Define and use singletons instead of new stateless instances for each

call The following now define singletons: - org.apache.hc.core5.http.impl.routing.UriPathRouter.BestMatcher - org.apache.hc.core5.http.impl.routing.UriPathRouter.OrderedMatcher - org.apache.hc.core5.http.impl.routing.UriPathRouter.RegexMatcher
apache · Oct 29, 2024 · 7e507b6 · 7e507b6
1 parent e33ad8a
commit 7e507b6
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Showing 2 changed files with 58 additions and 13 deletions.
diff --git a/httpcore5/src/main/java/org/apache/hc/core5/http/impl/routing/UriPathRouter.java b/httpcore5/src/main/java/org/apache/hc/core5/http/impl/routing/UriPathRouter.java
@@ -60,15 +60,15 @@ public String toString() {
     }
 
     static <T> UriPathRouter<?, T> bestMatch(final List<PathRoute<String, T>> routes) {
-        return new UriPathRouter<>(Function.identity(), new BestMatcher<>(), routes);
+        return new UriPathRouter<>(Function.identity(), BestMatcher.getInstance(), routes);
     }
 
     static <T> UriPathRouter<?, T> ordered(final List<PathRoute<String, T>> routes) {
-        return new UriPathRouter<>(Function.identity(), new OrderedMatcher<>(), routes);
+        return new UriPathRouter<>(Function.identity(), OrderedMatcher.getInstance(), routes);
     }
 
     static <T> UriPathRouter<?, T> regEx(final List<PathRoute<String, T>> routes) {
-        return new UriPathRouter<>(Pattern::compile, new RegexMatcher<>(), routes);
+        return new UriPathRouter<>(Pattern::compile, RegexMatcher.getInstance(), routes);
     }
 
     private static final PathPatternMatcher PATH_PATTERN_MATCHER = PathPatternMatcher.INSTANCE;
@@ -83,9 +83,24 @@ static <T> UriPathRouter<?, T> regEx(final List<PathRoute<String, T>> routes) {
      * <li>{@code *<uri-path>}</li>
      * <li>{@code <uri-path>*}</li>
      * </ul>
+     * <p>
+     * This class has no instance state.
+     * </p>
      */
     final static class BestMatcher<T> implements BiFunction<String, List<PathRoute<String, T>>, T> {
 
+        @SuppressWarnings("rawtypes") // raw by design
+        private static final BestMatcher INSTANCE = new BestMatcher();
+
+        @SuppressWarnings({ "cast", "unchecked" }) // cast to call site
+        static <T> BestMatcher<T> getInstance() {
+            return (BestMatcher<T>) INSTANCE;
+        }
+
+        private BestMatcher() {
+            // singleton instance only
+        }
+
         @Override
         public T apply(final String path, final List<PathRoute<String, T>> routes) {
             PathRoute<String, T> bestMatch = null;
@@ -115,9 +130,24 @@ public T apply(final String path, final List<PathRoute<String, T>> routes) {
      * <li>{@code *<uri-path>}</li>
      * <li>{@code <uri-path>*}</li>
      * </ul>
+     * <p>
+     * This class has no instance state.
+     * </p>
      */
     final static class OrderedMatcher<T> implements BiFunction<String, List<PathRoute<String, T>>, T> {
 
+        @SuppressWarnings("rawtypes") // raw by design
+        private static final OrderedMatcher INSTANCE = new OrderedMatcher();
+
+        @SuppressWarnings({ "cast", "unchecked" }) // cast to call site
+        static <T> OrderedMatcher<T> getInstance() {
+            return (OrderedMatcher<T>) INSTANCE;
+        }
+
+        private OrderedMatcher() {
+            // singleton instance only
+        }
+
         @Override
         public T apply(final String path, final List<PathRoute<String, T>> routes) {
             for (final PathRoute<String, T> route : routes) {
@@ -135,9 +165,24 @@ public T apply(final String path, final List<PathRoute<String, T>> routes) {
 
     /**
      * Finds a match for the given path from a collection of regular expressions.
+     * <p>
+     * This class has no instance state.
+     * </p>
      */
     final static class RegexMatcher<T> implements BiFunction<String, List<PathRoute<Pattern, T>>, T> {
 
+        @SuppressWarnings("rawtypes") // raw by design
+        private static final RegexMatcher INSTANCE = new RegexMatcher();
+
+        @SuppressWarnings({ "cast", "unchecked" }) // cast to call site
+        static <T> RegexMatcher<T> getInstance() {
+            return (RegexMatcher<T>) INSTANCE;
+        }
+
+        private RegexMatcher() {
+            // singleton instance only
+        }
+
         @Override
         public T apply(final String path, final List<PathRoute<Pattern, T>> routes) {
             for (final PathRoute<Pattern, T> route : routes) {

diff --git a/httpcore5/src/test/java/org/apache/hc/core5/http/impl/routing/TestUriPathRouter.java b/httpcore5/src/test/java/org/apache/hc/core5/http/impl/routing/TestUriPathRouter.java
@@ -38,7 +38,7 @@ class TestUriPathRouter {
 
     @Test
     void testBestMatchWildCardMatching() {
-        final UriPathRouter.BestMatcher<Long> matcher = new UriPathRouter.BestMatcher<>();
+        final UriPathRouter.BestMatcher<Long> matcher = UriPathRouter.BestMatcher.getInstance();
         final List<PathRoute<String, Long>> routes = Arrays.asList(
                 new PathRoute<>("*", 0L),
                 new PathRoute<>("/one/*", 1L),
@@ -58,7 +58,7 @@ void testBestMatchWildCardMatching() {
 
     @Test
     void testBestMatchWildCardMatchingSuffixPrefixPrecedence() {
-        final UriPathRouter.BestMatcher<Long> matcher = new UriPathRouter.BestMatcher<>();
+        final UriPathRouter.BestMatcher<Long> matcher = UriPathRouter.BestMatcher.getInstance();
         final List<PathRoute<String, Long>> routes = Arrays.asList(
                 new PathRoute<>("/ma*", 1L),
                 new PathRoute<>("*tch", 2L));
@@ -67,7 +67,7 @@ void testBestMatchWildCardMatchingSuffixPrefixPrecedence() {
 
     @Test
     void testBestMatchWildCardMatchingExactMatch() {
-        final UriPathRouter.BestMatcher<Long> matcher = new UriPathRouter.BestMatcher<>();
+        final UriPathRouter.BestMatcher<Long> matcher = UriPathRouter.BestMatcher.getInstance();
         final List<PathRoute<String, Long>> routes = Arrays.asList(
                 new PathRoute<>("exact", 1L),
                 new PathRoute<>("*", 0L));
@@ -76,7 +76,7 @@ void testBestMatchWildCardMatchingExactMatch() {
 
     @Test
     void testBestMatchWildCardMatchingNoMatch() {
-        final UriPathRouter.BestMatcher<Long> matcher = new UriPathRouter.BestMatcher<>();
+        final UriPathRouter.BestMatcher<Long> matcher = UriPathRouter.BestMatcher.getInstance();
         final List<PathRoute<String, Long>> routes = Arrays.asList(
                 new PathRoute<>("/this/*", 1L),
                 new PathRoute<>("/that/*", 2L));
@@ -85,7 +85,7 @@ void testBestMatchWildCardMatchingNoMatch() {
 
     @Test
     void testOrderedWildCardMatching1() {
-        final UriPathRouter.OrderedMatcher<Long> matcher = new UriPathRouter.OrderedMatcher<>();
+        final UriPathRouter.OrderedMatcher<Long> matcher = UriPathRouter.OrderedMatcher.getInstance();
         final List<PathRoute<String, Long>> routes = Arrays.asList(
                 new PathRoute<>("*", 0L),
                 new PathRoute<>("/one/*", 1L),
@@ -121,7 +121,7 @@ void testOrderedWildCardMatching1() {
 
     @Test
     void testOrderedWildCardMatchingSuffixPrefixPrecedence() {
-        final UriPathRouter.OrderedMatcher<Long> matcher = new UriPathRouter.OrderedMatcher<>();
+        final UriPathRouter.OrderedMatcher<Long> matcher = UriPathRouter.OrderedMatcher.getInstance();
         final List<PathRoute<String, Long>> routes = Arrays.asList(
                 new PathRoute<>("/ma*", 1L),
                 new PathRoute<>("*tch", 2L));
@@ -130,7 +130,7 @@ void testOrderedWildCardMatchingSuffixPrefixPrecedence() {
 
     @Test
     void testOrderedStarAndExact() {
-        final UriPathRouter.OrderedMatcher<Long> matcher = new UriPathRouter.OrderedMatcher<>();
+        final UriPathRouter.OrderedMatcher<Long> matcher = UriPathRouter.OrderedMatcher.getInstance();
         final List<PathRoute<String, Long>> routes = Arrays.asList(
                 new PathRoute<>("*", 0L),
                 new PathRoute<>("exact", 1L));
@@ -139,7 +139,7 @@ void testOrderedStarAndExact() {
 
     @Test
     void testOrderedExactAndStar() {
-        final UriPathRouter.OrderedMatcher<Long> matcher = new UriPathRouter.OrderedMatcher<>();
+        final UriPathRouter.OrderedMatcher<Long> matcher = UriPathRouter.OrderedMatcher.getInstance();
         final List<PathRoute<String, Long>> routes = Arrays.asList(
                 new PathRoute<>("exact", 1L),
                 new PathRoute<>("*", 0L));
@@ -148,7 +148,7 @@ void testOrderedExactAndStar() {
 
     @Test
     void testRegExMatching() {
-        final UriPathRouter.RegexMatcher<Long> matcher = new UriPathRouter.RegexMatcher<>();
+        final UriPathRouter.RegexMatcher<Long> matcher = UriPathRouter.RegexMatcher.getInstance();
         final List<PathRoute<Pattern, Long>> routes = Arrays.asList(
                 new PathRoute<>(Pattern.compile("/one/two/three/.*"), 3L),
                 new PathRoute<>(Pattern.compile("/one/two/.*"), 2L),
@@ -167,7 +167,7 @@ void testRegExMatching() {
 
     @Test
     void testRegExWildCardMatchingSuffixPrefixPrecedence() {
-        final UriPathRouter.RegexMatcher<Long> matcher = new UriPathRouter.RegexMatcher<>();
+        final UriPathRouter.RegexMatcher<Long> matcher = UriPathRouter.RegexMatcher.getInstance();
         final List<PathRoute<Pattern, Long>> routes = Arrays.asList(
                 new PathRoute<>(Pattern.compile("/ma.*"), 1L),
                 new PathRoute<>(Pattern.compile(".*tch"), 2L));