Play Framework/Scala example source code file (ReflectionsCache.scala)

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

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

Play Framework tags/keywords

classloader, lib, library, map, none, option, play, play framework, reflections, reflectionscache, softreference, some, string

The ReflectionsCache.scala Play Framework example source code

/*
 * Copyright (C) 2009-2013 Typesafe Inc. <http://www.typesafe.com>
 */
package play.libs

import org.reflections.util.FilterBuilder

/**
 * Provides a cache for reflections, so that classloader scanning over the same classloader for the same package
 * multiple times doesn't need to be done.
 *
 * This is most useful in tests, when each test starts a new FakeApplication, and so things like Ebean scan the
 * classloader for @Entity annotated classes in a given package.  Profiling shows that without this cache, over 90%
 * of a tests time might be spent in classpath scanning.
 */
object ReflectionsCache {
  import ref.SoftReference
  import org.reflections.{ scanners, util, Reflections }
  import scala.collection.concurrent._

  // A soft reference is used so that we don't force the classloader or reflections to be live after a test run,
  // but we don't use weak reference as this is the only reference to the tuple, and it will just always get collected
  // on each eden space collection if it was weak.
  @volatile private var reflectionsMapRef: Option[SoftReference[(ClassLoader, Map[String, Reflections])]] = None

  def getReflections(classLoader: ClassLoader, pkg: String) = {
    // Detect if the classloader is different from last time, if it is, create a new cache and replace the old
    val reflectionsMap = reflectionsMapRef.flatMap(_.get).filter(_._1 == classLoader).map(_._2).getOrElse {
      val map = TrieMap.empty[String, Reflections]
      reflectionsMapRef = Some(new SoftReference((classLoader, map), null))
      map
    }
    reflectionsMap.get(pkg).getOrElse {

      val reflections = new Reflections(new util.ConfigurationBuilder()
        .addUrls(util.ClasspathHelper.forPackage(pkg, classLoader))
        .filterInputsBy(new FilterBuilder().include(FilterBuilder.prefix(pkg + ".")))
        .setScanners(new scanners.TypeAnnotationsScanner, new scanners.TypesScanner))

      reflectionsMap.putIfAbsent(pkg, reflections).getOrElse(reflections)
    }
  }
}