perf config: Introduce new init() and exit()

Many sub-commands use perf_config() but everytime perf_config() is
called, perf_config() always read config files.  (i.e. user config
'~/.perfconfig' and system config '$(sysconfdir)/perfconfig')

But it is better to use the config set that already contains all config
key-value pairs to avoid this repetitive work reading the config files
in perf_config(). (the config set mean a static variable 'config_set')

In other words, if new perf_config__init() is called, only first time
'config_set' is initialized collecting all configs from the config
files.  And then we could use new perf_config() like old perf_config().
When a sub-command finished, free the config set by perf_config__exit()
at run_builtin().

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

In summary, in order to use features about configuration,
we can call the functions at perf.c and other source files as below.

    # initialize a config set
    perf_config__init()

    # configure actual variables from a config set
    perf_config()

    # eliminate allocated config set
    perf_config__exit()

    # destroy existing config set and initialize a new config set.
    perf_config__refresh()

Signed-off-by: Taeung Song <treeze.taeung@gmail.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1466691272-24117-3-git-send-email-treeze.taeung@gmail.com
[ 'init' counterpart is 'exit', not 'finish' ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-config.c

@@ -80,6 +80,10 @@ int cmd_config(int argc, const char **argv, const char *prefix __maybe_unused)
 	else if (use_user_config)
 		config_exclusive_filename = user_config;
 
+	/*
+	 * At only 'config' sub-command, individually use the config set
+	 * because of reinitializing with options config file location.
+	 */
 	set = perf_config_set__new();
 	if (!set) {
 		ret = -1;

tools/perf/perf.c

@@ -355,6 +355,7 @@ 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__exit();
 	exit_browser(status);
 	perf_env__exit(&perf_env);
 	bpf__clear();
@@ -522,6 +523,7 @@ int main(int argc, const char **argv)
 
 	srandom(time(NULL));
 
+	perf_config__init();
 	perf_config(perf_default_config, NULL);
 	set_buildid_dir(NULL);
 

tools/perf/util/config.c

@@ -26,6 +26,7 @@ static FILE *config_file;
 static const char *config_file_name;
 static int config_linenr;
 static int config_file_eof;
+static struct perf_config_set *config_set;
 
 const char *config_exclusive_filename;
 
@@ -478,51 +479,6 @@ static int perf_config_global(void)
 	return !perf_env_bool("PERF_CONFIG_NOGLOBAL", 0);
 }
 
-int perf_config(config_fn_t fn, void *data)
-{
-	int ret = -1;
-	const char *home = NULL;
-
-	/* Setting $PERF_CONFIG makes perf read _only_ the given config file. */
-	if (config_exclusive_filename)
-		return perf_config_from_file(fn, config_exclusive_filename, data);
-	if (perf_config_system() && !access(perf_etc_perfconfig(), R_OK)) {
-		if (perf_config_from_file(fn, perf_etc_perfconfig(), data) < 0)
-			goto out;
-	}
-
-	home = getenv("HOME");
-	if (perf_config_global() && home) {
-		char *user_config = strdup(mkpath("%s/.perfconfig", home));
-		struct stat st;
-
-		if (user_config == NULL) {
-			warning("Not enough memory to process %s/.perfconfig, "
-				"ignoring it.", home);
-			goto out;
-		}
-
-		if (stat(user_config, &st) < 0)
-			goto out_free;
-
-		if (st.st_uid && (st.st_uid != geteuid())) {
-			warning("File %s not owned by current user or root, "
-				"ignoring it.", user_config);
-			goto out_free;
-		}
-
-		if (!st.st_size)
-			goto out_free;
-
-		ret = perf_config_from_file(fn, user_config, data);
-
-out_free:
-		free(user_config);
-	}
-out:
-	return ret;
-}
-
 static struct perf_config_section *find_section(struct list_head *sections,
 						const char *section_name)
 {
@@ -706,6 +662,52 @@ struct perf_config_set *perf_config_set__new(void)
 	return set;
 }
 
+int perf_config(config_fn_t fn, void *data)
+{
+	int ret = 0;
+	char key[BUFSIZ];
+	struct perf_config_section *section;
+	struct perf_config_item *item;
+
+	if (config_set == NULL)
+		return -1;
+
+	perf_config_set__for_each_entry(config_set, section, item) {
+		char *value = item->value;
+
+		if (value) {
+			scnprintf(key, sizeof(key), "%s.%s",
+				  section->name, item->name);
+			ret = fn(key, value, data);
+			if (ret < 0) {
+				pr_err("Error: wrong config key-value pair %s=%s\n",
+				       key, value);
+				break;
+			}
+		}
+	}
+
+	return ret;
+}
+
+void perf_config__init(void)
+{
+	if (config_set == NULL)
+		config_set = perf_config_set__new();
+}
+
+void perf_config__exit(void)
+{
+	perf_config_set__delete(config_set);
+	config_set = NULL;
+}
+
+void perf_config__refresh(void)
+{
+	perf_config__exit();
+	perf_config__init();
+}
+
 static void perf_config_item__delete(struct perf_config_item *item)
 {
 	zfree(&item->name);

tools/perf/util/config.h

@@ -33,5 +33,34 @@ const char *perf_etc_perfconfig(void);
 
 struct perf_config_set *perf_config_set__new(void);
 void perf_config_set__delete(struct perf_config_set *set);
+void perf_config__init(void);
+void perf_config__exit(void);
+void perf_config__refresh(void);
+
+/**
+ * perf_config_sections__for_each - iterate thru all the sections
+ * @list: list_head instance to iterate
+ * @section: struct perf_config_section iterator
+ */
+#define perf_config_sections__for_each_entry(list, section)	\
+        list_for_each_entry(section, list, node)
+
+/**
+ * perf_config_items__for_each - iterate thru all the items
+ * @list: list_head instance to iterate
+ * @item: struct perf_config_item iterator
+ */
+#define perf_config_items__for_each_entry(list, item)	\
+        list_for_each_entry(item, list, node)
+
+/**
+ * perf_config_set__for_each - iterate thru all the config section-item pairs
+ * @set: evlist instance to iterate
+ * @section: struct perf_config_section iterator
+ * @item: struct perf_config_item iterator
+ */
+#define perf_config_set__for_each_entry(set, section, item)			\
+	perf_config_sections__for_each_entry(&set->sections, section)		\
+	perf_config_items__for_each_entry(&section->items, item)
 
 #endif /* __PERF_CONFIG_H */