Small performance optimization for ignore rules/fnmatcher

- don't check empty segments generated by String.split() - don't continue to add segments if the matcher fails to match input - don't add empty heads - don't iterate over empty heads. Bug: 440732 Change-Id: I7d04dccfe24d91275d17ba246662337d6dba66df Signed-off-by: Andrey Loskutov <loskutov@gmx.de> Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
10 years ago · 3a161ac467
2 changed files with 28 additions and 8 deletions
--- a/org.eclipse.jgit/src/org/eclipse/jgit/fnmatch/FileNameMatcher.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/fnmatch/FileNameMatcher.java
@ -307,7 +307,11 @@ public class FileNameMatcher {
 			return new WildCardHead(star);
 	}

-	private void extendStringToMatchByOneCharacter(final char c) {
+	/**
+	 * @param c new character to append
+	 * @return true to continue, false if the matcher can stop appending
+	 */
+	private boolean extendStringToMatchByOneCharacter(final char c) {
 		final List<Head> newHeads = listForLocalUseage;
 		newHeads.clear();
 		List<Head> lastAddedHeads = null;
@ -320,12 +324,14 @@ public class FileNameMatcher {
 			// This is the case with the heads "a" and "*" of "a*b" which
 			// both can return the list ["*","b"]
 			if (headsToAdd != lastAddedHeads) {
-				newHeads.addAll(headsToAdd);
+				if (!headsToAdd.isEmpty())
+					newHeads.addAll(headsToAdd);
 				lastAddedHeads = headsToAdd;
 			}
 		}
 		listForLocalUseage = heads;
 		heads = newHeads;
+		return !newHeads.isEmpty();
 	}

 	private static int indexOfUnescaped(final String searchString,
@ -349,7 +355,8 @@ public class FileNameMatcher {
 	public void append(final String stringToMatch) {
 		for (int i = 0; i < stringToMatch.length(); i++) {
 			final char c = stringToMatch.charAt(i);
-			extendStringToMatchByOneCharacter(c);
+			if (!extendStringToMatchByOneCharacter(c))
+				break;
 		}
 	}

@ -378,6 +385,9 @@ public class FileNameMatcher {
 	 * @return true, if the string currently being matched does match.
 	 */
 	public boolean isMatch() {
+		if (heads.isEmpty())
+			return false;
+
 		final ListIterator<Head> headIterator = heads
 				.listIterator(heads.size());
 		while (headIterator.hasPrevious()) {
--- a/org.eclipse.jgit/src/org/eclipse/jgit/ignore/IgnoreRule.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/ignore/IgnoreRule.java
@ -191,6 +191,9 @@ public class IgnoreRule {
 				final String[] segments = target.split("/"); //$NON-NLS-1$
 				for (int idx = 0; idx < segments.length; idx++) {
 					final String segmentName = segments[idx];
+					// String.split("/") creates empty segment for leading slash
+					if (segmentName.length() == 0)
+						continue;
 					if (segmentName.equals(pattern) &&
 							doesMatchDirectoryExpectations(isDirectory, idx, segments.length))
 						return true;
@ -207,6 +210,9 @@ public class IgnoreRule {
 			if (nameOnly) {
 				for (int idx = 0; idx < segments.length; idx++) {
 					final String segmentName = segments[idx];
+					// String.split("/") creates empty segment for leading slash
+					if (segmentName.length() == 0)
+						continue;
 					//Iterate through each sub-directory
 					matcher.reset();
 					matcher.append(segmentName);
@ -218,14 +224,18 @@ public class IgnoreRule {
 				//TODO: This is the slowest operation
 				//This matches e.g. "/src/ne?" to "/src/new/file.c"
 				matcher.reset();
+
 				for (int idx = 0; idx < segments.length; idx++) {
 					final String segmentName = segments[idx];
-					if (segmentName.length() > 0) {
-						matcher.append("/" + segmentName); //$NON-NLS-1$
-					}
+					// String.split("/") creates empty segment for leading slash
+					if (segmentName.length() == 0)
+						continue;

-					if (matcher.isMatch() &&
-							doesMatchDirectoryExpectations(isDirectory, idx, segments.length))
+					matcher.append("/" + segmentName); //$NON-NLS-1$
+
+					if (matcher.isMatch()
+							&& doesMatchDirectoryExpectations(isDirectory, idx,
+									segments.length))
 						return true;
 				}
 			}