From c17843a200ffd70903d3f7170883d671bafc80af Mon Sep 17 00:00:00 2001
From: Jan Vcelak <jan.vcelak@nic.cz>
Date: Fri, 12 Sep 2014 13:33:15 +0200
Subject: [PATCH] suspend background workers during reload
refs #296
---
src/knot/server/server.c | 8 +++++---
src/knot/worker/pool.c | 30 +++++++++++++++++++++++++++++-
src/knot/worker/pool.h | 10 ++++++++++
src/knot/zone/events.c | 2 +-
4 files changed, 45 insertions(+), 5 deletions(-)
diff --git a/src/knot/server/server.c b/src/knot/server/server.c
index d36ddd57a..a165b5a77 100644
--- a/src/knot/server/server.c
+++ b/src/knot/server/server.c
@@ -588,12 +588,13 @@ int server_update_zones(const struct conf_t *conf, void *data)
{
server_t *server = (server_t *)data;
- /* Prevent new events on zones waiting to be replaced. */
+ /* Prevent emitting of new zone events. */
if (server->zone_db) {
knot_zonedb_foreach(server->zone_db, zone_events_freeze);
}
- /* Finish operations already in the queue. */
+ /* Suspend workers, clear wating events, finish running events. */
+ worker_pool_suspend(server->workers);
worker_pool_clear(server->workers);
worker_pool_wait(server->workers);
@@ -603,7 +604,8 @@ int server_update_zones(const struct conf_t *conf, void *data)
/* Trim extra heap. */
mem_trim();
- /* Plan events on new zones. */
+ /* Resume workers and allow events on new zones. */
+ worker_pool_resume(server->workers);
if (server->zone_db) {
knot_zonedb_foreach(server->zone_db, zone_events_start);
}
diff --git a/src/knot/worker/pool.c b/src/knot/worker/pool.c
index aede4e9aa..ac71deadf 100644
--- a/src/knot/worker/pool.c
+++ b/src/knot/worker/pool.c
@@ -35,6 +35,7 @@ struct worker_pool {
pthread_cond_t wake;
bool terminating; /*!< Is the pool terminating? .*/
+ bool suspended; /*!< Is execution temporarily suspended? .*/
int running; /*!< Number of running threads. */
worker_queue_t tasks;
};
@@ -61,7 +62,11 @@ static int worker_main(dthread_t *thread)
break;
}
- task_t *task = worker_queue_dequeue(&pool->tasks);
+ task_t *task = NULL;
+ if (!pool->suspended) {
+ task = worker_queue_dequeue(&pool->tasks);
+ }
+
if (task == NULL) {
pthread_cond_wait(&pool->wake, &pool->lock);
continue;
@@ -162,6 +167,29 @@ void worker_pool_stop(worker_pool_t *pool)
dt_stop(pool->threads);
}
+void worker_pool_suspend(worker_pool_t *pool)
+{
+ if (!pool) {
+ return;
+ }
+
+ pthread_mutex_lock(&pool->lock);
+ pool->suspended = true;
+ pthread_mutex_unlock(&pool->lock);
+}
+
+void worker_pool_resume(worker_pool_t *pool)
+{
+ if (!pool) {
+ return;
+ }
+
+ pthread_mutex_lock(&pool->lock);
+ pool->suspended = false;
+ pthread_cond_broadcast(&pool->wake);
+ pthread_mutex_unlock(&pool->lock);
+}
+
void worker_pool_join(worker_pool_t *pool)
{
if (!pool) {
diff --git a/src/knot/worker/pool.h b/src/knot/worker/pool.h
index fcaae2880..424b5b11c 100644
--- a/src/knot/worker/pool.h
+++ b/src/knot/worker/pool.h
@@ -45,6 +45,16 @@ void worker_pool_start(worker_pool_t *pool);
*/
void worker_pool_stop(worker_pool_t *pool);
+/*!
+ * \brief Temporarily suspend the execution of worker pool.
+ */
+void worker_pool_suspend(worker_pool_t *pool);
+
+/*!
+ * \brief Resume the execution of worker pool.
+ */
+void worker_pool_resume(worker_pool_t *pool);
+
/*!
* \brief Wait for all threads to terminate.
*/
diff --git a/src/knot/zone/events.c b/src/knot/zone/events.c
index 1235dad54..0252eeb77 100644
--- a/src/knot/zone/events.c
+++ b/src/knot/zone/events.c
@@ -921,7 +921,7 @@ void zone_events_enqueue(zone_t *zone, zone_event_type_t type)
pthread_mutex_lock(&events->mx);
- /* Possible only if no event is running at the moment. */
+ /* Bypass scheduler if no event is running. */
if (!events->running && !events->frozen) {
events->running = true;
event_set_time(events, type, ZONE_EVENT_IMMEDIATE);
--
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