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Date: Thu, 25 Jul 2013 21:20:43 +0800
From: Liu Yuan <namei.unix@gmail.com>
Message-ID: <20130725132043.GA9877@ubuntu-precise>
References: <1374741125-31859-1-git-send-email-morita.kazutaka@lab.ntt.co.jp>
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	<m2mwparebp.wl%morita.kazutaka@gmail.com>
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In-Reply-To: <m2mwparebp.wl%morita.kazutaka@gmail.com>
Subject: Re: [Qemu-devel] [sheepdog] [PATCH v3 07/10] sheepdog: try to
 reconnect to sheepdog after network error
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To: MORITA Kazutaka <morita.kazutaka@gmail.com>
Cc: Kevin Wolf <kwolf@redhat.com>, sheepdog@lists.wpkg.org, qemu-devel@nongnu.org, Stefan Hajnoczi <stefanha@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>, MORITA Kazutaka <morita.kazutaka@lab.ntt.co.jp>

On Thu, Jul 25, 2013 at 09:53:14PM +0900, MORITA Kazutaka wrote:
> At Thu, 25 Jul 2013 17:13:46 +0800,
> Liu Yuan wrote:
> > 
> > > +
> > > +    /* Try to reconnect the sheepdog server every one second. */
> > > +    while (s->fd < 0) {
> > > +        s->fd = get_sheep_fd(s);
> > > +        if (s->fd < 0) {
> > > +            dprintf("Wait for connection to be established\n");
> > > +            co_aio_sleep_ns(1000000000ULL);
> > > +        }
> > > +    };
> > > +
> > > +    /* Move all the inflight requests to the failed queue. */
> > > +    QLIST_FOREACH_SAFE(aio_req, &s->inflight_aio_head, aio_siblings, next) {
> > > +        QLIST_REMOVE(aio_req, aio_siblings);
> > > +        QLIST_INSERT_HEAD(&s->failed_aio_head, aio_req, aio_siblings);
> > > +    }
> > > +
> > > +    /* Resend all the failed aio requests. */
> > > +    while (!QLIST_EMPTY(&s->failed_aio_head)) {
> > > +        aio_req = QLIST_FIRST(&s->failed_aio_head);
> > > +        QLIST_REMOVE(aio_req, aio_siblings);
> > > +        QLIST_INSERT_HEAD(&s->inflight_aio_head, aio_req, aio_siblings);
> > > +        resend_aioreq(s, aio_req);
> > > +    }
> > > +}
> > > +
> > 
> > Is failed queue necessary? Here you just move requests from inflight queue to
> > failed queue, then interate the failed queue to send them all.
> > 
> > Isn't it simpler we just resend the requests in the inflight queue like
> > 
> > > +    QLIST_FOREACH(aio_req, &s->inflight_aio_head, aio_siblings, next) {
> > > +        resend_aioreq(s, aio_req);
> > > +    }
> 
> resend_aioreq() can yield and a new aio request can be added to the
> inflight queue during this loop.  To avoid mixing new requests and
> failed ones, I think the failed queue is necessary.
> 

Okay, make sense. This should be included in the source file. You can add my

Tested-and-reviewed-by: Liu Yuan <namei.unix@gmail.com>

to sheepdog patches

Thanks,
Yuan