Hi Sergei,
Ok to push. I'm sorry for the delay with this.
On Wed, May 20, 2015 at 08:09:36AM +0000, s...@mariadb.org wrote:
> revision-id: d1f5dfe67703a22f017eb25dd48b1eb5246a9c54
> parent(s): 80333ad847d9f1708fa02fb47a976e96f014bc50
> committer: Sergey Vojtovich
> branch nick: mariadb
> timestamp: 2015-05-20 12:04:32 +0400
> message:
>
> MDEV-8030 - Apc_target::disable() locks mutex twice
>
> Moved Apc_target::destroy(), Apc_target::enable() and Apc_targe::disable()
> definitions to my_apc.h so that they can be inlined.
>
> Apc_targe::disable() now calls Apc_target::process_apc_requests() only if
> there're APC requests. This saves one pthread_mutex_lock() call.
>
> Overhead change:
> Apc_target::disable 0.04% -> out of radar
> Apc_target::enable 0.03% -> out of radar
> Apc_target::process_apc_requests 0.02% -> out of radar
> pthread_mutex_lock 0.43% -> 0.42%
> pthread_mutex_unlock 0.26% -> 0.25%
>
> ---
> sql/my_apc.cc | 39 ---------------------------------------
> sql/my_apc.h | 27 +++++++++++++++++++++++----
> 2 files changed, 23 insertions(+), 43 deletions(-)
>
> diff --git a/sql/my_apc.cc b/sql/my_apc.cc
> index 1766068..91f5cd3 100644
> --- a/sql/my_apc.cc
> +++ b/sql/my_apc.cc
> @@ -41,45 +41,6 @@ void Apc_target::init(mysql_mutex_t *target_mutex)
> }
>
>
> -/*
> - Destroy the target. The target must be disabled when this call is made.
> -*/
> -void Apc_target::destroy()
> -{
> - DBUG_ASSERT(!enabled);
> -}
> -
> -
> -/*
> - Enter ther state where the target is available for serving APC requests
> -*/
> -void Apc_target::enable()
> -{
> - /* Ok to do without getting/releasing the mutex: */
> - enabled++;
> -}
> -
> -
> -/*
> - Make the target unavailable for serving APC requests.
> -
> - @note
> - This call will serve all requests that were already enqueued
> -*/
> -
> -void Apc_target::disable()
> -{
> - bool process= FALSE;
> - DBUG_ASSERT(enabled);
> - mysql_mutex_lock(LOCK_thd_data_ptr);
> - if (!(--enabled))
> - process= TRUE;
> - mysql_mutex_unlock(LOCK_thd_data_ptr);
> - if (process)
> - process_apc_requests();
> -}
> -
> -
> /* [internal] Put request qe into the request list */
>
> void Apc_target::enqueue_request(Call_request *qe)
> diff --git a/sql/my_apc.h b/sql/my_apc.h
> index dfeef5e..20b1ee4 100644
> --- a/sql/my_apc.h
> +++ b/sql/my_apc.h
> @@ -50,10 +50,29 @@ class Apc_target
> ~Apc_target() { DBUG_ASSERT(!enabled && !apc_calls);}
>
> void init(mysql_mutex_t *target_mutex);
> - void destroy();
> - void enable();
> - void disable();
> -
> +
> + /* Destroy the target. The target must be disabled when this call is made.
> */
> + void destroy() { DBUG_ASSERT(!enabled); }
> +
> + /* Enter ther state where the target is available for serving APC requests
> */
> + void enable() { enabled++; }
> +
> + /*
> + Make the target unavailable for serving APC requests.
> +
> + @note
> + This call will serve all requests that were already enqueued
> + */
> + void disable()
> + {
> + DBUG_ASSERT(enabled);
> + mysql_mutex_lock(LOCK_thd_data_ptr);
> + bool process= !--enabled && have_apc_requests();
> + mysql_mutex_unlock(LOCK_thd_data_ptr);
> + if (unlikely(process))
> + process_apc_requests();
> + }
> +
> void process_apc_requests();
> /*
> A lightweight function, intended to be used in frequent checks like this:
> _______________________________________________
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--
BR
Sergei
--
Sergei Petrunia, Software Developer
MariaDB Corporation | Skype: sergefp | Blog: http://s.petrunia.net/blog
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