player: make all external file loading actions async

Still missing: not freezing when removing a track (i.e. closing demuxer)
with the sub-remove/audio-remove/rescan-external-files commands.

DOCS/man/input.rst

@@ -910,7 +910,8 @@ which will be fixed later. Using the ``async`` prefix makes them run the file
 saving code in a detached manner.
 
 Currently the following commands have different waiting characteristics with
-sync vs. async: sub-add, audio-add
+sync vs. async: sub-add, audio-add, sub-reload, audio-reload,
+rescan-external-files.
 
 Input Sections
 --------------

player/command.c

@@ -5520,7 +5520,7 @@ static void cmd_track_add(void *p)
             return;
         }
     }
-    int first = mp_add_external_file(mpctx, cmd->args[0].v.s, type, true);
+    int first = mp_add_external_file(mpctx, cmd->args[0].v.s, type);
     if (first < 0) {
         cmd->success = false;
         return;
@@ -5584,7 +5584,7 @@ static void cmd_track_reload(void *p)
     if (t && t->is_external && t->external_filename) {
         char *filename = talloc_strdup(NULL, t->external_filename);
         mp_remove_track(mpctx, t);
-        nt_num = mp_add_external_file(mpctx, filename, type, false);
+        nt_num = mp_add_external_file(mpctx, filename, type);
         talloc_free(filename);
     }
 
@@ -6044,7 +6044,9 @@ const struct mp_cmd_def mp_cmds[] = {
     { "sub-remove", cmd_track_remove, { OARG_INT(-1) },
         .priv = &(const int){STREAM_SUB}, },
     { "sub-reload", cmd_track_reload, { OARG_INT(-1) },
-        .priv = &(const int){STREAM_SUB}, },
+        .priv = &(const int){STREAM_SUB},
+        .spawn_thread = true,
+    },
 
     { "tv-last-channel", cmd_tv_last_channel, },
 
@@ -6175,12 +6177,16 @@ const struct mp_cmd_def mp_cmds[] = {
     { "audio-remove", cmd_track_remove, { OARG_INT(-1) },
         .priv = &(const int){STREAM_AUDIO}, },
     { "audio-reload", cmd_track_reload, { OARG_INT(-1) },
-        .priv = &(const int){STREAM_AUDIO}, },
+        .priv = &(const int){STREAM_AUDIO},
+        .spawn_thread = true,
+    },
 
     { "rescan-external-files", cmd_rescan_external_files, {
         OARG_CHOICE(1, ({"keep-selection", 0},
                         {"reselect", 1})),
-    }},
+        },
+        .spawn_thread = true,
+    },
 
     { "apply-profile", cmd_apply_profile, {ARG_STRING } },
 

player/core.h

@@ -296,6 +296,8 @@ typedef struct MPContext {
     struct track **tracks;
     int num_tracks;
 
+    int64_t death_hack; // don't fucking ask, just don't
+
     char *track_layout_hash;
 
     // Selected tracks. NULL if no track selected.
@@ -488,7 +490,7 @@ struct playlist_entry *mp_check_playlist_resume(struct MPContext *mpctx,
 void mp_abort_playback_async(struct MPContext *mpctx);
 void uninit_player(struct MPContext *mpctx, unsigned int mask);
 int mp_add_external_file(struct MPContext *mpctx, char *filename,
-                         enum stream_type filter, bool unlock);
+                         enum stream_type filter);
 #define FLAG_MARK_SELECTION 1
 void mp_switch_track(struct MPContext *mpctx, enum stream_type type,
                      struct track *track, int flags);

player/loadfile.c

@@ -26,6 +26,8 @@
 #include "config.h"
 #include "mpv_talloc.h"
 
+#include "misc/thread_pool.h"
+#include "misc/thread_tools.h"
 #include "osdep/io.h"
 #include "osdep/terminal.h"
 #include "osdep/threads.h"
@@ -578,8 +580,9 @@ bool mp_remove_track(struct MPContext *mpctx, struct track *track)
 
 // Add the given file as additional track. The filter argument controls how or
 // if tracks are auto-selected at any point.
+// To be run on a worker thread, locked (temporarily unlocks core).
 int mp_add_external_file(struct MPContext *mpctx, char *filename,
-                         enum stream_type filter, bool unlock)
+                         enum stream_type filter)
 {
     struct MPOpts *opts = mpctx->opts;
     if (!filename || mp_cancel_test(mpctx->playback_abort))
@@ -600,7 +603,6 @@ int mp_add_external_file(struct MPContext *mpctx, char *filename,
         break;
     }
 
-    if (unlock)
     mp_core_unlock(mpctx);
 
     struct demuxer *demuxer =
@@ -608,9 +610,17 @@ int mp_add_external_file(struct MPContext *mpctx, char *filename,
     if (demuxer)
         enable_demux_thread(mpctx, demuxer);
 
-    if (unlock)
     mp_core_lock(mpctx);
 
+    // The command could have overlapped with playback exiting. (We don't care
+    // if playback has started again meanwhile - weird, but not a problem.)
+    if (!mpctx->playing) {
+        mp_core_unlock(mpctx);
+        free_demuxer_and_stream(demuxer);
+        mp_core_lock(mpctx);
+        return -1;
+    }
+
     if (!demuxer)
         goto err_out;
 
@@ -627,10 +637,8 @@ int mp_add_external_file(struct MPContext *mpctx, char *filename,
     }
 
     if (!has_any) {
-        if (unlock)
         mp_core_unlock(mpctx);
         free_demuxer_and_stream(demuxer);
-        if (unlock)
         mp_core_lock(mpctx);
         char *tname = mp_tprintf(20, "%s ", stream_type_name(filter));
         if (filter == STREAM_TYPE_COUNT)
@@ -660,11 +668,18 @@ err_out:
     return -1;
 }
 
+// to be run on a worker thread, locked (temporarily unlocks core)
 static void open_external_files(struct MPContext *mpctx, char **files,
                                 enum stream_type filter)
 {
+    // Need a copy, because the option value could be mutated during iteration.
+    void *tmp = talloc_new(NULL);
+    files = mp_dup_str_array(tmp, files);
+
     for (int n = 0; files && files[n]; n++)
-        mp_add_external_file(mpctx, files[n], filter, false);
+        mp_add_external_file(mpctx, files[n], filter);
+
+    talloc_free(tmp);
 }
 
 void autoload_external_files(struct MPContext *mpctx)
@@ -703,7 +718,7 @@ void autoload_external_files(struct MPContext *mpctx)
             goto skip;
         if (list[i].type == STREAM_AUDIO && !sc[STREAM_VIDEO])
             goto skip;
-        int first = mp_add_external_file(mpctx, filename, list[i].type, false);
+        int first = mp_add_external_file(mpctx, filename, list[i].type);
         if (first < 0)
             goto skip;
 
@@ -771,20 +786,25 @@ static void process_hooks(struct MPContext *mpctx, char *name)
         mp_idle(mpctx);
 }
 
+// to be run on a worker thread, locked (temporarily unlocks core)
 static void load_chapters(struct MPContext *mpctx)
 {
     struct demuxer *src = mpctx->demuxer;
     bool free_src = false;
     char *chapter_file = mpctx->opts->chapter_file;
     if (chapter_file && chapter_file[0]) {
+        chapter_file = talloc_strdup(NULL, chapter_file);
+        mp_core_unlock(mpctx);
         struct demuxer *demux = demux_open_url(chapter_file, NULL,
                                         mpctx->playback_abort, mpctx->global);
+        mp_core_lock(mpctx);
         if (demux) {
             src = demux;
             free_src = true;
         }
         talloc_free(mpctx->chapters);
         mpctx->chapters = NULL;
+        talloc_free(chapter_file);
     }
     if (src && !mpctx->chapters) {
         talloc_free(mpctx->chapters);
@@ -795,8 +815,11 @@ static void load_chapters(struct MPContext *mpctx)
                 mpctx->chapters[n].pts -= src->start_time;
         }
     }
-    if (free_src)
+    if (free_src) {
+        mp_core_unlock(mpctx);
         free_demuxer_and_stream(src);
+        mp_core_lock(mpctx);
+    }
 }
 
 static void load_per_file_options(m_config_t *conf,
@@ -1143,6 +1166,44 @@ void update_lavfi_complex(struct MPContext *mpctx)
     }
 }
 
+
+// Worker thread for loading external files and such. This is needed to avoid
+// freezing the core when waiting for network while loading these.
+static void load_external_opts_thread(void *p)
+{
+    void **a = p;
+    struct MPContext *mpctx = a[0];
+    struct mp_waiter *waiter = a[1];
+
+    mp_core_lock(mpctx);
+
+    load_chapters(mpctx);
+    open_external_files(mpctx, mpctx->opts->audio_files, STREAM_AUDIO);
+    open_external_files(mpctx, mpctx->opts->sub_name, STREAM_SUB);
+    open_external_files(mpctx, mpctx->opts->external_files, STREAM_TYPE_COUNT);
+    autoload_external_files(mpctx);
+
+    mp_waiter_wakeup(waiter, 0);
+    mp_wakeup_core(mpctx);
+    mp_core_unlock(mpctx);
+}
+
+static void load_external_opts(struct MPContext *mpctx)
+{
+    struct mp_waiter wait = MP_WAITER_INITIALIZER;
+
+    void *a[] = {mpctx, &wait};
+    if (!mp_thread_pool_queue(mpctx->thread_pool, load_external_opts_thread, a)) {
+        mpctx->stop_play = PT_ERROR;
+        return;
+    }
+
+    while (!mp_waiter_poll(&wait))
+        mp_idle(mpctx);
+
+    mp_waiter_wait(&wait);
+}
+
 // Start playing the current playlist entry.
 // Handle initialization and deinitialization.
 static void play_current_file(struct MPContext *mpctx)
@@ -1264,13 +1325,11 @@ reopen_file:
         demux_set_ts_offset(mpctx->demuxer, -mpctx->demuxer->start_time);
     enable_demux_thread(mpctx, mpctx->demuxer);
 
-    load_chapters(mpctx);
     add_demuxer_tracks(mpctx, mpctx->demuxer);
 
-    open_external_files(mpctx, opts->audio_files, STREAM_AUDIO);
+    load_external_opts(mpctx);
-    open_external_files(mpctx, opts->sub_name, STREAM_SUB);
+    if (mpctx->stop_play)
-    open_external_files(mpctx, opts->external_files, STREAM_TYPE_COUNT);
+        goto terminate_playback;
-    autoload_external_files(mpctx);
 
     check_previous_track_selection(mpctx);
 
@@ -1465,6 +1524,8 @@ terminate_playback:
 
     if (mpctx->playing)
         playlist_entry_unref(mpctx->playing);
+    // Note: a lot of things assume that the core won't be unlocked between
+    // uninitializing various playback-only resources (such as tracks).
     mpctx->playing = NULL;
     talloc_free(mpctx->filename);
     mpctx->filename = NULL;