markov: Move prune behavior to Bot, from Chain

Markov chains used to prune the chains themselves from memory, but now
that behavior is specifically delegated up the chain to the Bot
structure instead.

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

plugins/markov.py

@@ -106,7 +106,7 @@ class Chain:
         )
         self.__dirty = False
 
-    def save(self, retain: bool = True):
+    def save(self):
         if not self.__cache:
             return
         if self.__dirty:
@@ -127,10 +127,6 @@ class Chain:
                 json.dump(obj, fp)
             self.__dirty = False
 
-        if not retain:
-            log.debug("Pruning markov chain %s from memory", self.path)
-            self.clear_cache()
-
     def clear_cache(self):
         self.__cache.clear()
         self.__dirty = False
@@ -266,11 +262,14 @@ class Markov(Plugin):
             log.info("Saving markov chains")
             for chains in self.__chains.values():
                 for chain in chains.values():
+                    chain.save()
+                    # Prune
+                    retain = True
                     if retain_after is not None:
                         retain = chain.last_access > retain_after
-                    else:
-                        retain = True
-                    chain.save(retain=retain)
+                    if not retain:
+                        log.debug("Pruning markov chain %s from memory", chain.path)
+                        chain.clear_cache()
             log.info("Done")
 
     async def on_unload(self, conn: IrcProtocol):