SERVER-13542: include electionId in isMaster when primary

6 files changed, 31 insertions, 4 deletions

diff --git a/src/mongo/db/repl/is_master_response.cpp b/src/mongo/db/repl/is_master_response.cpp
index 4ac169e2f10..a789fd7b6dd 100644
--- a/src/mongo/db/repl/is_master_response.cpp
+++ b/src/mongo/db/repl/is_master_response.cpp
@@ -33,6 +33,7 @@
 #include "mongo/db/repl/is_master_response.h"
 
 #include "mongo/base/status.h"
+#include "mongo/bson/oid.h"
 #include "mongo/bson/util/bson_extract.h"
 #include "mongo/db/jsobj.h"
 #include "mongo/util/mongoutils/str.h"
@@ -56,6 +57,7 @@ namespace {
     const std::string kSlaveDelayFieldName = "slaveDelay";
     const std::string kTagsFieldName = "tags";
     const std::string kMeFieldName = "me";
+    const std::string kElectionIdFieldName = "electionId";
 
     // field name constants that don't directly correspond to member variables
     const std::string kInfoFieldName = "info";
@@ -89,6 +91,7 @@ namespace {
             _slaveDelaySet(false),
             _tagsSet(false),
             _meSet(false),
+            _electionId(OID()),
             _configSet(true),
             _shutdownInProgress(false)
             {}
@@ -159,6 +162,8 @@ namespace {
         }
         invariant(_meSet);
         builder->append(kMeFieldName, _me.toString());
+        if (_electionId.isSet())
+            builder->append(kElectionIdFieldName, _electionId);
     }
 
     BSONObj IsMasterResponse::toBSON() const {
@@ -344,6 +349,15 @@ namespace {
             _tagsSet = true;
         }
 
+        if (doc.hasField(kElectionIdFieldName)) {
+            BSONElement electionIdElem;
+            status = bsonExtractTypedField(doc, kElectionIdFieldName, jstOID, &electionIdElem);
+            if (!status.isOK()) {
+                return status;
+            }
+            _electionId = electionIdElem.OID();
+        }
+
         std::string meString;
         status = bsonExtractStringField(doc, kMeFieldName, &meString);
         if (!status.isOK()) {
@@ -430,6 +444,10 @@ namespace {
         _me = me;
     }
 
+    void IsMasterResponse::setElectionId(const OID& electionId) {
+        _electionId = electionId;
+    }
+
     void IsMasterResponse::markAsNoConfig() { _configSet = false; }
 
     void IsMasterResponse::markAsShutdownInProgress() { _shutdownInProgress = true; }
diff --git a/src/mongo/db/repl/is_master_response.h b/src/mongo/db/repl/is_master_response.h
index 91bcc400ebe..dd0eda70e2b 100644
--- a/src/mongo/db/repl/is_master_response.h
+++ b/src/mongo/db/repl/is_master_response.h
@@ -31,6 +31,7 @@
 #include <string>
 #include <vector>
 
+#include "mongo/bson/oid.h"
 #include "mongo/platform/unordered_map.h"
 #include "mongo/util/net/hostandport.h"
 #include "mongo/util/time_support.h"
@@ -106,6 +107,8 @@ namespace repl {
 
         const HostAndPort& getMe() const { return _me; }
 
+        const OID& getElectionId() const { return _electionId; }
+
         /**
          * If false, calls to toBSON/addToBSON will ignore all other fields and add a specific
          * message to indicate that we have no replica set config.
@@ -151,6 +154,8 @@ namespace repl {
 
         void setMe(const HostAndPort& me);
 
+        void setElectionId(const OID& electionId);
+
         /**
          * Marks _configSet as false, which will cause future calls to toBSON/addToBSON to ignore
          * all other member variables and output a hardcoded response indicating that we have no
@@ -197,6 +202,7 @@ namespace repl {
         bool _tagsSet;
         HostAndPort _me;
         bool _meSet;
+        OID _electionId;
 
         // If _configSet is false this means we don't have a valid repl set config, so toBSON
         // will return a set of hardcoded values that indicate this.
diff --git a/src/mongo/db/repl/repl_coordinator_impl.cpp b/src/mongo/db/repl/repl_coordinator_impl.cpp
index b2dd2968b00..cdd1be23537 100644
--- a/src/mongo/db/repl/repl_coordinator_impl.cpp
+++ b/src/mongo/db/repl/repl_coordinator_impl.cpp
@@ -1267,7 +1267,7 @@ namespace {
 
     OID ReplicationCoordinatorImpl::getElectionId() {
         boost::lock_guard<boost::mutex> lock(_mutex);
-        return _electionID;
+        return _electionId;
     }
 
     OID ReplicationCoordinatorImpl::getMyRID() const {
diff --git a/src/mongo/db/repl/repl_coordinator_impl.h b/src/mongo/db/repl/repl_coordinator_impl.h
index 13bfaada056..76b7e817d68 100644
--- a/src/mongo/db/repl/repl_coordinator_impl.h
+++ b/src/mongo/db/repl/repl_coordinator_impl.h
@@ -797,7 +797,7 @@ namespace repl {
         bool _inShutdown;                                                                 // (M)
 
         // Election ID of the last election that resulted in this node becoming primary.
-        OID _electionID;                                                                  // (M)
+        OID _electionId;                                                                  // (M)
 
         // Vector containing known information about each member (such as replication
         // progress and member ID) in our replica set or each member replicating from
diff --git a/src/mongo/db/repl/repl_coordinator_impl_elect.cpp b/src/mongo/db/repl/repl_coordinator_impl_elect.cpp
index 601787f96f4..b2e349e65f2 100644
--- a/src/mongo/db/repl/repl_coordinator_impl_elect.cpp
+++ b/src/mongo/db/repl/repl_coordinator_impl_elect.cpp
@@ -257,8 +257,8 @@ namespace {
         _freshnessChecker.reset(NULL);
         _electCmdRunner.reset(NULL);
         boost::unique_lock<boost::mutex> lk(_mutex);
-        _electionID = OID::gen();
-        _topCoord->processWinElection(_electionID,
+        _electionId = OID::gen();
+        _topCoord->processWinElection(_electionId,
                                       OpTime(Milliseconds(_replExecutor.now()).total_seconds(), 0));
         const PostMemberStateUpdateAction action =
             _updateCurrentMemberStateFromTopologyCoordinator_inlock();
diff --git a/src/mongo/db/repl/topology_coordinator_impl.cpp b/src/mongo/db/repl/topology_coordinator_impl.cpp
index b1cb52460a7..aa19f8a29cf 100644
--- a/src/mongo/db/repl/topology_coordinator_impl.cpp
+++ b/src/mongo/db/repl/topology_coordinator_impl.cpp
@@ -1468,6 +1468,9 @@ namespace {
             }
         }
         response->setMe(selfConfig.getHostAndPort());
+        if (_iAmPrimary()) {
+            response->setElectionId(_electionId);
+        }
     }
 
     void TopologyCoordinatorImpl::prepareFreezeResponse(