SERVER-45323 Make MigrationCoordinator persist the decision before sending the decision to itself and the recipient

4 files changed, 39 insertions, 0 deletions

diff --git a/src/mongo/db/s/migration_coordinator.cpp b/src/mongo/db/s/migration_coordinator.cpp
index 8b59fea4366..0ce9e9a5b18 100644
--- a/src/mongo/db/s/migration_coordinator.cpp
+++ b/src/mongo/db/s/migration_coordinator.cpp
@@ -79,6 +79,9 @@ void MigrationCoordinator::startMigration(OperationContext* opCtx, bool waitForD
 }
 
 void MigrationCoordinator::commitMigrationOnDonorAndRecipient(OperationContext* opCtx) {
+    LOG(0) << _logPrefix() << "Making commit decision durable";
+    migrationutil::persistCommitDecision(opCtx, _migrationInfo.getId());
+
     LOG(0) << _logPrefix() << "Deleting range deletion task on recipient";
     migrationutil::deleteRangeDeletionTaskOnRecipient(opCtx,
                                                       _migrationInfo.getRecipientShardId(),
@@ -91,6 +94,9 @@ void MigrationCoordinator::commitMigrationOnDonorAndRecipient(OperationContext*
 }
 
 void MigrationCoordinator::abortMigrationOnDonorAndRecipient(OperationContext* opCtx) {
+    LOG(0) << _logPrefix() << "Making abort decision durable";
+    migrationutil::persistAbortDecision(opCtx, _migrationInfo.getId());
+
     LOG(0) << _logPrefix() << "Deleting range deletion task on donor";
     migrationutil::deleteRangeDeletionTaskLocally(opCtx, _migrationInfo.getId());
 
diff --git a/src/mongo/db/s/migration_coordinator_document.idl b/src/mongo/db/s/migration_coordinator_document.idl
index e5e4f1a5ab1..74814abda01 100644
--- a/src/mongo/db/s/migration_coordinator_document.idl
+++ b/src/mongo/db/s/migration_coordinator_document.idl
@@ -73,3 +73,7 @@ structs:
             preMigrationChunkVersion:
                 type: ChunkVersion
                 description: "The version, at the start of the migration, of the chunk being moved."
+            decision:
+                type: string
+                description: "Whether the migration committed or aborted."
+                optional: true
diff --git a/src/mongo/db/s/migration_util.cpp b/src/mongo/db/s/migration_util.cpp
index e9628544bfd..c6bee0d5377 100644
--- a/src/mongo/db/s/migration_util.cpp
+++ b/src/mongo/db/s/migration_util.cpp
@@ -331,6 +331,23 @@ void persistRangeDeletionTaskLocally(OperationContext* opCtx,
     }
 }
 
+void persistCommitDecision(OperationContext* opCtx, const UUID& migrationId) {
+    PersistentTaskStore<MigrationCoordinatorDocument> store(
+        opCtx, NamespaceString::kMigrationCoordinatorsNamespace);
+    store.update(
+        opCtx,
+        QUERY(MigrationCoordinatorDocument::kIdFieldName << migrationId),
+        BSON("$set" << BSON(MigrationCoordinatorDocument::kDecisionFieldName << "committed")));
+}
+
+void persistAbortDecision(OperationContext* opCtx, const UUID& migrationId) {
+    PersistentTaskStore<MigrationCoordinatorDocument> store(
+        opCtx, NamespaceString::kMigrationCoordinatorsNamespace);
+    store.update(
+        opCtx,
+        QUERY(MigrationCoordinatorDocument::kIdFieldName << migrationId),
+        BSON("$set" << BSON(MigrationCoordinatorDocument::kDecisionFieldName << "aborted")));
+}
 void deleteRangeDeletionTaskOnRecipient(OperationContext* opCtx,
                                         const ShardId& recipientId,
                                         const UUID& migrationId,
diff --git a/src/mongo/db/s/migration_util.h b/src/mongo/db/s/migration_util.h
index 92daa285d31..8f99930f601 100644
--- a/src/mongo/db/s/migration_util.h
+++ b/src/mongo/db/s/migration_util.h
@@ -116,6 +116,18 @@ void persistRangeDeletionTaskLocally(OperationContext* opCtx,
                                      const RangeDeletionTask& deletionTask);
 
 /**
+ * Updates the migration coordinator document to set the decision field to "committed" and waits for
+ * majority writeConcern.
+ */
+void persistCommitDecision(OperationContext* opCtx, const UUID& migrationId);
+
+/**
+ * Updates the migration coordinator document to set the decision field to "aborted" and waits for
+ * majority writeConcern.
+ */
+void persistAbortDecision(OperationContext* opCtx, const UUID& migrationId);
+
+/**
  * Deletes the range deletion task document with the specified id from config.rangeDeletions and
  * waits for majority write concern.
  */