MDEV-5262, MDEV-5914, MDEV-5941, MDEV-6020: Deadlocks during parallel...

MDEV-5262, MDEV-5914, MDEV-5941, MDEV-6020: Deadlocks during parallel replication causing replication to fail.

After-review changes. Fix InnoDB coding style issues.

storage/innobase/handler/ha_innodb.cc

@@ -4218,21 +4218,23 @@ innobase_kill_query(
 
 	trx = thd_to_trx(thd);
 
-        if (trx)
-        {
+	if (trx) {
 		THD *cur = current_thd;
 		THD *owner = trx->current_lock_mutex_owner;
 
 		/* Cancel a pending lock request. */
-	  if (owner != cur)
+		if (owner != cur) {
 			lock_mutex_enter();
+		}
 		trx_mutex_enter(trx);
-          if (trx->lock.wait_lock)
+		if (trx->lock.wait_lock) {
 			lock_cancel_waiting_and_release(trx->lock.wait_lock);
+		}
 		trx_mutex_exit(trx);
-	  if (owner != cur)
+		if (owner != cur) {
 			lock_mutex_exit();
 		}
+	}
 
 	DBUG_VOID_RETURN;
 }

storage/innobase/lock/lock0lock.cc

@@ -399,9 +399,9 @@ UNIV_INTERN ibool	lock_print_waits	= FALSE;
 
 /* Buffer to collect THDs to report waits for. */
 struct thd_wait_reports {
-	struct thd_wait_reports *next;
-	ulint used;
-	trx_t *waitees[64];
+	struct thd_wait_reports *next;	/*!< List link */
+	ulint used;			/*!< How many elements in waitees[] */
+	trx_t *waitees[64];		/*!< Trxs for thd_report_wait_for() */
 };
 
 
@@ -3916,11 +3916,14 @@ lock_deadlock_search(
 
 		} else {
 			/* We do not need to report autoinc locks to the upper
-		    layer. These locks are released before commit, so they can
-		    not cause deadlocks with binlog-fixed commit order. */
-		    if (waitee_ptr && (lock_get_type_low(lock) != LOCK_TABLE ||
+			layer. These locks are released before commit, so they
+			can not cause deadlocks with binlog-fixed commit
+			order. */
+			if (waitee_ptr &&
+			    (lock_get_type_low(lock) != LOCK_TABLE ||
 			     lock_get_mode(lock) != LOCK_AUTO_INC)) {
-			    if (waitee_ptr->used == sizeof(waitee_ptr->waitees)/
+				if (waitee_ptr->used ==
+				    sizeof(waitee_ptr->waitees) /
 				    sizeof(waitee_ptr->waitees[0])) {
 					waitee_ptr->next =
 						(struct thd_wait_reports *)
@@ -4028,22 +4031,28 @@ lock_deadlock_trx_rollback(
 	trx_mutex_exit(trx);
 }
 
-static void
-mysql_report_waiters(struct thd_wait_reports *waitee_buf_ptr,
-		     THD *mysql_thd,
-		     trx_id_t victim_trx_id)
-{
-	struct thd_wait_reports *p = waitee_buf_ptr;
-	while (p) {
-		struct thd_wait_reports *q;
-		ulint i = 0;
+static
+void
+lock_report_waiters_to_mysql(
+/*=======================*/
+	struct thd_wait_reports*	waitee_buf_ptr,	/*!< in: set of trxs */
+	THD*				mysql_thd,	/*!< in: THD */
+	trx_id_t			victim_trx_id)	/*!< in: Trx selected
+							as deadlock victim, if
+							any */
+{
+	struct thd_wait_reports*	p;
+	struct thd_wait_reports*	q;
+	ulint				i;
 
+	p = waitee_buf_ptr;
+	while (p) {
+		i = 0;
 		while (i < p->used) {
 			trx_t *w_trx = p->waitees[i];
 			/*  There is no need to report waits to a trx already
 			selected as a victim. */
-			if (w_trx->id != victim_trx_id)
-			{
+			if (w_trx->id != victim_trx_id) {
 				/* If thd_report_wait_for() decides to kill the
 				transaction, then we will get a call back into
 				innobase_kill_query. We mark this by setting
@@ -4056,8 +4065,9 @@ mysql_report_waiters(struct thd_wait_reports *waitee_buf_ptr,
 			++i;
 		}
 		q = p->next;
-		if (p != waitee_buf_ptr)
+		if (p != waitee_buf_ptr) {
 			mem_free(p);
+		}
 		p = q;
 	}
 }
@@ -4079,7 +4089,8 @@ lock_deadlock_check_and_resolve(
 	const trx_t*	trx)	/*!< in: transaction */
 {
 	trx_id_t		victim_trx_id;
-	struct thd_wait_reports	waitee_buf, *waitee_buf_ptr;
+	struct thd_wait_reports	waitee_buf;
+	struct thd_wait_reports*waitee_buf_ptr;
 	THD*			start_mysql_thd;
 
 	ut_ad(trx != NULL);
@@ -4088,10 +4099,11 @@ lock_deadlock_check_and_resolve(
 	assert_trx_in_list(trx);
 
 	start_mysql_thd = trx->mysql_thd;
-	if (start_mysql_thd && thd_need_wait_for(start_mysql_thd))
+	if (start_mysql_thd && thd_need_wait_for(start_mysql_thd)) {
 		waitee_buf_ptr = &waitee_buf;
-	else
+	} else {
 		waitee_buf_ptr = NULL;
+	}
 
 	/* Try and resolve as many deadlocks as possible. */
 	do {
@@ -4113,9 +4125,11 @@ lock_deadlock_check_and_resolve(
 		victim_trx_id = lock_deadlock_search(&ctx, waitee_buf_ptr);
 
 		/* Report waits to upper layer, as needed. */
-		if (waitee_buf_ptr)
-			mysql_report_waiters(waitee_buf_ptr, start_mysql_thd,
+		if (waitee_buf_ptr) {
+			lock_report_waiters_to_mysql(waitee_buf_ptr,
+						     start_mysql_thd,
 						     victim_trx_id);
+		}
 
 		/* Search too deep, we rollback the joining transaction. */
 		if (ctx.too_deep) {

storage/innobase/trx/trx0trx.cc

@@ -1921,10 +1921,11 @@ trx_weight_ge(
 	/* First ask the upper server layer if it has any preference for which
 	to prefer as a deadlock victim. */
 	pref= thd_deadlock_victim_preference(a->mysql_thd, b->mysql_thd);
-	if (pref < 0)
+	if (pref < 0) {
 		return FALSE;
-	else if (pref > 0)
+	} else if (pref > 0) {
 		return TRUE;
+	}
 
 	/* Upper server layer had no preference, we fall back to comparing the
 	number of altered/locked rows. */

storage/xtradb/handler/ha_innodb.cc

@@ -4704,13 +4704,13 @@ innobase_kill_connection(
 
 	trx = thd_to_trx(thd);
 
-	if (trx)
-	{
+	if (trx) {
 		THD *cur = current_thd;
 		THD *owner = trx->current_lock_mutex_owner;
 
-		if (owner != cur)
+		if (owner != cur) {
 			lock_mutex_enter();
+		}
 		trx_mutex_enter(trx);
 
 		/* Cancel a pending lock request. */
@@ -4718,9 +4718,10 @@ innobase_kill_connection(
 			lock_cancel_waiting_and_release(trx->lock.wait_lock);
 
 		trx_mutex_exit(trx);
-		if (owner != cur)
+		if (owner != cur) {
 			lock_mutex_exit();
 		}
+	}
 
 	DBUG_VOID_RETURN;
 }

storage/xtradb/lock/lock0lock.cc

@@ -399,9 +399,9 @@ UNIV_INTERN ibool	lock_print_waits	= FALSE;
 
 /* Buffer to collect THDs to report waits for. */
 struct thd_wait_reports {
-	struct thd_wait_reports *next;
-	ulint used;
-	trx_t *waitees[64];
+	struct thd_wait_reports *next;	/*!< List link */
+	ulint used;			/*!< How many elements in waitees[] */
+	trx_t *waitees[64];		/*!< Trxs for thd_report_wait_for() */
 };
 
 
@@ -3939,11 +3939,14 @@ lock_deadlock_search(
 
 		} else {
 			/* We do not need to report autoinc locks to the upper
-		    layer. These locks are released before commit, so they can
-		    not cause deadlocks with binlog-fixed commit order. */
-		    if (waitee_ptr && (lock_get_type_low(lock) != LOCK_TABLE ||
+			layer. These locks are released before commit, so they
+			can not cause deadlocks with binlog-fixed commit
+			order. */
+			if (waitee_ptr &&
+			    (lock_get_type_low(lock) != LOCK_TABLE ||
 			     lock_get_mode(lock) != LOCK_AUTO_INC)) {
-			    if (waitee_ptr->used == sizeof(waitee_ptr->waitees)/
+				if (waitee_ptr->used ==
+				    sizeof(waitee_ptr->waitees) /
 				    sizeof(waitee_ptr->waitees[0])) {
 					waitee_ptr->next =
 						(struct thd_wait_reports *)
@@ -4051,22 +4054,28 @@ lock_deadlock_trx_rollback(
 	trx_mutex_exit(trx);
 }
 
-static void
-mysql_report_waiters(struct thd_wait_reports *waitee_buf_ptr,
-		     THD *mysql_thd,
-		     trx_id_t victim_trx_id)
-{
-	struct thd_wait_reports *p = waitee_buf_ptr;
-	while (p) {
-		struct thd_wait_reports *q;
-		ulint i = 0;
+static
+void
+lock_report_waiters_to_mysql(
+/*=======================*/
+	struct thd_wait_reports*	waitee_buf_ptr,	/*!< in: set of trxs */
+	THD*				mysql_thd,	/*!< in: THD */
+	trx_id_t			victim_trx_id)	/*!< in: Trx selected
+							as deadlock victim, if
+							any */
+{
+	struct thd_wait_reports*	p;
+	struct thd_wait_reports*	q;
+	ulint				i;
 
+	p = waitee_buf_ptr;
+	while (p) {
+		i = 0;
 		while (i < p->used) {
 			trx_t *w_trx = p->waitees[i];
 			/*  There is no need to report waits to a trx already
 			selected as a victim. */
-			if (w_trx->id != victim_trx_id)
-			{
+			if (w_trx->id != victim_trx_id) {
 				/* If thd_report_wait_for() decides to kill the
 				transaction, then we will get a call back into
 				innobase_kill_query. We mark this by setting
@@ -4079,8 +4088,9 @@ mysql_report_waiters(struct thd_wait_reports *waitee_buf_ptr,
 			++i;
 		}
 		q = p->next;
-		if (p != waitee_buf_ptr)
+		if (p != waitee_buf_ptr) {
 			mem_free(p);
+		}
 		p = q;
 	}
 }
@@ -4102,7 +4112,8 @@ lock_deadlock_check_and_resolve(
 	const trx_t*	trx)	/*!< in: transaction */
 {
 	trx_id_t		victim_trx_id;
-	struct thd_wait_reports	waitee_buf, *waitee_buf_ptr;
+	struct thd_wait_reports	waitee_buf;
+	struct thd_wait_reports*waitee_buf_ptr;
 	THD*			start_mysql_thd;
 
 	ut_ad(trx != NULL);
@@ -4111,10 +4122,11 @@ lock_deadlock_check_and_resolve(
 	assert_trx_in_list(trx);
 
 	start_mysql_thd = trx->mysql_thd;
-	if (start_mysql_thd && thd_need_wait_for(start_mysql_thd))
+	if (start_mysql_thd && thd_need_wait_for(start_mysql_thd)) {
 		waitee_buf_ptr = &waitee_buf;
-	else
+	} else {
 		waitee_buf_ptr = NULL;
+	}
 
 	/* Try and resolve as many deadlocks as possible. */
 	do {
@@ -4136,9 +4148,11 @@ lock_deadlock_check_and_resolve(
 		victim_trx_id = lock_deadlock_search(&ctx, waitee_buf_ptr);
 
 		/* Report waits to upper layer, as needed. */
-		if (waitee_buf_ptr)
-			mysql_report_waiters(waitee_buf_ptr, start_mysql_thd,
+		if (waitee_buf_ptr) {
+			lock_report_waiters_to_mysql(waitee_buf_ptr,
+						     start_mysql_thd,
 						     victim_trx_id);
+		}
 
 		/* Search too deep, we rollback the joining transaction. */
 		if (ctx.too_deep) {

storage/xtradb/trx/trx0trx.cc

@@ -2142,9 +2142,8 @@ trx_assert_started(
 #endif /* UNIV_DEBUG */
 
 /*******************************************************************//**
-Compares the "weight" (or size) of two transactions. Transactions that
-have edited non-transactional tables are considered heavier than ones
-that have not.
+Compares the "weight" (or size) of two transactions. The heavier the weight,
+the more reluctant we will be to choose the transaction as a deadlock victim.
 @return	TRUE if weight(a) >= weight(b) */
 UNIV_INTERN
 ibool
@@ -2158,10 +2157,11 @@ trx_weight_ge(
 	/* First ask the upper server layer if it has any preference for which
 	to prefer as a deadlock victim. */
 	pref= thd_deadlock_victim_preference(a->mysql_thd, b->mysql_thd);
-	if (pref < 0)
+	if (pref < 0) {
 		return FALSE;
-	else if (pref > 0)
+	} else if (pref > 0) {
 		return TRUE;
+	}
 
 	/* Upper server layer had no preference, we fall back to comparing the
 	number of altered/locked rows. */