KARAF-7174: Implement a SSH channel resource clearner whiteboard

Author: jbonofre

log/src/main/java/org/apache/karaf/log/command/LogTail.java

@@ -22,6 +22,7 @@
 import org.apache.karaf.shell.api.action.Command;
 import org.apache.karaf.shell.api.action.lifecycle.Reference;
 import org.apache.karaf.shell.api.action.lifecycle.Service;
+import org.apache.karaf.shell.api.console.ChannelResourceCleaner;
 import org.apache.karaf.shell.api.console.Session;
 import org.ops4j.pax.logging.spi.PaxAppender;
 import org.osgi.framework.BundleContext;
@@ -31,7 +32,8 @@
 
 @Command(scope = "log", name = "tail", description = "Continuously display log entries. Use ctrl-c to quit this command")
 @Service
-public class LogTail extends DisplayLog {
+public class LogTail extends DisplayLog implements ChannelResourceCleaner {
+
     @Reference
     Session session;
 
@@ -52,6 +54,9 @@ public Object execute() throws Exception {
         PaxAppender appender = event -> printEvent(out, event, minLevel);
         ServiceTracker<LogService, LogService> tracker = new LogServiceTracker(context, LogService.class, null, appender);
         tracker.open();
+        
+        context.registerService(ChannelResourceCleaner.class, this, null);
+
         try {
             synchronized (this) {
                 wait();
@@ -65,6 +70,12 @@ public Object execute() throws Exception {
         out.println();
         return null;
     }
+
+    @Override
+    public void close() {
+        System.out.println("STOP TAIL");
+        stopTail();
+    }
 
     private synchronized void stopTail() {
         notifyAll();

shell/core/src/main/java/org/apache/karaf/shell/api/console/ChannelResourceCleaner.java

@@ -0,0 +1,25 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.karaf.shell.api.console;
+
+public interface ChannelResourceCleaner {
+
+    void close();
+
+}

shell/ssh/src/main/java/org/apache/karaf/shell/ssh/Activator.java

@@ -22,9 +22,11 @@
 import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.time.Duration;
+import java.util.Collection;
 import java.util.Collections;
 
 import org.apache.karaf.shell.api.action.lifecycle.Manager;
+import org.apache.karaf.shell.api.console.ChannelResourceCleaner;
 import org.apache.karaf.shell.api.console.CommandLoggingFilter;
 import org.apache.karaf.shell.api.console.Session;
 import org.apache.karaf.shell.api.console.SessionFactory;
@@ -34,8 +36,11 @@
 import org.apache.karaf.util.tracker.annotation.Managed;
 import org.apache.karaf.util.tracker.annotation.RequireService;
 import org.apache.karaf.util.tracker.annotation.Services;
+import org.apache.sshd.common.channel.Channel;
+import org.apache.sshd.common.channel.ChannelListener;
 import org.apache.sshd.common.file.virtualfs.VirtualFileSystemFactory;
 import org.apache.sshd.common.keyprovider.KeyPairProvider;
+import org.apache.sshd.common.session.SessionListener;
 import org.apache.sshd.core.CoreModuleProperties;
 import org.apache.sshd.scp.server.ScpCommandFactory;
 import org.apache.sshd.server.SshServer;
@@ -189,6 +194,20 @@ protected SshServer createSshServer(SessionFactory sessionFactory) {
         server.setKeyExchangeFactories(SshUtils.buildKexAlgorithms(kexAlgorithms));
         server.setSignatureFactories(SshUtils.buildSigAlgorithms(sigAlgorithms));
         server.setShellFactory(new ShellFactoryImpl(sessionFactory));
+        server.addSessionListener(new SessionListener() {
+            @Override
+            public void sessionDisconnect(org.apache.sshd.common.session.Session session, int reason, String msg, String language, boolean initiator) {
+                try {
+                    Collection<ServiceReference<ChannelResourceCleaner>> references = bundleContext.getServiceReferences(ChannelResourceCleaner.class, null);
+                    for (ServiceReference<ChannelResourceCleaner> reference : references) {
+                        ChannelResourceCleaner cleaner = bundleContext.getService(reference);
+                        cleaner.close();
+                    }
+                } catch (Exception e) {
+                    // no-op
+                }
+            }
+        });
 
         if (sftpEnabled) {
             server.setCommandFactory(new ScpCommandFactory.Builder().withDelegate((channel, cmd) -> new ShellCommand(sessionFactory, cmd)).build());