From: Karsten Blees <karsten.blees@gmail.com>
Date: Fri, 21 Mar 2014 18:40:19 GMT
Subject: Re: [PATCH] Enable index-pack threading in msysgit.
Message-ID: <532C8793.8050202@gmail.com>
In-Reply-To: <CACsJy8D01gxeSoxgD9QkLgS85B=Af8aXytuqn6CBkF+_7WjZtQ@mail.gmail.com>

Am 20.03.2014 02:25, schrieb Duy Nguyen:
> On Thu, Mar 20, 2014 at 4:35 AM, Stefan Zager <szager@chromium.org> wrote:
>> This adds a Windows implementation of pread.  Note that it is NOT
>> safe to intersperse calls to read() and pread() on a file
>> descriptor.  According to the ReadFile spec, using the 'overlapped'
>> argument should not affect the implicit position pointer of the
>> descriptor.  Experiments have shown that this is, in fact, a lie.
>>
>> To accomodate that fact, this change also incorporates:
>>
>> http://article.gmane.org/gmane.comp.version-control.git/196042
>>
>> ... which gives each index-pack thread its own file descriptor.
> 
> If the problem is mixing read() and pread() then perhaps it's enough to do
> 
> output_fd = dup(output_fd);
> 

Unfortunately not, dup() / DuplicateHandle() just opens another handle to the same file object (i.e. sharing the same file position).