[FIXED JENKINS-33319] Premtively wake the acceptor thread to let it c…

…lose cleanly - Also adds a Ping Agent protocol that could be used by nagios monitoring, etc. to verify that the slave agent listener is alive - We use the ping agent protocol to ensure that the acceptor thread wakes up, loops and sees that the shutdown is started that prevents the socket close exception from being thrown
jenkinsci · Mar 4, 2016 · 2a61f30 · 2a61f30
1 parent 0cace71
commit 2a61f30
Showing 1 changed file with 92 additions and 3 deletions.
diff --git a/core/src/main/java/hudson/TcpSlaveAgentListener.java b/core/src/main/java/hudson/TcpSlaveAgentListener.java
@@ -24,6 +24,12 @@
 package hudson;
 
 import hudson.slaves.OfflineCause;
+import java.io.DataOutputStream;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.io.UnsupportedEncodingException;
+import java.net.SocketAddress;
+import java.util.Arrays;
 import jenkins.AgentProtocol;
 
 import java.io.BufferedWriter;
@@ -37,6 +43,7 @@
 import java.nio.channels.ServerSocketChannel;
 import java.util.logging.Level;
 import java.util.logging.Logger;
+import org.apache.commons.io.IOUtils;
 
 /**
  * Listens to incoming TCP connections from JNLP slave agents and CLI.
@@ -91,7 +98,7 @@ public int getPort() {
     public void run() {
         try {
             // the loop eventually terminates when the socket is closed.
-            while (true) {
+            while (!shuttingDown) {
                 Socket s = serverSocket.accept().socket();
 
                 // this prevents a connection from silently terminated by the router in between or the other peer
@@ -115,6 +122,16 @@ public void run() {
      */
     public void shutdown() {
         shuttingDown = true;
+        try {
+            SocketAddress localAddress = serverSocket.getLocalAddress();
+            if (localAddress instanceof InetSocketAddress) {
+                InetSocketAddress address = (InetSocketAddress) localAddress;
+                Socket client = new Socket(address.getHostName(), address.getPort());
+                new PingAgentProtocol().connect(client);
+            }
+        } catch (IOException e) {
+            LOGGER.log(Level.FINE, "Failed to send Ping to wake acceptor loop", e);
+        }
         try {
             serverSocket.close();
         } catch (IOException e) {
@@ -140,7 +157,7 @@ public ConnectionHandler(Socket s) {
         @Override
         public void run() {
             try {
-                LOGGER.info("Accepted connection #"+id+" from "+s.getRemoteSocketAddress());
+                LOGGER.log(Level.INFO, "Accepted connection #{0} from {1}", new Object[]{id,s.getRemoteSocketAddress()});
 
                 DataInputStream in = new DataInputStream(s.getInputStream());
                 PrintWriter out = new PrintWriter(
@@ -183,6 +200,78 @@ private void error(PrintWriter out, String msg) throws IOException {
         }
     }
 
+    /**
+     * This extension provides a Ping protocol that allows people to verify that the TcpSlaveAgentListener is alive.
+     * We also use this
+     * @since
+     */
+    @Extension
+    public static class PingAgentProtocol extends AgentProtocol {
+
+        private final byte[] ping;
+
+        public PingAgentProtocol() {
+            try {
+                ping = "Ping\n".getBytes("UTF-8");
+            } catch (UnsupportedEncodingException e) {
+                throw new IllegalStateException("JLS mandates support for UTF-8 charset", e);
+            }
+        }
+
+        @Override
+        public String getName() {
+            return "Ping";
+        }
+
+        @Override
+        public void handle(Socket socket) throws IOException, InterruptedException {
+            try {
+                OutputStream stream = socket.getOutputStream();
+                try {
+                    LOGGER.log(Level.FINE, "Received ping request from {0}", socket.getRemoteSocketAddress());
+                    stream.write(ping);
+                    stream.flush();
+                    LOGGER.log(Level.FINE, "Sent ping response to {0}", socket.getRemoteSocketAddress());
+                } finally {
+                    stream.close();
+                }
+            } finally {
+                socket.close();
+            }
+        }
+
+        public boolean connect(Socket socket) throws IOException {
+            try {
+                DataOutputStream out = null;
+                InputStream in = null;
+                try {
+                    LOGGER.log(Level.FINE, "Requesting ping from {0}", socket.getRemoteSocketAddress());
+                    out = new DataOutputStream(socket.getOutputStream());
+                    out.writeUTF("Protocol:Ping");
+                    in = socket.getInputStream();
+                    byte[] response = new byte[ping.length];
+                    int responseLength = in.read(response);
+                    if (responseLength == ping.length && Arrays.equals(response, ping)) {
+                        LOGGER.log(Level.FINE, "Received ping response from {0}", socket.getRemoteSocketAddress());
+                        return true;
+                    } else {
+                        LOGGER.log(Level.FINE, "Expected ping response from {0} of {1} got {2}", new Object[]{
+                                socket.getRemoteSocketAddress(),
+                                new String(ping, "UTF-8"),
+                                new String(response, 0, responseLength, "UTF-8")
+                        });
+                        return false;
+                    }
+                } finally {
+                    IOUtils.closeQuietly(out);
+                    IOUtils.closeQuietly(in);
+                }
+            } finally {
+                socket.close();
+            }
+        }
+    }
+
     /**
      * Connection terminated because we are reconnected from the current peer.
      */
@@ -238,4 +327,4 @@ Note also that the JAR file(s) for the JWS application should not be on
 can't do anything useful without going through a protected path or doing
 something to present credentials that could only have come from a valid
 user.
-*/
+*/