Re: [PATCH v7 3/7] perf config: Add global variable 'config_set'
From: Taeung Song
Date: Wed Jun 08 2016 - 08:38:29 EST
My answer was too long..
To be short,
many sub-commands use perf_config() so
wherever new perf_config() is called,
the config set that already contains all configs from config files
should be shared.
And when a sub-command is done,
we need to free the config set at run_builtin() as below.
So, IMHO we need to use 'config_set' as a global variable.
Anyway I sent v8 recasting this patchset with other way.
(But 'config_set' is still a global variable.)
Please, reconsider it again.
Thanks,
Taeung
On 06/08/2016 12:14 AM, Taeung Song wrote:
Good afternoon :)
On 06/07/2016 11:05 PM, Arnaldo Carvalho de Melo wrote:
Em Tue, Jun 07, 2016 at 06:26:13PM +0900, Taeung Song escreveu:
The config set is prepared by collecting
all configs from config files (i.e. user config
~/.perfconfig and system config $(sysconfdir)/perfconfig)
so the config set contains all config key-value pairs.
We need to use it as global variable to share it.
We should generally avoid global variables, and in this case, from
looking just at this patch, I'm not convinced we need to introduce more
global variables, isn't this object instantiated and deleted at the
cmd_config() function? So, can't we just pass it to any function needing
to access it?
The reason why I added global variable 'config_set'
that all config key-value pairs from config files
is because of upcoming perf_config_set__delete() and perf_config().
This variable can be used not only at cmd_config()
but also at new perf_config() and future perf_config_set__delete().
Wherever new perf_config() is called, this function check
whether the global variable 'config_set' is initialized or not.
And this function use the variable 'config_set' like below.
(One of intended purposes of new perf_config() is
to avoid the repetitive work that read config files, every time
it is called and to reuse the global variable 'config_set' that
already contains all config info.)
+int perf_config(config_fn_t fn, void *data)
+{
+ if (config_set == NULL)
+ config_set = perf_config_set__new();
+
+ return perf_config_set__iter(config_set, fn, data);
+}
Finally, after sub-command finished, called perf_config_set__delete()
use the global variable as argument to free it as below.
diff --git a/tools/perf/perf.c b/tools/perf/perf.c
index 15982ce..058d5dc 100644
--- a/tools/perf/perf.c
+++ b/tools/perf/perf.c
@@ -391,6 +391,7 @@ static int run_builtin(struct cmd_struct *p, int
argc, const char **argv)
perf_env__set_cmdline(&perf_env, argc, argv);
status = p->fn(argc, argv, prefix);
+ perf_config_set__delete(&config_set);
exit_browser(status);
perf_env__exit(&perf_env);
bpf__clear();
Sure, we can avoid 'extern' for the global variable 'config_set'.
But IMHO, we may need to use a global variable 'config_set'
at only util/config.c at least.
(If perf_config_set__delete() don't take arguments)
(But it seems natural that we should pair between destructor
and constructor as you said.
http://marc.info/?l=linux-kernel&m=146463657721848&w=2 )
And of course, there are other way e.g.
modifying arguments of perf_config(), using perf_config_set__new()
at the very beginning at main() or etc...
Nevertheless,
if we haven't to use the global variable,
I'd find other way.
I applied the first two patches.
Thank you!
Taeung
And in near future, the variable will be handled in perf_config()
and other functions at util/config.c
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Signed-off-by: Taeung Song <treeze.taeung@xxxxxxxxx>
---
tools/perf/builtin-config.c | 9 ++++-----
tools/perf/util/config.c | 1 +
tools/perf/util/config.h | 2 ++
3 files changed, 7 insertions(+), 5 deletions(-)
diff --git a/tools/perf/builtin-config.c b/tools/perf/builtin-config.c
index fe1b77f..b3bc01a 100644
--- a/tools/perf/builtin-config.c
+++ b/tools/perf/builtin-config.c
@@ -62,7 +62,6 @@ static int show_config(struct perf_config_set *set)
int cmd_config(int argc, const char **argv, const char *prefix
__maybe_unused)
{
int ret = 0;
- struct perf_config_set *set;
char *user_config = mkpath("%s/.perfconfig", getenv("HOME"));
argc = parse_options(argc, argv, config_options, config_usage,
@@ -80,8 +79,8 @@ int cmd_config(int argc, const char **argv, const
char *prefix __maybe_unused)
else if (use_user_config)
config_exclusive_filename = user_config;
- set = perf_config_set__new();
- if (!set) {
+ config_set = perf_config_set__new();
+ if (!config_set) {
ret = -1;
goto out_err;
}
@@ -92,7 +91,7 @@ int cmd_config(int argc, const char **argv, const
char *prefix __maybe_unused)
pr_err("Error: takes no arguments\n");
parse_options_usage(config_usage, config_options, "l", 1);
} else {
- ret = show_config(set);
+ ret = show_config(config_set);
if (ret < 0) {
const char * config_filename =
config_exclusive_filename;
if (!config_exclusive_filename)
@@ -106,7 +105,7 @@ int cmd_config(int argc, const char **argv, const
char *prefix __maybe_unused)
usage_with_options(config_usage, config_options);
}
- perf_config_set__delete(set);
+ perf_config_set__delete(config_set);
out_err:
return ret;
}
diff --git a/tools/perf/util/config.c b/tools/perf/util/config.c
index 8749eca..02fc6d5 100644
--- a/tools/perf/util/config.c
+++ b/tools/perf/util/config.c
@@ -28,6 +28,7 @@ static int config_linenr;
static int config_file_eof;
const char *config_exclusive_filename;
+struct perf_config_set *config_set;
static int get_next_char(void)
{
diff --git a/tools/perf/util/config.h b/tools/perf/util/config.h
index 22ec626..ea157a4 100644
--- a/tools/perf/util/config.h
+++ b/tools/perf/util/config.h
@@ -20,6 +20,8 @@ struct perf_config_set {
struct list_head sections;
};
+extern struct perf_config_set *config_set;
+
struct perf_config_set *perf_config_set__new(void);
void perf_config_set__delete(struct perf_config_set *set);
--
2.5.0