mon: explicitly refresh_from_paxos() when leveldb state changes

Instead of opportunistically calling each service's update_from_paxos(),
instead explicitly refresh all in-memory state whenever we know the
paxos state may have changed.  This is simpler and less fragile.

Signed-off-by: Sage Weil <sage@inktank.com>
(cherry picked from commit cc339c07312006e65854207523f50542d00ecf87)

5 files changed, 27 insertions, 18 deletions

diff --git a/src/mon/Monitor.cc b/src/mon/Monitor.cc
index 65577b699ae..522434997d1 100644
--- a/src/mon/Monitor.cc
+++ b/src/mon/Monitor.cc
@@ -515,11 +515,8 @@ void Monitor::init_paxos()
   paxos->init();
 
   // update paxos
-  for (int i = 0; i < PAXOS_NUM; ++i) {
-    if (paxos->is_consistent()) {
-      paxos_service[i]->update_from_paxos();
-    }
-  }
+  if (paxos->is_consistent())
+    refresh_from_paxos();
 
   // init services
   for (int i = 0; i < PAXOS_NUM; ++i) {
@@ -529,6 +526,14 @@ void Monitor::init_paxos()
   }
 }
 
+void Monitor::refresh_from_paxos()
+{
+  dout(10) << __func__ << dendl;
+  for (int i = 0; i < PAXOS_NUM; ++i) {
+    paxos_service[i]->refresh();
+  }
+}
+
 void Monitor::register_cluster_logger()
 {
   if (!cluster_logger_registered) {
@@ -3336,13 +3341,6 @@ bool Monitor::_ms_dispatch(Message *m)
 	}
 
 	paxos->dispatch((PaxosServiceMessage*)m);
-
-	// make sure service finds out about any state changes
-	if (paxos->is_active()) {
-	  vector<PaxosService*>::iterator service_it = paxos_service.begin();
-	  for ( ; service_it != paxos_service.end(); ++service_it)
-	    (*service_it)->update_from_paxos();
-	}
       }
       break;
 
diff --git a/src/mon/Monitor.h b/src/mon/Monitor.h
index 74a94be4e0a..cea2a23d978 100644
--- a/src/mon/Monitor.h
+++ b/src/mon/Monitor.h
@@ -1412,6 +1412,7 @@ public:
   int preinit();
   int init();
   void init_paxos();
+  void refresh_from_paxos();
   void shutdown();
   void tick();
 
diff --git a/src/mon/Paxos.cc b/src/mon/Paxos.cc
index f5cbe89092b..6adf191ee91 100644
--- a/src/mon/Paxos.cc
+++ b/src/mon/Paxos.cc
@@ -509,12 +509,12 @@ void Paxos::begin(bufferlist& v)
     // we're alone, take it easy
     commit();
     state = STATE_ACTIVE;
+    mon->refresh_from_paxos();
     finish_proposal();
     finish_contexts(g_ceph_context, waiting_for_active);
     finish_contexts(g_ceph_context, waiting_for_commit);
     finish_contexts(g_ceph_context, waiting_for_readable);
     finish_contexts(g_ceph_context, waiting_for_writeable);
-
     return;
   }
 
@@ -627,6 +627,8 @@ void Paxos::handle_accept(MMonPaxos *accept)
     // yay!
     state = STATE_ACTIVE;
     extend_lease();
+
+    mon->refresh_from_paxos();
   
     finish_proposal();
 
@@ -713,9 +715,11 @@ void Paxos::handle_commit(MMonPaxos *commit)
   }
 
   store_state(commit);
-  
+
   commit->put();
 
+  mon->refresh_from_paxos();
+
   finish_contexts(g_ceph_context, waiting_for_commit);
 }
 
diff --git a/src/mon/PaxosService.cc b/src/mon/PaxosService.cc
index 0421078b0d5..cb808036b2e 100644
--- a/src/mon/PaxosService.cc
+++ b/src/mon/PaxosService.cc
@@ -63,9 +63,6 @@ bool PaxosService::dispatch(PaxosServiceMessage *m)
     return true;
   }
 
-  // make sure service has latest from paxos.
-  update_from_paxos();
-
   // preprocess
   if (preprocess_query(m)) 
     return true;  // easy!
@@ -106,6 +103,13 @@ bool PaxosService::dispatch(PaxosServiceMessage *m)
   return true;
 }
 
+void PaxosService::refresh()
+{
+  dout(10) << __func__ << dendl;
+  update_from_paxos();
+}
+
+
 void PaxosService::scrub()
 {
   dout(10) << __func__ << dendl;
@@ -252,7 +256,7 @@ void PaxosService::_active()
   dout(10) << "_active" << dendl;
 
   // pull latest from paxos
-  update_from_paxos();
+  refresh();
 
   scrub();
 
diff --git a/src/mon/PaxosService.h b/src/mon/PaxosService.h
index 4de73ea4b19..158eda7def8 100644
--- a/src/mon/PaxosService.h
+++ b/src/mon/PaxosService.h
@@ -313,6 +313,8 @@ public:
    */
   bool dispatch(PaxosServiceMessage *m);
 
+  void refresh();
+
   /**
    * @defgroup PaxosService_h_override_funcs Functions that should be
    *					     overridden.