SERVER-60730 shardsvrDropDatabase should always join existing coordinator

(cherry picked from commit 0bd0ddfb1d6875c3ce4390d30e0566b107256f29)

2 files changed, 22 insertions, 2 deletions

diff --git a/src/mongo/db/s/sharding_ddl_coordinator.h b/src/mongo/db/s/sharding_ddl_coordinator.h
index a3d9fc342a8..3108965947a 100644
--- a/src/mongo/db/s/sharding_ddl_coordinator.h
+++ b/src/mongo/db/s/sharding_ddl_coordinator.h
@@ -90,6 +90,10 @@ public:
         return metadata().getForwardableOpMetadata().get();
     }
 
+    const boost::optional<mongo::DatabaseVersion>& getDatabaseVersion() const& {
+        return metadata().getDatabaseVersion();
+    }
+
     // Cached LSIDs shared between DDL coordinator instances
     class SessionCache {
 
diff --git a/src/mongo/db/s/shardsvr_drop_database_command.cpp b/src/mongo/db/s/shardsvr_drop_database_command.cpp
index 08e49131c98..a8aaef5fbcf 100644
--- a/src/mongo/db/s/shardsvr_drop_database_command.cpp
+++ b/src/mongo/db/s/shardsvr_drop_database_command.cpp
@@ -34,6 +34,7 @@
 #include "mongo/db/commands.h"
 #include "mongo/db/curop.h"
 #include "mongo/db/s/drop_database_coordinator.h"
+#include "mongo/db/s/operation_sharding_state.h"
 #include "mongo/db/s/sharding_ddl_coordinator_service.h"
 #include "mongo/db/s/sharding_state.h"
 #include "mongo/logv2/log.h"
@@ -85,8 +86,23 @@ public:
             coordinatorDoc.setShardingDDLCoordinatorMetadata(
                 {{ns(), DDLCoordinatorTypeEnum::kDropDatabase}});
             auto service = ShardingDDLCoordinatorService::getService(opCtx);
-            auto dropDatabaseCoordinator = checked_pointer_cast<DropDatabaseCoordinator>(
-                service->getOrCreateInstance(opCtx, coordinatorDoc.toBSON()));
+            const auto requestVersion = OperationShardingState::get(opCtx).getDbVersion(ns().db());
+            auto dropDatabaseCoordinator = [&]() {
+                while (true) {
+                    auto currentCoordinator = checked_pointer_cast<DropDatabaseCoordinator>(
+                        service->getOrCreateInstance(opCtx, coordinatorDoc.toBSON()));
+                    const auto currentDbVersion = currentCoordinator->getDatabaseVersion();
+                    if (currentDbVersion == requestVersion) {
+                        return currentCoordinator;
+                    }
+                    LOGV2_DEBUG(6073000,
+                                2,
+                                "DbVersion mismatch, waiting for existing coordinator to finish",
+                                "requestedVersion"_attr = requestVersion,
+                                "coordinatorVersion"_attr = currentDbVersion);
+                    currentCoordinator->getCompletionFuture().wait(opCtx);
+                }
+            }();
             dropDatabaseCoordinator->getCompletionFuture().get(opCtx);
         }