Re: Proposal for Allow postgresql.conf values to be changed via SQL [review]

On Monday, January 14, 2013 6:48 PM Boszormenyi Zoltan wrote:
2013-01-14 07:47 keltezéssel, Amit kapila írta:
> On Sunday, January 13, 2013 2:45 PM Boszormenyi Zoltan wrote:
> 2013-01-13 05:49 keltezéssel, Amit kapila írta:
>> On Sunday, January 13, 2013 12:41 AM Tom Lane wrote:
>> Boszormenyi Zoltan <zb(at)cybertec(dot)at> writes:

>>>> I can think of below ways to generate tmp file
>>>> 1. Generate session specific tmp file name during operation. This will
be similar to what is
>>>> currently being done in OpenTemporaryFileinTablespace() to
generate a tempfilename.
>>>> 2. Generate global tmp file name. For this we need to maintain global
counter.
>>>> 3. Always generate temp file with same name "postgresql.auto.conf.tmp",
as at a time only one
>>>> session is allowed to operate.
>>> What's wrong with mkstemp("config_dir/postgresql.auto.conf.XXXXXX")
>>> that returns a file descriptor for an already created file with a
unique name?
>> I think for Windows exactly same behavior API might not exist, we might
need to use GetTempFileName.
>> It will generate some different kind of name, which means cleanup also
need to take care of different kind of names.
>> So if this is right, I think it might not be very appropriate to use it.

> In that case (and also because the LWLock still serialize the whole
procedure)
> you can use GetTempFileName() on Windows and tempnam(3) for non-Windows.
> GetTempFileName() and tempnam() return the constructed temporary file name
> out of the directory and the filename prefix components.

On using mktemp, linux compilation gives below warning
warning: the use of `mktemp' is dangerous, better use `mkstemp'

So I planned to use mkstemp.

In Windows, there is an api _mktemp_s, followed by open call, behaves in a similar way as mkstemp available in linux.
The code is changed to use of mkstemp functionality to generate a unique temporary file name instead of .lock file.
Please check this part of code, I am not very comfortable with using this API.

Removed the code which is used for deleting the .lock file in case of backend crash or during server startup.

Added a new function RemoveAutoConfTmpFiles used for deleting the temp files left out any during previous
postmaster session in the server startup.

In SendDir(), used sizeof() -1

With Regards,
Amit Kapila.