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fix: Racing condition happens when editing playlist. Fixes azlux#279.
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@TerryGeng
TerryGeng committed May 24, 2021
1 parent 33a9e75 commit b65e7b2
Showing 1 changed file with 141 additions and 107 deletions.
248 changes: 141 additions & 107 deletions media/playlist.py
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Original file line number Diff line number Diff line change
Expand Up @@ -46,6 +46,7 @@ def __init__(self):
self.pending_items = []
self.log = logging.getLogger("bot")
self.validating_thread_lock = threading.Lock()
self.playlist_lock = threading.RLock()

def is_empty(self):
return True if len(self) == 0 else False
Expand All @@ -59,69 +60,82 @@ def from_list(self, _list, current_index):
return self

def append(self, item: CachedItemWrapper):
self.version += 1
super().append(item)
self.pending_items.append(item)
with self.playlist_lock:
self.version += 1
super().append(item)
self.pending_items.append(item)

self.async_validate()

return item

def insert(self, index, item):
self.version += 1
with self.playlist_lock:
self.version += 1
if index == -1:
index = self.current_index

if index == -1:
index = self.current_index
super().insert(index, item)

super().insert(index, item)
if index <= self.current_index:
self.current_index += 1

if index <= self.current_index:
self.current_index += 1
self.pending_items.append(item)

self.pending_items.append(item)
self.async_validate()

return item

def extend(self, items):
self.version += 1
super().extend(items)
self.pending_items.extend(items)
print("extend to-enter")
with self.playlist_lock:
print("extend enter")
self.version += 1
super().extend(items)
self.pending_items.extend(items)

print("extend leave")

self.async_validate()
return items

def next(self):
if len(self) == 0:
return False
with self.playlist_lock:
if len(self) == 0:
return False

if self.current_index < len(self) - 1:
self.current_index += 1
return self[self.current_index]
else:
return False
if self.current_index < len(self) - 1:
self.current_index += 1
return self[self.current_index]
else:
return False

def point_to(self, index):
if -1 <= index < len(self):
self.current_index = index
with self.playlist_lock:
if -1 <= index < len(self):
self.current_index = index

def find(self, id):
for index, wrapper in enumerate(self):
if wrapper.item.id == id:
return index
with self.playlist_lock:
for index, wrapper in enumerate(self):
if wrapper.item.id == id:
return index
return None

def __delitem__(self, key):
return self.remove(key)

def remove(self, index):
self.version += 1
if index > len(self) - 1:
return False
with self.playlist_lock:
self.version += 1
if index > len(self) - 1:
return False

removed = self[index]
super().__delitem__(index)
removed = self[index]
super().__delitem__(index)

if self.current_index > index:
self.current_index -= 1
if self.current_index > index:
self.current_index -= 1

# reference counter
counter = 0
Expand All @@ -146,47 +160,54 @@ def remove_by_id(self, id):
self.remove(index)

def current_item(self):
if len(self) == 0:
return False
with self.playlist_lock:
if len(self) == 0:
return False

return self[self.current_index]
return self[self.current_index]

def next_index(self):
if self.current_index < len(self) - 1:
return self.current_index + 1
else:
return False
with self.playlist_lock:
if self.current_index < len(self) - 1:
return self.current_index + 1

return False

def next_item(self):
if self.current_index < len(self) - 1:
return self[self.current_index + 1]
else:
return False
with self.playlist_lock:
if self.current_index < len(self) - 1:
return self[self.current_index + 1]

return False

def randomize(self):
# current_index will lose track after shuffling, thus we take current music out before shuffling
# current = self.current_item()
# del self[self.current_index]
with self.playlist_lock:
# current_index will lose track after shuffling, thus we take current music out before shuffling
# current = self.current_item()
# del self[self.current_index]

random.shuffle(self)
random.shuffle(self)

# self.insert(0, current)
self.current_index = -1
self.version += 1
# self.insert(0, current)
self.current_index = -1
self.version += 1

def clear(self):
self.version += 1
self.current_index = -1
with self.playlist_lock:
self.version += 1
self.current_index = -1
super().clear()

var.cache.free_all()
super().clear()

def save(self):
var.db.remove_section("playlist_item")
assert self.current_index is not None
var.db.set("playlist", "current_index", self.current_index)
with self.playlist_lock:
var.db.remove_section("playlist_item")
assert self.current_index is not None
var.db.set("playlist", "current_index", self.current_index)

for index, music in enumerate(self):
var.db.set("playlist_item", str(index), json.dumps({'id': music.id, 'user': music.user}))
for index, music in enumerate(self):
var.db.set("playlist_item", str(index), json.dumps({'id': music.id, 'user': music.user}))

def load(self):
current_index = var.db.getint("playlist", "current_index", fallback=-1)
Expand Down Expand Up @@ -243,8 +264,8 @@ def _check_valid(self):
self.log.debug("playlist: validating failed.")
if var.bot:
var.bot.send_channel_msg(e.msg)
var.cache.free_and_delete(item.id)
self.remove_by_id(item.id)
var.cache.free_and_delete(item.id)
continue

if item.version > ver:
Expand All @@ -261,35 +282,42 @@ def __init__(self):
self.current_index = -1

def current_item(self):
if self.current_index == -1:
self.current_index = 0
with self.playlist_lock:
if len(self) == 0:
self.current_index = -1
return False

if self.current_index == -1:
self.current_index = 0

return self[self.current_index]
return self[self.current_index]

def from_list(self, _list, current_index):
if len(_list) > 0:
if current_index > -1:
for i in range(current_index):
_list.pop(0)
return super().from_list(_list, 0)
return super().from_list(_list, -1)
return self
with self.playlist_lock:
if len(_list) > 0:
if current_index > -1:
for i in range(current_index):
_list.pop(0)
return super().from_list(_list, 0)
return super().from_list(_list, -1)
return self

def next(self):
if len(self) > 0:
self.version += 1
with self.playlist_lock:
if len(self) > 0:
self.version += 1

if self.current_index != -1:
super().__delitem__(self.current_index)
if len(self) == 0:
return False
else:
self.current_index = 0
if self.current_index != -1:
super().__delitem__(self.current_index)
if len(self) == 0:
return False
else:
self.current_index = 0

return self[0]
else:
self.current_index = -1
return False
return self[0]
else:
self.current_index = -1
return False

def next_index(self):
if len(self) > 1:
Expand All @@ -304,10 +332,11 @@ def next_item(self):
return False

def point_to(self, index):
self.version += 1
self.current_index = -1
for i in range(index):
super().__delitem__(0)
with self.playlist_lock:
self.version += 1
self.current_index = -1
for i in range(index):
super().__delitem__(0)


class RepeatPlaylist(BasePlaylist):
Expand All @@ -316,23 +345,27 @@ def __init__(self):
self.mode = "repeat"

def next(self):
if len(self) == 0:
return False
with self.playlist_lock:
if len(self) == 0:
return False

if self.current_index < len(self) - 1:
self.current_index += 1
return self[self.current_index]
else:
self.current_index = 0
return self[0]
if self.current_index < len(self) - 1:
self.current_index += 1
return self[self.current_index]
else:
self.current_index = 0
return self[0]

def next_index(self):
if self.current_index < len(self) - 1:
return self.current_index + 1
else:
return 0
with self.playlist_lock:
if self.current_index < len(self) - 1:
return self.current_index + 1
else:
return 0

def next_item(self):
if len(self) == 0:
return False
return self[self.next_index()]


Expand All @@ -347,17 +380,18 @@ def from_list(self, _list, current_index):
return super().from_list(_list, -1)

def next(self):
if len(self) == 0:
return False
with self.playlist_lock:
if len(self) == 0:
return False

if self.current_index < len(self) - 1:
self.current_index += 1
return self[self.current_index]
else:
self.version += 1
self.randomize()
self.current_index = 0
return self[0]
if self.current_index < len(self) - 1:
self.current_index += 1
return self[self.current_index]
else:
self.version += 1
self.randomize()
self.current_index = 0
return self[0]


class AutoPlaylist(OneshotPlaylist):
Expand Down

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