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author | Jason Zaugg <jzaugg@gmail.com> | 2013-11-01 11:40:26 +0100 |
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committer | Jason Zaugg <jzaugg@gmail.com> | 2013-11-01 11:56:54 +0100 |
commit | a1d9656299a90d9ea4d5aa14a7873e3b4941eb59 (patch) | |
tree | 21affb2ad94f25be36b2b2c53c3f19b5c5e8a21f /src/compiler/scala/tools/cmd/FromString.scala | |
parent | c38235fd44f1ccb280e31a2f34f58deb59c5b2ee (diff) | |
download | scala-a1d9656299a90d9ea4d5aa14a7873e3b4941eb59.tar.gz scala-a1d9656299a90d9ea4d5aa14a7873e3b4941eb59.tar.bz2 scala-a1d9656299a90d9ea4d5aa14a7873e3b4941eb59.zip |
Don't use runtime reflection from the batch compiler.
Not only does this save a big chunk of time on startup by avoiding
classloading and symbol table population, but it also seems to
improve steady state performance of the compiler.
Theory: JIT can optimize more aggressively without the
SynchronizedXxx decorators and the like being in the classloader.
See "Class Heirarchy Analyis" in [1]
This commit does this by:
- Avoiding use of FromString in pattern matcher, instead
using an established mechanism to parse system properties.
- Changes FromString back to use OptManifest. AFAICT, this
is now only a dependency of scala.tools.cmd.gen.Codegen,
so this is just a defensive measure.
The REPL still uses runtime reflection, so will pay a little
performance tax.
Benchmark:
avg shortest 10 times 744ms # before
avg shortest 10 times 675ms # after
[1] https://wikis.oracle.com/display/HotSpotInternals/PerformanceTechniques
Diffstat (limited to 'src/compiler/scala/tools/cmd/FromString.scala')
-rw-r--r-- | src/compiler/scala/tools/cmd/FromString.scala | 19 |
1 files changed, 9 insertions, 10 deletions
diff --git a/src/compiler/scala/tools/cmd/FromString.scala b/src/compiler/scala/tools/cmd/FromString.scala index 433bbb167e..0b074efc0f 100644 --- a/src/compiler/scala/tools/cmd/FromString.scala +++ b/src/compiler/scala/tools/cmd/FromString.scala @@ -6,21 +6,20 @@ package scala.tools package cmd -import scala.tools.nsc.io.{ File, Directory } -import scala.reflect.runtime.{universe => ru} -import scala.tools.reflect.StdRuntimeTags._ +import nsc.io.{ Path, File, Directory } +import scala.reflect.OptManifest /** A general mechanism for defining how a command line argument * (always a String) is transformed into an arbitrary type. A few * example instances are in the companion object, but in general * either IntFromString will suffice or you'll want custom transformers. */ -abstract class FromString[+T](implicit t: ru.TypeTag[T]) extends PartialFunction[String, T] { +abstract class FromString[+T](implicit m: OptManifest[T]) extends PartialFunction[String, T] { def apply(s: String): T def isDefinedAt(s: String): Boolean = true def zero: T = apply("") - def targetString: String = t.toString + def targetString: String = m.toString } object FromString { @@ -29,13 +28,13 @@ object FromString { /** Path related stringifiers. */ - val ExistingDir: FromString[Directory] = new FromString[Directory]()(tagOfDirectory) { + val ExistingDir: FromString[Directory] = new FromString[Directory] { override def isDefinedAt(s: String) = toDir(s).isDirectory def apply(s: String): Directory = if (isDefinedAt(s)) toDir(s) else cmd.runAndExit(println("'%s' is not an existing directory." format s)) } - def ExistingDirRelativeTo(root: Directory) = new FromString[Directory]()(tagOfDirectory) { + def ExistingDirRelativeTo(root: Directory) = new FromString[Directory] { private def resolve(s: String) = (toDir(s) toAbsoluteWithRoot root).toDirectory override def isDefinedAt(s: String) = resolve(s).isDirectory def apply(s: String): Directory = @@ -46,19 +45,19 @@ object FromString { /** Argument expander, i.e. turns single argument "foo bar baz" into argument * list "foo", "bar", "baz". */ - val ArgumentsFromString: FromString[List[String]] = new FromString[List[String]]()(tagOfListOfString) { + val ArgumentsFromString: FromString[List[String]] = new FromString[List[String]] { def apply(s: String) = toArgs(s) } /** Identity. */ - implicit val StringFromString: FromString[String] = new FromString[String]()(tagOfString) { + implicit val StringFromString: FromString[String] = new FromString[String] { def apply(s: String): String = s } /** Implicit as the most likely to be useful as-is. */ - implicit val IntFromString: FromString[Int] = new FromString[Int]()(tagOfInt) { + implicit val IntFromString: FromString[Int] = new FromString[Int] { override def isDefinedAt(s: String) = safeToInt(s).isDefined def apply(s: String) = safeToInt(s).get def safeToInt(s: String): Option[Int] = try Some(java.lang.Integer.parseInt(s)) catch { case _: NumberFormatException => None } |