Abort master proposal when master has been elected.

Note: This doesn't really work. We need to do this based on serial
number, otherwise the proposal may be canceled before it has begun,
with the result that the proposal doesn't get canceled at all.

1 files changed, 17 insertions, 4 deletions

diff --git a/same/src/main/java/com/orbekk/same/Client.java b/same/src/main/java/com/orbekk/same/Client.java
index 69d0e33..4f42c4e 100644
--- a/same/src/main/java/com/orbekk/same/Client.java
+++ b/same/src/main/java/com/orbekk/same/Client.java
@@ -18,7 +18,7 @@ import com.orbekk.util.DelayedOperation;
 import com.orbekk.util.WorkQueue;
 
 public class Client implements DiscoveryListener {
-    public static final long MASTER_TAKEOVER_TIMEOUT = 4000l;
+    public static long MASTER_TAKEOVER_TIMEOUT = 4000l;
     private Logger logger = LoggerFactory.getLogger(getClass());
     /** TODO: Not really useful yet. Remove? */
     private ConnectionState connectionState = ConnectionState.DISCONNECTED;
@@ -29,6 +29,7 @@ public class Client implements DiscoveryListener {
     private int masterId = -1;
     private MasterController masterController = null;
     private Broadcaster broadcaster;
+    private Future<Integer> currentMasterProposal = null;
     
     private List<StateChangedListener> stateListeners =
             new ArrayList<StateChangedListener>();
@@ -124,6 +125,9 @@ public class Client implements DiscoveryListener {
         @Override
         public void masterTakeover(String masterUrl, String networkName, 
                 int masterId) throws Exception {
+            logger.info("MasterTakeover({}, {}, {})",
+                    new Object[]{masterUrl, networkName, masterId});
+            abortMasterElection();
             Client.this.masterUrl = masterUrl;
             connectionState = ConnectionState.STABLE;
         }
@@ -267,19 +271,28 @@ public class Client implements DiscoveryListener {
                 }
             }
         };
-        Future<Integer> proposal = proposer.startProposalTask(1, sleeperTask);
+        synchronized (this) {
+            currentMasterProposal = proposer.startProposalTask(1, sleeperTask);
+        }
         Integer result = null;
         try {
-            result = proposal.get();
+            result = currentMasterProposal.get();
         } catch (InterruptedException e) {
         } catch (ExecutionException e) {
         } catch (CancellationException e) {
         }
-        if (!proposal.isCancelled() && result != null) {
+        if (!currentMasterProposal.isCancelled() && result != null) {
             masterController.enableMaster(state);
         }
     }
     
+    private synchronized void abortMasterElection() {
+        if (currentMasterProposal != null && !currentMasterProposal.isDone()) {
+            boolean status = currentMasterProposal.cancel(true);
+            logger.info("Abort status: {}", status);
+        }
+    }
+    
     public void startMasterElection() {
         List<String> participants = state.getList(".participants");
         broadcaster.broadcast(participants, new ServiceOperation() {