Shared ambiguity instance

src/main/java/org/apache/ibatis/session/Configuration.java

@@ -1106,6 +1106,7 @@ protected static class StrictMap<V> extends ConcurrentHashMap<String, V> {
     private static final long serialVersionUID = -4950446264854982944L;
     private final String name;
     private BiFunction<V, V, String> conflictMessageProducer;
+    private static final Object AMBIGUITY_INSTANCE = new Object();
 
     public StrictMap(String name, int initialCapacity, float loadFactor) {
       super(initialCapacity, loadFactor);
@@ -1155,7 +1156,7 @@ public V put(String key, V value) {
         if (super.get(shortKey) == null) {
           super.put(shortKey, value);
         } else {
-          super.put(shortKey, (V) new Ambiguity(shortKey));
+          super.put(shortKey, (V) AMBIGUITY_INSTANCE);
         }
       }
       return super.put(key, value);
@@ -1176,25 +1177,13 @@ public V get(Object key) {
       if (value == null) {
         throw new IllegalArgumentException(name + " does not contain value for " + key);
       }
-      if (value instanceof Ambiguity) {
-        throw new IllegalArgumentException(((Ambiguity) value).getSubject() + " is ambiguous in " + name
+      if (AMBIGUITY_INSTANCE == value) {
+        throw new IllegalArgumentException(key + " is ambiguous in " + name
             + " (try using the full name including the namespace, or rename one of the entries)");
       }
       return value;
     }
 
-    protected static class Ambiguity {
-      private final String subject;
-
-      public Ambiguity(String subject) {
-        this.subject = subject;
-      }
-
-      public String getSubject() {
-        return subject;
-      }
-    }
-
     private String getShortName(String key) {
       final String[] keyParts = key.split("\\.");
       return keyParts[keyParts.length - 1];

src/test/java/org/apache/ibatis/submitted/global_variables_defaults/ConfigurationTest.java

@@ -17,10 +17,15 @@
 
 import java.io.IOException;
 import java.io.Reader;
+import java.util.ArrayList;
 import java.util.Properties;
 
+import org.apache.ibatis.builder.StaticSqlSource;
 import org.apache.ibatis.datasource.unpooled.UnpooledDataSource;
 import org.apache.ibatis.io.Resources;
+import org.apache.ibatis.mapping.MappedStatement;
+import org.apache.ibatis.mapping.ResultMap;
+import org.apache.ibatis.mapping.SqlCommandType;
 import org.apache.ibatis.parsing.PropertyParser;
 import org.apache.ibatis.session.Configuration;
 import org.apache.ibatis.session.SqlSessionFactory;
@@ -79,4 +84,27 @@ void applyPropertyValueOnXmlConfiguration() throws IOException {
 
   }
 
+  @Test
+  void testAmbiguityCache() {
+    Configuration configuration = new Configuration();
+    configuration.addMappedStatement(
+      new MappedStatement.Builder(configuration,
+        "org.apache.ibatis.submitted.DemoMapper1.selectById",
+        new StaticSqlSource(configuration, "select * from test where id = 1"), SqlCommandType.SELECT).build()
+    );
+    configuration.addMappedStatement(
+      new MappedStatement.Builder(configuration,
+        "org.apache.ibatis.submitted.DemoMapper1.test",
+        new StaticSqlSource(configuration, "select * from test"), SqlCommandType.SELECT).build()
+    );
+    configuration.addMappedStatement(
+      new MappedStatement.Builder(configuration,
+        "org.apache.ibatis.submitted.DemoMapper2.test",
+        new StaticSqlSource(configuration, "select * from test"), SqlCommandType.SELECT).build()
+    );
+    Assertions.assertThat(configuration.getMappedStatement("selectById")).isNotNull();
+    Assertions.assertThatThrownBy(() -> configuration.getMappedStatement("test"))
+      .isInstanceOf(IllegalArgumentException.class).hasMessage("test is ambiguous in Mapped Statements collection (try using the full name including the namespace, or rename one of the entries)");
+  }
+
 }