On Nov 1, 2007, at 9:26 AM, Sape Mullender wrote:
One could have only client-server-client calls like this:
Tcache asks whether the server is prepared to cache
Rcache makes lease available with parameters, Rerror says no.
Tlease says, ok start my lease now (almost immediately follows Rache)
Rlease lease expired or lease needs to be given back early
Tcache done with old lease (may immediately ask for a new lease)
etc.
So Tcache serves two purposes: it gives up an old lease if one existed
and immediately asks for a new one if one is needed.
This might give all the functionality we need without using callbacks.
(Of course, the client still needs a proc waiting for that Rlease
while
doing its reads and writes).
In the case of read cache (which is probably going to be used more
often than write-cache), the client needs to send two RPC every time
a writer modifies the cached file. What if Rlease doesn't necessary
break the lease, but have an option (negotiated in Tcache) to let the
client know that the file is changed without breaking the lease.
Thanks,
Lucho
