QPID-4428: HA add UUID tag to avoid using an out of date queue/exchange.

Imagine a cluster with primary A and backups B and C. A queue Q is created on A
and replicated to B, C. Now A dies and B takes over as primary. Before C can
connect to B, a client destroys Q and creates a new queue with the same name.
When B connects it sees Q and incorrectly assumes it is the same Q that it has
already replicated. Now C has an inconsistent replica of Q.

The fix is to tag queues/exchanges with a UUID so a backup can tell if a queue
is not the same as the one it has already replicated, even if the names are the
same.  This all also applies to exchanges.

- Minor imrovements to printing UUIDs in a FieldTable.
- Fix comparison of void Variants, added operator !=

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1409241 13f79535-47bb-0310-9956-ffa450edef68

1 files changed, 3 insertions, 0 deletions

diff --git a/qpid/cpp/src/qpid/ha/Primary.h b/qpid/cpp/src/qpid/ha/Primary.h
index 22b231ed72..c713115176 100644
--- a/qpid/cpp/src/qpid/ha/Primary.h
+++ b/qpid/cpp/src/qpid/ha/Primary.h
@@ -60,6 +60,7 @@ class Primary
 {
   public:
     typedef boost::shared_ptr<broker::Queue> QueuePtr;
+    typedef boost::shared_ptr<broker::Exchange> ExchangePtr;
 
     static Primary* get() { return instance; }
 
@@ -72,6 +73,8 @@ class Primary
     // Called via ConfigurationObserver
     void queueCreate(const QueuePtr&);
     void queueDestroy(const QueuePtr&);
+    void exchangeCreate(const ExchangePtr&);
+    void exchangeDestroy(const ExchangePtr&);
 
     // Called via ConnectionObserver
     void opened(broker::Connection& connection);