SERVER-28013 Ensure that last op for client only moves forward

(cherry picked from commit 34c00f16a8890775c71c63c860e2086c6bb603aa)

4 files changed, 22 insertions, 7 deletions

diff --git a/src/mongo/db/repl/oplog.cpp b/src/mongo/db/repl/oplog.cpp
index 833da2a2e86..24700262de6 100644
--- a/src/mongo/db/repl/oplog.cpp
+++ b/src/mongo/db/repl/oplog.cpp
@@ -375,10 +375,10 @@ void _logOpsInner(OperationContext* txn,
     checkOplogInsert(oplogCollection->insertDocumentsForOplog(txn, writers, nWriters));
 
     // Set replCoord last optime only after we're sure the WUOW didn't abort and roll back.
-    txn->recoveryUnit()->onCommit(
-        [replCoord, finalOpTime] { replCoord->setMyLastAppliedOpTimeForward(finalOpTime); });
-
-    ReplClientInfo::forClient(txn->getClient()).setLastOp(finalOpTime);
+    txn->recoveryUnit()->onCommit([txn, replCoord, finalOpTime] {
+        replCoord->setMyLastAppliedOpTimeForward(finalOpTime);
+        ReplClientInfo::forClient(txn->getClient()).setLastOp(finalOpTime);
+    });
 }
 
 void logOp(OperationContext* txn,
diff --git a/src/mongo/db/repl/repl_client_info.cpp b/src/mongo/db/repl/repl_client_info.cpp
index 678938f2755..3e98a0cb9d3 100644
--- a/src/mongo/db/repl/repl_client_info.cpp
+++ b/src/mongo/db/repl/repl_client_info.cpp
@@ -43,6 +43,11 @@ namespace repl {
 const Client::Decoration<ReplClientInfo> ReplClientInfo::forClient =
     Client::declareDecoration<ReplClientInfo>();
 
+void ReplClientInfo::setLastOp(const OpTime& ot) {
+    invariant(ot >= _lastOp);
+    _lastOp = ot;
+}
+
 void ReplClientInfo::setLastOpToSystemLastOpTime(OperationContext* txn) {
     ReplicationCoordinator* replCoord = repl::ReplicationCoordinator::get(txn->getServiceContext());
     if (replCoord->isReplEnabled() && txn->writesAreReplicated()) {
diff --git a/src/mongo/db/repl/repl_client_info.h b/src/mongo/db/repl/repl_client_info.h
index 4c01119b794..3c81953d65f 100644
--- a/src/mongo/db/repl/repl_client_info.h
+++ b/src/mongo/db/repl/repl_client_info.h
@@ -45,13 +45,17 @@ class ReplClientInfo {
 public:
     static const Client::Decoration<ReplClientInfo> forClient;
 
-    void setLastOp(const OpTime& op) {
-        _lastOp = op;
-    }
+    void setLastOp(const OpTime& op);
+
     OpTime getLastOp() const {
         return _lastOp;
     }
 
+    // Resets the last op on this client; should only be used in testing.
+    void clearLastOp_forTest() {
+        _lastOp = OpTime();
+    }
+
     void setLastSnapshot(SnapshotName name) {
         _lastSnapshot = name;
     }
diff --git a/src/mongo/dbtests/repltests.cpp b/src/mongo/dbtests/repltests.cpp
index e547f4aa8a6..e10f536c21f 100644
--- a/src/mongo/dbtests/repltests.cpp
+++ b/src/mongo/dbtests/repltests.cpp
@@ -45,6 +45,7 @@
 #include "mongo/db/ops/update.h"
 #include "mongo/db/repl/master_slave.h"
 #include "mongo/db/repl/oplog.h"
+#include "mongo/db/repl/repl_client_info.h"
 #include "mongo/db/repl/replication_coordinator_global.h"
 #include "mongo/db/repl/replication_coordinator_mock.h"
 #include "mongo/db/repl/sync_tail.h"
@@ -78,6 +79,11 @@ public:
         replSettings.setMaster(true);
         setGlobalReplicationCoordinator(new repl::ReplicationCoordinatorMock(replSettings));
 
+        // Since the Client object persists across tests, even though the global
+        // ReplicationCoordinator does not, we need to clear the last op associated with the client
+        // to avoid the invariant in ReplClientInfo::setLastOp that the optime only goes forward.
+        repl::ReplClientInfo::forClient(_txn.getClient()).clearLastOp_forTest();
+
         getGlobalServiceContext()->setOpObserver(stdx::make_unique<OpObserverImpl>());
 
         setOplogCollectionName();