[lttng-dev] [PATCH lttng-tool] Mi & save/load: add option to indent or not on config writer creation

[Simon Marchi]

On 6 August 2014 10:13, Jonathan Rajotte Julien
<jonathan.r.julien at gmail.com> wrote:
> The presence of tabulation and newline in mi is irrelevant and
> can impact client performance. The parsing & processing of a lot of data from mi
> with many /t and /n impact performance. This aim to fix the problem at the
> source. Style is useless for machine.

Just by curiosity, did you manage to put a number on that performance impact?

> Signed-off-by: Jonathan Rajotte Julien <jonathan.r.julien at gmail.com>
> ---
>  src/bin/lttng-sessiond/save.c | 2 +-
>  src/common/config/config.c    | 8 ++++----
>  src/common/config/config.h    | 5 ++++-
>  src/common/mi-lttng.c         | 2 +-
>  4 files changed, 10 insertions(+), 7 deletions(-)
>
> diff --git a/src/bin/lttng-sessiond/save.c b/src/bin/lttng-sessiond/save.c
> index 90b3a3b..28844e3 100644
> --- a/src/bin/lttng-sessiond/save.c
> +++ b/src/bin/lttng-sessiond/save.c
> @@ -1514,7 +1514,7 @@ int save_session(struct ltt_session *session,
>         }
>         file_opened = 1;
>
> -       writer = config_writer_create(fd);
> +       writer = config_writer_create(fd, 1);
>         if (!writer) {
>                 ret = LTTNG_ERR_NOMEM;
>                 goto end;
> diff --git a/src/common/config/config.c b/src/common/config/config.c
> index bfb2576..1dccd26 100644
> --- a/src/common/config/config.c
> +++ b/src/common/config/config.c
> @@ -353,7 +353,7 @@ end:
>  }
>
>  LTTNG_HIDDEN
> -struct config_writer *config_writer_create(int fd_output)
> +struct config_writer *config_writer_create(int fd_output, int indent)
>  {
>         int ret;
>         struct config_writer *writer;
> @@ -379,12 +379,12 @@ struct config_writer *config_writer_create(int fd_output)
>
>         ret = xmlTextWriterSetIndentString(writer->writer,
>                 BAD_CAST config_xml_indent_string);
> -       if (ret)  {
> +       if (ret) {
>                 goto error_destroy;
>         }
>
> -       ret = xmlTextWriterSetIndent(writer->writer, 1);
> -       if (ret)  {
> +       ret = xmlTextWriterSetIndent(writer->writer, indent);
> +       if (ret) {
>                 goto error_destroy;
>         }
>
> diff --git a/src/common/config/config.h b/src/common/config/config.h
> index 9a5671a..2fed612 100644
> --- a/src/common/config/config.h
> +++ b/src/common/config/config.h
> @@ -81,11 +81,14 @@ int config_parse_value(const char *value);
>   * fd_output File to which the XML content must be written. The file will be
>   * closed once the config_writer has been destroyed.
>   *
> + * indent If other than 0 the XML will be pretty printed
> + * with indentation and newline.
> + *
>   * Returns an instance of a configuration writer on success, NULL on
>   * error.
>   */
>  LTTNG_HIDDEN
> -struct config_writer *config_writer_create(int fd_output);
> +struct config_writer *config_writer_create(int fd_output, int indent);
>
>  /*
>   * Destroy an instance of a configuration writer.
> diff --git a/src/common/mi-lttng.c b/src/common/mi-lttng.c
> index a636c71..31fa610 100644
> --- a/src/common/mi-lttng.c
> +++ b/src/common/mi-lttng.c
> @@ -352,7 +352,7 @@ struct mi_writer *mi_lttng_writer_create(int fd_output, int mi_output_type)
>                 goto end;
>         }
>         if (mi_output_type == LTTNG_MI_XML) {
> -               mi_writer->writer = config_writer_create(fd_output);
> +               mi_writer->writer = config_writer_create(fd_output, 0);
>                 if (!mi_writer->writer) {
>                         goto err_destroy;
>                 }
> --
> 2.0.0
>
>
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