client API: fix potential sporadic freezes on termination

Although this was never observed to be happening, it seems definitely
possible: we first tell the main thread to exit, and then we ask the
main thread to do some work for us (with mp_dispatch_run()). Obviously
this is racy, and the main thread could exit without doing this, which
would block mp_dispatch_run() forever.

Fix this by changing the order of operation, so that it makes sense.

We could also just store the pthread_t of the main thread in some
variable, but the fact that pthread_create() might set the pthread_t
argument _after_ starting the thread makes this a bit messy (at least it
doesn't seem to be guaranteed on a superficial look at the manpage).

1 files changed, 4 insertions, 4 deletions

diff --git a/player/client.c b/player/client.c
index 1fe38881ad..edd929c203 100644
--- a/player/client.c
+++ b/player/client.c
@@ -452,16 +452,16 @@ static void mp_destroy_client(mpv_handle *ctx, bool terminate)
         mpctx->stop_play = PT_QUIT;
         mp_dispatch_unlock(mpctx->dispatch);
 
-        // Stop the core thread.
+        pthread_t playthread;
+        mp_dispatch_run(mpctx->dispatch, get_thread, &playthread);
+
+        // Ask the core thread to stop.
         pthread_mutex_lock(&clients->lock);
         clients->terminate_core_thread = true;
         pthread_mutex_unlock(&clients->lock);
         mp_wakeup_core(mpctx);
 
         // Blocking wait for all clients and core thread to terminate.
-        pthread_t playthread;
-        mp_dispatch_run(mpctx->dispatch, get_thread, &playthread);
-
         pthread_join(playthread, NULL);
 
         mp_destroy(mpctx);