@matheusbsbs / matheus-bagliano / commits / f3c1db4b2a

bulk-checkin: remove ODB transaction nesting

ODB transactions support being nested. Only the outermost {begin,end}_odb_transaction() start and finish a transaction. This allows internal object write codepaths to be optimized with ODB transactions without worrying about whether a transaction is already active. When {begin,end}_odb_transaction() is invoked during an active transaction, these operations are essentially treated as no-ops. This can make the interface a bit awkward to use, as calling end_odb_transaction() does not guarantee that a transaction is actually ended. Thus, in situations where a transaction needs to be explicitly flushed, flush_odb_transaction() must be used. To remove the need for an explicit transaction flush operation via flush_odb_transaction() and better clarify transaction semantics, drop the transaction nesting mechanism in favor of begin_odb_transaction() returning a NULL transaction value to signal it was a no-op, and end_odb_transaction() behaving as a no-op when a NULL transaction value is passed. This is safe for existing callers as the transaction value wired to end_odb_transaction() already comes from begin_odb_transaction() and thus continues the same no-op behavior when a transaction is already pending. With this model, passing a pending transaction to end_odb_transaction() ensures it is committed at that point in time. Signed-off-by: Justin Tobler <jltobler@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Justin Tobler committed Sep 16, 2025 at 13:29 UTC f3c1db4b2a23fac171a699b10f9328f8df52602f

3 files changed +14 -18

bulk-checkin.c

+10 -12

@@ -33,7 +33,6 @@ struct bulk_checkin_packfile {

33 struct odb_transaction {

34 struct object_database *odb;

36 - int nesting;

36 struct tmp_objdir *objdir;

37 struct bulk_checkin_packfile packfile;

38 };

@@ -368,12 +367,11 @@ void fsync_loose_object_bulk_checkin(struct odb_transaction *transaction,

367

368 struct odb_transaction *begin_odb_transaction(struct object_database *odb)

369 {

371 - if (!odb->transaction) {

372 - CALLOC_ARRAY(odb->transaction, 1);

373 - odb->transaction->odb = odb;

374 - }

370 + if (odb->transaction)

371 + return NULL;

372

376 - odb->transaction->nesting += 1;

373 + CALLOC_ARRAY(odb->transaction, 1);

374 + odb->transaction->odb = odb;

375

376 return odb->transaction;

377 }

@@ -389,14 +387,14 @@ void flush_odb_transaction(struct odb_transaction *transaction)

387

388 void end_odb_transaction(struct odb_transaction *transaction)

389 {

392 - if (!transaction || transaction->nesting == 0)

393 - BUG("Unbalanced ODB transaction nesting");

394 -

395 - transaction->nesting -= 1;

396 -

397 - if (transaction->nesting)

390 + if (!transaction)

391 return;

392

393 + /*

394 + * Ensure the transaction ending matches the pending transaction.

395 + */

396 + ASSERT(transaction == transaction->odb->transaction);

397 +

398 flush_odb_transaction(transaction);

399 transaction->odb->transaction = NULL;

400 free(transaction);

bulk-checkin.h

+3 -5

@@ -38,9 +38,8 @@ int index_blob_bulk_checkin(struct odb_transaction *transaction,

38 /*

39 * Tell the object database to optimize for adding

40 * multiple objects. end_odb_transaction must be called

41 - * to make new objects visible. Transactions can be nested,

42 - * and objects are only visible after the outermost transaction

43 - * is complete or the transaction is flushed.

41 + * to make new objects visible. If a transaction is already

42 + * pending, NULL is returned.

43 */

44 struct odb_transaction *begin_odb_transaction(struct object_database *odb);

@@ -53,8 +52,7 @@ void flush_odb_transaction(struct odb_transaction *transaction);

53 /*

54 * Tell the object database to make any objects from the

56 - * current transaction visible if this is the final nested

57 - * transaction.

55 + * current transaction visible.

56 */

57 void end_odb_transaction(struct odb_transaction *transaction);

object-file.c

+1 -1

@@ -1267,7 +1267,7 @@ int index_fd(struct index_state *istate, struct object_id *oid,

1267 struct odb_transaction *transaction;

1268

1269 transaction = begin_odb_transaction(the_repository->objects);

1270 - ret = index_blob_bulk_checkin(transaction,

1270 + ret = index_blob_bulk_checkin(the_repository->objects->transaction,

1271 oid, fd, xsize_t(st->st_size),

1272 path, flags);

1273 end_odb_transaction(transaction);