1 files changed, 113 insertions, 0 deletions
diff --git a/tests/lib/test_heavy_thread.c b/tests/lib/test_heavy_thread.c
new file mode 100644
index 0000000..4fb9ebf
--- /dev/null
+++ b/tests/lib/test_heavy_thread.c
@@ -0,0 +1,113 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ */
+
+/* This programme shows the effects of 'heavy' long-running functions
+ * on the cooperative threading model, as demonstrated by heavy.c, and how
+ * they can be mitigated using a background thread.
+ *
+ * Run it with a config file containing 'password whatever', telnet to it
+ * (it defaults to port 4000) and enter the 'clear foo string' command.
+ * then type whatever and observe that, unlike heavy.c, the vty interface
+ * remains responsive.
+ */
+#include <zebra.h>
+#include <math.h>
+
+#include "frrevent.h"
+#include "vty.h"
+#include "command.h"
+#include "memory.h"
+#include "log.h"
+
+#include "tests.h"
+
+extern struct event_loop *master;
+
+enum { ITERS_FIRST = 0,
+       ITERS_ERR = 100,
+       ITERS_LATER = 400,
+       ITERS_PRINT = 10,
+       ITERS_MAX = 1000,
+};
+
+struct work_state {
+	struct vty *vty;
+	char *str;
+	int i;
+};
+
+static void slow_func(struct vty *vty, const char *str, const int i)
+{
+	double x = 1;
+	int j;
+
+	for (j = 0; j < 300; j++)
+		x += sin(x) * j;
+
+	if ((i % ITERS_LATER) == 0)
+		printf("%s: %d, temporary error, save this somehow and do it later..\n",
+		       __func__, i);
+
+	if ((i % ITERS_ERR) == 0)
+		printf("%s: hard error\n", __func__);
+
+	if ((i % ITERS_PRINT) == 0)
+		printf("%s did %d, x = %g\n", str, i, x);
+}
+
+static void clear_something(struct event *thread)
+{
+	struct work_state *ws = EVENT_ARG(thread);
+
+	/* this could be like iterating through 150k of route_table
+	 * or worse, iterating through a list of peers, to bgp_stop them with
+	 * each having 150k route tables to process...
+	 */
+	while (ws->i < ITERS_MAX) {
+		slow_func(ws->vty, ws->str, ws->i);
+		ws->i++;
+		if (event_should_yield(thread)) {
+			event_add_timer_msec(master, clear_something, ws, 0,
+					     NULL);
+			return;
+		}
+	}
+
+	/* All done! */
+	XFREE(MTYPE_TMP, ws->str);
+	XFREE(MTYPE_TMP, ws);
+}
+
+DEFUN (clear_foo,
+       clear_foo_cmd,
+       "clear foo LINE...",
+       "clear command\n"
+       "arbitrary string\n")
+{
+	char *str;
+	struct work_state *ws;
+
+	if (!argc) {
+		vty_out(vty, "%% string argument required\n");
+		return CMD_WARNING;
+	}
+
+	str = argv_concat(argv, argc, 0);
+
+	ws = XMALLOC(MTYPE_TMP, sizeof(*ws));
+
+	ws->str = XSTRDUP(MTYPE_TMP, str);
+
+	ws->vty = vty;
+	ws->i = ITERS_FIRST;
+
+	event_add_timer_msec(master, clear_something, ws, 0, NULL);
+
+	return CMD_SUCCESS;
+}
+
+void test_init(void)
+{
+	install_element(VIEW_NODE, &clear_foo_cmd);
+}