8000 Merge pull request #3860 from gourlaysama/wip/t7710-backport · scala/scala-dev@ac7e102 · GitHub
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gkossakowskigkossakowski
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Merge pull request #3860 from gourlaysama/wip/t7710-backport
[backport] SI-7710 fix memory performance of RegexParsers in jdk7u6+
2 parents b5759ef + fceae70 commit ac7e102

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3 files changed

+39
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‎bincompat-forward.whitelist.conf

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@@ -177,7 +177,11 @@ filter {
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{
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matchName="scala.reflect.runtime.JavaMirrors#JavaMirror.scala$reflect$runtime$JavaMirrors$JavaMirror$$followStatic"
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problemName=MissingMethodProblem
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},
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{
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# only accessible from util.parsing.combinator package
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matchName="scala.util.parsing.combinator.SubSequence"
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problemName=MissingClassProblem
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}
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]
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}

‎src/library/scala/util/parsing/combinator/RegexParsers.scala

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@@ -72,7 +72,7 @@ trait RegexParsers extends Parsers {
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*/
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protected def handleWhiteSpace(source: java.lang.CharSequence, offset: Int): Int =
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if (skipWhitespace)
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(whiteSpace findPrefixMatchOf (source.subSequence(offset, source.length))) match {
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(whiteSpace findPrefixMatchOf (new SubSequence(source, offset))) match {
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case Some(matched) => offset + matched.end
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case None => offset
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}
@@ -106,7 +106,7 @@ trait RegexParsers extends Parsers {
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val source = in.source
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val offset = in.offset
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val start = handleWhiteSpace(source, offset)
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(r findPrefixMatchOf (source.subSequence(start, source.length))) match {
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(r findPrefixMatchOf (new SubSequence(source, start))) match {
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case Some(matched) =>
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Success(source.subSequence(start, start + matched.end).toString,
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in.drop(start + matched.end - offset))

‎src/library/scala/util/parsing/combinator/SubSequence.scala

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@@ -0,0 +1,32 @@
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/* __ *\
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** ________ ___ / / ___ Scala API **
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** / __/ __// _ | / / / _ | (c) 2006-2013, LAMP/EPFL **
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** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ **
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** /____/\___/_/ |_/____/_/ | | **
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** |/ **
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\* */
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package scala
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package util.parsing.combinator
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// A shallow wrapper over another CharSequence (usually a String)
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//
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// See SI-7710: in jdk7u6 String.subSequence stopped sharing the char array of the original
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// string and began copying it.
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// RegexParsers calls subSequence twice per input character: that's a lot of array copying!
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private[combinator] class SubSequence(s: CharSequence, start: Int, val length: Int) extends CharSequence {
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def this(s: CharSequence, start: Int) = this(s, start, s.length - start)
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def charAt(i: Int) =
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if (i >= 0 && i < length) s.charAt(start + i) else throw new IndexOutOfBoundsException(s"index: $i, length: $length")
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def subSequence(_start: Int, _end: Int) = {
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if (_start < 0 || _end < 0 || _end > length || _start > _end)
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throw new IndexOutOfBoundsException(s"start: ${_start}, end: ${_end}, length: $length")
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new SubSequence(s, start + _start, _end - _start)
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}
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override def toString = s.subSequence(start, start + length).toString
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}

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