From 6aabbf6024ab3c9d3fc4562a3dea0b79e73b8142 Mon Sep 17 00:00:00 2001
From: Ruslan Kashapov <ruslan.kashapov@pantheon.tech>
Date: Mon, 2 Oct 2023 13:41:53 +0300
Subject: [PATCH] Fix NetconfMessage not sent on EmbeddedChannel

The EmbeddedChannel implementation uses built-in implementation
for event loop (EmbeddedEventLoop) which has no own executor.
The tasks placed via execute() method are queued but not executed
unless predefined events like channel closure.

Explicit triggering of pending tasks processing resolves the issue
for now, but this needs to be revisited.

JIRA: NETCONF-1106
Change-Id: Ief1d9566651c39e10310c961e5899324e73fa923
Signed-off-by: Ruslan Kashapov <ruslan.kashapov@pantheon.tech>
Signed-off-by: Robert Varga <robert.varga@pantheon.tech>
---
 .../netconf/nettyutil/AbstractNetconfSession.java        | 9 +++++++++
 .../opendaylight/netconf/server/NetconfSubsystem.java    | 1 +
 2 files changed, 10 insertions(+)

diff --git a/netconf/netconf-netty-util/src/main/java/org/opendaylight/netconf/nettyutil/AbstractNetconfSession.java b/netconf/netconf-netty-util/src/main/java/org/opendaylight/netconf/nettyutil/AbstractNetconfSession.java
index 7f1009613a..3eaf83156f 100644
--- a/netconf/netconf-netty-util/src/main/java/org/opendaylight/netconf/nettyutil/AbstractNetconfSession.java
+++ b/netconf/netconf-netty-util/src/main/java/org/opendaylight/netconf/nettyutil/AbstractNetconfSession.java
@@ -15,6 +15,7 @@ import io.netty.channel.ChannelHandler;
 import io.netty.channel.ChannelHandlerContext;
 import io.netty.channel.ChannelPromise;
 import io.netty.channel.SimpleChannelInboundHandler;
+import io.netty.channel.embedded.EmbeddedChannel;
 import io.netty.handler.codec.ByteToMessageDecoder;
 import io.netty.handler.codec.MessageToByteEncoder;
 import java.io.EOFException;
@@ -92,6 +93,14 @@ public abstract class AbstractNetconfSession<S extends NetconfSession, L extends
             }
         });
 
+        // FIXME: NETCONF-1106: this is a workaround for netconf-server's NetconfSubsystem using EmbeddedChannel instead
+        //                      of correctly integrating with the underlying transport channel
+        if (channel instanceof EmbeddedChannel embeddedChannel) {
+            // Embedded event loop implementation has no executor, it requires explicit invocation to process
+            synchronized (channel) {
+                embeddedChannel.runPendingTasks();
+            }
+        }
         return promise;
     }
 
diff --git a/protocol/netconf-server/src/main/java/org/opendaylight/netconf/server/NetconfSubsystem.java b/protocol/netconf-server/src/main/java/org/opendaylight/netconf/server/NetconfSubsystem.java
index 50ae962e17..7571b71300 100644
--- a/protocol/netconf-server/src/main/java/org/opendaylight/netconf/server/NetconfSubsystem.java
+++ b/protocol/netconf-server/src/main/java/org/opendaylight/netconf/server/NetconfSubsystem.java
@@ -27,6 +27,7 @@ import org.opendaylight.netconf.shaded.sshd.server.command.AsyncCommand;
 
 final class NetconfSubsystem extends AbstractCommandSupport
         implements AsyncCommand, ChannelSessionAware, ChannelDataReceiver {
+    // FIXME: NETCONF-1106: do not use EmbeddedChannel here!
     private final EmbeddedChannel innerChannel = new EmbeddedChannel();
     private final ServerChannelInitializer channelInitializer;
 
-- 
2.36.6