AVRO-3377: Deserialization of record of mangled Java class throws Cla…

…ssCastException (#1527)

* AVRO-3377: Mangle class identifier if required when initializing class

Use same mangling code that existed in the compiler (now moved to
the core library) to mangle type identifer so that the correct class
can be found more often.

* Cleaning up after merge

lang/java/avro/src/main/java/org/apache/avro/specific/SpecificData.java

@@ -111,6 +111,32 @@ public class SpecificData extends GenericData {
       // Class names used internally by the avro code generator
       "Builder"));
 
+  /* Reserved words for accessor/mutator methods */
+  public static final Set<String> ACCESSOR_MUTATOR_RESERVED_WORDS = new HashSet<>(
+      Arrays.asList("class", "schema", "classSchema"));
+
+  static {
+    // Add reserved words to accessor/mutator reserved words
+    ACCESSOR_MUTATOR_RESERVED_WORDS.addAll(RESERVED_WORDS);
+  }
+
+  /* Reserved words for type identifiers */
+  public static final Set<String> TYPE_IDENTIFIER_RESERVED_WORDS = new HashSet<>(
+      Arrays.asList("var", "yield", "record"));
+
+  static {
+    // Add reserved words to type identifier reserved words
+    TYPE_IDENTIFIER_RESERVED_WORDS.addAll(RESERVED_WORDS);
+  }
+
+  /* Reserved words for error types */
+  public static final Set<String> ERROR_RESERVED_WORDS = new HashSet<>(Arrays.asList("message", "cause"));
+
+  static {
+    // Add accessor/mutator reserved words to error reserved words
+    ERROR_RESERVED_WORDS.addAll(ACCESSOR_MUTATOR_RESERVED_WORDS);
+  }
+
   /**
    * Read/write some common builtin classes as strings. Representing these as
    * strings isn't always best, as they aren't always ordered ideally, but at
@@ -238,6 +264,89 @@ protected Schema getEnumSchema(Object datum) {
   }.getClass();
   private static final Schema NULL_SCHEMA = Schema.create(Schema.Type.NULL);
 
+  /**
+   * Utility to mangle the fully qualified class name into a valid symbol.
+   */
+  public static String mangleFullyQualified(String fullName) {
+    int lastDot = fullName.lastIndexOf('.');
+
+    if (lastDot < 0) {
+      return mangleTypeIdentifier(fullName);
+    } else {
+      String namespace = fullName.substring(0, lastDot);
+      String typeName = fullName.substring(lastDot + 1);
+
+      return mangle(namespace) + "." + mangleTypeIdentifier(typeName);
+    }
+  }
+
+  /**
+   * Utility for template use. Adds a dollar sign to reserved words.
+   */
+  public static String mangle(String word) {
+    return mangle(word, false);
+  }
+
+  /**
+   * Utility for template use. Adds a dollar sign to reserved words.
+   */
+  public static String mangle(String word, boolean isError) {
+    return mangle(word, isError ? ERROR_RESERVED_WORDS : RESERVED_WORDS);
+  }
+
+  /**
+   * Utility for template use. Adds a dollar sign to reserved words in type
+   * identifiers.
+   */
+  public static String mangleTypeIdentifier(String word) {
+    return mangleTypeIdentifier(word, false);
+  }
+
+  /**
+   * Utility for template use. Adds a dollar sign to reserved words in type
+   * identifiers.
+   */
+  public static String mangleTypeIdentifier(String word, boolean isError) {
+    return mangle(word, isError ? ERROR_RESERVED_WORDS : TYPE_IDENTIFIER_RESERVED_WORDS);
+  }
+
+  /**
+   * Utility for template use. Adds a dollar sign to reserved words.
+   */
+  public static String mangle(String word, Set<String> reservedWords) {
+    return mangle(word, reservedWords, false);
+  }
+
+  public static String mangleMethod(String word, boolean isError) {
+    return mangle(word, isError ? ERROR_RESERVED_WORDS : ACCESSOR_MUTATOR_RESERVED_WORDS, true);
+  }
+
+  /**
+   * Utility for template use. Adds a dollar sign to reserved words.
+   */
+  public static String mangle(String word, Set<String> reservedWords, boolean isMethod) {
+    if (isBlank(word)) {
+      return word;
+    }
+    if (word.contains(".")) {
+      // If the 'word' is really a full path of a class we must mangle just the
+      String[] packageWords = word.split("\\.");
+      String[] newPackageWords = new String[packageWords.length];
+
+      for (int i = 0; i < packageWords.length; i++) {
+        String oldName = packageWords[i];
+        newPackageWords[i] = mangle(oldName, reservedWords, false);
+      }
+
+      return String.join(".", newPackageWords);
+    }
+    if (reservedWords.contains(word) || (isMethod && reservedWords
+        .contains(Character.toLowerCase(word.charAt(0)) + ((word.length() > 1) ? word.substring(1) : "")))) {
+      return word + "$";
+    }
+    return word;
+  }
+
   /** Undoes mangling for reserved words. */
   protected static String unmangle(String word) {
     while (word.endsWith("$")) {
@@ -246,6 +355,21 @@ protected static String unmangle(String word) {
     return word;
   }
 
+  private static boolean isBlank(CharSequence cs) {
+    int strLen = cs == null ? 0 : cs.length();
+    if (strLen == 0) {
+      return true;
+    } else {
+      for (int i = 0; i < strLen; ++i) {
+        if (!Character.isWhitespace(cs.charAt(i))) {
+          return false;
+        }
+      }
+
+      return true;
+    }
+  }
+
   /** Return the class that implements a schema, or null if none exists. */
   public Class getClass(Schema schema) {
     switch (schema.getType()) {
@@ -331,26 +455,8 @@ public static String getClassName(Schema schema) {
     String name = schema.getName();
     if (namespace == null || "".equals(namespace))
       return name;
-
-    StringBuilder classNameBuilder = new StringBuilder();
-    String[] words = namespace.split("\\.");
-
-    for (int i = 0; i < words.length; i++) {
-      String word = words[i];
-      classNameBuilder.append(word);
-
-      if (RESERVED_WORDS.contains(word)) {
-        classNameBuilder.append(RESERVED_WORD_ESCAPE_CHAR);
-      }
-
-      if (i != words.length - 1 || !word.endsWith("$")) { // back-compatibly handle $
-        classNameBuilder.append(".");
-      }
-    }
-
-    classNameBuilder.append(name);
-
-    return classNameBuilder.toString();
+    String dot = namespace.endsWith("$") ? "" : "."; // back-compatibly handle $
+    return mangle(namespace) + dot + mangleTypeIdentifier(name);
   }
 
   // cache for schemas created from Class objects. Use ClassValue to avoid

lang/java/avro/src/test/java/org/apache/avro/specific/TestSpecificData.java

@@ -185,4 +185,9 @@ void classNameContainingReservedWords() {
 
     assertEquals("db.public$.table.AnyName", SpecificData.getClassName(schema));
   }
+
+  @Test
+  void testCanGetClassOfMangledType() {
+    assertEquals("org.apache.avro.specific.int$", SpecificData.getClassName(int$.getClassSchema()));
+  }
 }