Improve AntPathMatcher matching performance

This commit speeds up the AntPathMatcher implementation by
pre-processing patterns and checking that candidates are likely
matches if they start with the static prefix of the pattern.

Those changes can result in a small performance penalty for positive
matches, but with a significant boost for checking candidates that don't
match. Overall, this tradeoff is acceptable since this feature is often
used to select a few matching patterns in a much bigger list.

This will lead to small but consistent performance improvements in
Spring MVC when matching a given request with the available routes.

Issue: SPR-13913

spring-core/src/main/java/org/springframework/util/AntPathMatcher.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2016 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -85,7 +85,7 @@ public class AntPathMatcher implements PathMatcher {
 
 	private volatile Boolean cachePatterns;
 
-	private final Map<String, String[]> tokenizedPatternCache = new ConcurrentHashMap<String, String[]>(256);
+	private final Map<String, PreprocessedPattern> tokenizedPatternCache = new ConcurrentHashMap<String, PreprocessedPattern>(256);
 
 	final Map<String, AntPathStringMatcher> stringMatcherCache = new ConcurrentHashMap<String, AntPathStringMatcher>(256);
 
@@ -187,7 +187,11 @@ public class AntPathMatcher implements PathMatcher {
 			return false;
 		}
 
-		String[] pattDirs = tokenizePattern(pattern);
+		PreprocessedPattern preprocessedPattern = tokenizePattern(pattern);
+		if (fullMatch && this.caseSensitive && preprocessedPattern.certainlyNotMatch(path)) {
+			return false;
+		}
+		String[] pattDirs = preprocessedPattern.tokenized;
 		String[] pathDirs = tokenizePath(path);
 
 		int pattIdxStart = 0;
@@ -314,14 +318,14 @@ public class AntPathMatcher implements PathMatcher {
 	 * @param pattern the pattern to tokenize
 	 * @return the tokenized pattern parts
 	 */
-	protected String[] tokenizePattern(String pattern) {
+	protected PreprocessedPattern tokenizePattern(String pattern) {
-		String[] tokenized = null;
+		PreprocessedPattern tokenized = null;
 		Boolean cachePatterns = this.cachePatterns;
 		if (cachePatterns == null || cachePatterns.booleanValue()) {
 			tokenized = this.tokenizedPatternCache.get(pattern);
 		}
 		if (tokenized == null) {
-			tokenized = tokenizePath(pattern);
+			tokenized = compiledPattern(pattern);
 			if (cachePatterns == null && this.tokenizedPatternCache.size() >= CACHE_TURNOFF_THRESHOLD) {
 				// Try to adapt to the runtime situation that we're encountering:
 				// There are obviously too many different patterns coming in here...
@@ -345,6 +349,31 @@ public class AntPathMatcher implements PathMatcher {
 		return StringUtils.tokenizeToStringArray(path, this.pathSeparator, this.trimTokens, true);
 	}
 
+	private int firstSpecialCharIdx(int specialCharIdx, int prevFoundIdx) {
+		if (specialCharIdx != -1) {
+			return prevFoundIdx == -1 ? specialCharIdx : Math.min(prevFoundIdx, specialCharIdx);
+		}
+		else {
+			return prevFoundIdx;
+		}
+	}
+
+	private PreprocessedPattern compiledPattern(String pattern) {
+		String[] tokenized = tokenizePath(pattern);
+		int specialCharIdx = -1;
+		specialCharIdx = firstSpecialCharIdx(pattern.indexOf('*'), specialCharIdx);
+		specialCharIdx = firstSpecialCharIdx(pattern.indexOf('?'), specialCharIdx);
+		specialCharIdx = firstSpecialCharIdx(pattern.indexOf('{'), specialCharIdx);
+		final String prefix;
+		if (specialCharIdx != -1) {
+			prefix = pattern.substring(0, specialCharIdx);
+		}
+		else {
+			prefix = pattern;
+		}
+		return new PreprocessedPattern(tokenized, prefix.isEmpty() ? null : prefix);
+	}
+
 	/**
 	 * Test whether or not a string matches against a pattern.
 	 * @param pattern the pattern to match against (never {@code null})
@@ -847,4 +876,19 @@ public class AntPathMatcher implements PathMatcher {
 		}
 	}
 
+	private static class PreprocessedPattern {
+		private final String[] tokenized;
+
+		private final String prefix;
+
+		public PreprocessedPattern(String[] tokenized, String prefix) {
+			this.tokenized = tokenized;
+			this.prefix = prefix;
+		}
+
+		private boolean certainlyNotMatch(String path) {
+			return prefix != null && !path.startsWith(prefix);
+		}
+	}
+
 }

spring-core/src/test/java/org/springframework/util/AntPathMatcherTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2016 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -418,8 +418,8 @@ public class AntPathMatcherTests {
 		assertEquals("/*.html", pathMatcher.combine("/**", "/*.html"));
 		assertEquals("/*.html", pathMatcher.combine("/*", "/*.html"));
 		assertEquals("/*.html", pathMatcher.combine("/*.*", "/*.html"));
-		assertEquals("/{foo}/bar", pathMatcher.combine("/{foo}", "/bar"));	// SPR-8858
+		assertEquals("/{foo}/bar", pathMatcher.combine("/{foo}", "/bar"));    // SPR-8858
-		assertEquals("/user/user", pathMatcher.combine("/user", "/user"));	// SPR-7970
+		assertEquals("/user/user", pathMatcher.combine("/user", "/user"));    // SPR-7970
 		assertEquals("/{foo:.*[^0-9].*}/edit/", pathMatcher.combine("/{foo:.*[^0-9].*}", "/edit/")); // SPR-10062
 		assertEquals("/1.0/foo/test", pathMatcher.combine("/1.0", "/foo/test")); // SPR-10554
 		assertEquals("/hotel", pathMatcher.combine("/", "/hotel")); // SPR-12975
@@ -454,8 +454,8 @@ public class AntPathMatcherTests {
 
 		// SPR-10550
 		assertEquals(-1, comparator.compare("/hotels/{hotel}/bookings/{booking}/cutomers/{customer}", "/**"));
-		assertEquals(1, comparator.compare("/**","/hotels/{hotel}/bookings/{booking}/cutomers/{customer}"));
+		assertEquals(1, comparator.compare("/**", "/hotels/{hotel}/bookings/{booking}/cutomers/{customer}"));
-		assertEquals(0, comparator.compare("/**","/**"));
+		assertEquals(0, comparator.compare("/**", "/**"));
 
 		assertEquals(-1, comparator.compare("/hotels/{hotel}", "/hotels/*"));
 		assertEquals(1, comparator.compare("/hotels/*", "/hotels/{hotel}"));
@@ -618,12 +618,44 @@ public class AntPathMatcherTests {
 		assertTrue(pathMatcher.stringMatcherCache.size() > 20);
 
 		for (int i = 0; i < 65536; i++) {
-			pathMatcher.match("test" + i, "test");
+			pathMatcher.match("test" + i, "test" + i);
 		}
 		// Cache keeps being alive due to the explicit cache setting
 		assertTrue(pathMatcher.stringMatcherCache.size() > 65536);
 	}
 
+	@Test
+	public void preventCreatingStringMatchersIfPathDoesNotStartsWithPatternPrefix() {
+		pathMatcher.setCachePatterns(true);
+		assertEquals(0, pathMatcher.stringMatcherCache.size());
+
+		pathMatcher.match("test?", "test");
+		assertEquals(1, pathMatcher.stringMatcherCache.size());
+
+		pathMatcher.match("test?", "best");
+		pathMatcher.match("test/*", "view/test.jpg");
+		pathMatcher.match("test/**/test.jpg", "view/test.jpg");
+		pathMatcher.match("test/{name}.jpg", "view/test.jpg");
+		assertEquals(1, pathMatcher.stringMatcherCache.size());
+	}
+
+	@Test
+	public void creatingStringMatchersIfPatternPrefixCannotDetermineIfPathMatch() {
+		pathMatcher.setCachePatterns(true);
+		assertEquals(0, pathMatcher.stringMatcherCache.size());
+
+		pathMatcher.match("test", "testian");
+		pathMatcher.match("test?", "testFf");
+		pathMatcher.match("test/*", "test/dir/name.jpg");
+		pathMatcher.match("test/{name}.jpg", "test/lorem.jpg");
+		pathMatcher.match("bla/**/test.jpg", "bla/test.jpg");
+		pathMatcher.match("**/{name}.jpg", "test/lorem.jpg");
+		pathMatcher.match("/**/{name}.jpg", "/test/lorem.jpg");
+		pathMatcher.match("/*/dir/{name}.jpg", "/*/dir/lorem.jpg");
+
+		assertEquals(7, pathMatcher.stringMatcherCache.size());
+	}
+
 	@Test
 	public void cachePatternsSetToFalse() {
 		pathMatcher.setCachePatterns(false);