cleanup on comments and debug logging

Signed-off-by: Eric Wei <mengwei.eric@gmail.com>

Author: mengweieric

core/src/main/java/org/opensearch/sql/executor/autocomplete/GrammarBundle.java

@@ -8,17 +8,12 @@
 import lombok.Builder;
 import lombok.Data;
 
-/**
- * Grammar bundle containing everything needed for client-side ANTLR-based parsing.
- *
- * <p>Includes serialized ATN data (lexer + parser), vocabulary, and rule/channel/mode names.
- * Language-agnostic — usable for PPL, SQL, or any ANTLR4 grammar.
- */
+/** Response payload for the {@code GET /_plugins/_ppl/_grammar} endpoint. */
 @Data
 @Builder
 public class GrammarBundle {
 
-  /** Bundle format version. Increment when the schema changes. */
+  /** Bundle format version. */
   private String bundleVersion;
 
   /** SHA-256 hash of the serialized ATN data. Clients may use this to detect grammar changes. */

plugin/src/main/java/org/opensearch/sql/plugin/rest/RestPPLGrammarAction.java

@@ -20,21 +20,7 @@
 import org.opensearch.sql.ppl.autocomplete.PPLGrammarBundleBuilder;
 import org.opensearch.transport.client.node.NodeClient;
 
-/**
- * REST handler for PPL grammar metadata endpoint.
- *
- * <p>Endpoint: GET /_plugins/_ppl/_grammar
- *
- * <p>Returns grammar data for client-side parsing, autocomplete, syntax highlighting, etc:
- *
- * <ul>
- *   <li>Serialized ANTLR ATN data (lexer + parser)
- *   <li>Vocabulary (literal and symbolic names)
- *   <li>Rule names (parser and lexer)
- *   <li>Channel and mode names
- * </ul>
- *
- */
+/** REST handler for {@code GET /_plugins/_ppl/_grammar}. */
 @Log4j2
 public class RestPPLGrammarAction extends BaseRestHandler {
 
@@ -58,18 +44,14 @@ public List<Route> routes() {
   protected RestChannelConsumer prepareRequest(RestRequest request, NodeClient client)
       throws IOException {
 
-    log.debug("Received PPL grammar request");
-
     return channel -> {
       try {
         GrammarBundle bundle = getOrBuildBundle();
 
         XContentBuilder builder = channel.newBuilder();
         serializeBundle(builder, bundle);
 
-        BytesRestResponse response = new BytesRestResponse(RestStatus.OK, builder);
-        log.info("Returning PPL grammar (size: {} bytes)", response.content().length());
-        channel.sendResponse(response);
+        channel.sendResponse(new BytesRestResponse(RestStatus.OK, builder));
 
       } catch (Exception e) {
         log.error("Error building or serializing PPL grammar", e);
@@ -78,20 +60,13 @@ protected RestChannelConsumer prepareRequest(RestRequest request, NodeClient cli
     };
   }
 
-  /**
-   * Get cached bundle or build it if not yet initialized.
-   *
-   * <p>Thread-safe lazy initialization with double-checked locking.
-   */
+  // Thread-safe lazy initialization with double-checked locking.
   private GrammarBundle getOrBuildBundle() {
-    // First check without lock (common case: already initialized)
     if (cachedBundle != null) {
       return cachedBundle;
     }
-
-    // Acquire lock for initialization
     synchronized (bundleLock) {
-      // Double-check after acquiring lock
+      // double-check after acquiring lock
       if (cachedBundle == null) {
         log.info("Building PPL grammar bundle (first request)...");
         long startTime = System.currentTimeMillis();
@@ -106,22 +81,14 @@ private GrammarBundle getOrBuildBundle() {
     }
   }
 
-  /**
-   * Invalidate cached bundle (for testing or grammar updates).
-   *
-   * <p>Note: This only affects the current node. In a multi-node cluster, each node maintains its
-   * own cache.
-   */
+  /** Invalidate the cached bundle, forcing a rebuild on the next request. */
   public void invalidateCache() {
     synchronized (bundleLock) {
       log.info("Invalidating cached PPL grammar bundle");
       cachedBundle = null;
     }
   }
 
-  /**
-   * Serialize {@link GrammarBundle} to JSON.
-   */
   private void serializeBundle(XContentBuilder builder, GrammarBundle bundle)
       throws IOException {
     builder.startObject();
@@ -134,7 +101,6 @@ private void serializeBundle(XContentBuilder builder, GrammarBundle bundle)
     // Lexer ATN & metadata
     if (bundle.getLexerSerializedATN() != null) {
       builder.field("lexerSerializedATN", bundle.getLexerSerializedATN());
-      log.debug("Lexer ATN: {} elements", bundle.getLexerSerializedATN().length);
     }
 
     if (bundle.getLexerRuleNames() != null) {
@@ -152,7 +118,6 @@ private void serializeBundle(XContentBuilder builder, GrammarBundle bundle)
     // Parser ATN & metadata
     if (bundle.getParserSerializedATN() != null) {
       builder.field("parserSerializedATN", bundle.getParserSerializedATN());
-      log.debug("Parser ATN: {} elements", bundle.getParserSerializedATN().length);
     }
 
     if (bundle.getParserRuleNames() != null) {

plugin/src/test/java/org/opensearch/sql/plugin/rest/RestPPLGrammarActionTest.java

@@ -23,17 +23,7 @@
 import org.opensearch.test.rest.FakeRestRequest;
 import org.opensearch.transport.client.node.NodeClient;
 
-/**
- * Unit tests for RestPPLGrammarAction.
- *
- * <p>Tests:
- *
- * <ul>
- *   <li>200 OK response with grammar bundle
- *   <li>Grammar structure validation
- *   <li>Cache behavior
- * </ul>
- */
+/** Unit tests for {@link RestPPLGrammarAction}. */
 public class RestPPLGrammarActionTest extends OpenSearchTestCase {
 
   private RestPPLGrammarAction action;
@@ -83,8 +73,7 @@ public void testGetGrammar_ReturnsBundle() throws Exception {
   }
 
   @Test
-  public void testGetGrammar_ArtifactIsCached() throws Exception {
-    // Make two requests
+  public void testGetGrammar_BundleIsCached() throws Exception {
     FakeRestRequest request1 =
         new FakeRestRequest.Builder(NamedXContentRegistry.EMPTY)
             .withMethod(RestRequest.Method.GET)
@@ -96,7 +85,6 @@ public void testGetGrammar_ArtifactIsCached() throws Exception {
     action.prepareRequest(request1, client).accept(channel1);
     long elapsed1 = System.currentTimeMillis() - startTime1;
 
-    // Second request should be faster (cached)
     FakeRestRequest request2 =
         new FakeRestRequest.Builder(NamedXContentRegistry.EMPTY)
             .withMethod(RestRequest.Method.GET)
@@ -108,7 +96,6 @@ public void testGetGrammar_ArtifactIsCached() throws Exception {
     action.prepareRequest(request2, client).accept(channel2);
     long elapsed2 = System.currentTimeMillis() - startTime2;
 
-    // Second request should be faster (bundle cached)
     assertTrue(
         "Second request should be faster due to caching (elapsed1="
             + elapsed1
@@ -120,7 +107,6 @@ public void testGetGrammar_ArtifactIsCached() throws Exception {
 
   @Test
   public void testInvalidateCache() throws Exception {
-    // Get grammar
     FakeRestRequest request1 =
         new FakeRestRequest.Builder(NamedXContentRegistry.EMPTY)
             .withMethod(RestRequest.Method.GET)
@@ -131,10 +117,8 @@ public void testInvalidateCache() throws Exception {
     action.prepareRequest(request1, client).accept(channel1);
     assertEquals(RestStatus.OK, channel1.getResponse().status());
 
-    // Invalidate cache
     action.invalidateCache();
 
-    // Get grammar again — should still return 200 OK with same content
     FakeRestRequest request2 =
         new FakeRestRequest.Builder(NamedXContentRegistry.EMPTY)
             .withMethod(RestRequest.Method.GET)

ppl/src/main/java/org/opensearch/sql/ppl/autocomplete/PPLGrammarBundleBuilder.java

@@ -8,7 +8,6 @@
 import java.nio.charset.StandardCharsets;
 import java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;
-import lombok.extern.log4j.Log4j2;
 import org.antlr.v4.runtime.CharStreams;
 import org.antlr.v4.runtime.CommonTokenStream;
 import org.antlr.v4.runtime.Vocabulary;
@@ -18,33 +17,22 @@
 import org.opensearch.sql.ppl.antlr.parser.OpenSearchPPLParser;
 
 /** Builds the {@link GrammarBundle} for the PPL language from the generated ANTLR lexer/parser. */
-@Log4j2
 public class PPLGrammarBundleBuilder {
 
   private static final String ANTLR_VERSION = "4.13.2";
   private static final String BUNDLE_VERSION = "1.0";
 
-  /**
-   * Build the PPL grammar bundle.
-   *
-   * <p>Uses {@link ATNSerializer} to re-serialize the ATN into the int[] format expected by the
-   * antlr4ng runtime on the frontend. Do NOT use {@code lexer.getSerializedATN().chars().toArray()}
-   * — that yields raw UTF-16 char values which cause "state type 65535 is not valid" errors.
-   *
-   * @return {@link GrammarBundle} ready for JSON serialization
-   */
   public GrammarBundle build() {
-    log.info("Building PPL grammar bundle...");
-
     OpenSearchPPLLexer lexer = new OpenSearchPPLLexer(CharStreams.fromString(""));
     CommonTokenStream tokens = new CommonTokenStream(lexer);
     OpenSearchPPLParser parser = new OpenSearchPPLParser(tokens);
 
+    // ATNSerializer re-serializes the ATN into the int[] format expected by antlr4ng.
+    // Do not use lexer.getSerializedATN().chars().toArray() — that yields raw UTF-16 char values
+    // which cause "state type 65535 is not valid" errors in the frontend deserializer.
     int[] lexerATN = new ATNSerializer(lexer.getATN()).serialize().toArray();
     int[] parserATN = new ATNSerializer(parser.getATN()).serialize().toArray();
 
-    log.info("Lexer ATN: {} elements, Parser ATN: {} elements", lexerATN.length, parserATN.length);
-
     Vocabulary vocabulary = parser.getVocabulary();
     int maxTokenType = vocabulary.getMaxTokenType();
     String[] literalNames = new String[maxTokenType + 1];
@@ -54,23 +42,19 @@ public GrammarBundle build() {
       symbolicNames[i] = vocabulary.getSymbolicName(i);
     }
 
-    GrammarBundle bundle =
-        GrammarBundle.builder()
-            .bundleVersion(BUNDLE_VERSION)
-            .grammarHash(computeGrammarHash(lexerATN, parserATN))
-            .lexerSerializedATN(lexerATN)
-            .parserSerializedATN(parserATN)
-            .lexerRuleNames(lexer.getRuleNames())
-            .parserRuleNames(parser.getRuleNames())
-            .channelNames(lexer.getChannelNames())
-            .modeNames(lexer.getModeNames())
-            .startRuleIndex(0)
-            .literalNames(literalNames)
-            .symbolicNames(symbolicNames)
-            .build();
-
-    log.info("Built PPL grammar bundle: {} tokens", symbolicNames.length);
-    return bundle;
+    return GrammarBundle.builder()
+        .bundleVersion(BUNDLE_VERSION)
+        .grammarHash(computeGrammarHash(lexerATN, parserATN))
+        .lexerSerializedATN(lexerATN)
+        .parserSerializedATN(parserATN)
+        .lexerRuleNames(lexer.getRuleNames())
+        .parserRuleNames(parser.getRuleNames())
+        .channelNames(lexer.getChannelNames())
+        .modeNames(lexer.getModeNames())
+        .startRuleIndex(0)
+        .literalNames(literalNames)
+        .symbolicNames(symbolicNames)
+        .build();
   }
 
   private static String computeGrammarHash(int[] lexerATN, int[] parserATN) {