[jboss-cvs] JBossAS SVN: r65550 - branches/Branch_4_2/cluster/src/main/org/jboss/ha/framework/interfaces.

[jboss-cvs-commits at lists.jboss.org]

Author: bstansberry at jboss.com
Date: 2007-09-22 01:19:05 -0400 (Sat, 22 Sep 2007)
New Revision: 65550

Modified:
   branches/Branch_4_2/cluster/src/main/org/jboss/ha/framework/interfaces/HARMIClient.java
Log:
[JBAS-4740] Wrap the cause of ServiceUnavailable, giving preference to wrapping NoSuchObjectException

Modified: branches/Branch_4_2/cluster/src/main/org/jboss/ha/framework/interfaces/HARMIClient.java
===================================================================
--- branches/Branch_4_2/cluster/src/main/org/jboss/ha/framework/interfaces/HARMIClient.java	2007-09-22 05:17:57 UTC (rev 65549)
+++ branches/Branch_4_2/cluster/src/main/org/jboss/ha/framework/interfaces/HARMIClient.java	2007-09-22 05:19:05 UTC (rev 65550)
@@ -26,6 +26,10 @@
 import java.io.ObjectInputStream;
 import java.io.ObjectOutputStream;
 import java.lang.reflect.Method;
+import java.rmi.ConnectException;
+import java.rmi.ConnectIOException;
+import java.rmi.NoSuchObjectException;
+import java.rmi.UnknownHostException;
 import java.util.ArrayList;
 
 import org.jboss.invocation.MarshalledInvocation;
@@ -154,13 +158,56 @@
    }
 
 
+   /**
+    * Invoke the given method against a remote server. If the call results
+    * in certain {@link RemoteException} subtypes, catch the exception and
+    * attempt to fail over to another server.
+    * <p>
+    * Failover will only be attempted if the remote call throws an exception
+    * whose type indicates the call never reached the server: 
+    * <ul>
+    * <li>{@link java.rmi.ConnectException}</li>
+    * <li>{@link java.rmi.ConnectIOException}</li>
+    * <li>{@link java.rmi.NoSuchObjectException}</li>
+    * <li>{@link java.rmi.UnknownHostException}</li>
+    * </ul>
+    * </p>
+    * <p>
+    * All other exception types will not be caught.
+    * </p>
+    * <p>
+    * If one of the above exception types is caught when invoking against the
+    * last known server, then a {@link RemoteException} will be thrown.  This
+    * exception will include as its {@link Throwable#getCause() cause} either
+    * <ol>
+    * <li>any {@link java.rmi.NoSuchObjectException} that was caught</li>
+    * <li>or, if no {@link java.rmi.NoSuchObjectException} that was caught,
+    * the exception thrown on the last failover attempt</li> 
+    * </ol>
+    * Preference is given to including <code>NoSuchObjectException</code> as
+    * the cause, as that exception indicates that a server was listening on
+    * the expected address and port but that this client has an RMI stub that
+    * is out of sync with the server.  This would typically happen due to 
+    * a server restart or service redeploy.  Knowledge of this failure condition
+    * could potentially be useful to the caller.
+    * </p>
+    * 
+    * @param proxy  the proxy object that's being invoked
+    * @param method the method to invoke
+    * @param args   arguments to the method
+    * @return       any return value from the invocation, or <code>null</code>
+    * 
+    * @throws Throwable Throwable thrown when making remote call, or the
+    *                   <code>RemoteException</code> discussed above.
+    */
    public Object invokeRemote(Object proxy, Method method, Object[] args) throws Throwable
    {
       boolean trace = log.isTraceEnabled();
       HARMIServer target = (HARMIServer)getRemoteTarget();
+      NoSuchObjectException nsoe = null;
+      Exception lastException = null;
       while (target != null)
       {
-         Exception lastException = null;
          try
          {
             if( trace )
@@ -183,19 +230,21 @@
 
             return rsp.response;
          }
-         catch (java.rmi.ConnectException e)
+         catch (ConnectException e)
          {
             lastException = e;
          }
-         catch (java.rmi.ConnectIOException e)
+         catch (ConnectIOException e)
          {
             lastException = e;
          }
-         catch (java.rmi.NoSuchObjectException e)
+         catch (NoSuchObjectException e)
          {
+            // JBAS-4740 preserve this exception
+            nsoe = e;
             lastException = e;
          }
-         catch (java.rmi.UnknownHostException e)
+         catch (UnknownHostException e)
          {
             lastException = e;
          }
@@ -206,7 +255,10 @@
          target = (HARMIServer)getRemoteTarget();
       }
       // if we get here this means list was exhausted
-      throw new java.rmi.RemoteException("Service unavailable.");
+      // JBAS-4740 wrap any NSOE in preference to 'lastException' since
+      // an NSOE indicates a server was running
+      Exception toWrap = (nsoe == null) ? lastException : nsoe;
+      throw new java.rmi.RemoteException("Service unavailable.", toWrap);
 
    }
 
@@ -219,6 +271,12 @@
 
    // InvocationHandler implementation ----------------------------------------------   
 
+   /**
+    * Invoke the given method, locally if possible; if not then
+    * {@link #invokeRemote(Object, Method, Object[]) invoke against a remote server}.
+    * 
+    * @see #invokeRemote(Object, Method, Object[])
+    */
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable
    {
       // The isLocal call is handled by the proxy