SERVER-72146 Add statistic to count the number of bytes cloned from the donor of a migration

(cherry picked from commit a61cb340c33e123b273071488658811be5361d60)

3 files changed, 7 insertions, 0 deletions

diff --git a/src/mongo/db/s/migration_chunk_cloner_source_legacy.cpp b/src/mongo/db/s/migration_chunk_cloner_source_legacy.cpp
index 2272599806e..4d98453d5fc 100644
--- a/src/mongo/db/s/migration_chunk_cloner_source_legacy.cpp
+++ b/src/mongo/db/s/migration_chunk_cloner_source_legacy.cpp
@@ -712,6 +712,7 @@ void MigrationChunkClonerSourceLegacy::_nextCloneBatchFromIndexScan(OperationCon
             lk.unlock();
 
             ShardingStatistics::get(opCtx).countDocsClonedOnDonor.addAndFetch(1);
+            ShardingStatistics::get(opCtx).countBytesClonedOnDonor.addAndFetch(obj.objsize());
         }
     } catch (DBException& exception) {
         exception.addContext("Executor error while scanning for documents belonging to chunk");
@@ -782,6 +783,7 @@ void MigrationChunkClonerSourceLegacy::_nextCloneBatchFromCloneLocs(OperationCon
         }
         arrBuilder->append(doc->value());
         ShardingStatistics::get(opCtx).countDocsClonedOnDonor.addAndFetch(1);
+        ShardingStatistics::get(opCtx).countBytesClonedOnDonor.addAndFetch(doc->value().objsize());
     }
 }
 
diff --git a/src/mongo/db/s/sharding_statistics.cpp b/src/mongo/db/s/sharding_statistics.cpp
index d103ad001fa..de15166cf66 100644
--- a/src/mongo/db/s/sharding_statistics.cpp
+++ b/src/mongo/db/s/sharding_statistics.cpp
@@ -71,6 +71,7 @@ void ShardingStatistics::report(BSONObjBuilder* builder) const {
     builder->append("countBytesClonedOnCatchUpOnRecipient",
                     countBytesClonedOnCatchUpOnRecipient.load());
     builder->append("countDocsClonedOnDonor", countDocsClonedOnDonor.load());
+    builder->append("countBytesClonedOnDonor", countBytesClonedOnDonor.load());
     builder->append("countRecipientMoveChunkStarted", countRecipientMoveChunkStarted.load());
     builder->append("countDocsDeletedOnDonor", countDocsDeletedOnDonor.load());
     builder->append("countDonorMoveChunkLockTimeout", countDonorMoveChunkLockTimeout.load());
diff --git a/src/mongo/db/s/sharding_statistics.h b/src/mongo/db/s/sharding_statistics.h
index 7a7efeb1464..d1b3ed2a816 100644
--- a/src/mongo/db/s/sharding_statistics.h
+++ b/src/mongo/db/s/sharding_statistics.h
@@ -83,6 +83,10 @@ struct ShardingStatistics {
     // node.
     AtomicWord<long long> countDocsClonedOnDonor{0};
 
+    // Cumulative, always-increasing counter of how many bytes have been cloned on the donor
+    // node.
+    AtomicWord<long long> countBytesClonedOnDonor{0};
+
     // Cumulative, always-increasing counter of how many documents have been deleted by the
     // rangeDeleter.
     AtomicWord<long long> countDocsDeletedOnDonor{0};