SERVER-31979 Include chunk migration stats in `moveChunk.commit` changelog entries

5 files changed, 17 insertions, 7 deletions

diff --git a/src/mongo/db/s/migration_chunk_cloner_source.h b/src/mongo/db/s/migration_chunk_cloner_source.h
index ff3d31132fa..65b2a6d23f6 100644
--- a/src/mongo/db/s/migration_chunk_cloner_source.h
+++ b/src/mongo/db/s/migration_chunk_cloner_source.h
@@ -95,7 +95,7 @@ public:
      *
      * NOTE: Must be called without any locks.
      */
-    virtual Status commitClone(OperationContext* opCtx) = 0;
+    virtual StatusWith<BSONObj> commitClone(OperationContext* opCtx) = 0;
 
     /**
      * Tells the recipient to abort the clone and cleanup any unused data. This method's
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 95914f9c4b0..78cf1102ef4 100644
--- a/src/mongo/db/s/migration_chunk_cloner_source_legacy.cpp
+++ b/src/mongo/db/s/migration_chunk_cloner_source_legacy.cpp
@@ -332,7 +332,7 @@ Status MigrationChunkClonerSourceLegacy::awaitUntilCriticalSectionIsAppropriate(
     return {ErrorCodes::ExceededTimeLimit, "Timed out waiting for the cloner to catch up"};
 }
 
-Status MigrationChunkClonerSourceLegacy::commitClone(OperationContext* opCtx) {
+StatusWith<BSONObj> MigrationChunkClonerSourceLegacy::commitClone(OperationContext* opCtx) {
     invariant(_state == kCloning);
     invariant(!opCtx->lockState()->isLocked());
 
@@ -346,7 +346,8 @@ Status MigrationChunkClonerSourceLegacy::commitClone(OperationContext* opCtx) {
                     "destination shard finished committing but there are still some session "
                     "metadata that needs to be transferred"};
         }
-        return Status::OK();
+
+        return responseStatus;
     }
 
     cancelClone(opCtx);
diff --git a/src/mongo/db/s/migration_chunk_cloner_source_legacy.h b/src/mongo/db/s/migration_chunk_cloner_source_legacy.h
index 28981b21c15..17979a5c2ef 100644
--- a/src/mongo/db/s/migration_chunk_cloner_source_legacy.h
+++ b/src/mongo/db/s/migration_chunk_cloner_source_legacy.h
@@ -68,7 +68,7 @@ public:
     Status awaitUntilCriticalSectionIsAppropriate(OperationContext* opCtx,
                                                   Milliseconds maxTimeToWait) override;
 
-    Status commitClone(OperationContext* opCtx) override;
+    StatusWith<BSONObj> commitClone(OperationContext* opCtx) override;
 
     void cancelClone(OperationContext* opCtx) override;
 
diff --git a/src/mongo/db/s/migration_source_manager.cpp b/src/mongo/db/s/migration_source_manager.cpp
index fb1ebee0293..558e32f667a 100644
--- a/src/mongo/db/s/migration_source_manager.cpp
+++ b/src/mongo/db/s/migration_source_manager.cpp
@@ -358,7 +358,7 @@ Status MigrationSourceManager::commitChunkOnRecipient(OperationContext* opCtx) {
     auto scopedGuard = MakeGuard([&] { cleanupOnError(opCtx); });
 
     // Tell the recipient shard to fetch the latest changes.
-    Status commitCloneStatus = _cloneDriver->commitClone(opCtx);
+    auto commitCloneStatus = _cloneDriver->commitClone(opCtx);
 
     if (MONGO_FAIL_POINT(failMigrationCommit) && commitCloneStatus.isOK()) {
         commitCloneStatus = {ErrorCodes::InternalError,
@@ -366,7 +366,11 @@ Status MigrationSourceManager::commitChunkOnRecipient(OperationContext* opCtx) {
     }
 
     if (!commitCloneStatus.isOK()) {
-        return commitCloneStatus.withContext("commit clone failed");
+        return commitCloneStatus.getStatus().withContext("commit clone failed");
+    }
+
+    if (commitCloneStatus.getValue()["counts"].type() == BSONType::Object) {
+        _recipientCloneCounts = commitCloneStatus.getValue()["counts"].Obj().getOwned();
     }
 
     _state = kCloneCompleted;
@@ -571,7 +575,9 @@ Status MigrationSourceManager::commitChunkMetadataOnConfig(OperationContext* opC
                     BSON("min" << _args.getMinKey() << "max" << _args.getMaxKey() << "from"
                                << _args.getFromShardId()
                                << "to"
-                               << _args.getToShardId()),
+                               << _args.getToShardId()
+                               << "counts"
+                               << _recipientCloneCounts),
                     ShardingCatalogClient::kMajorityWriteConcern)
         .ignore();
 
diff --git a/src/mongo/db/s/migration_source_manager.h b/src/mongo/db/s/migration_source_manager.h
index 050fd8e43bf..cb24599e519 100644
--- a/src/mongo/db/s/migration_source_manager.h
+++ b/src/mongo/db/s/migration_source_manager.h
@@ -250,6 +250,9 @@ private:
     // The transition from false to true is protected by the collection X-lock, which happens just
     // before the config server metadata commit is scheduled.
     bool _readsShouldWaitOnCritSec{false};
+
+    // The statistics about a chunk migration to be included in moveChunk.commit
+    BSONObj _recipientCloneCounts;
 };
 
 }  // namespace mongo