more sync resuming changes

The server now returns the next usn after every addFiles(), so an interrupted
upload doesn't cause the uploaded material to be sent back down.

anki/media.py

@@ -264,11 +264,12 @@ If the same name exists, compare checksums."""
         cnt = 0
         files = {}
         cur = self.db.execute(
-            "select fname from log where type = ? limit 300", MEDIA_ADD)
+            "select fname from log where type = ?", MEDIA_ADD)
         fnames = []
         while 1:
             fname = cur.fetchone()
             if not fname:
+                # add a flag so the server knows it can clean up
                 z.writestr("_finished", "")
                 break
             fname = fname[0]

anki/sync.py

@@ -570,15 +570,13 @@ class MediaSyncer(object):
         while 1:
             runHook("sync", "streamMedia")
             zip, fnames = self.files()
+            if not fnames:
+                # finished
+                break
             usn = self.server.addFiles(zip=zip)
             # after server has replied, safe to remove from log
             self.col.media.forgetAdded(fnames)
-            # when server has run out of files, it returns bumped usn
-            if usn is not False:
-                break
-        # update usn from addFiles() and cached mtime
-        self.col.media.setUsn(usn)
-        #self.col.media.syncMod()
+            self.col.media.setUsn(usn)
         return "success"
 
     def removed(self):