Merge pull request #280 from TerryGeng/racing

fix: Racing condition happens when editing playlist.

media/playlist.py

@@ -46,6 +46,7 @@ class BasePlaylist(list):
         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
@@ -59,16 +60,18 @@ class BasePlaylist(list):
         return self
 
     def append(self, item: CachedItemWrapper):
+        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):
+        with self.playlist_lock:
             self.version += 1
-
             if index == -1:
                 index = self.current_index
 
@@ -78,18 +81,26 @@ class BasePlaylist(list):
                 self.current_index += 1
 
             self.pending_items.append(item)
+
         self.async_validate()
 
         return item
 
     def extend(self, 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):
+        with self.playlist_lock:
             if len(self) == 0:
                 return False
 
@@ -100,10 +111,12 @@ class BasePlaylist(list):
                 return False
 
     def point_to(self, index):
+        with self.playlist_lock:
             if -1 <= index < len(self):
                 self.current_index = index
 
     def find(self, id):
+        with self.playlist_lock:
             for index, wrapper in enumerate(self):
                 if wrapper.item.id == id:
                     return index
@@ -113,6 +126,7 @@ class BasePlaylist(list):
         return self.remove(key)
 
     def remove(self, index):
+        with self.playlist_lock:
             self.version += 1
             if index > len(self) - 1:
                 return False
@@ -146,24 +160,28 @@ class BasePlaylist(list):
             self.remove(index)
 
     def current_item(self):
+        with self.playlist_lock:
             if len(self) == 0:
                 return False
 
             return self[self.current_index]
 
     def next_index(self):
+        with self.playlist_lock:
             if self.current_index < len(self) - 1:
                 return self.current_index + 1
-        else:
+
         return False
 
     def next_item(self):
+        with self.playlist_lock:
             if self.current_index < len(self) - 1:
                 return self[self.current_index + 1]
-        else:
+
         return False
 
     def randomize(self):
+        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]
@@ -175,12 +193,15 @@ class BasePlaylist(list):
             self.version += 1
 
     def clear(self):
+        with self.playlist_lock:
             self.version += 1
             self.current_index = -1
-        var.cache.free_all()
             super().clear()
 
+        var.cache.free_all()
+
     def save(self):
+        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)
@@ -243,8 +264,8 @@ class BasePlaylist(list):
                 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:
@@ -261,12 +282,18 @@ class OneshotPlaylist(BasePlaylist):
         self.current_index = -1
 
     def current_item(self):
+        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]
 
     def from_list(self, _list, current_index):
+        with self.playlist_lock:
             if len(_list) > 0:
                 if current_index > -1:
                     for i in range(current_index):
@@ -276,6 +303,7 @@ class OneshotPlaylist(BasePlaylist):
             return self
 
     def next(self):
+        with self.playlist_lock:
             if len(self) > 0:
                 self.version += 1
 
@@ -304,6 +332,7 @@ class OneshotPlaylist(BasePlaylist):
             return False
 
     def point_to(self, index):
+        with self.playlist_lock:
             self.version += 1
             self.current_index = -1
             for i in range(index):
@@ -316,6 +345,7 @@ class RepeatPlaylist(BasePlaylist):
         self.mode = "repeat"
 
     def next(self):
+        with self.playlist_lock:
             if len(self) == 0:
                 return False
 
@@ -327,12 +357,15 @@ class RepeatPlaylist(BasePlaylist):
                 return self[0]
 
     def next_index(self):
+        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()]
 
 
@@ -347,6 +380,7 @@ class RandomPlaylist(BasePlaylist):
         return super().from_list(_list, -1)
 
     def next(self):
+        with self.playlist_lock:
             if len(self) == 0:
                 return False