fixes #1572 nng creates too many threads

This further limits some of the thread counts, but principally it
offers a new runtime facility, nng_init_set_parameter(), which can
be used to set certain runtime parameters on the number of threads,
provided it is called before the rest of application start up.

This facility is quite intentionally "undocumented", at least for now,
as we want to limit our commitment to it.  Still this should be helpful
for applications that need to reduce the number of threads that are
created.

1 files changed, 140 insertions, 0 deletions

diff --git a/src/core/init_test.c b/src/core/init_test.c
new file mode 100644
index 00000000..9b9e26b4
--- /dev/null
+++ b/src/core/init_test.c
@@ -0,0 +1,140 @@
+//
+// Copyright 2024 Staysail Systems, Inc. <info@staysail.tech>
+//
+// This software is supplied under the terms of the MIT License, a
+// copy of which should be located in the distribution where this
+// file was obtained (LICENSE.txt).  A copy of the license may also be
+// found online at https://opensource.org/licenses/MIT.
+//
+
+#include <nuts.h>
+
+uint64_t nni_init_get_param(
+    nng_init_parameter parameter, uint64_t default_value);
+uint64_t nni_init_get_effective(nng_init_parameter p);
+void     nni_init_set_effective(nng_init_parameter p, uint64_t);
+
+void
+test_init_param(void)
+{
+	NUTS_ASSERT(nni_init_get_param(NNG_INIT_PARAMETER_NONE, 456) == 456);
+	nng_init_set_parameter(NNG_INIT_PARAMETER_NONE, 123);
+	NUTS_ASSERT(nni_init_get_param(NNG_INIT_PARAMETER_NONE, 567) == 123);
+	nni_init_set_effective(NNG_INIT_PARAMETER_NONE, 124);
+	NUTS_ASSERT(nni_init_get_effective(NNG_INIT_PARAMETER_NONE) == 124);
+	NUTS_ASSERT(nni_init_get_param(NNG_INIT_PARAMETER_NONE, 567) == 123);
+	nng_fini();
+	NUTS_ASSERT(nni_init_get_param(NNG_INIT_PARAMETER_NONE, 567) == 567);
+}
+
+void
+test_set_effective(void)
+{
+	nni_init_set_effective(NNG_INIT_PARAMETER_NONE, 999);
+	NUTS_ASSERT(nni_init_get_param(NNG_INIT_PARAMETER_NONE, 0) == 0);
+	NUTS_ASSERT(nni_init_get_effective(NNG_INIT_PARAMETER_NONE) == 999);
+	nng_fini();
+}
+
+void
+test_init_zero_resolvers(void)
+{
+	nng_socket s;
+	nng_init_set_parameter(NNG_INIT_NUM_RESOLVER_THREADS, 0);
+	NUTS_OPEN(s);
+	NUTS_CLOSE(s);
+	NUTS_ASSERT(
+	    nni_init_get_effective(NNG_INIT_NUM_RESOLVER_THREADS) == 1);
+	nng_fini();
+}
+
+void
+test_init_one_task_thread(void)
+{
+	nng_socket s;
+	nng_init_set_parameter(NNG_INIT_NUM_TASK_THREADS, 0);
+	nng_init_set_parameter(NNG_INIT_MAX_TASK_THREADS, 1);
+	NUTS_OPEN(s);
+	NUTS_CLOSE(s);
+	NUTS_ASSERT(nni_init_get_effective(NNG_INIT_NUM_TASK_THREADS) == 2);
+	nng_fini();
+}
+
+void
+test_init_too_many_task_threads(void)
+{
+	nng_socket s;
+	nng_init_set_parameter(NNG_INIT_NUM_TASK_THREADS, 256);
+	nng_init_set_parameter(NNG_INIT_MAX_TASK_THREADS, 4);
+	NUTS_OPEN(s);
+	NUTS_CLOSE(s);
+	NUTS_ASSERT(nni_init_get_effective(NNG_INIT_NUM_TASK_THREADS) == 4);
+	nng_fini();
+}
+
+void
+test_init_no_expire_thread(void)
+{
+	nng_socket s;
+	nng_init_set_parameter(NNG_INIT_NUM_EXPIRE_THREADS, 0);
+	nng_init_set_parameter(NNG_INIT_MAX_EXPIRE_THREADS, 0);
+	NUTS_OPEN(s);
+	NUTS_CLOSE(s);
+	NUTS_ASSERT(nni_init_get_effective(NNG_INIT_NUM_EXPIRE_THREADS) == 1);
+	nng_fini();
+}
+
+void
+test_init_too_many_expire_threads(void)
+{
+	nng_socket s;
+	nng_init_set_parameter(NNG_INIT_NUM_EXPIRE_THREADS, 256);
+	nng_init_set_parameter(NNG_INIT_MAX_EXPIRE_THREADS, 2);
+	NUTS_OPEN(s);
+	NUTS_CLOSE(s);
+	NUTS_ASSERT(nni_init_get_effective(NNG_INIT_NUM_EXPIRE_THREADS) == 2);
+	nng_fini();
+}
+
+// poller tuning only supported on Windows right now
+#ifdef NNG_PLATFORM_WINDOWS
+void
+test_init_poller_no_threads(void)
+{
+	nng_socket s;
+	nng_init_set_parameter(NNG_INIT_NUM_POLLER_THREADS, 0);
+	nng_init_set_parameter(NNG_INIT_MAX_POLLER_THREADS, 0);
+	NUTS_OPEN(s);
+	NUTS_CLOSE(s);
+	NUTS_ASSERT(nni_init_get_effective(NNG_INIT_NUM_POLLER_THREADS) == 1);
+	nng_fini();
+}
+
+void
+test_init_too_many_poller_threads(void)
+{
+	nng_socket s;
+	nng_init_set_parameter(NNG_INIT_NUM_POLLER_THREADS, 256);
+	nng_init_set_parameter(NNG_INIT_MAX_POLLER_THREADS, 2);
+	NUTS_OPEN(s);
+	NUTS_CLOSE(s);
+	NUTS_ASSERT(nni_init_get_effective(NNG_INIT_NUM_POLLER_THREADS) == 2);
+	nng_fini();
+}
+#endif
+
+NUTS_TESTS = {
+	{ "init parameter", test_init_param },
+	{ "init set effective", test_set_effective },
+	{ "init zero resolvers", test_init_zero_resolvers },
+	{ "init one task thread", test_init_one_task_thread },
+	{ "init too many task threads", test_init_too_many_task_threads },
+	{ "init no expire thread", test_init_no_expire_thread },
+	{ "init too many expire threads", test_init_too_many_expire_threads },
+#ifdef NNG_PLATFORM_WINDOWS
+	{ "init no poller thread", test_init_poller_no_threads },
+	{ "init too many poller threads", test_init_too_many_poller_threads },
+#endif
+
+	{ NULL, NULL },
+};
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