Fix cluster elder calculation to ensure unique elder.

Race condition in the previous algorithm allowed several cluster
members to consider themselves the elder.


git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk/qpid@903826 13f79535-47bb-0310-9956-ffa450edef68

1 files changed, 9 insertions, 5 deletions

diff --git a/cpp/src/qpid/cluster/Cluster.cpp b/cpp/src/qpid/cluster/Cluster.cpp
index 53100fa0c1..d398f30a86 100644
--- a/cpp/src/qpid/cluster/Cluster.cpp
+++ b/cpp/src/qpid/cluster/Cluster.cpp
@@ -189,11 +189,13 @@ struct ClusterDispatcher : public framing::AMQP_AllOperations::ClusterHandler {
 
     void initialStatus(uint32_t version, bool active, const Uuid& clusterId,
                        uint8_t storeState, const Uuid& shutdownId,
-                       const framing::SequenceNumber& configSeq)
+                       const framing::SequenceNumber& configSeq,
+                       const std::string& firstConfig)
     {
         cluster.initialStatus(
             member, version, active, clusterId,
-            framing::cluster::StoreState(storeState), shutdownId, configSeq, l);
+            framing::cluster::StoreState(storeState), shutdownId, configSeq,
+            firstConfig, l);
     }
     void ready(const std::string& url) { cluster.ready(member, url, l); }
     void configChange(const std::string& current) { cluster.configChange(member, current, l); }
@@ -553,7 +555,7 @@ void Cluster::configChange (
              << AddrList(joined, nJoined, "joined: ")
              << AddrList(left, nLeft, "left: ")
              << ")");
-    std::string addresses;
+    string addresses;
     for (const cpg_address* p = current; p < current+nCurrent; ++p) 
         addresses.append(MemberId(*p).str());
     deliverEvent(Event::control(ClusterConfigChangeBody(ProtocolVersion(), addresses), self));
@@ -625,7 +627,8 @@ void Cluster::configChange(const MemberId&, const std::string& configStr, Lock&
         mcast.mcastControl(
             ClusterInitialStatusBody(
                 ProtocolVersion(), CLUSTER_VERSION, state > INIT, clusterId, 
-                store.getState(), store.getShutdownId(), store.getConfigSeq()
+                store.getState(), store.getShutdownId(), store.getConfigSeq(),
+                initMap.getFirstConfigStr()
             ),
             self);
     }
@@ -673,6 +676,7 @@ void Cluster::initialStatus(const MemberId& member, uint32_t version, bool activ
                             framing::cluster::StoreState store,
                             const framing::Uuid& shutdownId,
                             const framing::SequenceNumber& configSeq,
+                            const std::string& firstConfig,
                             Lock& l)
 {
     if (version != CLUSTER_VERSION) {
@@ -684,7 +688,7 @@ void Cluster::initialStatus(const MemberId& member, uint32_t version, bool activ
     initMap.received(
         member,
         ClusterInitialStatusBody(ProtocolVersion(), version, active, id,
-                                 store, shutdownId, configSeq)
+                                 store, shutdownId, configSeq, firstConfig)
     );
     if (initMap.transitionToComplete()) initMapCompleted(l);
 }