[pgpool-hackers: 2347] Re: [pgpool-committers: 4036] pgpool: Use volatile pointer for Req_info variable.

[Muhammad Usama]

On the related node I think this patch introduces some compilation
warnings.

See below the warnings when I compile the code on CentOS 7

main/pgpool_main.c: In function ‘register_node_operation_request’:
main/pgpool_main.c:496:3: warning: passing argument 1 of ‘memcpy’ discards
‘volatile’ qualifier from pointer target type [enabled by default]
   memcpy(Req_info->request[index].node_id, node_id_set, (sizeof(int) *
count));
   ^
In file included from /usr/include/sys/un.h:37:0,
                 from main/pgpool_main.c:26:
/usr/include/string.h:42:14: note: expected ‘void * __restrict__’ but
argument is of type ‘volatile int *’
 extern void *memcpy (void *__restrict __dest, const void *__restrict __src,
              ^
main/pgpool_main.c: In function ‘failover’:
main/pgpool_main.c:1536:3: warning: passing argument 2 of ‘memcpy’ discards
‘volatile’ qualifier from pointer target type [enabled by default]
   memcpy(node_id_set, Req_info->request[queue_index].node_id ,
(sizeof(int) * Req_info->request[queue_index].count));
   ^
In file included from /usr/include/sys/un.h:37:0,
                 from main/pgpool_main.c:26:
/usr/include/string.h:42:14: note: expected ‘const void * __restrict__’ but
argument is of type ‘volatile int *’
 extern void *memcpy (void *__restrict __dest, const void *__restrict __src,

Thanks
Best Regards
Muhammad Usama


On Thu, May 18, 2017 at 5:49 PM, Muhammad Usama <m.usama at gmail.com> wrote:

>
>
> On Tue, May 16, 2017 at 4:55 PM, Tatsuo Ishii <ishii at sraoss.co.jp> wrote:
>
>> Usama,
>>
>> Watchdog uses shared memory and I wonder if some of pointer variables
>> to the shared memory are may need "volatile" to make sure that they
>> fetch the fresh value. What do you think?
>>
>
> *ipc_shared_key* and *watchdog_ipc_address* are only set once at the
> startup time and never changed So I don't think we need to make it volatile.
> But I think we may need watchdog_require_cleanup and
> watchdog_node_escalated to be declared as volatile.
>
> Regards
> Muhammad Usama
>
>>
>> /* shared memory variables */
>> char *watchdog_ipc_address = NULL;
>> bool *watchdog_require_cleanup = NULL;  /* shared memory variable set to
>> true
>>
>>        * when watchdog process terminates abnormally
>>
>>        */
>> bool *watchdog_node_escalated = NULL;   /* shared memory variable set to
>> true
>>
>>        * when watchdog process has performed escalation
>>
>>        */
>> unsigned int *ipc_shared_key = NULL;   /* key lives in shared memory
>>
>>       * used to identify the ipc internal
>>
>>       * clients
>>
>>       */
>
> > Use volatile pointer for Req_info variable.
>> >
>> > Since Req_info points to shared memory area, using volatile pointer
>> > will allow to fetch the fresh value.
>> >
>> > Branch
>> > ------
>> > master
>> >
>> > Details
>> > -------
>> > https://git.postgresql.org/gitweb?p=pgpool2.git;a=commitdiff
>> ;h=a4de4bfc1421d787b53789eb62eb7e9cb26e91c1
>> >
>> > Modified Files
>> > --------------
>> > src/include/pool.h                                               | 2 +-
>> > src/main/pgpool_main.c                                           | 2 +-
>> > src/test/regression/tests/010.rewrite_timestamp/timestamp/main.c | 2 +-
>> > 3 files changed, 3 insertions(+), 3 deletions(-)
>> >
>> _______________________________________________
>> pgpool-hackers mailing list
>> pgpool-hackers at pgpool.net
>> http://www.pgpool.net/mailman/listinfo/pgpool-hackers
>>
>
>
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