Re: Streaming Replication on win32

From: Magnus Hagander <magnus(at)hagander(dot)net>
To: Fujii Masao <masao(dot)fujii(at)gmail(dot)com>
Cc: Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Streaming Replication on win32
Date: 2010-01-18 09:40:11
Message-ID: 9837222c1001180140q6ca9d49eia1a80da0f2808f5e@mail.gmail.com
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On Mon, Jan 18, 2010 at 10:30, Fujii Masao <masao(dot)fujii(at)gmail(dot)com> wrote:
> On Mon, Jan 18, 2010 at 5:22 AM, Heikki Linnakangas
> <heikki(dot)linnakangas(at)enterprisedb(dot)com> wrote:
>>> This could be because the win32 socket emulation layer simply wasn't
>>> designed to deal with non-blocking sockets. Specifically, it actually
>>> *always* sets the socket to non-blocking mode, and then uses that to
>>> properly emulate how sockets work under unix.
>>
>> I presume the win32 emulation layer can be taught about non-blocking
>> sockets? Or maybe pq_getbyte_if_available() can be implemented using
>> some other simpler method on Windows.
>
> How about checking the socket by using select/poll before calling
> pq_getbyte_if_available()? This would prevent pgwin32_recv() from
> being blocked because a message is guaranteed to have already arrived.
> When the renegotiation happens, SSL_read (instead of pqwin32_recv())
> is called with non-blocking socket, so it's not blocked.

SSL_read calls into pqwin32_recv(), so you have the same problem. (see
my_sock_read() and my_sock_write() in be-secure.c)

--
Magnus Hagander
Me: http://www.hagander.net/
Work: http://www.redpill-linpro.com/

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