Re: pgstat_reset_remove_files ignores its argument

in 9.3 and 9.4, pgstat_reset_remove_files uses the global variable
pgstat_stat_directory rather than the argument it is passed, "directory".
On crash recovery, this means the tmp directory gets cleared twice and the
permanent pg_stat doesn't get cleared at all.

It seems like the obvious one line change would fix it, but I haven't
tested it because I don't know how to cause a crash without pg_stat already
being empty.

pgstat_reset_remove_files(const char *directory)
{
DIR *dir;
struct dirent *entry;
char fname[MAXPGPATH];

dir = AllocateDir(pgstat_stat_directory);

Cheers,

Jeff

On Wed, Aug 14, 2013 at 12:13 AM, Jeff Janes <jeff(dot)janes(at)gmail(dot)com> wrote:
> in 9.3 and 9.4, pgstat_reset_remove_files uses the global variable
> pgstat_stat_directory rather than the argument it is passed, "directory".
> On crash recovery, this means the tmp directory gets cleared twice and the
> permanent pg_stat doesn't get cleared at all.
>
> It seems like the obvious one line change would fix it, but I haven't tested
> it because I don't know how to cause a crash without pg_stat already being
> empty.

I think there are three lines to change, as in the attached patch.

Am I wrong?

...Robert

On 16.8.2013 21:38, Robert Haas wrote:
> On Wed, Aug 14, 2013 at 12:13 AM, Jeff Janes <jeff(dot)janes(at)gmail(dot)com>
> wrote:
>> in 9.3 and 9.4, pgstat_reset_remove_files uses the global variable
>> pgstat_stat_directory rather than the argument it is passed,
>> "directory". On crash recovery, this means the tmp directory gets
>> cleared twice and the permanent pg_stat doesn't get cleared at
>> all.
>>
>> It seems like the obvious one line change would fix it, but I
>> haven't tested it because I don't know how to cause a crash without
>> pg_stat already being empty.
>
> I think there are three lines to change, as in the attached patch.
>
> Am I wrong?
>
> ...Robert

I think the patch is OK.

Tomas

On Fri, Aug 16, 2013 at 12:38 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> On Wed, Aug 14, 2013 at 12:13 AM, Jeff Janes <jeff(dot)janes(at)gmail(dot)com> wrote:
>> in 9.3 and 9.4, pgstat_reset_remove_files uses the global variable
>> pgstat_stat_directory rather than the argument it is passed, "directory".
>> On crash recovery, this means the tmp directory gets cleared twice and the
>> permanent pg_stat doesn't get cleared at all.
>>
>> It seems like the obvious one line change would fix it, but I haven't tested
>> it because I don't know how to cause a crash without pg_stat already being
>> empty.
>
> I think there are three lines to change, as in the attached patch.
>
> Am I wrong?

No, you are right, I too realized I missed a couple more spots. Your
patch looks just like the one I eventually arrived at, before I got
distracted thinking about how to implement the regex
/^(global|db_\d+)\.stat$/ in C and forgot to post a correction.

Is the regex code in src/backend/regex allowed to be used from "flat"
C code, or does it have to be in the context of a transaction, memory
context, etc.?

Cheers,

Jeff

Jeff Janes escribió:

> No, you are right, I too realized I missed a couple more spots. Your
> patch looks just like the one I eventually arrived at, before I got
> distracted thinking about how to implement the regex
> /^(global|db_\d+)\.stat$/ in C and forgot to post a correction.
>
> Is the regex code in src/backend/regex allowed to be used from "flat"
> C code, or does it have to be in the context of a transaction, memory
> context, etc.?

See 20130819180437(dot)GF9264(at)eldon(dot)alvh(dot)no-ip(dot)org .. the only thing missing
there is the $, AFAICT.

--
Álvaro Herrera http://www.2ndQuadrant.com/
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