[BugFix] Fix graceful exit handling in MySQLReadListener to preserve pre-query SQL connections

[Copilot]

Why I'm doing:

During graceful exit (leader transfer), MySQLReadListener was terminating all connections after query execution, breaking JDBC clients that send initialization queries like select @@query_timeout before actual user queries.

What I'm doing:

Added isTerminated() method with graceful exit awareness:

• Fast-path returns true if connection already terminated
• Returns false if no statements executed yet (null executor)
• During graceful exit, only terminates connections after non-pre-query SQLs
• Null-safe: handles executor and parsed statement nullability

Refactored handleRequest() to use isTerminated() instead of direct terminated flag check.

private boolean isTerminated() {
    if (terminated) {
        return true;
    }
    StmtExecutor executor = connectProcessor.getExecutor();
    if (executor == null) {
        return false;
    }
    final StatementBase lastStmt = executor.getParsedStmt();
    return GracefulExitFlag.isGracefulExit() && !SqlUtils.isPreQuerySQL(lastStmt);
}

Added unit tests covering terminated flag, graceful exit scenarios, null safety, and pre-query SQL types (SET statements, connection_id(), query_timeout).

What type of PR is this:

• BugFix
• Feature
• Enhancement
• Refactor
• UT
• Doc
• Tool

Does this PR entail a change in behavior?

• Yes, this PR will result in a change in behavior.
• No, this PR will not result in a change in behavior.

If yes, please specify the type of change:

• Interface/UI changes: syntax, type conversion, expression evaluation, display information
• Parameter changes: default values, similar parameters but with different default values
• Policy changes: use new policy to replace old one, functionality automatically enabled
• Feature removed
• Miscellaneous: upgrade & downgrade compatibility, etc.

Checklist:

• I have added test cases for my bug fix or my new feature
• This pr needs user documentation (for new or modified features or behaviors)
  • I have added documentation for my new feature or new function
  • This pr needs auto generate documentation
• This is a backport pr

Bugfix cherry-pick branch check:

• I have checked the version labels which the pr will be auto-backported to the target branch
  • 4.1
  • 4.0
  • 3.5
  • 3.4

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• mirror.iscas.ac.cn
  • Triggering command: /usr/lib/jvm/temurin-17-jdk-amd64/bin/java /usr/lib/jvm/temurin-17-jdk-amd64/bin/java --enable-native-access=ALL-UNNAMED -classpath /usr/share/apache-maven-3.9.12/boot/plexus-classworlds-2.9.0.jar -Dclassworlds.conf=/usr/share/apache-maven-3.9.12/bin/m2.conf -Dmaven.home=/usr/share/apache-maven-3.9.12 -Dlibrary.jansi.path=/usr/share/apache-maven-3.9.12/lib/jansi-native -Dmaven.multiModuleProjectDirectory=/home/REDACTED/work/starrocks/starrocks/fe/fe-core org.codehaus.plexus.classworlds.launcher.Launcher test-compile -Dtest=MySQLReadListenerTest (dns block)
• repository.cloudera.com
  • Triggering command: /usr/lib/jvm/temurin-17-jdk-amd64/bin/java /usr/lib/jvm/temurin-17-jdk-amd64/bin/java --enable-native-access=ALL-UNNAMED -classpath /usr/share/apache-maven-3.9.12/boot/plexus-classworlds-2.9.0.jar -Dclassworlds.conf=/usr/share/apache-maven-3.9.12/bin/m2.conf -Dmaven.home=/usr/share/apache-maven-3.9.12 -Dlibrary.jansi.path=/usr/share/apache-maven-3.9.12/lib/jansi-native -Dmaven.multiModuleProjectDirectory=/home/REDACTED/work/starrocks/starrocks/fe/fe-core org.codehaus.plexus.classworlds.launcher.Launcher test-compile -Dtest=MySQLReadListenerTest (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

In the StarRocks/starrocks repository, a bug exists in the MySQLReadListener.java file that causes improper handling of graceful exits. The problem lies in the method determining termination, which does not adequately check for the combination of graceful exit flags and SQL types. The current implementation directly references the terminated variable without considering additional logical conditions proposed in the isTerminated method introduced by your patch.

To resolve this issue, enhance the MySQLReadListener class with an improved termination condition and refactor the handleRequest method to use this. These changes will:

1. Introduce a new isTerminated method to encapsulate termination logic.
2. Ensure termination considers both the GracefulExitFlag and pre-query SQL status appropriately.

The patch includes the following key update:

• Adds a new method isTerminated() to handle graceful exit flag checks combined with the parsed statement SQL type.
• Refactors the handleRequest method to utilize isTerminated() instead of directly checking the terminated variable.

Here was the provided patch:

@@ -15,12 +15,15 @@
 package com.starrocks.mysql.nio;
 
 import com.starrocks.common.Config;
+import com.starrocks.common.util.SqlUtils;
 import com.starrocks.mysql.MysqlPackageDecoder;
 import com.starrocks.mysql.RequestPackage;
 import com.starrocks.mysql.ssl.SSLDecoder;
 import com.starrocks.qe.ConnectContext;
 import com.starrocks.qe.ConnectProcessor;
 import com.starrocks.rpc.RpcException;
+import com.starrocks.server.GracefulExitFlag;
+import com.starrocks.sql.ast.StatementBase;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.xnio.ChannelListener;
@@ -114,11 +117,19 @@ public class MySQLReadListener implements ChannelListener<ConduitStreamSourceCha
         ctx.cleanup();
     }

+    private boolean isTerminated() {
+        if (terminated) {
+            return true;
+        }
+        final StatementBase lastStmt = connectProcessor.getExecutor().getParsedStmt();
+        return GracefulExitFlag.isGracefulExit() && !SqlUtils.isPreQuerySQL(lastStmt);
+    }
+
     private synchronized void handleRequest(RequestPackage req) {
         ctx.setThreadLocalInfo();
         try {
             connectProcessor.processOnce(req);
-            if (ctx.isKilled() || terminated) {
+            if (ctx.isKilled() || isTerminated()) {
                 ctx.stopAcceptQuery();
                 ctx.cleanup();
             }

Please review the details provided and test the implementation for correctness, especially focusing on ensuring all edge cases are well-covered.

This pull request was created from Copilot chat.

---

✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.

---

Note

Improves connection termination behavior during leader transfer to avoid dropping JDBC initialization queries.

• Adds isTerminated() that returns true if terminated, false if executor is null, and during GracefulExitFlag.isGracefulExit() only terminates when last stmt is not pre-query via SqlUtils.isPreQuerySQL
• Updates handleRequest() to use isTerminated() instead of checking terminated directly
• Introduces unit tests for terminated flag, graceful exit with pre-query vs non-pre-query SQL, null executor/parsed stmt, and common pre-query cases (select @@query_timeout, set query_timeout=..., select connection_id())

^{Written by Cursor Bugbot for commit d484e78. This will update automatically on new commits. Configure here.}

[alvin-celerdata]

@cursor review

[cursor]

✅ Bugbot reviewed your changes and found no bugs!

[sonarqubecloud]

Quality Gate passed

Issues
12 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[github-actions]

[Java-Extensions Incremental Coverage Report]

✅ pass : 0 / 0 (0%)

[github-actions]

[FE Incremental Coverage Report]

✅ pass : 8 / 8 (100.00%)

file detail

	path	covered_line	new_line	coverage	not_covered_line_detail
🔵	com/starrocks/mysql/nio/MySQLReadListener.java	8	8	100.00%	[]

[github-actions]

[BE Incremental Coverage Report]

✅ pass : 0 / 0 (0%)

[github-actions]

@Mergifyio backport branch-4.0

[github-actions]

@Mergifyio backport branch-4.1

[mergify]

backport branch-4.0

✅ Backports have been created

Details

• #68037 [BugFix] Fix graceful exit handling in MySQLReadListener to preserve pre-query SQL connections (backport #67917) has been created for branch branch-4.0

[mergify]

backport branch-4.1

✅ Backports have been created

Details

• #68038 [BugFix] Fix graceful exit handling in MySQLReadListener to preserve pre-query SQL connections (backport #67917) has been created for branch branch-4.1