SERVER-30895 Implement infrastructure for retrieving session states from the source shard during migration

1 files changed, 13 insertions, 3 deletions

diff --git a/src/mongo/db/session.cpp b/src/mongo/db/session.cpp
index 2c217fb7d70..e58b2a5406d 100644
--- a/src/mongo/db/session.cpp
+++ b/src/mongo/db/session.cpp
@@ -60,10 +60,20 @@ void updateSessionEntry(OperationContext* opCtx, const UpdateRequest& updateRequ
                           << " collection has been manually deleted.",
             autoColl.getCollection());
 
-    const auto updateResult = update(opCtx, autoColl.getDb(), updateRequest);
+    try {
+        const auto updateResult = update(opCtx, autoColl.getDb(), updateRequest);
 
-    if (!updateResult.numDocsModified && updateResult.upserted.isEmpty()) {
-        throw WriteConflictException();
+        if (!updateResult.numDocsModified && updateResult.upserted.isEmpty()) {
+            throw WriteConflictException();
+        }
+    } catch (const DBException& excep) {
+        if (excep.code() == ErrorCodes::DuplicateKey) {
+            // Duplicate key means that another thread already created the session this is trying
+            // to upsert. Throw WriteCoflict to make it retry and check the current state again.
+            throw WriteConflictException();
+        }
+
+        throw;
     }
 }