Re: [PATCH] Introduce dvbpsi_new2() which calls logging callback with extra context parameter

Hi Andrey,

Thanks for the patch, but I hate to spoil it for you ;)

On Sun, May 26, 2013 at 8:09 PM, Andrey Utkin <
[email protected]> wrote:

> This does not break original dvbpsi_new() mechanism.
> Rationale: when dvbpsi contexts are created in many objects, you may
> need to figure out, which object is the owner.
> ---
>  src/dvbpsi.c | 19 +++++++++++++++++++
>  src/dvbpsi.h |  8 ++++++++
>  2 files changed, 27 insertions(+)
>

The functionality you require is already present in libdvbpsi in the form
of a private pointer inside the dvbpsi_t structure, from dvbpsi.h header
file:

/*****************************************************************************
 * dvbpsi_t
 *****************************************************************************/
/*!
 * \struct dvbpsi_s
 * \brief DVBPSI handle structure
 *
 * This structure provides a handle to libdvbpsi API and should be used
instead
 * of dvbpsi_decoder_t.
 */
/*!
 * \typedef struct dvbpsi_s dvbpsi_t
 * \brief dvbpsi_t type definition.
 */
struct dvbpsi_s
{
    dvbpsi_decoder_t             *p_decoder;          /*!< private pointer
to
                                                          specific decoder
*/
    /* Messages callback */
    dvbpsi_message_cb             pf_message;           /*!< Log message
callback */
    enum dvbpsi_msg_level         i_msg_level;          /*!< Log level */

    /* private data pointer for use by caller, not by libdvbpsi itself ! */
    void                         *p_sys;                /*!< pointer to
private data
                                                          from caller. Do
not use
                                                          from inside
libdvbpsi. It
                                                          will crash any
application. */
};

The p_sys pointer can be used to attach your context. I think the
documentation for this could be improved,
since you missed this use case.

In addtion each PSI table attache function "dvbpsi_XXX_attach()" also
allows for passing private data to the callback function.  The
example program dvbinfo makes use of this mechanism to pass on a 'context'.
The function
libdvbpsi_init() shows you how to use this, eg: lines 1747
(dvbpsi_pat_attach function), 648 (PAT callback function)

Kind regards,
Jean-Paul Saman.


> diff --git a/src/dvbpsi.c b/src/dvbpsi.c
> index 4d27720..e9a9ad9 100644
> --- a/src/dvbpsi.c
> +++ b/src/dvbpsi.c
> @@ -60,6 +60,19 @@ dvbpsi_t *dvbpsi_new(dvbpsi_message_cb callback, enum
> dvbpsi_msg_level level)
>      return p_dvbpsi;
>  }
>
> +dvbpsi_t *dvbpsi_new2(void *context, dvbpsi_message_cb2 callback, enum
> dvbpsi_msg_level level)
> +{
> +    dvbpsi_t *p_dvbpsi = calloc(1, sizeof(dvbpsi_t));
> +    if (p_dvbpsi == NULL)
> +        return NULL;
> +
> +    p_dvbpsi->p_decoder  = NULL;
> +    p_dvbpsi->context = context;
> +    p_dvbpsi->pf_message2 = callback;
> +    p_dvbpsi->i_msg_level = level;
> +    return p_dvbpsi;
> +}
> +
>
>  /*****************************************************************************
>   * dvbpsi_delete
>
> *****************************************************************************/
> @@ -537,6 +550,8 @@ void dvbpsi_message(dvbpsi_t *dvbpsi, const
> dvbpsi_msg_level_t level, const char
>          if (err > DVBPSI_MSG_NONE) {
>              if (dvbpsi->pf_message)
>                  dvbpsi->pf_message(dvbpsi, level, msg);
> +            else if (dvbpsi->pf_message2)
> +                dvbpsi->pf_message2(dvbpsi->context, dvbpsi, level, msg);
>          }
>          free(msg);
>      }
> @@ -563,6 +578,8 @@ void dvbpsi_message(dvbpsi_t *dvbpsi, const
> dvbpsi_msg_level_t level, const char
>          if (err > 0) {                                          \
>              if (dvbpsi->pf_message)                             \
>                  dvbpsi->pf_message(dvbpsi, level, msg);         \
> +            else if (dvbpsi->pf_message2)                       \
> +                dvbpsi->pf_message2(dvbpsi->context, dvbpsi, level, msg);\
>          }                                                       \
>          free(msg);                                              \
>      } while(0);
> @@ -581,6 +598,8 @@ void dvbpsi_message(dvbpsi_t *dvbpsi, const
> dvbpsi_msg_level_t level, const char
>          if (err > 0) {                                          \
>              if (dvbpsi->pf_message)                             \
>                  dvbpsi->pf_message(dvbpsi, level, msg);         \
> +            else if (dvbpsi->pf_message2)                       \
> +                dvbpsi->pf_message2(dvbpsi->context, dvbpsi, level, msg);\
>          }                                                       \
>          free(msg);                                              \
>      } while(0);
> diff --git a/src/dvbpsi.h b/src/dvbpsi.h
> index 062a9db..cb28b96 100644
> --- a/src/dvbpsi.h
> +++ b/src/dvbpsi.h
> @@ -95,6 +95,11 @@ typedef void (* dvbpsi_message_cb)(dvbpsi_t *handle,
>                                     const dvbpsi_msg_level_t level,
>                                     const char* msg);
>
> +typedef void (* dvbpsi_message_cb2)(void *context,
> +                                    dvbpsi_t *handle,
> +                                    const dvbpsi_msg_level_t level,
> +                                    const char* msg);
> +
>
>  /*****************************************************************************
>   * dvbpsi_decoder_t
>
> *****************************************************************************/
> @@ -145,6 +150,8 @@ struct dvbpsi_s
>                                                            specific
> decoder */
>      /* Messages callback */
>      dvbpsi_message_cb             pf_message;           /*!< Log message
> callback */
> +    void                         *context;
> +    dvbpsi_message_cb2            pf_message2;          /*!< Log message
> callback */
>      enum dvbpsi_msg_level         i_msg_level;          /*!< Log level */
>
>      /* private data pointer for use by caller, not by libdvbpsi itself !
> */
> @@ -169,6 +176,7 @@ struct dvbpsi_s
>   * handle must be freed with dvbpsi_delete().
>   */
>  dvbpsi_t *dvbpsi_new(dvbpsi_message_cb callback, enum dvbpsi_msg_level
> level);
> +dvbpsi_t *dvbpsi_new2(void *context, dvbpsi_message_cb2 callback, enum
> dvbpsi_msg_level level);
>
>
>  /*****************************************************************************
>   * dvbpsi_delete
> --
> 1.8.1.5
>
> _______________________________________________
> libdvbpsi-devel mailing list
> [email protected]
> http://mailman.videolan.org/listinfo/libdvbpsi-devel
>

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