Before polling or sleeping to wait for a test to complete, print out
": Running (<num> remaining)" where the number of remaining tests is
determined by iterating over the remaining tests and seeing which
return true for check_if_command_finished. The line erasing and
printing out only occur if the number of runnings tests changes to
avoid the line flickering excessively. Knowing tests are running
allows a user to know a test is running and in parallel mode how many
of the tests are waiting to complete. If color mode is disabled then
avoid displaying the "Running" message as deleting the line isn't
reliable.

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/tests/builtin-test.c | 94 ++++++++++++++++++++++-----------
 tools/perf/util/color.h         |  1 +
 2 files changed, 64 insertions(+), 31 deletions(-)

diff --git a/tools/perf/tests/builtin-test.c b/tools/perf/tests/builtin-test.c
index 470a9709427d..df0466d3def6 100644
--- a/tools/perf/tests/builtin-test.c
+++ b/tools/perf/tests/builtin-test.c
@@ -242,7 +242,10 @@ static int run_test_child(struct child_process *process)
 	return -err;
 }
 
-static int print_test_result(struct test_suite *t, int i, int subtest, int result, int width)
+#define TEST_RUNNING -3
+
+static int print_test_result(struct test_suite *t, int i, int subtest, int result, int width,
+			     int remaining)
 {
 	if (has_subtests(t)) {
 		int subw = width > 2 ? width - 2 : width;
@@ -252,6 +255,9 @@ static int print_test_result(struct test_suite *t, int i, int subtest, int resul
 		pr_info("%3d: %-*s:", i + 1, width, test_description(t, subtest));
 
 	switch (result) {
+	case TEST_RUNNING:
+		color_fprintf(stderr, PERF_COLOR_YELLOW, " Running (%d remaining)\n", remaining);
+		break;
 	case TEST_OK:
 		pr_info(" Ok\n");
 		break;
@@ -273,14 +279,17 @@ static int print_test_result(struct test_suite *t, int i, int subtest, int resul
 	return 0;
 }
 
-static int finish_test(struct child_test *child_test, int width)
+static int finish_test(struct child_test **child_tests, int running_test, int child_test_num,
+		       int width)
 {
+	struct child_test *child_test = child_tests[running_test];
 	struct test_suite *t = child_test->test;
 	int i = child_test->test_num;
 	int subi = child_test->subtest;
 	int err = child_test->process.err;
-	bool err_done = err <= 0;
+	bool err_done = false;
 	struct strbuf err_output = STRBUF_INIT;
+	int last_tests_in_progress = -1;
 	int ret;
 
 	/*
@@ -294,7 +303,7 @@ static int finish_test(struct child_test *child_test, int width)
 	 * Busy loop reading from the child's stdout/stderr that are set to be
 	 * non-blocking until EOF.
 	 */
-	if (!err_done)
+	if (err > 0)
 		fcntl(err, F_SETFL, O_NONBLOCK);
 	if (verbose > 1) {
 		if (has_subtests(t))
@@ -308,38 +317,61 @@ static int finish_test(struct child_test *child_test, int width)
 			  .events = POLLIN | POLLERR | POLLHUP | POLLNVAL,
 			},
 		};
-		char buf[512];
-		ssize_t len;
-
-		/* Poll to avoid excessive spinning, timeout set for 100ms. */
-		poll(pfds, ARRAY_SIZE(pfds), /*timeout=*/100);
-		if (!err_done && pfds[0].revents) {
-			errno = 0;
-			len = read(err, buf, sizeof(buf) - 1);
-
-			if (len <= 0) {
-				err_done = errno != EAGAIN;
-			} else {
-				buf[len] = '\0';
-				if (verbose > 1)
-					fprintf(stdout, "%s", buf);
-				else
+		if (perf_use_color_default) {
+			int tests_in_progress = running_test;
+
+			for (int y = running_test; y < child_test_num; y++) {
+				if (check_if_command_finished(&child_tests[y]->process))
+					tests_in_progress++;
+			}
+			if (tests_in_progress != last_tests_in_progress) {
+				if (last_tests_in_progress != -1) {
+					/*
+					 * Erase "Running (.. remaining)" line
+					 * printed before poll/sleep.
+					 */
+					fprintf(debug_file(), PERF_COLOR_DELETE_LINE);
+				}
+				print_test_result(t, i, subi, TEST_RUNNING, width,
+						  child_test_num - tests_in_progress);
+				last_tests_in_progress = tests_in_progress;
+			}
+		}
+
+		err_done = true;
+		if (err <= 0) {
+			/* No child stderr to poll, sleep for 10ms for child to complete. */
+			usleep(10 * 1000);
+		} else {
+			/* Poll to avoid excessive spinning, timeout set for 100ms. */
+			poll(pfds, ARRAY_SIZE(pfds), /*timeout=*/100);
+			if (pfds[0].revents) {
+				char buf[512];
+				ssize_t len;
+
+				len = read(err, buf, sizeof(buf) - 1);
+
+				if (len > 0) {
+					err_done = false;
+					buf[len] = '\0';
 					strbuf_addstr(&err_output, buf);
+				}
 			}
 		}
+		if (err_done)
+			err_done = check_if_command_finished(&child_test->process);
+	}
+	if (perf_use_color_default && last_tests_in_progress != -1) {
+		/* Erase "Running (.. remaining)" line printed before poll/sleep. */
+		fprintf(debug_file(), PERF_COLOR_DELETE_LINE);
 	}
 	/* Clean up child process. */
 	ret = finish_command(&child_test->process);
-	if (verbose == 1 && ret == TEST_FAIL) {
-		/* Add header for test that was skipped above. */
-		if (has_subtests(t))
-			pr_info("%3d.%1d: %s:\n", i + 1, subi + 1, test_description(t, subi));
-		else
-			pr_info("%3d: %s:\n", i + 1, test_description(t, -1));
+	if (verbose > 1 || (verbose == 1 && ret == TEST_FAIL))
 		fprintf(stderr, "%s", err_output.buf);
-	}
+
 	strbuf_release(&err_output);
-	print_test_result(t, i, subi, ret, width);
+	print_test_result(t, i, subi, ret, width, /*remaining=*/0);
 	if (err > 0)
 		close(err);
 	return 0;
@@ -355,7 +387,7 @@ static int start_test(struct test_suite *test, int i, int subi, struct child_tes
 		pr_debug("--- start ---\n");
 		err = test_function(test, subi)(test, subi);
 		pr_debug("---- end ----\n");
-		print_test_result(test, i, subi, err, width);
+		print_test_result(test, i, subi, err, width, /*remaining=*/0);
 		return 0;
 	}
 
@@ -380,7 +412,7 @@ static int start_test(struct test_suite *test, int i, int subi, struct child_tes
 	err = start_command(&(*child)->process);
 	if (err || !sequential)
 		return  err;
-	return finish_test(*child, width);
+	return finish_test(child, /*running_test=*/0, /*child_test_num=*/1, width);
 }
 
 #define for_each_test(j, k, t)					\
@@ -465,7 +497,7 @@ static int __cmd_test(int argc, const char *argv[], struct intlist *skiplist)
 	}
 	for (i = 0; i < child_test_num; i++) {
 		if (!sequential) {
-			int ret  = finish_test(child_tests[i], width);
+			int ret  = finish_test(child_tests, i, child_test_num, width);
 
 			if (ret)
 				return ret;
diff --git a/tools/perf/util/color.h b/tools/perf/util/color.h
index 01f7bed21c9b..4b9f8d5d4439 100644
--- a/tools/perf/util/color.h
+++ b/tools/perf/util/color.h
@@ -22,6 +22,7 @@
 #define MIN_GREEN	0.5
 #define MIN_RED		5.0
 
+#define PERF_COLOR_DELETE_LINE	"\033[A\33[2K\r"
 /*
  * This variable stores the value of color.ui
  */
-- 
2.47.0.rc1.288.g06298d1525-goog