Scala example source code file (Instrumentation.scala)

This example Scala source code file (Instrumentation.scala) is included in my "Source Code Warehouse" project. The intent of this project is to help you more easily find Scala source code examples by using tags.

All credit for the original source code belongs to scala-lang.org; I'm just trying to make examples easier to find. (For my Scala work, see my Scala examples and tutorials.)

Scala tags/keywords

boolean, instrumentation, int, map, method, methodcalltrace, ordering, statistics, string, unit

The Instrumentation.scala Scala example source code

/* NEST (New Scala Test)
 * Copyright 2007-2013 LAMP/EPFL
 * @author Grzegorz Kossakowski
 */

package scala.tools.partest.instrumented

import scala.collection.JavaConverters._

case class MethodCallTrace(className: String, methodName: String, methodDescriptor: String) {
  override def toString(): String = className + "." + methodName + methodDescriptor
}
object MethodCallTrace {
  implicit val ordering: Ordering[MethodCallTrace] = Ordering.by(x => (x.className, x.methodName, x.methodDescriptor))
}

/**
 * An object that controls profiling of instrumented byte-code. The instrumentation is achieved
 * by using `java.lang.instrument` package. The instrumentation agent can be found in
 * `scala.tools.partest.javaagent` package.
 *
 * At the moment the following classes are being instrumented:
 *   * all classes with empty package
 *   * all classes from scala package (except for classes responsible for instrumentation)
 *
 * The canonical way of using instrumentation is have a test-case in `files/instrumented` directory.
 * The following code in main:
 *
 * {{{
 * import scala.tools.partest.instrumented.Instrumentation._
 * def main(args: Array[String]): Unit = {
 *   startProfiling()
 *   // should box the boolean
    println(true)
    stopProfiling()
    printStatistics()
 * }
 * }}}
 *
 *
 * should print:
 *
 * {{{
 * true
 * Method call statistics:
 * scala/Predef$.println(Ljava/lang/Object;)V: 1
 * scala/runtime/BoxesRunTime.boxToBoolean(Z)Ljava/lang/Boolean;: 1
 * }}}
 */
object Instrumentation {

  type Statistics = Map[MethodCallTrace, Int]

  def startProfiling(): Unit = Profiler.startProfiling()
  def stopProfiling(): Unit = Profiler.stopProfiling()
  def resetProfiling(): Unit = Profiler.resetProfiling()
  def isProfiling(): Boolean = Profiler.isProfiling()

  def getStatistics: Statistics = {
    val isProfiling = Profiler.isProfiling()
    if (isProfiling) {
      Profiler.stopProfiling()
    }
    val stats = Profiler.getStatistics().asScala.toSeq.map {
      case (trace, count) => MethodCallTrace(trace.className, trace.methodName, trace.methodDescriptor) -> count.intValue
    }
    val res = Map(stats: _*)
    if (isProfiling) {
      Profiler.startProfiling()
    }
    res
  }

  val standardFilter: MethodCallTrace => Boolean = t => {
    // ignore all calls to Console trigger by printing
    t.className != "scala/Console$" &&
    // console accesses DynamicVariable, let's discard it too
    !t.className.startsWith("scala/util/DynamicVariable")
  }

  // Used in tests.
  def printStatistics(stats: Statistics = getStatistics, filter: MethodCallTrace => Boolean = standardFilter): Unit = {
    val stats = getStatistics
    println("Method call statistics:")
    val toBePrinted = stats.toSeq.filter(p => filter(p._1)).sortBy(_._1)
    // <count> <trace>
    val format = "%5d  %s\n"
    toBePrinted foreach {
      case (trace, count) => printf(format, count, trace)
    }
  }

}