Re: pg_hba_lookup function to get all matching pg_hba.conf entries

On Thu, Dec 10, 2015 at 2:29 PM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> On Thu, Dec 10, 2015 at 6:46 AM, Haribabu Kommi <kommi(dot)haribabu(at)gmail(dot)com>
> wrote:
>>
>> On Thu, Dec 10, 2015 at 4:22 AM, Alvaro Herrera
>> <alvherre(at)2ndquadrant(dot)com> wrote:
>> > Haribabu Kommi wrote:
>> >
>> >> Reverting the context release patch is already provided in the first
>> >> mail of this
>> >> thread [1]. Forgot to mention about the same in further mails.
>> >>
>> >> Here I attached the same patch. This patch needs to be applied first
>> >> before
>> >> pg_hba_lookup patch. I tested it in windows version also.
>> >
>> > So if you change the file and reload repeatedly, we leak all the memory
>> > allocated for HBA lines in TopMemoryContext? This doesn't sound great.
>> > Perhaps we need a dedicated context which can be reset at will so that
>> > it can be refilled with the right info when we reload the file.
>>
>> No. There is no leaks associated with pg_hba.conf parsing. we already have
>> a memory context called "hba parser context" allocated from Postmaster
>> context. The "revert_hba_context_release_in_backend" patch changes it to
>> TopMemoryContext. The memory required for parsing and storing parsed
>> hba lines is obtained from this context.
>>
>
> tokenize_file() is called before creation of hba parser context, so below
> change would be problem.
>
> *** 386,392 **** tokenize_file(const char *filename, FILE *file,
>
> MemoryContext linecxt;
>
> MemoryContext oldcxt;
>
>
>
> ! linecxt = AllocSetContextCreate(CurrentMemoryContext,
>
> "tokenize file cxt",
>
> ALLOCSET_DEFAULT_MINSIZE,
>
> ALLOCSET_DEFAULT_INITSIZE,
>
> --- 386,392 ----
>
> MemoryContext linecxt;
>
> MemoryContext oldcxt;
>
>
>
> ! linecxt = AllocSetContextCreate(TopMemoryContext,
>
> "tokenize file cxt",
>
> ALLOCSET_DEFAULT_MINSIZE,
>
> ALLOCSET_DEFAULT_INITSIZE,
>
>
> How about creating "hba parser context" and "ident parser context"
> at the beginning of their respective functions and don't change
> anything in tokenize_file()?

The tokenize file cxt is deleted after a successful load of pg_hba.conf or
pg_ident.conf files. we don't need this memory once the pg_hba.conf
or pg_ident file is loaded, because of this reason, it is created as a
separate context and deleted later.

Regards,
Hari Babu
Fujitsu Australia