From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 19 Dec 2008 12:10:10 -0800 From: Roman Shaposhnik In-reply-to: To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net> Message-id: <998EB623-CFD3-4E15-BD85-D2111D8A896B@sun.com> MIME-version: 1.0 Content-type: text/plain; delsp=yes; format=flowed; charset=US-ASCII Content-transfer-encoding: 7BIT References: Subject: Re: [9fans] 9pfuse and O_APPEND Topicbox-Message-UUID: 6a96b9e0-ead4-11e9-9d60-3106f5b1d025 On Dec 19, 2008, at 11:56 AM, erik quanstrom wrote: >> Two questions: >> 1. But before I ask this one: I don't deny that per-file append- >> only >> is *extremely* useful. My question is a different one: what is >> the danger of N clients accesing the file X in append-only mode >> and M clients accesing it in random access mode? Could you, >> please, give a concrete scenario? > > credit geoff for bringing this up: upas mailboxes. > suppose you have upas/deliver trying to deliver a message and at > the same time you have upas/fs trying to rewrite the mailbox. > (play along for a bit. ignore L.mbox and the temporary mbox > tricks.) It is difficult to answer your question without knowing what rewrite actually does and how mailboxes are structured. But in an imaginary world where a mailbox is a list of constant sized blocks (size