Support large number of routing instances

Following changes are implemented:

- Use bgp::ShowCommand task for neighbor introspect.  This makes the
  intropsect commands more responsive because they no longer have to
  run exclusively with db::DBTable tasks.
- Fix BgpServer::VisitBgpPeers to not iterate all routing instances.
  Instead we can simply go through the BgpPeerList in BgpServer.

Change-Id: I6557b5f6fb1d00cddbb5072ca97a331c3f9c30fa
Partial-Bug: 1596089

src/bgp/bgp_server.cc

@@ -554,12 +554,9 @@ uint32_t BgpServer::num_down_static_routes() const {
 }
 
 void BgpServer::VisitBgpPeers(BgpServer::VisitorFn fn) const {
-    for (RoutingInstanceMgr::RoutingInstanceIterator rit = inst_mgr_->begin();
-         rit != inst_mgr_->end(); ++rit) {
-        BgpPeerKey key = BgpPeerKey();
-        while (BgpPeer *peer = rit->peer_manager()->NextPeer(key)) {
-            fn(peer);
-        }
+    for (BgpPeerList::const_iterator loc = peer_list_.begin();
+         loc != peer_list_.end(); ++loc) {
+        fn(loc->second);
     }
 }
 

src/bgp/bgp_show_neighbor.cc

@@ -132,7 +132,7 @@ void BgpNeighborReq::HandleRequest() const {
     RequestPipeline::StageSpec s1;
     TaskScheduler *scheduler = TaskScheduler::GetInstance();
 
-    s1.taskId_ = scheduler->GetTaskId("bgp::PeerMembership");
+    s1.taskId_ = scheduler->GetTaskId("bgp::ShowCommand");
     s1.cbFn_ = boost::bind(&BgpShowHandler<
         BgpNeighborReq,
         BgpNeighborReqIterate,
@@ -156,7 +156,7 @@ void BgpNeighborReqIterate::HandleRequest() const {
     RequestPipeline::StageSpec s1;
     TaskScheduler *scheduler = TaskScheduler::GetInstance();
 
-    s1.taskId_ = scheduler->GetTaskId("bgp::PeerMembership");
+    s1.taskId_ = scheduler->GetTaskId("bgp::ShowCommand");
     s1.cbFn_ = boost::bind(&BgpShowHandler<
         BgpNeighborReq,
         BgpNeighborReqIterate,
@@ -180,7 +180,7 @@ void ShowBgpNeighborSummaryReq::HandleRequest() const {
     RequestPipeline::StageSpec s1;
     TaskScheduler *scheduler = TaskScheduler::GetInstance();
 
-    s1.taskId_ = scheduler->GetTaskId("bgp::PeerMembership");
+    s1.taskId_ = scheduler->GetTaskId("bgp::ShowCommand");
     s1.cbFn_ = boost::bind(&BgpShowHandler<
         ShowBgpNeighborSummaryReq,
         ShowBgpNeighborSummaryReqIterate,
@@ -204,7 +204,7 @@ void ShowBgpNeighborSummaryReqIterate::HandleRequest() const {
     RequestPipeline::StageSpec s1;
     TaskScheduler *scheduler = TaskScheduler::GetInstance();
 
-    s1.taskId_ = scheduler->GetTaskId("bgp::PeerMembership");
+    s1.taskId_ = scheduler->GetTaskId("bgp::ShowCommand");
     s1.cbFn_ = boost::bind(&BgpShowHandler<
         ShowBgpNeighborSummaryReq,
         ShowBgpNeighborSummaryReqIterate,

src/bgp/scheduling_group.cc

@@ -509,7 +509,7 @@ bool SchedulingGroup::empty() const {
 // Return true if the IPeer is in sync.
 //
 bool SchedulingGroup::PeerInSync(IPeerUpdate *peer) const {
-    CHECK_CONCURRENCY("bgp::PeerMembership");
+    CHECK_CONCURRENCY("bgp::PeerMembership", "bgp::ShowCommand");
 
     PeerState *ps = peer_state_imap_.Find(peer);
     return (ps) ? ps->in_sync() : false;