* passed as an implicit third parameter. Here's a simple example of its use:
*
*
*
* failAfter(Span(100, Millis)) {
* Thread.sleep(200)
* }
*
*
*
* The above code, after 100 milliseconds, will produce a TestFailedDueToTimeoutException with a message
* that indicates a timeout expired:
*
*
*
* The code passed to failAfter did not complete within 100 milliseconds.
*
*
*
* If you prefer you can mix in or import the members of SpanSugar and place a units value after the integer timeout.
* Here are some examples:
*
*
*
* import org.scalatest.time.SpanSugar._
*
* failAfter(100 millis) {
* Thread.sleep(200)
* }
*
* failAfter(1 second) {
* Thread.sleep(2000)
* }
*
*
*
* The code passed via the by-name parameter to failAfter will be executed by the thread that invoked
* failAfter, so that no synchronization is necessary to access variables declared outside the by-name.
*
*
*
* var result = -1 // No need to make this volatile
* failAfter(100 millis) {
* result = accessNetService()
* }
* result should be (99)
*
*
*
* The failAfter method will create a timer that runs on a different thread than the thread that
* invoked failAfter, so that it can detect when the timeout has expired and attempt to interrupt
* the main thread. Because different operations can require different interruption strategies, the failAfter
* method accepts an implicit third parameter of type Interruptor that is responsible for interrupting
* the main thread.
*
*
* Configuring failAfter with an Interruptor
*
*
* This trait declares an implicit val named defaultInterruptor,
* initialized with a ThreadInterruptor, which attempts to interrupt the main thread by invoking
* Thread.interrupt. If you wish to use a different strategy, you can override this val (or hide
* it, for example if you imported the members of Timeouts rather than mixing it in). Here's an example
* in which the default interruption method is changed to DoNotInterrupt, which does not attempt to
* interrupt the main thread in any way:
*
*
*
* override val defaultInterruptor = DoNotInterrupt
* failAfter(100 millis) {
* Thread.sleep(500)
* }
*
*
*
* As with the default Interruptor, the above code will eventually produce a
* TestFailedDueToTimeoutException with a message that indicates a timeout expired. However, instead
* of throwing the exception after approximately 100 milliseconds, it will throw it after approximately 500 milliseconds.
*
*
*
* This illustrates an important feature of failAfter: it will throw a TestFailedDueToTimeoutException
* if the code passed as the by-name parameter takes longer than the specified timeout to execute, even if it
* is allowed to run to completion beyond the specified timeout and returns normally.
*
*
*
* ScalaTest provides the following Interruptor implementations:
*
*
*
*
*
* Interruptor implementation
*
*
* Usage
*
*
*
*
* ThreadInterruptor
*
*
* The default interruptor, invokes interrupt on the main test thread. This will
* set the interrupted status for the main test thread and,
* if the main thread is blocked, will in some cases cause the main thread complete abruptly with
* an InterruptedException.
*
*
*
*
* DoNotInterrupt
*
*
* Does not attempt to interrupt the main test thread in any way
*
*
*
*
* SelectorInterruptor
*
*
* Invokes wakeup on the passed java.nio.channels.Selector, which
* will cause the main thread, if blocked in Selector.select, to complete abruptly with a
* ClosedSelectorException.
*
*
*
*
* SocketInterruptor
*
*
* Invokes close on the java.io.Socket, which
* will cause the main thread, if blocked in a read or write of an java.io.InputStream or
* java.io.OutputStream that uses the Socket, to complete abruptly with a
* SocketException.
*
*
*
*
*
* You may wish to create your own Interruptor in some situations. For example, if your operation is performing
* a loop and can check a volatile flag each pass through the loop. You could in that case write an Interruptor that
* sets that flag so that the next time around, the loop would exit.
*
*
* @author Chua Chee Seng
* @author Bill Venners
*/
trait Timeouts {
private class TimeoutTask(testThread: Thread, interrupt: Interruptor) extends TimerTask {
@volatile var timedOut = false
@volatile var needToResetInterruptedStatus = false
override def run() {
timedOut = true
val beforeIsInterrupted = testThread.isInterrupted()
interrupt(testThread)
val afterIsInterrupted = testThread.isInterrupted()
if(!beforeIsInterrupted && afterIsInterrupted)
needToResetInterruptedStatus = true
}
}
/**
* Implicit Interruptor value defining a default interruption strategy for the failAfter method.
*
*
* To change the default Interruptor configuration, override or hide this val with another implicit
* Interruptor.
*
*/
implicit val defaultInterruptor: Interruptor = ThreadInterruptor
/**
* Executes the passed function, enforcing the passed time limit by attempting to interrupt the function if the
* time limit is exceeded, and throwing TestFailedDueToTimeoutException if the time limit has been
* exceeded after the function completes.
*
*
* If the function completes before the timeout expires:
*
*
*
* - If the function returns normally, this method will return normally.
* - If the function completes abruptly with an exception, this method will complete abruptly with that same exception.
*
*
*
* If the function completes after the timeout expires:
*
*
*
* - If the function returns normally, this method will complete abruptly with a
TestFailedDueToTimeoutException.
* - If the function completes abruptly with an exception, this method will complete abruptly with a
TestFailedDueToTimeoutException that includes the exception thrown by the function as its cause.
*
*
*
* If the interrupted status of the main test thread (the thread that invoked failAfter) was not invoked
* when failAfter was invoked, but is set after the operation times out, it is reset by this method before
* it completes abruptly with a TestFailedDueToTimeoutException. The interrupted status will be set by
* ThreadInterruptor, the default Interruptor implementation.
*
*
* @param timeout the maximimum amount of time allowed for the passed operation
* @param fun the operation on which to enforce the passed timeout
* @param interruptor a strategy for interrupting the passed operation
*/
def failAfter[T](timeout: Span)(fun: => T)(implicit interruptor: Interruptor): T = {
timeoutAfter(
timeout,
fun,
interruptor,
t => new TestFailedDueToTimeoutException(
sde => Some(Resources("timeoutFailedAfter", timeout.prettyString)), t, getStackDepthFun("Timeouts.scala", "failAfter"), None, timeout
)
)
}
/* Uncomment for 2.0
def cancelAfter[T](timeout: Span)(f: => T)(implicit interruptor: Interruptor): T = {
timeoutAfter(timeout, f, interruptor, t => new TestCanceledException(sde => Some(Resources("timeoutCanceledAfter", timeout.toString)), t, getStackDepthFun("Timeouts.scala", "cancelAfter")))
}
*/
private def timeoutAfter[T](timeout: Span, f: => T, interruptor: Interruptor, exceptionFun: Option[Throwable] => StackDepthException): T = {
val timer = new Timer()
val task = new TimeoutTask(Thread.currentThread(), interruptor)
timer.schedule(task, timeout.totalNanos / 1000 / 1000) // TODO: Probably use a sleep so I can use nanos
try {
val result = f
timer.cancel()
if (task.timedOut) {
if (task.needToResetInterruptedStatus)
Thread.interrupted() // To reset the flag probably. He only does this if it was not set before and was set after, I think.
throw exceptionFun(None)
}
result
}
catch {
case t: Throwable =>
timer.cancel() // Duplicate code could be factored out I think. Maybe into a finally? Oh, not that doesn't work. So a method.
if(task.timedOut) {
if (task.needToResetInterruptedStatus)
Thread.interrupted() // Clear the interrupt status (There's a race condition here, but not sure we an do anything about that.)
throw exceptionFun(Some(t))
}
else
throw t
}
}
}
/**
* Companion object that facilitates the importing of Timeouts members as
* an alternative to mixing in the trait. One use case is to import Timeouts's members so you can use
* them in the Scala interpreter.
*/
object Timeouts extends Timeouts