touch-packages team mailing list archive

[Michi Henning <michi.henning@xxxxxxxxxxxxx>]

After discussing this with James, here are some thoughts.

Adding direct download of arbitrary remote images opens an attack/bug
vector. For example, a caller could ask for http://<whatever> and it
turns out that the remote server (maliciously or otherwise), is very
slow, or doesn't respond at all until the request times out. This means
that one application can disable access to remote images for other
applications because the thumbnailer allows only a limited number of
outstanding HTTP requests at a time. Or the server could potentially
return garbage images each and every time, each of which would result in
an entry in our failure cache. That can have negative performance impact
on other apps.

But, I don't think all is lost. The pragmatic answer to the problem
would be for the application to download the image (or audio file, or
whatever) and simply drop it into the file system somewhere. Then pass a
URL to that file to the thumbnailer, and it will do the rest
(extraction, scaling, rotating, caching, etc.)

This isn't quite as convenient as having the thumbnailer do all of the
work, but I think it might be workable?

I'm open to suggestions though. I agree that having this feature would
be really nice. But we'd have to sort out the potential denial-of-
service/reliability issues. If the actions of one application can
disable access to thumbnails for other applications (or significantly
reduce throughput), we have a problem.

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to thumbnailer in Ubuntu.
https://bugs.launchpad.net/bugs/1532732

Title:
  Caching for arbitrary images on the web/remote hosts

Status in thumbnailer package in Ubuntu:
  New

Bug description:
  I frequently hit the use case that I query some host (might be in my
  local network, might be on the internet) for a list of things. The
  result set comes with images so I present a scrollable list of all
  those things to the user.

  Problem now is that with the images being fetched, the list scrolling
  is somewhat stuttery and also presents empty images at first which
  then are only filled with content a bit later. Scrolling the list back
  up, same thing again happens as the in-QML caches we have are based on
  RAM and with that can't hold tons of images. They are discarded and
  scrolling the list back up causes them to be reloaded.

  
  It would be great if the Thumbnailer could take care of this and fetch and cache them for the developer.

  One point to think about would be timeouts. Some use cases will always
  present the same image again. For example in kodimote I fetch the
  music artwork given by kodi. The artwork won't ever change, so the
  cache can be persistent. At the same time, fetching things from an
  online server *might* change over time. Ideally this would be
  configurable so that the developer can specify some cache time out for
  entries.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/thumbnailer/+bug/1532732/+subscriptions