refactor(nns): Move recompute_tally to inside of cast_vote_and_cascad…

…e_follow (#2977)

This removes a difficult edge case of trying to determine when to
re-tally. We know that any votes cast in cast_vote_and_cascade_follow
are either when a proposal is created, or when register_vote is called,
which makes sure the vote cast is cast while the proposal voting is
still open.

This helps later when votes can be processed across multiple messages.

rs/nns/governance/canbench/canbench_results.yml

@@ -1,61 +1,61 @@
 benches:
   add_neuron_active_maximum:
     total:
-      instructions: 36059483
+      instructions: 36059517
       heap_increase: 1
       stable_memory_increase: 0
     scopes: {}
   add_neuron_active_typical:
     total:
-      instructions: 1830111
+      instructions: 1830145
       heap_increase: 0
       stable_memory_increase: 0
     scopes: {}
   add_neuron_inactive_maximum:
     total:
-      instructions: 96070090
+      instructions: 96070124
       heap_increase: 1
       stable_memory_increase: 0
     scopes: {}
   add_neuron_inactive_typical:
     total:
-      instructions: 7372887
+      instructions: 7372921
       heap_increase: 0
       stable_memory_increase: 0
     scopes: {}
   cascading_vote_all_heap:
     total:
-      instructions: 31756954
+      instructions: 34047728
       heap_increase: 0
       stable_memory_increase: 0
     scopes: {}
   cascading_vote_heap_neurons_stable_index:
     total:
-      instructions: 54261919
+      instructions: 56554267
       heap_increase: 0
       stable_memory_increase: 0
     scopes: {}
   cascading_vote_stable_everything:
     total:
-      instructions: 160631204
+      instructions: 162950875
       heap_increase: 0
       stable_memory_increase: 0
     scopes: {}
   cascading_vote_stable_neurons_with_heap_index:
     total:
-      instructions: 138235474
+      instructions: 140555145
       heap_increase: 0
       stable_memory_increase: 0
     scopes: {}
   centralized_following_all_stable:
     total:
-      instructions: 66109851
+      instructions: 68428123
       heap_increase: 0
       stable_memory_increase: 0
     scopes: {}
   compute_ballots_for_new_proposal_with_stable_neurons:
     total:
-      instructions: 1826966
+      instructions: 1830966
       heap_increase: 0
       stable_memory_increase: 0
     scopes: {}
@@ -67,7 +67,7 @@ benches:
     scopes: {}
   draw_maturity_from_neurons_fund_stable:
     total:
-      instructions: 10256384
+      instructions: 10264384
       heap_increase: 0
       stable_memory_increase: 0
     scopes: {}
@@ -79,7 +79,7 @@ benches:
     scopes: {}
   list_neurons_ready_to_unstake_maturity_stable:
     total:
-      instructions: 37619197
+      instructions: 37739237
       heap_increase: 0
       stable_memory_increase: 0
     scopes: {}
@@ -91,7 +91,7 @@ benches:
     scopes: {}
   list_ready_to_spawn_neuron_ids_stable:
     total:
-      instructions: 37607898
+      instructions: 37727938
       heap_increase: 0
       stable_memory_increase: 0
     scopes: {}
@@ -103,26 +103,26 @@ benches:
     scopes: {}
   neuron_metrics_calculation_stable:
     total:
-      instructions: 1861928
+      instructions: 1865928
       heap_increase: 0
       stable_memory_increase: 0
     scopes: {}
   range_neurons_performance:
     total:
-      instructions: 48539417
+      instructions: 48547417
       heap_increase: 0
       stable_memory_increase: 0
     scopes: {}
   single_vote_all_stable:
     total:
-      instructions: 364631
+      instructions: 2690730
       heap_increase: 0
       stable_memory_increase: 0
     scopes: {}
   update_recent_ballots_stable_memory:
     total:
-      instructions: 13454595
+      instructions: 13454675
       heap_increase: 0
       stable_memory_increase: 0
     scopes: {}
-version: 0.1.7
+version: 0.1.8

rs/nns/governance/src/governance.rs

@@ -4107,16 +4107,6 @@ impl Governance {
         let topic = proposal.topic();
         let voting_period_seconds = voting_period_seconds_fn(topic);
 
-        // Recompute the tally here. It should correctly reflect all votes,
-        // even the ones after the proposal has been decided. It's possible
-        // to have Open status while it does not accept votes anymore, since
-        // the status change happens below this point.
-        if proposal.status() == ProposalStatus::Open
-            || proposal.accepts_vote(now_seconds, voting_period_seconds)
-        {
-            proposal.recompute_tally(now_seconds, voting_period_seconds);
-        }
-
         if proposal.status() != ProposalStatus::Open {
             return;
         }

rs/nns/governance/src/voting.rs

@@ -20,13 +20,19 @@ impl Governance {
         vote_of_neuron: Vote,
         topic: Topic,
     ) {
+        let voting_started = self.env.now();
+
         let neuron_store = &mut self.neuron_store;
-        let ballots = &mut self
-            .heap_data
-            .proposals
-            .get_mut(&proposal_id.id)
-            .unwrap()
-            .ballots;
+        let ballots = match self.heap_data.proposals.get_mut(&proposal_id.id) {
+            Some(proposal) => &mut proposal.ballots,
+            None => {
+                // This is a critical error, but there is nothing that can be done about it
+                // at this place.  We somehow have a vote for a proposal that doesn't exist.
+                eprintln!("error in cast_vote_and_cascade_follow when gathering induction votes: Proposal not found");
+                return;
+            }
+        };
+
         // Use of thread local storage to store the state machines prevents
         // more than one state machine per proposal, which limits the overall
         // memory usage for voting, which will be relevant when this can be used
@@ -44,6 +50,29 @@ impl Governance {
 
             voting_state_machines.remove_if_done(&proposal_id);
         });
+        // We use the time from the beginning of the function to retain the behaviors needed
+        // for wait for quiet even when votes can be processed asynchronously.
+        self.recompute_proposal_tally(proposal_id, voting_started);
+    }
+
+    /// Recompute the tally for a proposal, using the time provided as the current time.
+    fn recompute_proposal_tally(&mut self, proposal_id: ProposalId, now: u64) {
+        let voting_period_seconds_fn = self.voting_period_seconds();
+
+        let proposal = match self.heap_data.proposals.get_mut(&proposal_id.id) {
+            None => {
+                // This is a critical error, but there is nothing that can be done about it
+                // at this place.  We somehow have a vote for a proposal that doesn't exist.
+                eprintln!(
+                    "error in recompute_proposal_tally: Proposal not found: {}",
+                    proposal_id.id
+                );
+                return;
+            }
+            Some(proposal) => &mut *proposal,
+        };
+        let topic = proposal.topic();
+        proposal.recompute_tally(now, voting_period_seconds_fn(topic));
     }
 }
 
@@ -229,7 +258,7 @@ mod test {
         governance::{Governance, MIN_DISSOLVE_DELAY_FOR_VOTE_ELIGIBILITY_SECONDS},
         neuron::{DissolveStateAndAge, Neuron, NeuronBuilder},
         neuron_store::NeuronStore,
-        pb::v1::{neuron::Followees, Ballot, ProposalData, Topic, Vote},
+        pb::v1::{neuron::Followees, Ballot, ProposalData, Tally, Topic, Vote},
         test_utils::{MockEnvironment, StubCMC, StubIcpLedger},
         voting::ProposalVotingStateMachine,
     };
@@ -446,7 +475,7 @@ mod test {
         };
         let mut governance = Governance::new(
             governance_proto,
-            Box::new(MockEnvironment::new(Default::default(), 0)),
+            Box::new(MockEnvironment::new(Default::default(), 234)),
             Box::new(StubIcpLedger {}),
             Box::new(StubCMC {}),
         );
@@ -478,6 +507,22 @@ mod test {
                 6 => make_ballot(deciding_voting_power(NeuronId { id: 6 }), Vote::Unspecified),
             }
         );
+        let expected_tally = Tally {
+            timestamp_seconds: 234,
+            yes: 530,
+            no: 0,
+            total: 636,
+        };
+        assert_eq!(
+            governance
+                .heap_data
+                .proposals
+                .get(&1)
+                .unwrap()
+                .latest_tally
+                .unwrap(),
+            expected_tally
+        );
     }
 
     fn add_neuron_with_ballot(