AVRO-2838: Conditional Java String type schema modification

lang/java/compiler/src/main/java/org/apache/avro/compiler/specific/SpecificCompiler.java

@@ -122,6 +122,7 @@ void addLogicalTypeConversions(SpecificData specificData) {
   private boolean createAllArgsConstructor = true;
   private String outputCharacterEncoding;
   private boolean enableDecimalLogicalType = false;
+  private boolean modifySchema = true;
   private String suffix = ".java";
   private List<Object> additionalVelocityTools = Collections.emptyList();
 
@@ -560,7 +561,9 @@ protected void validateRecordForCompilation(Schema record) {
   }
 
   OutputFile compile(Schema schema) {
-    schema = addStringType(schema); // annotate schema as needed
+    if (modifySchema) {
+      schema = addStringType(schema); // annotate schema as needed
+    }
     String output = "";
     VelocityContext context = new VelocityContext();
     context.put("this", this);
@@ -1213,4 +1216,16 @@ public static void main(String[] args) throws Exception {
   public void setOutputCharacterEncoding(String outputCharacterEncoding) {
     this.outputCharacterEncoding = outputCharacterEncoding;
   }
+
+  /**
+   * Sets whether the input schema is modified with Java specific logical String
+   * type with field "avro.java.string". Modifications only occur if stringType is
+   * set to StringType.String AND modifySchema is true.
+   *
+   * @param modifySchema Whether to modify schemas with logical type (defaults to
+   *                     true)
+   */
+  public void setModifySchema(boolean modifySchema) {
+    this.modifySchema = modifySchema;
+  }
 }

lang/java/compiler/src/test/java/org/apache/avro/compiler/specific/TestSpecificCompiler.java

@@ -77,6 +77,10 @@ public void setUp() {
 
   private File src = new File("src/test/resources/simple_record.avsc");
 
+  // Need a test file with a string, modifying above breaks some tests that make
+  // file assumptions
+  private File srcWithString = new File("src/test/resources/simple_record_with_string.avsc");
+
   static void assertCompilesWithJavaCompiler(File dstDir, Collection<SpecificCompiler.OutputFile> outputs)
       throws IOException {
     assertCompilesWithJavaCompiler(dstDir, outputs, false);
@@ -136,8 +140,12 @@ private static Schema createSampleRecordSchema(int numStringFields, int numDoubl
   }
 
   private SpecificCompiler createCompiler() throws IOException {
+    return createCompiler(this.src);
+  }
+
+  private SpecificCompiler createCompiler(File sourceSchema) throws IOException {
     Schema.Parser parser = new Schema.Parser();
-    Schema schema = parser.parse(this.src);
+    Schema schema = parser.parse(sourceSchema);
     SpecificCompiler compiler = new SpecificCompiler(schema);
     String velocityTemplateDir = "src/main/velocity/org/apache/avro/compiler/specific/templates/java/classic/";
     compiler.setTemplateDir(velocityTemplateDir);
@@ -320,6 +328,33 @@ public void testSettingOutputCharacterEncoding() throws Exception {
         new String(fileInDefaultEncoding), equalTo(new String(fileInDifferentEncoding, differentEncoding)));
   }
 
+  @Test
+  public void testSettingDoNotModifySchema() throws Exception {
+    SpecificCompiler compiler = createCompiler(this.srcWithString);
+    compiler.setStringType(StringType.String); // This is only type in which schema is modified
+    // Generated file with Java types (default)
+    compiler.compileToDestination(this.srcWithString, this.OUTPUT_DIR.getRoot());
+    byte[] fileWithDefaultModification = new byte[(int) this.outputFile.length()];
+    FileInputStream is = new FileInputStream(this.outputFile);
+    is.read(fileWithDefaultModification);
+    is.close(); // close input stream otherwise delete might fail
+    if (!this.outputFile.delete()) {
+      throw new IllegalStateException("unable to delete " + this.outputFile); // delete otherwise compiler might not
+      // overwrite because src timestamp hasn't
+      // changed.
+    }
+    // Generate file without Java specific type (should be less bytes)
+    compiler.setModifySchema(false);
+    compiler.compileToDestination(this.srcWithString, this.OUTPUT_DIR.getRoot());
+    byte[] fileWithoutModification = new byte[(int) this.outputFile.length()];
+    is = new FileInputStream(this.outputFile);
+    is.read(fileWithoutModification);
+    is.close();
+    // Compare as bytes
+    assertThat("Generated file should contain different bytes", fileWithDefaultModification,
+        not(equalTo(fileWithoutModification)));
+  }
+
   @Test
   public void testJavaTypeWithDecimalLogicalTypeEnabled() throws Exception {
     SpecificCompiler compiler = createCompiler();

lang/java/compiler/src/test/resources/simple_record_with_string.avsc

@@ -0,0 +1,7 @@
+{
+  "type": "record", 
+  "name": "SimpleRecord",
+  "fields" : [
+    {"name": "value", "type": "string"}
+  ]
+}

lang/java/tools/src/main/java/org/apache/avro/tool/SpecificCompilerTool.java

@@ -48,14 +48,15 @@ public class SpecificCompilerTool implements Tool {
   @Override
   public int run(InputStream in, PrintStream out, PrintStream err, List<String> origArgs) throws Exception {
     if (origArgs.size() < 3) {
-      System.err
-          .println("Usage: [-encoding <outputencoding>] [-string] [-bigDecimal] [-fieldVisibility <visibilityType>] "
-              + "[-noSetters] [-addExtraOptionalGetters] [-optionalGetters <optionalGettersType>] "
-              + "[-templateDir <templateDir>] (schema|protocol) input... outputdir");
+      System.err.println("Usage: [-encoding <outputencoding>] [-string] [-doNotModifySchema] [-bigDecimal] "
+          + "[-fieldVisibility <visibilityType>] "
+          + "[-noSetters] [-addExtraOptionalGetters] [-optionalGetters <optionalGettersType>] "
+          + "[-templateDir <templateDir>] (schema|protocol) input... outputdir");
       System.err.println(" input - input files or directories");
       System.err.println(" outputdir - directory to write generated java");
       System.err.println(" -encoding <outputencoding> - set the encoding of " + "output file(s)");
       System.err.println(" -string - use java.lang.String instead of Utf8");
+      System.err.println(" -doNotModifySchema - do not modify schemas as provided");
       System.err.println(" -fieldVisibility [private|public] - use either and default private");
       System.err.println(" -noSetters - do not generate setters");
       System.err
@@ -192,6 +193,7 @@ private void executeCompiler(SpecificCompiler compiler, CompilerOptions opts, Fi
     compiler.setEnableDecimalLogicalType(opts.useLogicalDecimal);
     opts.encoding.ifPresent(compiler::setOutputCharacterEncoding);
     opts.fieldVisibility.ifPresent(compiler::setFieldVisibility);
+    compiler.setModifySchema(!opts.doNotModifySchema);
     compiler.compileToDestination(src, output);
   }
 
@@ -268,6 +270,7 @@ private static class CompilerOptions {
     boolean useLogicalDecimal;
     boolean createSetters;
     boolean addExtraOptionalGetters;
+    boolean doNotModifySchema;
     Optional<OptionalGettersType> optionalGettersType;
     Optional<String> templateDir;
   }