perf thread_map: Add thread_map__remove function

Add thread_map__remove function to remove thread from thread map.

Add automated test also.

Committer notes:

Testing it:

  # perf test "Remove thread map"
  39: Remove thread map                          : Ok
  # perf test -v "Remove thread map"
  39: Remove thread map                          :
  --- start ---
  test child forked, pid 4483
  2 threads: 4482, 4483
  1 thread: 4483
  0 thread:
  test child finished with 0
  ---- end ----
  Remove thread map: Ok
  #

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1481538943-21874-4-git-send-email-jolsa@kernel.org
[ Added stdlib.h, to get the free() declaration ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/tests/builtin-test.c

@@ -185,6 +185,10 @@ static struct test generic_tests[] = {
 		.desc = "Synthesize thread map",
 		.func = test__thread_map_synthesize,
 	},
+	{
+		.desc = "Remove thread map",
+		.func = test__thread_map_remove,
+	},
 	{
 		.desc = "Synthesize cpu map",
 		.func = test__cpu_map_synthesize,

tools/perf/tests/tests.h

@@ -80,6 +80,7 @@ const char *test__bpf_subtest_get_desc(int subtest);
 int test__bpf_subtest_get_nr(void);
 int test_session_topology(int subtest);
 int test__thread_map_synthesize(int subtest);
+int test__thread_map_remove(int subtest);
 int test__cpu_map_synthesize(int subtest);
 int test__synthesize_stat_config(int subtest);
 int test__synthesize_stat(int subtest);

tools/perf/tests/thread-map.c

@@ -1,3 +1,4 @@
+#include <stdlib.h>
 #include <sys/types.h>
 #include <unistd.h>
 #include <sys/prctl.h>
@@ -93,3 +94,46 @@ int test__thread_map_synthesize(int subtest __maybe_unused)
 
 	return 0;
 }
+
+int test__thread_map_remove(int subtest __maybe_unused)
+{
+	struct thread_map *threads;
+	char *str;
+	int i;
+
+	TEST_ASSERT_VAL("failed to allocate map string",
+			asprintf(&str, "%d,%d", getpid(), getppid()) >= 0);
+
+	threads = thread_map__new_str(str, NULL, 0);
+
+	TEST_ASSERT_VAL("failed to allocate thread_map",
+			threads);
+
+	if (verbose)
+		thread_map__fprintf(threads, stderr);
+
+	TEST_ASSERT_VAL("failed to remove thread",
+			!thread_map__remove(threads, 0));
+
+	TEST_ASSERT_VAL("thread_map count != 1", threads->nr == 1);
+
+	if (verbose)
+		thread_map__fprintf(threads, stderr);
+
+	TEST_ASSERT_VAL("failed to remove thread",
+			!thread_map__remove(threads, 0));
+
+	TEST_ASSERT_VAL("thread_map count != 0", threads->nr == 0);
+
+	if (verbose)
+		thread_map__fprintf(threads, stderr);
+
+	TEST_ASSERT_VAL("failed to not remove thread",
+			thread_map__remove(threads, 0));
+
+	for (i = 0; i < threads->nr; i++)
+		free(threads->map[i].comm);
+
+	free(threads);
+	return 0;
+}

tools/perf/util/thread_map.c

@@ -448,3 +448,25 @@ bool thread_map__has(struct thread_map *threads, pid_t pid)
 
 	return false;
 }
+
+int thread_map__remove(struct thread_map *threads, int idx)
+{
+	int i;
+
+	if (threads->nr < 1)
+		return -EINVAL;
+
+	if (idx >= threads->nr)
+		return -EINVAL;
+
+	/*
+	 * Free the 'idx' item and shift the rest up.
+	 */
+	free(threads->map[idx].comm);
+
+	for (i = idx; i < threads->nr - 1; i++)
+		threads->map[i] = threads->map[i + 1];
+
+	threads->nr--;
+	return 0;
+}

tools/perf/util/thread_map.h

@@ -58,4 +58,5 @@ static inline char *thread_map__comm(struct thread_map *map, int thread)
 
 void thread_map__read_comms(struct thread_map *threads);
 bool thread_map__has(struct thread_map *threads, pid_t pid);
+int thread_map__remove(struct thread_map *threads, int idx);
 #endif	/* __PERF_THREAD_MAP_H */