SERVER-42457 Check if atClusterTime has been set on TransactionRouter before observing from an external thread

2 files changed, 19 insertions, 1 deletions

diff --git a/src/mongo/s/transaction_router.cpp b/src/mongo/s/transaction_router.cpp
index 8bfb6cbbb39..5d7d08fbafb 100644
--- a/src/mongo/s/transaction_router.cpp
+++ b/src/mongo/s/transaction_router.cpp
@@ -402,6 +402,10 @@ LogicalTime TransactionRouter::AtClusterTime::getTime() const {
     return _atClusterTime;
 }
 
+bool TransactionRouter::AtClusterTime::timeHasBeenSet() const {
+    return _atClusterTime != LogicalTime::kUninitialized;
+}
+
 void TransactionRouter::AtClusterTime::setTime(LogicalTime atClusterTime, StmtId currentStmtId) {
     invariant(atClusterTime != LogicalTime::kUninitialized);
     _atClusterTime = atClusterTime;
@@ -682,6 +686,10 @@ void TransactionRouter::Router::setDefaultAtClusterTime(OperationContext* opCtx)
         opCtx, repl::ReadConcernArgs::get(opCtx).getArgsAfterClusterTime(), defaultTime);
 }
 
+bool TransactionRouter::Router::_atClusterTimeHasBeenSet() const {
+    return o().atClusterTime.is_initialized() && o().atClusterTime->timeHasBeenSet();
+}
+
 void TransactionRouter::Router::_setAtClusterTime(
     OperationContext* opCtx,
     const boost::optional<LogicalTime>& afterClusterTime,
@@ -1140,7 +1148,7 @@ std::string TransactionRouter::Router::_transactionInfoForLog(
 
     sb << "parameters:" << parametersBuilder.obj().toString() << ",";
 
-    if (o().atClusterTime) {
+    if (_atClusterTimeHasBeenSet()) {
         sb << " globalReadTimestamp:" << o().atClusterTime->getTime().toString() << ",";
     }
 
diff --git a/src/mongo/s/transaction_router.h b/src/mongo/s/transaction_router.h
index 82e7498523a..cf225ef0f9c 100644
--- a/src/mongo/s/transaction_router.h
+++ b/src/mongo/s/transaction_router.h
@@ -171,6 +171,11 @@ public:
         LogicalTime getTime() const;
 
         /**
+         * Returns true if the _atClusterTime has been changed from the default uninitialized value.
+         */
+        bool timeHasBeenSet() const;
+
+        /**
          * Sets the timestamp and remembers the statement id of the command that set it.
          */
         void setTime(LogicalTime atClusterTime, StmtId currentStmtId);
@@ -403,6 +408,11 @@ public:
         BSONObj _handOffCommitToCoordinator(OperationContext* opCtx);
 
         /**
+         * Returns true if the atClusterTime has been changed from the default uninitialized value.
+         */
+        bool _atClusterTimeHasBeenSet() const;
+
+        /**
          * Sets the given logical time as the atClusterTime for the transaction to be the greater of
          * the given time and the user's afterClusterTime, if one was provided.
          */