Fixes Restcomm#150 : Resubmissions of requests to alternate peers now possible until all peers exhausted, while respecting Weighted Round Robin balancing algorithm

.gitignore

@@ -7,6 +7,7 @@
 .classpath
 .project
 .settings
+.checkstyle
 
 # IntelliJ IDEA #
 #################
@@ -29,3 +30,7 @@ target
 Icon?
 ehthumbs.db
 Thumbs.db
+
+# Testsuite generated *_sctp.xml files #
+########################################
+testsuite/tests/*_sctp.xml

.project

@@ -1,15 +1,17 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <projectDescription>
-  <name>diameter-parent</name>
-  <comment/>
-  <projects/>
-  <buildSpec>
-    <buildCommand>
-      <name>org.eclipse.jdt.core.javabuilder</name>
-      <arguments/>
-    </buildCommand>
-  </buildSpec>
-  <natures>
-    <nature>org.eclipse.jdt.core.javanature</nature>
-  </natures>
-</projectDescription>
+	<name>diameter-parent</name>
+	<comment></comment>
+	<projects>
+	</projects>
+	<buildSpec>
+		<buildCommand>
+			<name>org.eclipse.jdt.core.javabuilder</name>
+			<arguments>
+			</arguments>
+		</buildCommand>
+	</buildSpec>
+	<natures>
+		<nature>org.eclipse.jdt.core.javanature</nature>
+	</natures>
+</projectDescription>

core/jdiameter/impl/src/main/java/org/jdiameter/client/api/router/IRouter.java

@@ -121,13 +121,39 @@ public interface IRouter  {
    */
   void processRedirectAnswer(IRequest request, IAnswer answer, IPeerTable table) throws InternalException, RouteException;
 
+
+  /**
+   * Indicates whether this router implementation is able to resubmit requests to an alternative peer,
+   * for which a Busy or Unable to Deliver Answer has already been received from one peer.<br /><br />
+   *
+   * <strong>Note: </strong> Returning <code>true</code> from this method when the router implementation has not been designed to
+   * handle resubmitting such requests can result in a request being resubmitted perpetually.
+   *
+   * @return <code>false</code> by default. <code>true</code> when and only when the router implementation has specific logic to handle
+   * submitting requests which have received a Busy or Unable to Deliver Answer from one peer, to an alternative peer, and to avoid
+   * perpetual re-submission of such requests.
+   */
+  boolean canProcessBusyOrUnableToDeliverAnswer();
+
+
+  /**
+   * Called when a 3002 or 3004 is received for a request. This method attempts to resubmit the request to an alternative peer.
+   *
+   * @param request
+   * @param table
+   */
+  void processBusyOrUnableToDeliverAnswer(IRequest request, IPeerTable table) throws InternalException, RouteException;
+
+
   /**
    * Based on Redirect entries or any other factors, this method changes route information.
    * @param message
    * @return
    * @throws RouteException
    * @throws AvpDataException
    */
+
+
   boolean updateRoute(IRequest message) throws RouteException, AvpDataException;
 
 }

core/jdiameter/impl/src/main/java/org/jdiameter/client/impl/controller/PeerImpl.java

@@ -383,6 +383,17 @@ private boolean isRedirectAnswer(Avp avpResCode, IMessage answer) {
     }
   }
 
+  private boolean isBusyOrUnableToDeliverAnswer(Avp avpResCode, IMessage answer) {
+    try {
+      // E-bit set indicating a protocol error, and Result Code one of 3002 or 3004
+      return (answer.getFlags() & 0x20) != 0 && avpResCode != null
+          && (avpResCode.getInteger32() == ResultCode.TOO_BUSY || avpResCode.getInteger32() == ResultCode.UNABLE_TO_DELIVER);
+    }
+    catch (AvpDataException e) {
+      return false;
+    }
+  }
+
   @Override
   public IStatistic getStatistic() {
     return statistic;
@@ -480,6 +491,24 @@ private IMessage processRedirectAnswer(IMessage request, IMessage answer) {
     return answer;
   }
 
+  private IMessage processBusyOrUnableToDeliverAnswer(IMessage request, IMessage answer) {
+    if (router.canProcessBusyOrUnableToDeliverAnswer()) {
+      try {
+        logger.debug("Message with [sessionId={}] received a Busy or Unable to Deliver Answer and will be resubmitted.", request.getSessionId());
+        router.processBusyOrUnableToDeliverAnswer(request, table);
+        return null;
+      }
+      catch (Throwable exc) {
+        // Any error when attempting a resubmit to an alternative peer simply results in the original
+        // Busy or Unable to Deliver Answer being returned
+        if (logger.isErrorEnabled()) {
+          logger.error("Failed to reprocess busy or unable to deliver response - all peers exhausted?", exc);
+        }
+      }
+    }
+    return answer;
+  }
+
   @Override
   public void connect() throws InternalException, IOException, IllegalDiameterStateException {
     if (getState(PeerState.class) != PeerState.DOWN) {
@@ -1034,6 +1063,12 @@ public boolean receiveMessage(IMessage message) {
             //if return value is not null, there was some error, lets try to invoke listener if it exists...
             isProcessed = message == null;
           }
+          avpResCode = message.getAvps().getAvp(RESULT_CODE);
+          if (isBusyOrUnableToDeliverAnswer(avpResCode, message)) {
+            message = processBusyOrUnableToDeliverAnswer(request, message);
+            // if return value is not null, there was some error, lets try to invoke listener if it exists...
+            isProcessed = message == null;
+          }
 
           if (message != null) {
             if (request.getEventListener() != null) {

core/jdiameter/impl/src/main/java/org/jdiameter/client/impl/router/RouterImpl.java

@@ -507,7 +507,7 @@ public IPeer getPeer(IMessage message, IPeerTable manager) throws RouteException
       }
 
       // Balancing
-      IPeer peer = selectPeer(availablePeers);
+      IPeer peer = selectPeer(message, availablePeers);
       if (peer == null) {
         throw new RouteException("Unable to find valid connection to peer[" + destHost + "] in realm[" + destRealm + "]");
       }
@@ -639,6 +639,33 @@ public void processRedirectAnswer(IRequest request, IAnswer answer, IPeerTable t
     }
   }
 
+  /**
+   * This method should always return false unless specifically designed to handle
+   * submitting requests which have received a Busy or Unable to Deliver Answer from one peer, to an alternative peer, and to avoid
+   * perpetual re-submission of such requests.
+   *
+   * @return <code>false</code>
+   */
+  @Override
+  public boolean canProcessBusyOrUnableToDeliverAnswer() {
+    return false;
+  }
+
+  public void processBusyOrUnableToDeliverAnswer(IRequest request, IPeerTable table) throws InternalException, RouteException {
+    try {
+      table.sendMessage((IMessage) request);
+    }
+    catch (AvpDataException exc) {
+      throw new InternalException(exc);
+    }
+    catch (IllegalDiameterStateException e) {
+      throw new InternalException(e);
+    }
+    catch (IOException e) {
+      throw new InternalException(e);
+    }
+  }
+
   /**
    *
    */
@@ -797,6 +824,10 @@ protected IPeer selectPeer(List<IPeer> availablePeers) {
     return p;
   }
 
+  protected IPeer selectPeer(IMessage message, List<IPeer> availablePeers) {
+    return selectPeer(availablePeers);
+  }
+
   //    protected void redirectProcessing(IMessage message, final String destRealm, final String destHost) throws AvpDataException {
   //        String userName = null;
   //        // get Session id

core/jdiameter/impl/src/main/java/org/jdiameter/client/impl/router/WeightedLeastConnectionsRouter.java

@@ -19,22 +19,23 @@
 
 package org.jdiameter.client.impl.router;
 
+import java.util.Arrays;
+import java.util.List;
+
 import org.jdiameter.api.Configuration;
 import org.jdiameter.api.MetaData;
 import org.jdiameter.api.PeerState;
 import org.jdiameter.client.api.IContainer;
+import org.jdiameter.client.api.IMessage;
 import org.jdiameter.client.api.controller.IPeer;
 import org.jdiameter.client.api.controller.IRealmTable;
 import org.jdiameter.common.api.concurrent.IConcurrentFactory;
 import org.jdiameter.common.api.statistic.IStatistic;
 import org.jdiameter.common.api.statistic.IStatisticRecord;
+import org.jdiameter.server.api.IRouter;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import java.util.Arrays;
-import java.util.List;
-import org.jdiameter.server.api.IRouter;
-
 /**
  * Weighted Least-Connections router implementation<br/><br/>
  *
@@ -102,13 +103,13 @@ public WeightedLeastConnectionsRouter(IContainer container, IConcurrentFactory c
    * <pre>
    * {@code
    *   for (m = 0; m < n; m++) {
-   *   if (W(Sm) > 0) {
-   *     for (i = m+1; i < n; i++) {
-   *     if (C(Sm)*W(Si) > C(Si)*W(Sm))
-   *       m = i;
+   *     if (W(Sm) > 0) {
+   *       for (i = m+1; i < n; i++) {
+   *         if (C(Sm)*W(Si) > C(Si)*W(Sm))
+   *           m = i;
+   *       }
+   *       return Sm;
    *     }
-   *     return Sm;
-   *   }
    *   }
    *   return NULL;
    * }
@@ -125,6 +126,19 @@ public WeightedLeastConnectionsRouter(IContainer container, IConcurrentFactory c
    */
   @Override
   public IPeer selectPeer(List<IPeer> availablePeers) {
+    return selectPeer(null, availablePeers);
+  }
+
+  /**
+   * Return peer with least connections
+   *
+   * @param message the message to be sent
+   * @param availablePeers list of peers that are in {@link PeerState#OKAY OKAY} state
+   * @return the selected peer according to algorithm
+   *
+   */
+  @Override
+  public IPeer selectPeer(IMessage message, List<IPeer> availablePeers) {
     int peerSize = availablePeers != null ? availablePeers.size() : 0;
 
     // Return none if empty, or first if only one member found