dthreads: add support for thread destructor

Called when before the thread is definitelly destroyed.

src/knot/server/dthreads.c

@@ -209,6 +209,13 @@ static void *thread_ep(void *data)
 		}
 	}
 
+	// Thread destructor
+	if (thread->destruct) {
+		dbg_dt("dthreads: [%p] entering destructor\n", thread);
+		thread->destruct(thread);
+		dbg_dt("dthreads: [%p] exited destructor\n", result);
+	}
+
 	// Report thread state change
 	dbg_dt("dthreads: [%p] thread finished\n", thread);
 	unit_signalize_change(unit);
@@ -372,7 +379,8 @@ dt_unit_t *dt_create(int count)
 	return unit;
 }
 
-dt_unit_t *dt_create_coherent(int count, runnable_t runnable, void *data)
+dt_unit_t *dt_create_coherent(int count, runnable_t runnable,
+                              runnable_t destructor, void *data)
 {
 	// Check count
 	if (count <= 0) {
@@ -393,6 +401,7 @@ dt_unit_t *dt_create_coherent(int count, runnable_t runnable, void *data)
 		dthread_t *thread = unit->threads[i];
 		lock_thread_rw(thread);
 		thread->run = runnable;
+		thread->destruct = destructor;
 		thread->_adata = data;
 		unlock_thread_rw(thread);
 	}

src/knot/server/dthreads.h

@@ -78,6 +78,7 @@ typedef int (*runnable_t)(struct dthread_t *);
 typedef struct dthread_t {
 	volatile unsigned  state; /*!< Bitfield of dt_flag flags. */
 	runnable_t           run; /*!< Runnable function or 0. */
+	runnable_t      destruct; /*!< Destructor function or 0. */
 	void               *data; /*!< Currently active data */
 	struct dt_unit_t   *unit; /*!< Reference to assigned unit. */
 	void             *_adata; /* Thread-specific data. */
@@ -123,12 +124,14 @@ dt_unit_t *dt_create(int count);
  *
  * \param count Requested thread count.
  * \param runnable Runnable function for all threads.
+ * \param destructor Destructor for all threads.
  * \param data Any data passed onto threads.
  *
  * \retval New instance if successful
  * \retval NULL on error
  */
-dt_unit_t *dt_create_coherent(int count, runnable_t runnable, void *data);
+dt_unit_t *dt_create_coherent(int count, runnable_t runnable,
+                              runnable_t destructor, void *data);
 
 /*!
  * \brief Free unit.

src/knot/server/server.c

@@ -334,7 +334,7 @@ server_t *server_create()
 	// Create event scheduler
 	dbg_server("server: creating event scheduler\n");
 	server->sched = evsched_new();
-	server->iosched = dt_create_coherent(1, evsched_run, server->sched);
+	server->iosched = dt_create_coherent(1, evsched_run, NULL, server->sched);
 
 	// Create name server
 	dbg_server("server: creating Name Server structure\n");
@@ -593,7 +593,8 @@ int server_conf_hook(const struct conf_t *conf, void *data)
 		/* Initialize I/O handlers. */
 		size_t udp_size = tu_size;
 		if (udp_size < 2) udp_size = 2;
-		dt_unit_t *tu = dt_create_coherent(udp_size, &udp_master, NULL);
+		dt_unit_t *tu = dt_create_coherent(udp_size, &udp_master, NULL,
+		                                   NULL);
 		server_init_handler(server->h + IO_UDP, server, tu, NULL);
 
 		/* Create at least CONFIG_XFERS threads for TCP for faster

src/knot/server/zones.c

@@ -1676,7 +1676,7 @@ static int zones_insert_zones(knot_nameserver_t *ns,
 	/* Initialize threads. */
 	size_t thrs = dt_optimal_size();
 	if (thrs > zcount) thrs = zcount;
-	dt_unit_t *unit =  dt_create_coherent(thrs, &zonewalker, zw);
+	dt_unit_t *unit =  dt_create_coherent(thrs, &zonewalker, NULL, zw);
 	if (unit != NULL) {
 		/* Start loading. */
 		dt_start(unit);

src/tests/knot/dthreads_tests.c

@@ -255,7 +255,7 @@ static int dt_tests_run(int argc, char *argv[])
 	/* Test 15: Wrong values. */
 	unit = dt_create(-1);
 	ok(unit == 0, "dthreads: create with negative count");
-	unit = dt_create_coherent(dt_optimal_size(), 0, 0);
+	unit = dt_create_coherent(dt_optimal_size(), 0, 0, 0);
 
 	/* Test 16: NULL runnable. */
 	cmp_ok(dt_start(unit), "==", 0, "dthreads: start with NULL runnable");