SERVER-50949: Return empty JournalListener token during rollback

10 files changed, 39 insertions, 12 deletions

diff --git a/src/mongo/db/repl/replication_coordinator.h b/src/mongo/db/repl/replication_coordinator.h
index e4f9db71181..5338ab09abd 100644
--- a/src/mongo/db/repl/replication_coordinator.h
+++ b/src/mongo/db/repl/replication_coordinator.h
@@ -408,8 +408,13 @@ public:
     /*
      * Returns the same as getMyLastAppliedOpTime() and additionally returns the wall clock time
      * corresponding to that OpTime.
+     *
+     * When rollbackSafe is true, this returns an empty OpTimeAndWallTime if the node is in ROLLBACK
+     * state. The lastAppliedOpTime during ROLLBACK might be temporarily pointing to an oplog entry
+     * in the divergent branch of history which would become invalid after the rollback finishes.
      */
-    virtual OpTimeAndWallTime getMyLastAppliedOpTimeAndWallTime() const = 0;
+    virtual OpTimeAndWallTime getMyLastAppliedOpTimeAndWallTime(
+        bool rollbackSafe = false) const = 0;
 
     /**
      * Returns the last optime recorded by setMyLastDurableOpTime.
diff --git a/src/mongo/db/repl/replication_coordinator_external_state_impl.cpp b/src/mongo/db/repl/replication_coordinator_external_state_impl.cpp
index feef90d04e8..5ecb4f7297b 100644
--- a/src/mongo/db/repl/replication_coordinator_external_state_impl.cpp
+++ b/src/mongo/db/repl/replication_coordinator_external_state_impl.cpp
@@ -1079,8 +1079,19 @@ JournalListener::Token ReplicationCoordinatorExternalStateImpl::getToken(Operati
         }
     }
 
-    // All other repl states use the last applied.
-    return repl::ReplicationCoordinator::get(_service)->getMyLastAppliedOpTimeAndWallTime();
+    // All other repl states use the 'lastApplied'.
+    //
+    // Setting 'rollbackSafe' will ensure that a safe lastApplied value is returned if we're in
+    // ROLLBACK state. 'lastApplied' may be momentarily set to an opTime from a divergent branch of
+    // history during rollback, so a benign default value will be returned instead to prevent a
+    // divergent 'lastApplied' from being used to forward the 'lastDurable' after rollback.
+    //
+    // No concurrency control is necessary and it is still safe if the node goes into ROLLBACK after
+    // getting the token because the JournalFlusher is shut down during rollback, before a divergent
+    // 'lastApplied' value is present. The JournalFlusher will start up again in ROLLBACK and never
+    // transition from non-ROLLBACK to ROLLBACK with a divergent 'lastApplied' value.
+    return repl::ReplicationCoordinator::get(_service)->getMyLastAppliedOpTimeAndWallTime(
+        /*rollbackSafe=*/true);
 }
 
 void ReplicationCoordinatorExternalStateImpl::onDurable(const JournalListener::Token& token) {
diff --git a/src/mongo/db/repl/replication_coordinator_impl.cpp b/src/mongo/db/repl/replication_coordinator_impl.cpp
index 564744ca4dd..8db38fa5803 100644
--- a/src/mongo/db/repl/replication_coordinator_impl.cpp
+++ b/src/mongo/db/repl/replication_coordinator_impl.cpp
@@ -1413,8 +1413,12 @@ OpTime ReplicationCoordinatorImpl::getMyLastAppliedOpTime() const {
     return _getMyLastAppliedOpTime_inlock();
 }
 
-OpTimeAndWallTime ReplicationCoordinatorImpl::getMyLastAppliedOpTimeAndWallTime() const {
+OpTimeAndWallTime ReplicationCoordinatorImpl::getMyLastAppliedOpTimeAndWallTime(
+    bool rollbackSafe) const {
     stdx::lock_guard<Latch> lock(_mutex);
+    if (rollbackSafe && _getMemberState_inlock().rollback()) {
+        return {};
+    }
     return _getMyLastAppliedOpTimeAndWallTime_inlock();
 }
 
diff --git a/src/mongo/db/repl/replication_coordinator_impl.h b/src/mongo/db/repl/replication_coordinator_impl.h
index dac623362a5..10437a4467f 100644
--- a/src/mongo/db/repl/replication_coordinator_impl.h
+++ b/src/mongo/db/repl/replication_coordinator_impl.h
@@ -184,7 +184,8 @@ public:
     virtual void setMyHeartbeatMessage(const std::string& msg);
 
     virtual OpTime getMyLastAppliedOpTime() const override;
-    virtual OpTimeAndWallTime getMyLastAppliedOpTimeAndWallTime() const override;
+    virtual OpTimeAndWallTime getMyLastAppliedOpTimeAndWallTime(
+        bool rollbackSafe = false) const override;
 
     virtual OpTime getMyLastDurableOpTime() const override;
     virtual OpTimeAndWallTime getMyLastDurableOpTimeAndWallTime() const override;
diff --git a/src/mongo/db/repl/replication_coordinator_mock.cpp b/src/mongo/db/repl/replication_coordinator_mock.cpp
index d55e79b67b5..c77cfbe570e 100644
--- a/src/mongo/db/repl/replication_coordinator_mock.cpp
+++ b/src/mongo/db/repl/replication_coordinator_mock.cpp
@@ -274,9 +274,12 @@ void ReplicationCoordinatorMock::resetMyLastOpTimes() {
     _myLastDurableWallTime = Date_t();
 }
 
-OpTimeAndWallTime ReplicationCoordinatorMock::getMyLastAppliedOpTimeAndWallTime() const {
+OpTimeAndWallTime ReplicationCoordinatorMock::getMyLastAppliedOpTimeAndWallTime(
+    bool rollbackSafe) const {
     stdx::lock_guard<Mutex> lk(_mutex);
-
+    if (rollbackSafe && _memberState.rollback()) {
+        return {};
+    }
     return {_myLastAppliedOpTime, _myLastAppliedWallTime};
 }
 
diff --git a/src/mongo/db/repl/replication_coordinator_mock.h b/src/mongo/db/repl/replication_coordinator_mock.h
index 13d85b97ed1..d7d74471e45 100644
--- a/src/mongo/db/repl/replication_coordinator_mock.h
+++ b/src/mongo/db/repl/replication_coordinator_mock.h
@@ -149,7 +149,7 @@ public:
 
     virtual void setMyHeartbeatMessage(const std::string& msg);
 
-    virtual OpTimeAndWallTime getMyLastAppliedOpTimeAndWallTime() const;
+    virtual OpTimeAndWallTime getMyLastAppliedOpTimeAndWallTime(bool rollbackSafe) const;
     virtual OpTime getMyLastAppliedOpTime() const;
 
     virtual OpTimeAndWallTime getMyLastDurableOpTimeAndWallTime() const;
diff --git a/src/mongo/db/repl/replication_coordinator_noop.cpp b/src/mongo/db/repl/replication_coordinator_noop.cpp
index ac3433eff02..e23efe39bd9 100644
--- a/src/mongo/db/repl/replication_coordinator_noop.cpp
+++ b/src/mongo/db/repl/replication_coordinator_noop.cpp
@@ -135,7 +135,8 @@ bool ReplicationCoordinatorNoOp::buildsIndexes() {
     MONGO_UNREACHABLE;
 }
 
-OpTimeAndWallTime ReplicationCoordinatorNoOp::getMyLastAppliedOpTimeAndWallTime() const {
+OpTimeAndWallTime ReplicationCoordinatorNoOp::getMyLastAppliedOpTimeAndWallTime(
+    bool rollbackSafe) const {
     MONGO_UNREACHABLE;
 }
 
diff --git a/src/mongo/db/repl/replication_coordinator_noop.h b/src/mongo/db/repl/replication_coordinator_noop.h
index 6cc54cb6664..22a91e840e9 100644
--- a/src/mongo/db/repl/replication_coordinator_noop.h
+++ b/src/mongo/db/repl/replication_coordinator_noop.h
@@ -131,7 +131,7 @@ public:
     void setMyHeartbeatMessage(const std::string&) final;
 
     OpTime getMyLastAppliedOpTime() const final;
-    OpTimeAndWallTime getMyLastAppliedOpTimeAndWallTime() const final;
+    OpTimeAndWallTime getMyLastAppliedOpTimeAndWallTime(bool rollbackSafe = false) const final;
 
     OpTime getMyLastDurableOpTime() const final;
     OpTimeAndWallTime getMyLastDurableOpTimeAndWallTime() const final;
diff --git a/src/mongo/embedded/replication_coordinator_embedded.cpp b/src/mongo/embedded/replication_coordinator_embedded.cpp
index 72b956887ca..b92deb55c45 100644
--- a/src/mongo/embedded/replication_coordinator_embedded.cpp
+++ b/src/mongo/embedded/replication_coordinator_embedded.cpp
@@ -228,7 +228,8 @@ void ReplicationCoordinatorEmbedded::resetMyLastOpTimes() {
     UASSERT_NOT_IMPLEMENTED;
 }
 
-OpTimeAndWallTime ReplicationCoordinatorEmbedded::getMyLastAppliedOpTimeAndWallTime() const {
+OpTimeAndWallTime ReplicationCoordinatorEmbedded::getMyLastAppliedOpTimeAndWallTime(
+    bool rollbackSafe) const {
     UASSERT_NOT_IMPLEMENTED;
 }
 
diff --git a/src/mongo/embedded/replication_coordinator_embedded.h b/src/mongo/embedded/replication_coordinator_embedded.h
index 502333a0b6b..15ab7521b1b 100644
--- a/src/mongo/embedded/replication_coordinator_embedded.h
+++ b/src/mongo/embedded/replication_coordinator_embedded.h
@@ -139,7 +139,8 @@ public:
     void setMyHeartbeatMessage(const std::string&) override;
 
     repl::OpTime getMyLastAppliedOpTime() const override;
-    repl::OpTimeAndWallTime getMyLastAppliedOpTimeAndWallTime() const override;
+    repl::OpTimeAndWallTime getMyLastAppliedOpTimeAndWallTime(
+        bool rollbackSafe = false) const override;
 
     repl::OpTime getMyLastDurableOpTime() const override;
     repl::OpTimeAndWallTime getMyLastDurableOpTimeAndWallTime() const override;