Re: [Fwd: Re: caching and XPCOM] (re-sent)

[Reshat Sabiq]

On Mon, 2005-05-30 at 23:30 -0500, Reshat Sabiq wrote:
> On Mon, 2005-05-30 at 16:14 -0500, Reshat Sabiq wrote:
> > On Mon, 2005-05-30 at 15:33 -0500, Reshat Sabiq wrote:
> > > email message attachment, "Forwarded message - Re: caching and XPCOM"
> > > On Mon, 2005-05-30 at 15:33 -0500, Reshat Sabiq wrote:
> > > > On Sun, 2005-05-22 at 21:11 +0200, Christian Biesinger wrote:
> > > > > mozilla-netlib would be a better place for this, fwiw
> > > > > 
> > > > > Reshat Sabiq wrote:
> > > > > > I played w/ it a little more, and found the following:
> > > > > > The Cache folder above indeed stores temporary files, however, 
> > > > > > there are
> > > > > > 2 unknowns for me at this time:
> > > > > > 1. How would i be able to identify which file an object is in, 
> > > > > > knowing
> > > > > > the object's URL, and possibly other characteristics (size, etc.)? 
> > > > > > There
> > > > > > appears to be something like md5sum involved, on the basis of 
> > > > > > several
> > > > > > object characteristics.
> > > > > 
> > > > > So, not all entities are stored as separate files. If they are small 
> > > > > enough, they are stored in the _CACHE_00x_ files. Only if they are 
> > > > > larger they are stored as a separate file.
> > > > > 
> > > > > Use nsICacheService 
> > > > > (http://lxr.mozilla.org/seamonkey/source/netwerk/cache/public/nsICacheService.idl)
> > > > >  
> > > > > and related interfaces.
> > > > > 
> > > > > 
> > > > I am able to get the instances of interfaces needed, but i'm getting 
> > > > NS_ERROR_CACHE_KEY_NOT_FOUND for every image URL i pass to:
> > > > result = cacheSession->OpenCacheEntry(url, nsICache::ACCESS_READ, 
> > > >   PR_TRUE,  getter_AddRefs(cacheEntry));
> > > > 
> > > > I have 2 question about this, and would appreciate any feedback:
> > > > 1. Why even when the image is in profile's cache as a separate file, i
> > > > still get this error? E.g., for char *url =
> > > > "http://us.news3.yimg.com/us.i2.yimg.com/p/rids/20050505/i/r1951409762.jpg?x=380&y=266&sig=Xj2W4LLjWxHTAWQ0QY9evA--";
> > > > which in my cache is stored as 3AAC0BF8d01. If the key is not URL, what
> > > > is it?
> > > > 2. This may be resolved by 1, by do i understand correctly that if item
> > > > is not in the Cache folder, then it will have an ICache in memory? The
> > > > small images are not in the hard-drive at all. I guess when i know the
> > > > key magic from question 1, i will be able to see if i get an ICache for
> > > > these as well.
> > > > 
> > > > Thanks.
> > > > 
> > I figured it out: i was using he wrong client ID. I didn't realize it
> > mattered.
> > Interesting, but for the image above, even though that key is also in
> > the cache it returns nothing unless the HTTP params are stripped to make
> > it:
> > http://us.news1.yimg.com/us.yimg.com/p/rids/20050505/i/r1951409762.jpg
> > 
> > So both of the questions above have been answered. But i now have
> > another one:
> > How could i save an image cache as a disk file?
> > 
> > Thanks.
> I think my question has been narrowed down to: how do i determine the
> data size of in-memory cache? That's what i'm figuring out right now,
> and it appears it should be in meta data...

Never mind. I think i've figured it all out so far, except a couple of
details that affect 5-10% of images. The extension i submitted is called
Image Assistant. Tested on Linux and submitted for it so far. Will do
Windows build later this week. This is 0.1.
Then will work on 0.2 in the next week or so.

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