[PATCH] txn: convert txn flags into bit mask

[Vladimir Davydov]

---
https://github.com/tarantool/tarantool/commits/dv/txn-flags

 src/box/txn.c | 35 +++++++++++++++++------------------
 src/box/txn.h | 38 ++++++++++++++++++++++----------------
 2 files changed, 39 insertions(+), 34 deletions(-)

diff --git a/src/box/txn.c b/src/box/txn.c
index c7d01b2e..93cc24c2 100644
--- a/src/box/txn.c
+++ b/src/box/txn.c
@@ -197,10 +197,7 @@ txn_begin()
 	txn->n_new_rows = 0;
 	txn->n_local_rows = 0;
 	txn->n_applier_rows = 0;
-	txn->has_triggers  = false;
-	txn->is_done = false;
-	txn->can_yield = true;
-	txn->is_aborted_by_yield = false;
+	txn->flags = TXN_CAN_YIELD;
 	txn->in_sub_stmt = 0;
 	txn->id = ++tsn;
 	txn->signature = -1;
@@ -396,13 +393,13 @@ txn_complete(struct txn *txn)
 		/* Undo the transaction. */
 		if (txn->engine)
 			engine_rollback(txn->engine, txn);
-		if (txn->has_triggers)
+		if (txn->flags & TXN_HAS_TRIGGERS)
 			txn_run_rollback_triggers(txn);
 	} else {
 		/* Commit the transaction. */
 		if (txn->engine != NULL)
 			engine_commit(txn->engine, txn);
-		if (txn->has_triggers)
+		if (txn->flags & TXN_HAS_TRIGGERS)
 			txn_run_commit_triggers(txn);
 
 		double stop_tm = ev_monotonic_now(loop());
@@ -422,7 +419,7 @@ txn_complete(struct txn *txn)
 	if (txn->fiber == NULL)
 		txn_free(txn);
 	else {
-		txn->is_done = true;
+		txn->flags |= TXN_IS_DONE;
 		if (txn->fiber != fiber())
 			/* Wake a waiting fiber up. */
 			fiber_wakeup(txn->fiber);
@@ -491,8 +488,8 @@ txn_write_to_wal(struct txn *txn)
 static int
 txn_prepare(struct txn *txn)
 {
-	if (txn->is_aborted_by_yield) {
-		assert(!txn->can_yield);
+	if (txn->flags & TXN_IS_ABORTED_BY_YIELD) {
+		assert(!(txn->flags & TXN_CAN_YIELD));
 		diag_set(ClientError, ER_TRANSACTION_YIELD);
 		diag_log();
 		return -1;
@@ -518,7 +515,7 @@ txn_prepare(struct txn *txn)
 			return -1;
 	}
 	trigger_clear(&txn->fiber_on_stop);
-	if (!txn->can_yield)
+	if (!(txn->flags & TXN_CAN_YIELD))
 		trigger_clear(&txn->fiber_on_yield);
 	return 0;
 }
@@ -558,7 +555,7 @@ txn_commit(struct txn *txn)
 	 * In case of non-yielding journal the transaction could already
 	 * be done and there is nothing to wait in such cases.
 	 */
-	if (!txn->is_done) {
+	if (!(txn->flags & TXN_IS_DONE)) {
 		bool cancellable = fiber_set_cancellable(false);
 		fiber_yield();
 		fiber_set_cancellable(cancellable);
@@ -586,7 +583,7 @@ txn_rollback(struct txn *txn)
 {
 	assert(txn == in_txn());
 	trigger_clear(&txn->fiber_on_stop);
-	if (!txn->can_yield)
+	if (!(txn->flags & TXN_CAN_YIELD))
 		trigger_clear(&txn->fiber_on_yield);
 	txn->signature = -1;
 	txn_complete(txn);
@@ -607,11 +604,13 @@ void
 txn_can_yield(struct txn *txn, bool set)
 {
 	assert(txn == in_txn());
-	assert(txn->can_yield != set);
-	txn->can_yield = set;
 	if (set) {
+		assert(!(txn->flags & TXN_CAN_YIELD));
+		txn->flags |= TXN_CAN_YIELD;
 		trigger_clear(&txn->fiber_on_yield);
 	} else {
+		assert(txn->flags & TXN_CAN_YIELD);
+		txn->flags &= ~TXN_CAN_YIELD;
 		trigger_create(&txn->fiber_on_yield, txn_on_yield, NULL, NULL);
 		trigger_add(&fiber()->on_yield, &txn->fiber_on_yield);
 	}
@@ -781,11 +780,11 @@ txn_on_yield(struct trigger *trigger, void *event)
 	(void) trigger;
 	(void) event;
 	struct txn *txn = in_txn();
-	assert(txn != NULL && !txn->can_yield);
+	assert(txn != NULL && !(txn->flags & TXN_CAN_YIELD));
 	txn_rollback_to_svp(txn, NULL);
-	if (txn->has_triggers) {
+	if (txn->flags & TXN_HAS_TRIGGERS) {
 		txn_run_rollback_triggers(txn);
-		txn->has_triggers = false;
+		txn->flags &= ~TXN_HAS_TRIGGERS;
 	}
-	txn->is_aborted_by_yield = true;
+	txn->flags |= TXN_IS_ABORTED_BY_YIELD;
 }
diff --git a/src/box/txn.h b/src/box/txn.h
index 2d5dea21..d5dceaed 100644
--- a/src/box/txn.h
+++ b/src/box/txn.h
@@ -51,6 +51,24 @@ struct tuple;
 struct xrow_header;
 struct Vdbe;
 
+/** Allowed values for txn::flags. */
+enum {
+	/** Transaction has been processed. */
+	TXN_IS_DONE		= 1 << 0,
+	/**
+	 * Transaction has been aborted by fiber yield so
+	 * should be rolled back at commit.
+	 */
+	TXN_IS_ABORTED_BY_YIELD	= 1 << 1,
+	/**
+	 * fiber_yield() is allowed inside the transaction.
+	 * See txn_can_yield() for more details.
+	 */
+	TXN_CAN_YIELD		= 1 << 2,
+	/** on_commit and/or on_rollback list is not empty. */
+	TXN_HAS_TRIGGERS	= 1 << 3,
+};
+
 enum {
 	/**
 	 * Maximum recursion depth for on_replace triggers.
@@ -160,20 +178,8 @@ struct txn {
 	 * already assigned LSN.
 	 */
 	int n_applier_rows;
-	/* True when transaction is processed. */
-	bool is_done;
-	/**
-	 * True if the transaction was aborted so should be
-	 * rolled back at commit.
-	 */
-	bool is_aborted_by_yield;
-	/**
-	 * True if yields are allowed inside a transaction,
-	 * see txn_can_yield().
-	 */
-	bool can_yield;
-	/** True if on_commit and on_rollback lists are non-empty. */
-	bool has_triggers;
+	/** Transaction flags, see TXN_*. */
+	unsigned flags;
 	/** The number of active nested statement-level transactions. */
 	int8_t in_sub_stmt;
 	/**
@@ -260,10 +266,10 @@ txn_write(struct txn *txn);
 static inline void
 txn_init_triggers(struct txn *txn)
 {
-	if (txn->has_triggers == false) {
+	if (!(txn->flags & TXN_HAS_TRIGGERS)) {
 		rlist_create(&txn->on_commit);
 		rlist_create(&txn->on_rollback);
-		txn->has_triggers = true;
+		txn->flags |= TXN_HAS_TRIGGERS;
 	}
 }
 
-- 
2.20.1