[plc4x] branch develop updated: Fix race condition causing RejectedExecutionException on PlcConnection.close() (#1151)

[hutcheb]

This is an automated email from the ASF dual-hosted git repository.

hutcheb pushed a commit to branch develop
in repository https://gitbox.apache.org/repos/asf/plc4x.git


The following commit(s) were added to refs/heads/develop by this push:
     new ab6aa8ddba Fix race condition causing RejectedExecutionException on 
PlcConnection.close() (#1151)
ab6aa8ddba is described below

commit ab6aa8ddba8417e140e18dba86b4641e9c3afc22
Author: Rajmund Takács <tak...@gmail.com>
AuthorDate: Mon Oct 16 19:20:40 2023 +0200

    Fix race condition causing RejectedExecutionException on 
PlcConnection.close() (#1151)
    
    The remote end might actively close the connection as a response to 
disconnect event,
    which can cause the Netty channel to be already closed when we want to 
explicitly
    close it on our side.
    
    Can be easily tested in OPC-UA driver, with a few seconds delay added 
before the
    original code block:
    
    ```java
    Thread.sleep(10000); // <-- delay
    
    channel.pipeline().fireUserEventTriggered(new CloseConnectionEvent());
    channel.close().awaitUninterruptibly();
    ```
---
 .../java/spi/connection/DefaultNettyPlcConnection.java    | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git 
a/plc4j/spi/src/main/java/org/apache/plc4x/java/spi/connection/DefaultNettyPlcConnection.java
 
b/plc4j/spi/src/main/java/org/apache/plc4x/java/spi/connection/DefaultNettyPlcConnection.java
index 5444609721..0ee4e6cf71 100644
--- 
a/plc4j/spi/src/main/java/org/apache/plc4x/java/spi/connection/DefaultNettyPlcConnection.java
+++ 
b/plc4j/spi/src/main/java/org/apache/plc4x/java/spi/connection/DefaultNettyPlcConnection.java
@@ -19,6 +19,7 @@
 package org.apache.plc4x.java.spi.connection;
 
 import io.netty.channel.*;
+import java.util.concurrent.RejectedExecutionException;
 import org.apache.plc4x.java.api.EventPlcConnection;
 import org.apache.plc4x.java.api.authentication.PlcAuthentication;
 import org.apache.plc4x.java.api.exceptions.PlcConnectionException;
@@ -171,8 +172,18 @@ public class DefaultNettyPlcConnection extends 
AbstractPlcConnection implements
         } catch (Exception e) {
             logger.error("Timeout while trying to close connection");
         }
-        channel.pipeline().fireUserEventTriggered(new CloseConnectionEvent());
-        channel.close().awaitUninterruptibly();
+
+        // The channel might have already been closed by the remote end.
+        if (channel.isOpen()) {
+            try {
+                channel.pipeline().fireUserEventTriggered(new 
CloseConnectionEvent());
+                channel.close().awaitUninterruptibly();
+            } catch (RejectedExecutionException ex) {
+                if (channel.isOpen()) {
+                    throw ex;
+                }
+            }
+        }
 
         if (!sessionDisconnectCompleteFuture.isDone()) {
             sessionDisconnectCompleteFuture.complete(null);