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Scala example source code file (Origins.scala)
The Origins.scala Scala example source code/* NSC -- new scala compiler * Copyright 2005-2013 LAMP/EPFL * @author Paul Phillips */ package scala package reflect package internal.util import scala.collection.{ mutable, immutable } /** A debugging class for logging from whence a method is being called. * Say you wanted to discover who was calling phase_= in SymbolTable. * You could do this: * * {{{ * private lazy val origins = Origins("arbitraryTag") * // Commented out original enclosed for contrast * // final def phase_=(p: Phase): Unit = { * final def phase_=(p: Phase): Unit = origins { * }}} * * And that's it. When the JVM exits it would issue a report something like this: {{{ >> Origins tag 'arbitraryTag' logged 145585 calls from 51 distinguished sources. 71114 scala.tools.nsc.symtab.Symbols$Symbol.unsafeTypeParams(Symbols.scala:862) 16584 scala.tools.nsc.symtab.Symbols$Symbol.rawInfo(Symbols.scala:757) 15411 scala.tools.nsc.symtab.Symbols$Symbol.unsafeTypeParams(Symbols.scala:869) 11507 scala.tools.nsc.symtab.Symbols$Symbol.rawInfo(Symbols.scala:770) 10285 scala.tools.nsc.symtab.Symbols$Symbol.unsafeTypeParams(Symbols.scala:864) 6860 scala.tools.nsc.transform.SpecializeTypes.specializedTypeVars(SpecializeTypes.scala:304) ... }}} * */ abstract class Origins { type Rep type StackSlice = Array[StackTraceElement] def tag: String def isCutoff(el: StackTraceElement): Boolean def newRep(xs: StackSlice): Rep def repString(rep: Rep): String private val origins = new mutable.HashMap[Rep, Int] withDefaultValue 0 private def add(xs: Rep) = origins(xs) += 1 private def total = origins.values.foldLeft(0L)(_ + _) // Create a stack and whittle it down to the interesting part. def readStack(): Array[StackTraceElement] = ( Thread.currentThread.getStackTrace dropWhile (x => !isCutoff(x)) dropWhile isCutoff drop 1 ) def apply[T](body: => T): T = { add(newRep(readStack())) body } def clear() = origins.clear() def show() = { println("\n>> Origins tag '%s' logged %s calls from %s distinguished sources.\n".format(tag, total, origins.keys.size)) origins.toList sortBy (-_._2) foreach { case (k, v) => println("%7s %s".format(v, repString(k))) } } def purge() = { show() clear() } } object Origins { private val counters = mutable.HashMap[String, Origins]() private val thisClass = this.getClass.getName locally { sys.addShutdownHook(counters.values foreach (_.purge())) } case class OriginId(className: String, methodName: String) { def matches(el: StackTraceElement) = ( (methodName == el.getMethodName) && (className startsWith el.getClassName) ) } def lookup(tag: String, orElse: String => Origins): Origins = counters.getOrElseUpdate(tag, orElse(tag)) def register(x: Origins): Origins = { counters(x.tag) = x x } private def preCutoff(el: StackTraceElement) = ( (el.getClassName == thisClass) || (el.getClassName startsWith "java.lang.") ) private def findCutoff() = { val cutoff = (Thread.currentThread.getStackTrace dropWhile preCutoff).head OriginId(cutoff.getClassName, cutoff.getMethodName) } def apply(tag: String): Origins = counters.getOrElseUpdate(tag, new OneLine(tag, findCutoff())) def apply(tag: String, frames: Int): Origins = counters.getOrElseUpdate(tag, new MultiLine(tag, findCutoff(), frames)) class OneLine(val tag: String, id: OriginId) extends Origins { type Rep = StackTraceElement def isCutoff(el: StackTraceElement) = id matches el def newRep(xs: StackSlice): Rep = if ((xs eq null) || (xs.length == 0)) null else xs(0) def repString(rep: Rep) = " " + rep } class MultiLine(val tag: String, id: OriginId, numLines: Int) extends Origins { type Rep = List[StackTraceElement] def isCutoff(el: StackTraceElement) = id matches el def newRep(xs: StackSlice): Rep = (xs take numLines).toList def repString(rep: Rep) = rep.map("\n " + _).mkString override def readStack() = super.readStack() drop 1 } } Other Scala source code examplesHere is a short list of links related to this Scala Origins.scala source code file: |
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