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Bug 565553 - Improve performance of build command parsers with large number of files

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When possible, precompute the group number in the replacement expression
when parsing option strings, instead of calling replaceAll which is
slower. If the replacement expression is not a simple numbered group,
fall-back to replaceAll.

I have benchmarked this save between 200ms to 2sec depending on the
project size.

Change-Id: Id48fdcf476e2d1739522c9267e214f4c88bf316a
Signed-off-by: Marc-Andre Laperle <malaperle@gmail.com>
This commit is contained in:
Marc-Andre Laperle 2020-10-24 03:35:20 -04:00 • committed by Marc-André Laperle
parent 3abe3d28e6
commit f5531cee19
1 changed files with 37 additions and 15 deletions
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52
build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/language/settings/providers/AbstractLanguageSettingsOutputScanner.java
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@ -147,14 +147,16 @@ public abstract class AbstractLanguageSettingsOutputScanner extends LanguageSett
protected static abstract class AbstractOptionParser {
private final int kind;
private final Pattern pattern;
private final String nameExpression;
private final String valueExpression;
private final int extraFlag;
private String parsedName;
private String parsedValue;
private final Pattern removeExtraFileNamePattern;
private static final Pattern numGroupPattern = Pattern.compile("\\$(\\d+)"); //$NON-NLS-1$
private final MatcherReplacement nameMatcherReplacement;
private final MatcherReplacement valueMatcherReplacement;
/**
* Constructor.
*
@ -169,12 +171,41 @@ public abstract class AbstractLanguageSettingsOutputScanner extends LanguageSett
public AbstractOptionParser(int kind, String pattern, String nameExpression, String valueExpression,
int extraFlag) {
this.kind = kind;
this.nameExpression = nameExpression;
this.valueExpression = valueExpression;
this.extraFlag = extraFlag;
this.pattern = Pattern.compile(pattern);
this.removeExtraFileNamePattern = Pattern.compile("(" + pattern + ").*"); //$NON-NLS-1$ //$NON-NLS-2$
nameMatcherReplacement = new MatcherReplacement(nameExpression);
valueMatcherReplacement = new MatcherReplacement(valueExpression);
}
// Represents a replacement to be applied on a matcher, pre-calculating the group number used in the replacement if possible.
private static class MatcherReplacement {
private final String replacementExpression;
private final int replacementGroupNum;
private MatcherReplacement(String replacementExpression) {
this.replacementExpression = replacementExpression;
int groupNum = -1;
if (replacementExpression != null) {
// If the expression is just a single numbered group reference (the common case), we can predetermine
// which group we will need to retrieve on the matcher when we will parse the option string.
Matcher numGroupMatcher = numGroupPattern.matcher(replacementExpression);
if (numGroupMatcher.matches())
groupNum = Integer.parseInt(numGroupMatcher.group(1));
}
replacementGroupNum = groupNum;
}
private String replace(Matcher matcher) {
if (replacementGroupNum != -1)
return matcher.group(replacementGroupNum);
// The expression is not a simple numbered group, fall-back to normal replacement (slow).
if (replacementExpression != null)
return matcher.replaceAll(replacementExpression);
return null;
}
}
/**
@ -207,15 +238,6 @@ public abstract class AbstractLanguageSettingsOutputScanner extends LanguageSett
return kind == ICSettingEntry.INCLUDE_PATH || kind == ICSettingEntry.LIBRARY_PATH;
}
/**
* Return value represented by the capturing group expression.
*/
private String parseStr(Matcher matcher, String str) {
if (str != null)
return matcher.replaceAll(str);
return null;
}
/**
* Test for a match and parse a portion of input string representing a single option
* to retrieve name and value.
@ -236,8 +258,8 @@ public abstract class AbstractLanguageSettingsOutputScanner extends LanguageSett
Matcher matcher = pattern.matcher(option);
boolean isMatch = matcher.matches();
if (isMatch) {
parsedName = parseStr(matcher, nameExpression);
parsedValue = parseStr(matcher, valueExpression);
parsedName = nameMatcherReplacement.replace(matcher);
parsedValue = valueMatcherReplacement.replace(matcher);
}
return isMatch;
}