Re: [squid-users] StoreID and concurrency?

On 6/6/2013 4:25 PM, csn233 wrote:
> On Wed, Jun 5, 2013 at 11:57 PM, Eliezer Croitoru <eliezer_at_ngtech.co.il> wrote:
>> StoreID is not related directly to cache_dir so it's not suppose to affect
>> dirty cache_dir.
>
> StoreID uses the output from the helper as the key to store the cached
> copy in cache_dir, does it not? So if the helper generates one key for
> the video and a *different* key for the same video next time (if I
> change the helper output), it will lead to inconsistency for that same
> video, will it not? Particularly relevant to YT which splits a video
> into parts (ranges), where each part gets its own key. So if I change
> the key halfway while the video is playing, things get confusing.
No it dosnt matter the only *thing* that will happen is that the two
videos will be served but not from cache.

>
> BTW, with reference to your example:
>
> #./new_helper.rb
> http://freefr.dl.sourceforge.net/project/vlc/2.0.5/win32/vlc-2.0.5-win32.exe
> OK store-id=http://dl.sourceforge.net.squid.internal/project/vlc/2.0.5/win32/vlc-2.0.5-win32.exe
>
> Maybe a different example would demonstrate the usefulness of StoreID
> a bit more. In your example above, the original URL is of a fixed
> format which be cached by default by Squid. StoreID would not provide
> any added value there. The URL-rewrite examples in StoreURL wiki would
> be better in the sense that they actually show a re-write of an
> un-cacheable URL into a cache-able one.
This is the best example to demonstrate how CDN urls are being and can
be used.
Right the next couple urls will result in the same storeID
http://freefr.dl.sourceforge.net/project/vlc/2.0.5/win32/vlc-2.0.5-win32.exe
http://freefr3.dl.sourceforge.net/project/vlc/2.0.5/win32/vlc-2.0.5-win32.exe
http://freefr2.dl.sourceforge.net/project/vlc/2.0.5/win32/vlc-2.0.5-win32.exe
http://freefr1.dl.sourceforge.net/project/vlc/2.0.5/win32/vlc-2.0.5-win32.exe
  OK
store-id=http://dl.sourceforge.net.squid.internal/project/vlc/2.0.5/win32/vlc-2.0.5-win32.exe
There is not such thing as un-cachable from the proxy point of view but
rather what the proxy prefers to not cache.
Youtube example is a really good and complex one.
it was explained long before I wrote my helper and code.
The reason you might not understand it is that you need to learn a bit
more to make sure you understand what StoreID and what StoreUrlRewrite does.
I am here for that..
>
>> if it works for you good for me and oyu.
>> why do you want to reduce browser cache??
>> it's not bad to have cache in the browser if you have enough ram.
>>
<SNIP>
>
> If you have a large browser cache, and you replay the video, you can't
> tell for sure if the video came from the browser cache, or Squid
> cache. Therefore one is liable to draw wrong conclusions as I did.
For what do you need that exactly?
if the browser prefers to not draw from cache in most cases the server
will cache it automatically.
youtube is cached but not by the browser but by the player unless you
play with html5 player.

Eliezer
Received on Thu Jun 06 2013 - 15:25:19 MDT