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Re: pipe chunking vs Windows

From: Andrew Dunstan <andrew(at)dunslane(dot)net>
To: Magnus Hagander <magnus(at)hagander(dot)net>
Cc: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: pipe chunking vs Windows
Date: 2007-07-29 15:36:58
Message-ID: 46ACB41A.1030300@dunslane.net (view raw or flat)
Thread:
Lists: pgsql-hackers

Magnus Hagander wrote:
> Andrew Dunstan wrote:
>   
>> I have just discovered that the recently implemented pipe chunking
>> protocol is broken on Windows. This is because the pipes are operating
>> in text mode and doing LF->CR-LF translation, so the number of bytes
>> received is not the number transmitted and set in the protocol header.
>>
>> I have not yet succeeded in turning this behaviour off (_setmode()
>> didn't seem to affect it). If we can't find a way to turn it off, the
>> only solution short of abandoning its use on Windows that I can think of
>> is to translate LF on input to something unlikely like 0x1C and then
>> translate it back when we read it from the pipe.
>>     
>
> At what point does it actually do the translation? Meaning what
> system/library call has it?
>
> Are we using the pipes from src/port/pipe.c? It does sound a bit weird
> that they'd do that, since it's basically just emulating stuff over
> standard tcp sockets, but perhaps something is broken in that code?
>
> Sorry, haven't really checked up on the chunk code yet, so I don't know
> offhand where to look.
>
>
>   

It looks like we aren't. In fact. it looks like the only call to 
pgpipe() in the whole source tree is in the syslogger and it's in 
specifically non-Windows code, meaning that that whole file is currently 
useless.

Maybe you should have a good look at src/backend/postmaster/syslogger.c. 
If we could get rid of the pipe-read threads and all the special Windows 
cruft there that would certainly be an advance.

cheers

andrew



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