SERVER-39875 Make router process readOnly field in responses to transaction statements

1 files changed, 12 insertions, 0 deletions

diff --git a/src/mongo/s/transaction_router.h b/src/mongo/s/transaction_router.h
index 983ad8ba4d4..eb7f7c48874 100644
--- a/src/mongo/s/transaction_router.h
+++ b/src/mongo/s/transaction_router.h
@@ -72,6 +72,8 @@ public:
      * the transaction that created it.
      */
     struct Participant {
+        enum class ReadOnly { kUnset, kReadOnly, kNotReadOnly };
+
         Participant(bool isCoordinator,
                     StmtId stmtIdCreatedAt,
                     SharedTransactionOptions sharedOptions);
@@ -84,6 +86,10 @@ public:
         // True if the participant has been chosen as the coordinator for its transaction
         const bool isCoordinator{false};
 
+        // Is updated to kReadOnly or kNotReadOnly based on the readOnly field in the participant's
+        // responses to statements.
+        ReadOnly readOnly{ReadOnly::kUnset};
+
         // The highest statement id of the request during which this participant was created.
         const StmtId stmtIdCreatedAt{kUninitializedStmtId};
 
@@ -156,6 +162,12 @@ public:
     BSONObj attachTxnFieldsIfNeeded(const ShardId& shardId, const BSONObj& cmdObj);
 
     /**
+     * Processes the transaction metadata in the response from the participant if the response
+     * indicates the operation succeeded.
+     */
+    void processParticipantResponse(const ShardId& shardId, const BSONObj& responseObj);
+
+    /**
      * Returns true if the current transaction can retry on a stale version error from a contacted
      * shard. This is always true except for an error received by a write that is not the first
      * overall statement in the sharded transaction. This is because the entire command will be