[tarantool-patches] [PATCH v5 3/7] txn: get rid of fiber_gc from txn_rollback

[Georgy Kirichenko <georgy@tarantool.org>]

Refactoring: don't touch a fiber gc storage on a transaction rollback
explicitly. This relaxes dependencies between fiber and transaction
life cycles.

Prerequisites: #1254
---
 src/box/applier.cc     |  9 ++++++---
 src/box/box.cc         |  6 ++++--
 src/box/call.c         | 22 ++++++++++++++++------
 src/box/memtx_engine.c |  3 ++-
 src/box/txn.c          | 23 ++++++++++++-----------
 src/box/txn.h          |  7 +++++--
 src/box/vy_scheduler.c | 10 +++++++---
 7 files changed, 52 insertions(+), 28 deletions(-)

diff --git a/src/box/applier.cc b/src/box/applier.cc
index d12a835d0..6f93759a8 100644
--- a/src/box/applier.cc
+++ b/src/box/applier.cc
@@ -190,7 +190,8 @@ apply_initial_join_row(struct xrow_header *row)
 	fiber_gc();
 	return rc;
 rollback:
-	txn_rollback();
+	txn_rollback(txn);
+	fiber_gc();
 	return -1;
 }
 
@@ -235,7 +236,8 @@ apply_final_join_row(struct xrow_header *row)
 	if (txn == NULL)
 		return -1;
 	if (apply_row(row) != 0) {
-		txn_rollback();
+		txn_rollback(txn);
+		fiber_gc();
 		return -1;
 	}
 	if (txn_commit(txn) != 0)
@@ -633,7 +635,8 @@ applier_apply_tx(struct stailq *rows)
 	return txn_commit(txn);
 
 rollback:
-	txn_rollback();
+	txn_rollback(txn);
+	fiber_gc();
 	return -1;
 }
 
diff --git a/src/box/box.cc b/src/box/box.cc
index a32f1ba0f..d53b0cdc5 100644
--- a/src/box/box.cc
+++ b/src/box/box.cc
@@ -213,8 +213,10 @@ box_process_rw(struct request *request, struct space *space,
 	return 0;
 
 rollback:
-	if (is_autocommit)
-		txn_rollback();
+	if (is_autocommit) {
+		txn_rollback(txn);
+		fiber_gc();
+	}
 error:
 	if (return_tuple)
 		tuple_unref(tuple);
diff --git a/src/box/call.c b/src/box/call.c
index 56da53fb3..7f6fc8bba 100644
--- a/src/box/call.c
+++ b/src/box/call.c
@@ -208,14 +208,18 @@ box_process_call(struct call_request *request, struct port *port)
 	if (orig_credentials)
 		fiber_set_user(fiber(), orig_credentials);
 
+	struct txn *txn = in_txn();
 	if (rc != 0) {
-		txn_rollback();
+		if (txn != NULL)
+			txn_rollback(txn);
+		fiber_gc();
 		return -1;
 	}
 
-	if (in_txn()) {
+	if (txn != NULL) {
 		diag_set(ClientError, ER_FUNCTION_TX_ACTIVE);
-		txn_rollback();
+		txn_rollback(txn);
+		fiber_gc();
 		return -1;
 	}
 
@@ -229,14 +233,20 @@ box_process_eval(struct call_request *request, struct port *port)
 	/* Check permissions */
 	if (access_check_universe(PRIV_X) != 0)
 		return -1;
+	struct txn *txn;
 	if (box_lua_eval(request, port) != 0) {
-		txn_rollback();
+		txn = in_txn();
+		if (txn != NULL)
+			txn_rollback(txn);
+		fiber_gc();
 		return -1;
 	}
 
-	if (in_txn()) {
+	txn = in_txn();
+	if (txn != NULL) {
 		diag_set(ClientError, ER_FUNCTION_TX_ACTIVE);
-		txn_rollback();
+		txn_rollback(txn);
+		fiber_gc();
 		return -1;
 	}
 
diff --git a/src/box/memtx_engine.c b/src/box/memtx_engine.c
index dae9955b2..f371d147f 100644
--- a/src/box/memtx_engine.c
+++ b/src/box/memtx_engine.c
@@ -274,7 +274,8 @@ memtx_engine_recover_snapshot_row(struct memtx_engine *memtx,
 		return -1;
 	/* no access checks here - applier always works with admin privs */
 	if (space_apply_initial_join_row(space, &request) != 0) {
-		txn_rollback();
+		txn_rollback(txn);
+		fiber_gc();
 		return -1;
 	}
 	int rc = txn_commit(txn);
diff --git a/src/box/txn.c b/src/box/txn.c
index 583ae6ce0..1eb4db6a3 100644
--- a/src/box/txn.c
+++ b/src/box/txn.c
@@ -345,8 +345,10 @@ txn_write_to_wal(struct txn *txn)
 	struct journal_entry *req = journal_entry_new(txn->n_new_rows +
 						      txn->n_applier_rows,
 						      &txn->region);
-	if (req == NULL)
+	if (req == NULL) {
+		txn_rollback(txn);
 		return -1;
+	}
 
 	struct txn_stmt *stmt;
 	struct xrow_header **remote_row = req->rows;
@@ -419,7 +421,7 @@ txn_commit(struct txn *txn)
 	if (txn->n_new_rows + txn->n_applier_rows > 0) {
 		txn->signature = txn_write_to_wal(txn);
 		if (txn->signature < 0)
-			goto fail;
+			return -1;
 	}
 	/*
 	 * Engine can be NULL if transaction contains IPROTO_NOP
@@ -443,7 +445,7 @@ txn_commit(struct txn *txn)
 	txn_free(txn);
 	return 0;
 fail:
-	txn_rollback();
+	txn_rollback(txn);
 	return -1;
 }
 
@@ -457,11 +459,9 @@ txn_rollback_stmt(struct txn *txn)
 }
 
 void
-txn_rollback()
+txn_rollback(struct txn *txn)
 {
-	struct txn *txn = in_txn();
-	if (txn == NULL)
-		return;
+	assert(txn == in_txn());
 	trigger_clear(&txn->fiber_on_stop);
 	if (txn->engine)
 		engine_rollback(txn->engine, txn);
@@ -473,8 +473,6 @@ txn_rollback()
 		panic("rollback trigger failed");
 	}
 
-	/** Free volatile txn memory. */
-	fiber_gc();
 	fiber_set_txn(fiber(), NULL);
 	txn_free(txn);
 }
@@ -550,11 +548,14 @@ int
 box_txn_rollback()
 {
 	struct txn *txn = in_txn();
+	if (txn == NULL)
+		return 0;
 	if (txn && txn->in_sub_stmt) {
 		diag_set(ClientError, ER_ROLLBACK_IN_SUB_STMT);
 		return -1;
 	}
-	txn_rollback(); /* doesn't throw */
+	txn_rollback(txn); /* doesn't throw */
+	fiber_gc();
 	return 0;
 }
 
@@ -632,6 +633,6 @@ txn_on_stop(struct trigger *trigger, void *event)
 {
 	(void) trigger;
 	(void) event;
-	txn_rollback();                 /* doesn't yield or fail */
+	txn_rollback(in_txn());                 /* doesn't yield or fail */
 }
 
diff --git a/src/box/txn.h b/src/box/txn.h
index 33926f6f3..f20428fad 100644
--- a/src/box/txn.h
+++ b/src/box/txn.h
@@ -221,9 +221,12 @@ txn_begin();
 int
 txn_commit(struct txn *txn);
 
-/** Rollback a transaction, if any. */
+/**
+ * Rollback a transaction.
+ * @pre txn == in_txn()
+ */
 void
-txn_rollback();
+txn_rollback(struct txn *txn);
 
 /**
  * Roll back the transaction but keep the object around.
diff --git a/src/box/vy_scheduler.c b/src/box/vy_scheduler.c
index ed8f7dd86..0df55818f 100644
--- a/src/box/vy_scheduler.c
+++ b/src/box/vy_scheduler.c
@@ -889,18 +889,22 @@ vy_deferred_delete_batch_process_f(struct cmsg *cmsg)
 	for (int i = 0; i < batch->count; i++) {
 		if (vy_deferred_delete_process_one(deferred_delete_space,
 						   pk->space_id, pk->mem_format,
-						   &batch->stmt[i]) != 0)
-			goto fail;
+						   &batch->stmt[i]) != 0) {
+			goto fail_rollback;
+		}
 	}
 
 	if (txn_commit(txn) != 0)
 		goto fail;
 	fiber_gc();
 	return;
+
+fail_rollback:
+	txn_rollback(txn);
+	fiber_gc();
 fail:
 	batch->is_failed = true;
 	diag_move(diag_get(), &batch->diag);
-	txn_rollback();
 }
 
 /**
-- 
2.22.0