From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <08c6e0866ba400c187f71a5a754d767c@plan9.bell-labs.com> To: 9fans@cse.psu.edu Subject: Re: [9fans] QTCTL? Date: Thu, 1 Nov 2007 12:27:11 -0400 From: Sape Mullender In-Reply-To: <43644094f7203744e1cc2345ccebb26a@plan9.bell-labs.com> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Topicbox-Message-UUID: e3853a04-ead2-11e9-9d60-3106f5b1d025 I Type too fast =E2=80=94 got A and B mixed up. Below is the fix: > That breaks single-copy semantics: A client may have acted on data aft= er > it had been changed by somebody else. Say, A and B are sharing the fil= e. > B has a read-lease on the file, A obtains a write lease, modifies the f= ile > and sends a message to B to read what was changed. B reads the file (w= hich > is still in the cache and has not been updated). Meanwhile, just after= A > obtained the write lease, the server notifies B that the lease is expir= ing > early, but this message travels slowly and doesn't arrive until the who= le > exchange is over.