[RFC][PATCH v4 0/6] perf config: Reimplement perf_config() using perf_config_set__inter()

[Taeung Song]

Everytime perf_config() is called, perf_config() always read config files.
(i.e. user config '~/.perfconfig' and system config '$(sysconfdir)/perfconfig')

But we need to use 'struct perf_config_set config_set' variable
that already contains all config key-value pairs
to avoid this repetitive work in perf_config().

In other words, if new perf_config() is called,
only first time 'config_set' is initialized
collecting all configs from config files and it work with perf_config_set__iter().

If we do, 'config_set' can be reused wherever using perf_config()
and a feature of old perf_config() is the same as new perf_config()
work without the repetitive work that read the config files.

IMHO, I think this patchset is needed because not only the repetitive work
should be avoided but also in near future, it would be smooth to manage perf configs.

Most important patch of this patchset is "[PATCH v4 4/6] perf config: Reimplement
perf_config() using perf_config_set__iter()" and PATCH 1/6 ~ 3/6 are preparation for it.

If you give me any feedback, I'd apprecicated it. :)

Thanks,
Taeung

v4:
- Keep perf_config_set__delete() as it is (Arnaldo)
- Remove perf_config_set__check() (Arnaldo)
- Keep the existing code about the config set at cmd_config() (Arnaldo)

v3:
- add freeing config set after sub-command work at run_builtin() (Namhyung)
- remove needless code about the config set at cmd_config()
- add a patch about a global variable 'config_set'

v2:
- split a patch into several patches
- reimplement show_config() using new perf_config()
- modify perf_config_set__delete using global variable 'config_set'
- reset config set when only 'config' sub-commaned work
  because of options for config file location

Taeung Song (6):
  perf config: Use new perf_config_set__init() to initialize config set
  perf config: Add global variable 'config_set'
  perf config: Use zfree() instead of free() at
    perf_config_set__delete()
  perf config: Reimplement perf_config() using perf_config_set__iter()
  perf config: Reset the config set at only 'config' sub-command
  perf config: Reimplement show_config() using perf_config()

 tools/perf/builtin-config.c |  41 +++++-------
 tools/perf/perf.c           |   1 +
 tools/perf/util/cache.h     |   1 +
 tools/perf/util/config.c    | 148 ++++++++++++++++++++++++++++----------------
 tools/perf/util/config.h    |   4 +-
 5 files changed, 115 insertions(+), 80 deletions(-)

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2.5.0