[PATCH 2/2] trace-cmd: improve main readability

[Federico Vaga]

Since now there is an uniform command implementation I can reduce the
 `main()` function to the minimum by using a lookup table. People can
 now directly focus on a command implementation because there is
 "nothing" in the `main()` function.

Signed-off-by: Federico Vaga <federico.vaga@xxxxxxxxxx>
---
 trace-cmd.c   | 116 ++++++++++++++++++++++++++++------------------------------
 trace-list.c  |   8 +++-
 trace-local.h |   4 +-
 trace-usage.c |   6 +++
 4 files changed, 71 insertions(+), 63 deletions(-)

diff --git a/trace-cmd.c b/trace-cmd.c
index 39bcc06..0f71e12 100644
--- a/trace-cmd.c
+++ b/trace-cmd.c
@@ -76,72 +76,66 @@ void *malloc_or_die(unsigned int size)
 }
 
 
+/**
+ * struct command
+ * @name command name
+ * @run function to execute on command `name`
+ */
+struct command {
+	char *name;
+	void (*run)(int argc, char **argv);
+};
+
+
+/**
+ * Lookup table that maps command names to functions
+ */
+struct command commands[] = {
+	{"report", trace_report},
+	{"snapshot", trace_snapshot},
+	{"hist", trace_hist},
+	{"mem", trace_mem},
+	{"listen", trace_listen},
+	{"split", trace_split},
+	{"restore", trace_restore},
+	{"stack", trace_stack},
+	{"check-events", trace_check_events},
+	{"record", trace_record},
+	{"start", trace_record},
+	{"extract", trace_record},
+	{"stop", trace_record},
+	{"stream", trace_record},
+	{"profile", trace_record},
+	{"restart", trace_record},
+	{"reset", trace_record},
+	{"stat", trace_stat},
+	{"options", trace_option},
+	{"show", trace_show},
+	{"list", trace_list},
+	{"help", trace_usage},
+	{"-h", trace_usage},
+};
+
+#define ARRAY_SIZE(_a) (sizeof(_a) / sizeof(_a[0]))
+
 int main (int argc, char **argv)
 {
+	int i;
+
 	errno = 0;
 
 	if (argc < 2)
-		usage(argv);
-
-	if (strcmp(argv[1], "report") == 0) {
-		trace_report(argc, argv);
-		exit(0);
-	} else if (strcmp(argv[1], "snapshot") == 0) {
-		trace_snapshot(argc, argv);
-		exit(0);
-	} else if (strcmp(argv[1], "hist") == 0) {
-		trace_hist(argc, argv);
-		exit(0);
-	} else if (strcmp(argv[1], "mem") == 0) {
-		trace_mem(argc, argv);
-		exit(0);
-	} else if (strcmp(argv[1], "listen") == 0) {
-		trace_listen(argc, argv);
-		exit(0);
-	} else if (strcmp(argv[1], "split") == 0) {
-		trace_split(argc, argv);
-		exit(0);
-	} else if (strcmp(argv[1], "restore") == 0) {
-		trace_restore(argc, argv);
-		exit(0);
-	} else if (strcmp(argv[1], "stack") == 0) {
-		trace_stack(argc, argv);
-		exit(0);
-	} else if (strcmp(argv[1], "check-events") == 0) {
-		trace_check_events(argc, argv);
-		exit(0);
-	} else if (strcmp(argv[1], "record") == 0 ||
-		   strcmp(argv[1], "start") == 0 ||
-		   strcmp(argv[1], "extract") == 0 ||
-		   strcmp(argv[1], "stop") == 0 ||
-		   strcmp(argv[1], "stream") == 0 ||
-		   strcmp(argv[1], "profile") == 0 ||
-		   strcmp(argv[1], "restart") == 0 ||
-		   strcmp(argv[1], "reset") == 0) {
-		trace_record(argc, argv);
-		exit(0);
-
-	} else if (strcmp(argv[1], "stat") == 0) {
-		trace_stat(argc, argv);
-		exit(0);
-
-	} else if (strcmp(argv[1], "options") == 0) {
-		show_plugin_options();
-		exit(0);
-	} else if (strcmp(argv[1], "show") == 0) {
-		trace_show(argc, argv);
-		exit(0);
-	} else if (strcmp(argv[1], "list") == 0) {
-		trace_list(argc, argv);
-		exit(0);
-	} else if (strcmp(argv[1], "-h") == 0 ||
-		   strcmp(argv[1], "help") == 0) {
-		usage(argv);
-	} else {
-		fprintf(stderr, "unknown command: %s\n", argv[1]);
-		usage(argv);
+		trace_usage(argc, argv);
+
+	for (i = 0; i < ARRAY_SIZE(commands); ++i) {
+		if (strcmp(argv[1], commands[i].name) == 0 ){
+			commands[i].run(argc, argv);
+			goto out;
+		}
 	}
 
-	return 0;
+	/* No valid command found, show help */
+	trace_usage(argc, argv);
+out:
+	exit(0);
 }
-
diff --git a/trace-list.c b/trace-list.c
index 3fdca34..293635f 100644
--- a/trace-list.c
+++ b/trace-list.c
@@ -319,7 +319,7 @@ static void show_buffers(void)
 }
 
 
-void show_plugin_options(void)
+static void show_plugin_options(void)
 {
 	struct pevent *pevent;
 	struct plugin_list *list;
@@ -341,6 +341,12 @@ void show_plugin_options(void)
 }
 
 
+void trace_option(int argc, char **argv)
+{
+	show_plugin_options();
+}
+
+
 static void show_plugins(void)
 {
 	struct pevent *pevent;
diff --git a/trace-local.h b/trace-local.h
index ee518fb..fa987bc 100644
--- a/trace-local.h
+++ b/trace-local.h
@@ -83,6 +83,8 @@ void trace_show(int argc, char **argv);
 
 void trace_list(int argc, char **argv);
 
+void trace_usage(int argc, char **argv);
+
 struct hook_list;
 
 void trace_init_profile(struct tracecmd_input *handle, struct hook_list *hooks,
@@ -189,7 +191,7 @@ char *get_instance_file(struct buffer_instance *instance, const char *file);
 void update_first_instance(struct buffer_instance *instance, int topt);
 
 void show_instance_file(struct buffer_instance *instance, const char *name);
-void show_plugin_options(void);
+
 int count_cpus(void);
 
 /* No longer in event-utils.h */
diff --git a/trace-usage.c b/trace-usage.c
index 5c1a692..9664aa6 100644
--- a/trace-usage.c
+++ b/trace-usage.c
@@ -327,3 +327,9 @@ void usage(char **argv)
 	printf("\n");
 	exit(-1);
 }
+
+
+void trace_usage(int argc, char **argv)
+{
+	usage(argv);
+}
-- 
2.9.3