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Fixing request_app_link reference counting for delayed requests.

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Router built with debug may stop with assertion during stalled requests
re-schedule.  This was caused by missing reference counting increment
before nxt_router_port_select() call.
This commit is contained in:
Max Romanov
2020-03-03 18:28:26 +03:00
parent c74f3a6c56
commit 9e295fa314
1 changed files with 36 additions and 9 deletions
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45
src/nxt_router.c
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@@ -4152,6 +4152,13 @@ nxt_router_app_port_release(nxt_task_t *task, nxt_port_t *port,
state.req_app_link = re_ra; state.req_app_link = re_ra;
state.app = app; state.app = app;
/*
* Need to increment use count "in advance" because
* nxt_router_port_select() will remove re_ra from lists
* and decrement use count.
*/
nxt_request_app_link_inc_use(re_ra);
nxt_router_port_select(task, &state); nxt_router_port_select(task, &state);
goto re_ra_cancelled; goto re_ra_cancelled;
@@ -4217,16 +4224,18 @@ re_ra_cancelled:
if (re_ra != NULL) { if (re_ra != NULL) {
if (nxt_router_port_post_select(task, &state) == NXT_OK) { if (nxt_router_port_post_select(task, &state) == NXT_OK) {
/* /*
* There should be call nxt_request_app_link_inc_use(re_ra), * Reference counter already incremented above, this will
* because of one more link in the queue. * keep re_ra while nxt_router_app_process_request()
* Corresponding decrement is in nxt_router_app_process_request(). * task is in queue. Reference counter decreased in
* nxt_router_app_process_request() after processing.
*/ */
nxt_request_app_link_inc_use(re_ra);
nxt_work_queue_add(&task->thread->engine->fast_work_queue, nxt_work_queue_add(&task->thread->engine->fast_work_queue,
nxt_router_app_process_request, nxt_router_app_process_request,
&task->thread->engine->task, app, re_ra); &task->thread->engine->task, app, re_ra);
} else {
nxt_request_app_link_use(task, re_ra, -1);
} }
} }
@@ -4234,15 +4243,14 @@ re_ra_cancelled:
/* /*
* There should be call nxt_request_app_link_inc_use(req_app_link), * There should be call nxt_request_app_link_inc_use(req_app_link),
* because of one more link in the queue. But one link was * because of one more link in the queue. But one link was
* recently removed from app->requests link. * recently removed from app->requests linked list.
* Corresponding decrement is in nxt_router_app_process_request().
*/ */
nxt_work_queue_add(&task->thread->engine->fast_work_queue, nxt_work_queue_add(&task->thread->engine->fast_work_queue,
nxt_router_app_process_request, nxt_router_app_process_request,
&task->thread->engine->task, app, req_app_link); &task->thread->engine->task, app, req_app_link);
/* ... skip nxt_request_app_link_use(task, req_app_link, -1) too. */
goto adjust_use; goto adjust_use;
} }
@@ -5185,6 +5193,13 @@ nxt_router_app_timeout(nxt_task_t *task, void *obj, void *data)
state.req_app_link = pending_ra; state.req_app_link = pending_ra;
state.app = app; state.app = app;
/*
* Need to increment use count "in advance" because
* nxt_router_port_select() will remove pending_ra from lists
* and decrement use count.
*/
nxt_request_app_link_inc_use(pending_ra);
nxt_router_port_select(task, &state); nxt_router_port_select(task, &state);
} else { } else {
@@ -5196,7 +5211,19 @@ nxt_router_app_timeout(nxt_task_t *task, void *obj, void *data)
if (pending_ra != NULL) { if (pending_ra != NULL) {
if (nxt_router_port_post_select(task, &state) == NXT_OK) { if (nxt_router_port_post_select(task, &state) == NXT_OK) {
nxt_router_app_prepare_request(task, pending_ra); /*
* Reference counter already incremented above, this will
* keep pending_ra while nxt_router_app_process_request()
* task is in queue. Reference counter decreased in
* nxt_router_app_process_request() after processing.
*/
nxt_work_queue_add(&task->thread->engine->fast_work_queue,
nxt_router_app_process_request,
&task->thread->engine->task, app, pending_ra);
} else {
nxt_request_app_link_use(task, pending_ra, -1);
} }
} }