Re:Re: Re: Squid storage method is redundancy?

Thanks, Adrian pal!

You have clarified all my doubts. :-)

Best regards,
George, Ma

----- Original Message -----
From: Adrian Chadd
To: maer727@sohu.com
Cc: squid-dev@squid-cache.org
Subject: Re: Re: Squid storage method is redundancy?
Sent: Tue Apr 09 13:27:08 CST 2002

>
> The storeclient doesn't get removed from the disk. Its never on the
> disk.
>
> Its just the "open file handle" used to track which client(s) are
> currently attachedto a storeentry, and where they're up to
> in reading/writing.
>
> When they've finished with the data, the client goes away, and so does
> the store client.
>
> The StoreEntry, which references a cache object, exists on the
> disk if its public and cacheable.
>
>
>
>
> adrian
>
> On Tue, Apr 09, 2002, maer727@sohu.com wrote:
> > Thanks, Adrian pal!
> >
> > In your reply, you mentioned the following:
> >
> > /////////////////////////////////////////////////////////////////////
> > When the server feeding data or the client reading data have finished,
> > the StoreEntry gets removed from the store client, and (eventually)
> > the store_client goes away.
> > /////////////////////////////////////////////////////////////////////
> >
> > When you are mentioning "gets removed" from storeclient, do you mean the StoreEntry
> > removed from disk? Or do you mean just removing the reference of the storeclient of
> > the StoreEntry? ( I think it is the latter. Am I correct?)
> >
> > When you are mentioning "store_client goes away", do you mean removing store_client
> > from disk? Or do you mean just removing the reference of the store_client to the StoreEntry
> > and keep the storeclient on disk? (I think it is the former. Am I correct?)
> >
> > Best regards,
> > George, Ma
> >
> > ----- Original Message -----
> > From: Adrian Chadd
> > To: maer727@sohu.com
> > Subject: Re: Squid storage method is redundancy?
> > Sent: Tue Apr 09 12:42:29 CST 2002
> >
> > > On Tue, Apr 09, 2002, maer727@sohu.com wrote:
> > > > Hi, pals.
> > > >
> > > > I am using Squid 2.4 STABLE.
> > > >
> > > > Squid use StoreEntry to store the metadata of a cached
> > > > object. Each StoreEntry has a list of storeclients. And
> > > > each of the storeclient has a reference to the object
> > > > on the disk/mem. So, each storeclient ( belongs to the
> > > > same StoreEntry ) has a reference to the same object on
> > > > disk/mem. Is that a redundancy?
> > >
> > > No. the store_client is for _open_ storeentry "entries".
> > > If the StoreEntry has been writeen or read completely,
> > > and its public, it won't have a store client.
> > >
> > > Imagine it like this.
> > >
> > > You have a big hash of StoreEntry's.
> > >
> > > Each StoreEntry is either private (the response isn't cacheable)
> > > or public (the response is cacheable). The public entries go into
> > > the hash, the private ones don't.
> > >
> > > When you create a StoreEntry you will have a store client to feed
> > > data into it (via storeAppend()).
> > >
> > > When you want an object, via storeLookup(), it looks at the hash,
> > > grabs the entry, knows that its public, attached a store client,
> > > and lets the client read (via storeClientCopy()).
> > >
> > > When the server feeding data or the client reading data have finished,
> > > the StoreEntry gets removed from the store client, and (eventually)
> > > the store_client goes away.
> > >
> > > Thats a simplistic view. Its not totally accurate (I haven't mentioned
> > > mem_obj's, which contain part or all of the object data) but it gives
> > > you an indication of what the bits do.
> > >
> > > > Why not just store the reference to the object in the
> > > > StoreEntry? (Now Squid just store metadata of object in
> > > > StoreEntry, like timestamp).
> > > >
> > > > Anyone has different opinions?
> > > >
> > > > Best regards,
> > > > George, Ma
> > > >
> >
Received on Tue Apr 09 2002 - 04:50:12 MDT