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playlist: Optimize playlist_remove_all_tracks()

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This was insanely slow for large playlists. Implement it as a
constant-time operation to avoid the O(N!) blowup, and add a
new "clear" command to the control file to avoid flooding it
with individual delete commands.

Change-Id: Ied82d1cba015591edd583f2a2ff6772108f4e176
This commit is contained in:
Aidan MacDonald 2023-01-22 01:27:16 +00:00
parent 2c4546ba99
commit 25bd3bc971
2 changed files with 89 additions and 21 deletions
Download patch file Download diff file Expand all files Collapse all files

109
apps/playlist.c
View file

@ -123,7 +123,16 @@
/* default load buffer size (should be at least 1 KiB) */
#define PLAYLIST_LOAD_BUFLEN (32*1024)
#define PLAYLIST_CONTROL_FILE_VERSION 2
/*
* Minimum supported version and current version of the control file.
* Any versions outside of this range will be rejected by the loader.
*
* v1 was the initial version when dynamic playlists were first implemented.
* v2 was added shortly thereafter and has been used since 2003.
* v3 added the (C)lear command and is otherwise identical to v2.
*/
#define PLAYLIST_CONTROL_FILE_MIN_VERSION 2
#define PLAYLIST_CONTROL_FILE_VERSION 3
#define PLAYLIST_COMMAND_SIZE (MAX_PATH+12)
@ -432,6 +441,9 @@ static int flush_cached_control_unlocked(struct playlist_info* playlist)
case PLAYLIST_COMMAND_RESET:
result = fdprintf(playlist->control_fd, "%s\n", "R");
break;
case PLAYLIST_COMMAND_CLEAR:
result = fdprintf(playlist->control_fd, "%s\n", "C");
break;
default:
break;
}
@ -1343,6 +1355,53 @@ static int create_and_play_dir(int direction, bool play_last)
return index;
}
/*
* remove all tracks, leaving the current track queued
*/
static int remove_all_tracks_unlocked(struct playlist_info *playlist, bool write)
{
if (playlist->amount <= 0)
return 0;
/* Move current track down to position 0 */
playlist->indices[0] = playlist->indices[playlist->index];
#ifdef HAVE_DIRCACHE
if (playlist->dcfrefs_handle)
{
struct dircache_fileref *dcfrefs =
core_get_data(playlist->dcfrefs_handle);
dcfrefs[0] = dcfrefs[playlist->index];
}
#endif
/* Update playlist state as if by remove_track_unlocked() */
bool inserted = playlist->indices[0] & PLAYLIST_INSERT_TYPE_MASK;
playlist->index = 0;
playlist->amount = 1;
playlist->indices[0] |= PLAYLIST_QUEUED;
if (inserted)
playlist->num_inserted_tracks = 1;
else
playlist->deleted = true;
playlist->first_index = 0;
if (playlist->last_insert_pos == 0)
playlist->last_insert_pos = -1;
else
playlist->last_insert_pos = 0;
if (write && playlist->control_fd >= 0)
{
update_control(playlist, PLAYLIST_COMMAND_CLEAR, -1, -1, NULL, NULL, NULL);
sync_control(playlist, false);
}
return 0;
}
/*
* Add track to playlist at specified position. There are seven special
* positions that can be specified:
@ -1444,7 +1503,7 @@ static int add_track_to_playlist_unlocked(struct playlist_info* playlist,
break;
}
case PLAYLIST_REPLACE:
if (playlist_remove_all_tracks(playlist) < 0)
if (remove_all_tracks_unlocked(playlist, true) < 0)
return -1;
int newpos = playlist->index + 1;
playlist->last_insert_pos = position = insert_position = newpos;
@ -2635,7 +2694,7 @@ int playlist_insert_directory(struct playlist_info* playlist,
if (position == PLAYLIST_REPLACE)
{
if (playlist_remove_all_tracks(playlist) == 0)
if (remove_all_tracks_unlocked(playlist, true) == 0)
position = PLAYLIST_INSERT_LAST;
else
{
@ -2727,7 +2786,7 @@ int playlist_insert_playlist(struct playlist_info* playlist, const char *filenam
if (position == PLAYLIST_REPLACE)
{
if (playlist_remove_all_tracks(playlist) == 0)
if (remove_all_tracks_unlocked(playlist, true) == 0)
position = PLAYLIST_INSERT_LAST;
else
{
@ -3221,8 +3280,6 @@ int playlist_randomise(struct playlist_info* playlist, unsigned int seed,
/*
* Removes all tracks, from the playlist, leaving the presently playing
* track queued.
*
* TODO: This is insanely slow for huge playlists. Must fix.
*/
int playlist_remove_all_tracks(struct playlist_info *playlist)
{
@ -3234,23 +3291,11 @@ int playlist_remove_all_tracks(struct playlist_info *playlist)
dc_thread_stop(playlist);
playlist_mutex_lock(&playlist->mutex);
while (playlist->index > 0)
if ((result = remove_track_unlocked(playlist, 0, true)) < 0)
goto out;
result = remove_all_tracks_unlocked(playlist, true);
while (playlist->amount > 1)
if ((result = remove_track_unlocked(playlist, 1, true)) < 0)
goto out;
if (playlist->amount == 1) {
playlist->indices[0] |= PLAYLIST_QUEUED;
}
out:
playlist_mutex_unlock(&playlist->mutex);
dc_thread_start(playlist, false);
return 0;
return result;
}
/*
@ -3384,7 +3429,17 @@ int playlist_resume(void)
version = atoi(str1);
if (version != PLAYLIST_CONTROL_FILE_VERSION)
/*
* TODO: Playlist control file version upgrades
*
* If an older version control file is loaded then
* the header should be updated to the latest version
* in case any incompatible commands are written out.
* (It's not a big deal since the error message will
* be practically the same either way...)
*/
if (version < PLAYLIST_CONTROL_FILE_MIN_VERSION ||
version > PLAYLIST_CONTROL_FILE_VERSION)
{
result = -3;
goto out;
@ -3523,6 +3578,15 @@ int playlist_resume(void)
playlist->last_insert_pos = -1;
break;
}
case PLAYLIST_COMMAND_CLEAR:
{
if (remove_all_tracks_unlocked(playlist, false) < 0)
{
result = -16;
goto out;
}
break;
}
case PLAYLIST_COMMAND_COMMENT:
default:
break;
@ -3570,6 +3634,9 @@ int playlist_resume(void)
case 'R':
current_command = PLAYLIST_COMMAND_RESET;
break;
case 'C':
current_command = PLAYLIST_COMMAND_CLEAR;
break;
case '#':
current_command = PLAYLIST_COMMAND_COMMENT;
break;

1
apps/playlist.h
View file

@ -47,6 +47,7 @@ enum playlist_command {
PLAYLIST_COMMAND_SHUFFLE,
PLAYLIST_COMMAND_UNSHUFFLE,
PLAYLIST_COMMAND_RESET,
PLAYLIST_COMMAND_CLEAR,
PLAYLIST_COMMAND_COMMENT
};