[PATCH 10/25] vinyl: do not free pending tasks on shutdown

[Vladimir Davydov]

This is a prerequisite for switching scheduler-worker communication from
pthread mutex/cond to cbus, which in turn is needed to generate and send
deferred DELETEs from workers back to tx (#2129).

After this patch, pending tasks will be leaked on shutdown. This is OK,
as we leak a lot of objects on shutdown anyway. The proper way of fixing
this leak would be to rework shutdown without atexit() so that we can
use cbus till the very end.

Needed for #2129
---
 src/box/vy_scheduler.c | 47 ++++++++++-------------------------------------
 1 file changed, 10 insertions(+), 37 deletions(-)

diff --git a/src/box/vy_scheduler.c b/src/box/vy_scheduler.c
index a82fe9f2..561e7b37 100644
--- a/src/box/vy_scheduler.c
+++ b/src/box/vy_scheduler.c
@@ -84,12 +84,8 @@ struct vy_task_ops {
 	 * This function is called by the scheduler if either ->execute
 	 * or ->complete failed. It may be used to undo changes done to
 	 * the LSM tree when preparing the task.
-	 *
-	 * If @in_shutdown is set, the callback is invoked from the
-	 * engine destructor.
 	 */
-	void (*abort)(struct vy_scheduler *scheduler, struct vy_task *task,
-		      bool in_shutdown);
+	void (*abort)(struct vy_scheduler *scheduler, struct vy_task *task);
 };
 
 struct vy_task {
@@ -279,15 +275,11 @@ vy_scheduler_start_workers(struct vy_scheduler *scheduler)
 static void
 vy_scheduler_stop_workers(struct vy_scheduler *scheduler)
 {
-	struct stailq task_queue;
-	stailq_create(&task_queue);
-
 	assert(scheduler->is_worker_pool_running);
 	scheduler->is_worker_pool_running = false;
 
-	/* Clear the input queue and wake up worker threads. */
+	/* Wake up worker threads. */
 	tt_pthread_mutex_lock(&scheduler->mutex);
-	stailq_concat(&task_queue, &scheduler->input_queue);
 	pthread_cond_broadcast(&scheduler->worker_cond);
 	tt_pthread_mutex_unlock(&scheduler->mutex);
 
@@ -298,15 +290,6 @@ vy_scheduler_stop_workers(struct vy_scheduler *scheduler)
 
 	free(scheduler->worker_pool);
 	scheduler->worker_pool = NULL;
-
-	/* Abort all pending tasks. */
-	struct vy_task *task, *next;
-	stailq_concat(&task_queue, &scheduler->output_queue);
-	stailq_foreach_entry_safe(task, next, &task_queue, link) {
-		if (task->ops->abort != NULL)
-			task->ops->abort(scheduler, task, true);
-		vy_task_delete(&scheduler->task_pool, task);
-	}
 }
 
 void
@@ -888,8 +871,7 @@ fail:
 }
 
 static void
-vy_task_dump_abort(struct vy_scheduler *scheduler, struct vy_task *task,
-		   bool in_shutdown)
+vy_task_dump_abort(struct vy_scheduler *scheduler, struct vy_task *task)
 {
 	struct vy_lsm *lsm = task->lsm;
 
@@ -902,17 +884,13 @@ vy_task_dump_abort(struct vy_scheduler *scheduler, struct vy_task *task,
 	 * It's no use alerting the user if the server is
 	 * shutting down or the LSM tree was dropped.
 	 */
-	if (!in_shutdown && !lsm->is_dropped) {
+	if (!lsm->is_dropped) {
 		struct error *e = diag_last_error(&task->diag);
 		error_log(e);
 		say_error("%s: dump failed", vy_lsm_name(lsm));
 	}
 
-	/* The metadata log is unavailable on shutdown. */
-	if (!in_shutdown)
-		vy_run_discard(task->new_run);
-	else
-		vy_run_unref(task->new_run);
+	vy_run_discard(task->new_run);
 
 	lsm->is_dumping = false;
 	vy_scheduler_update_lsm(scheduler, lsm);
@@ -1213,8 +1191,7 @@ vy_task_compact_complete(struct vy_scheduler *scheduler, struct vy_task *task)
 }
 
 static void
-vy_task_compact_abort(struct vy_scheduler *scheduler, struct vy_task *task,
-		      bool in_shutdown)
+vy_task_compact_abort(struct vy_scheduler *scheduler, struct vy_task *task)
 {
 	struct vy_lsm *lsm = task->lsm;
 	struct vy_range *range = task->range;
@@ -1226,18 +1203,14 @@ vy_task_compact_abort(struct vy_scheduler *scheduler, struct vy_task *task,
 	 * It's no use alerting the user if the server is
 	 * shutting down or the LSM tree was dropped.
 	 */
-	if (!in_shutdown && !lsm->is_dropped) {
+	if (!lsm->is_dropped) {
 		struct error *e = diag_last_error(&task->diag);
 		error_log(e);
 		say_error("%s: failed to compact range %s",
 			  vy_lsm_name(lsm), vy_range_str(range));
 	}
 
-	/* The metadata log is unavailable on shutdown. */
-	if (!in_shutdown)
-		vy_run_discard(task->new_run);
-	else
-		vy_run_unref(task->new_run);
+	vy_run_discard(task->new_run);
 
 	assert(range->heap_node.pos == UINT32_MAX);
 	vy_range_heap_insert(&lsm->range_heap, &range->heap_node);
@@ -1476,7 +1449,7 @@ vy_scheduler_complete_task(struct vy_scheduler *scheduler,
 {
 	if (task->lsm->is_dropped) {
 		if (task->ops->abort)
-			task->ops->abort(scheduler, task, false);
+			task->ops->abort(scheduler, task);
 		return 0;
 	}
 
@@ -1499,7 +1472,7 @@ vy_scheduler_complete_task(struct vy_scheduler *scheduler,
 	return 0;
 fail:
 	if (task->ops->abort)
-		task->ops->abort(scheduler, task, false);
+		task->ops->abort(scheduler, task);
 	diag_move(diag, &scheduler->diag);
 	return -1;
 }
-- 
2.11.0