SERVER-20245 use candidate index instead of candidate id in last vote

6 files changed, 17 insertions, 18 deletions

diff --git a/src/mongo/db/repl/last_vote.cpp b/src/mongo/db/repl/last_vote.cpp
index 94e88231bac..0b125624019 100644
--- a/src/mongo/db/repl/last_vote.cpp
+++ b/src/mongo/db/repl/last_vote.cpp
@@ -36,11 +36,11 @@ namespace mongo {
 namespace repl {
 namespace {
 
-const std::string kCandidateIdFieldName = "candidateId";
+const std::string kCandidateIndexFieldName = "candidateIndex";
 const std::string kTermFieldName = "term";
 
 const std::string kLegalFieldNames[] = {
-    kCandidateIdFieldName, kTermFieldName,
+    kCandidateIndexFieldName, kTermFieldName,
 };
 
 }  // namespace
@@ -54,7 +54,7 @@ Status LastVote::initialize(const BSONObj& argsObj) {
     if (!status.isOK())
         return status;
 
-    status = bsonExtractIntegerField(argsObj, kCandidateIdFieldName, &_candidateId);
+    status = bsonExtractIntegerField(argsObj, kCandidateIndexFieldName, &_candidateIndex);
     if (!status.isOK())
         return status;
 
@@ -65,23 +65,23 @@ void LastVote::setTerm(long long term) {
     _term = term;
 }
 
-void LastVote::setCandidateId(long long candidateId) {
-    _candidateId = candidateId;
+void LastVote::setCandidateIndex(long long candidateIndex) {
+    _candidateIndex = candidateIndex;
 }
 
 long long LastVote::getTerm() const {
     return _term;
 }
 
-long long LastVote::getCandidateId() const {
-    return _candidateId;
+long long LastVote::getCandidateIndex() const {
+    return _candidateIndex;
 }
 
 
 BSONObj LastVote::toBSON() const {
     BSONObjBuilder builder;
     builder.append(kTermFieldName, _term);
-    builder.append(kCandidateIdFieldName, _candidateId);
+    builder.append(kCandidateIndexFieldName, _candidateIndex);
     return builder.obj();
 }
 
diff --git a/src/mongo/db/repl/last_vote.h b/src/mongo/db/repl/last_vote.h
index fe1d67a3fe9..0466ffccbec 100644
--- a/src/mongo/db/repl/last_vote.h
+++ b/src/mongo/db/repl/last_vote.h
@@ -41,14 +41,14 @@ public:
     Status initialize(const BSONObj& argsObj);
 
     long long getTerm() const;
-    long long getCandidateId() const;
+    long long getCandidateIndex() const;
 
     void setTerm(long long term);
-    void setCandidateId(long long candidateId);
+    void setCandidateIndex(long long candidateIndex);
     BSONObj toBSON() const;
 
 private:
-    long long _candidateId = -1;
+    long long _candidateIndex = -1;
     long long _term = -1;
 };
 
diff --git a/src/mongo/db/repl/replication_coordinator_impl.cpp b/src/mongo/db/repl/replication_coordinator_impl.cpp
index ea05e1258e6..e18897c90fe 100644
--- a/src/mongo/db/repl/replication_coordinator_impl.cpp
+++ b/src/mongo/db/repl/replication_coordinator_impl.cpp
@@ -2731,7 +2731,7 @@ Status ReplicationCoordinatorImpl::processReplSetRequestVotes(
     if (response->getVoteGranted()) {
         LastVote lastVote;
         lastVote.setTerm(args.getTerm());
-        lastVote.setCandidateId(args.getCandidateId());
+        lastVote.setCandidateIndex(_rsConfig.findMemberIndexByConfigId(args.getCandidateId()));
 
         Status status = _externalState->storeLocalLastVoteDocument(txn, lastVote);
         if (!status.isOK()) {
@@ -3105,8 +3105,7 @@ void ReplicationCoordinatorImpl::_resetElectionInfoOnProtocolVersionUpgrade(
 
         LastVote lastVote;
         lastVote.setTerm(OpTime::kInitialTerm);
-        // TODO(sz) Change candidate Id to index.
-        lastVote.setCandidateId(-1);
+        lastVote.setCandidateIndex(-1);
         auto status = _externalState->storeLocalLastVoteDocument(cbData.txn, lastVote);
         invariant(status.isOK());
     });
diff --git a/src/mongo/db/repl/replication_coordinator_impl_elect_v1.cpp b/src/mongo/db/repl/replication_coordinator_impl_elect_v1.cpp
index 03f2c31afb4..d1f97c94c16 100644
--- a/src/mongo/db/repl/replication_coordinator_impl_elect_v1.cpp
+++ b/src/mongo/db/repl/replication_coordinator_impl_elect_v1.cpp
@@ -189,7 +189,7 @@ void ReplicationCoordinatorImpl::_onDryRunComplete(long long originalTerm) {
     // Store the vote in persistent storage.
     LastVote lastVote;
     lastVote.setTerm(originalTerm + 1);
-    lastVote.setCandidateId(getMyId());
+    lastVote.setCandidateIndex(_selfIndex);
 
     auto cbStatus = _replExecutor.scheduleDBWork(
         [this, lastVote](const ReplicationExecutor::CallbackArgs& cbData) {
diff --git a/src/mongo/db/repl/replication_coordinator_impl_elect_v1_test.cpp b/src/mongo/db/repl/replication_coordinator_impl_elect_v1_test.cpp
index c9ddd278ae3..7dcdd06b5b6 100644
--- a/src/mongo/db/repl/replication_coordinator_impl_elect_v1_test.cpp
+++ b/src/mongo/db/repl/replication_coordinator_impl_elect_v1_test.cpp
@@ -214,7 +214,7 @@ TEST_F(ReplCoordElectV1Test, ElectManyNodesSuccess) {
     // Check last vote
     auto lastVote = getExternalState()->loadLocalLastVoteDocument(nullptr);
     ASSERT(lastVote.isOK());
-    ASSERT_EQ(1, lastVote.getValue().getCandidateId());
+    ASSERT_EQ(0, lastVote.getValue().getCandidateIndex());
     ASSERT_EQ(1, lastVote.getValue().getTerm());
 
     stopCapturingLogMessages();
diff --git a/src/mongo/db/repl/topology_coordinator_impl.cpp b/src/mongo/db/repl/topology_coordinator_impl.cpp
index 9a8c091072e..baa8080e7a1 100644
--- a/src/mongo/db/repl/topology_coordinator_impl.cpp
+++ b/src/mongo/db/repl/topology_coordinator_impl.cpp
@@ -2388,7 +2388,7 @@ void TopologyCoordinatorImpl::processReplSetRequestVotes(const ReplSetRequestVot
     } else {
         if (!args.isADryRun()) {
             _lastVote.setTerm(args.getTerm());
-            _lastVote.setCandidateId(args.getCandidateId());
+            _lastVote.setCandidateIndex(_rsConfig.findMemberIndexByConfigId(args.getCandidateId()));
         }
         response->setVoteGranted(true);
     }
@@ -2416,7 +2416,7 @@ void TopologyCoordinatorImpl::loadLastVote(const LastVote& lastVote) {
 
 void TopologyCoordinatorImpl::voteForMyselfV1() {
     _lastVote.setTerm(_term);
-    _lastVote.setCandidateId(_selfConfig().getId());
+    _lastVote.setCandidateIndex(_selfIndex);
 }
 
 void TopologyCoordinatorImpl::setPrimaryIndex(long long primaryIndex) {