Provide versions of mutex, condvar, and aio init that never fail.

If the underlying platform fails (FreeBSD is the only one I'm aware
of that does this!), we use a global lock or condition variable instead.
This means that our lock initializers never ever fail.

Probably we could eliminate most of this for Linux and Darwin, since
on those platforms, mutex and condvar initialization reasonably never
fails.  Initial benchmarks show little difference either way -- so we
can revisit (optimize) later.

This removes a lot of otherwise untested code in error cases and so forth,
improving coverage and resilience in the face of allocation failures.

Platforms other than POSIX should follow a similar pattern if they need
this.  (VxWorks, I'm thinking of you.)  Most sane platforms won't have
an issue here, since normally these initializations do not need to allocate
memory. (Reportedly, even FreeBSD has plans to "fix" this in libthr2.)

While here, some bugs were fixed in initialization & teardown.

The fallback code is properly tested with dedicated test cases.

1 files changed, 292 insertions, 0 deletions

diff --git a/tests/synch.c b/tests/synch.c
new file mode 100644
index 00000000..a49e27e1
--- /dev/null
+++ b/tests/synch.c
@@ -0,0 +1,292 @@
+//
+// Copyright 2017 Garrett D'Amore <garrett@damore.org>
+// Copyright 2017 Capitar IT Group BV <info@capitar.com>
+//
+// 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 "convey.h"
+#include "core/nng_impl.h"
+#include "nng.h"
+
+// Notify tests for verifying condvars.
+struct notifyarg {
+	int     did;
+	int     when;
+	nni_mtx mx;
+	nni_cv  cv;
+};
+
+#ifdef PLATFORM_POSIX
+#ifndef NDEBUG
+#define SYNC_FALLBACK 1
+#endif
+#endif
+
+void
+notifyafter(void *arg)
+{
+	struct notifyarg *na = arg;
+
+	nni_usleep(na->when);
+	nni_mtx_lock(&na->mx);
+	na->did = 1;
+	nni_cv_wake(&na->cv);
+	nni_mtx_unlock(&na->mx);
+}
+
+struct notifyarg arg;
+nni_thr          thr;
+
+static void
+test_sync(void)
+{
+	Convey("Mutexes work", {
+		nni_mtx mx;
+
+		nni_mtx_init(&mx);
+
+		Convey("We can lock a mutex", {
+			nni_mtx_lock(&mx);
+			So(1);
+			Convey("And we can unlock it", {
+				nni_mtx_unlock(&mx);
+				So(1);
+				Convey("And then lock it again", {
+					nni_mtx_lock(&mx);
+					So(1);
+					nni_mtx_unlock(&mx);
+					So(1);
+				});
+			});
+			Convey("Things block properly", {
+
+				nni_mtx_init(&arg.mx);
+				nni_cv_init(&arg.cv, &arg.mx);
+				So(nni_thr_init(&thr, notifyafter, &arg) == 0);
+				arg.did  = 0;
+				arg.when = 0;
+				nni_mtx_lock(&arg.mx);
+				nni_thr_run(&thr);
+				nng_usleep(10000);
+				So(arg.did == 0);
+				nni_mtx_unlock(&arg.mx);
+				nng_usleep(10000);
+				nni_mtx_lock(&arg.mx);
+				while (!arg.did) {
+					nni_cv_wait(&arg.cv);
+				}
+				So(arg.did != 0);
+				nni_mtx_unlock(&arg.mx);
+				nni_thr_fini(&thr);
+				nni_cv_fini(&arg.cv);
+				nni_mtx_fini(&arg.mx);
+			})
+		});
+		Convey("We can finalize it", { nni_mtx_fini(&mx); });
+	});
+
+	Convey("Condition variables work", {
+
+		nni_mtx_init(&arg.mx);
+		nni_cv_init(&arg.cv, &arg.mx);
+		So(nni_thr_init(&thr, notifyafter, &arg) == 0);
+
+		Reset({
+			nni_cv_fini(&arg.cv);
+			nni_mtx_fini(&arg.mx);
+			nni_thr_fini(&thr);
+		});
+
+		Convey("Notification works", {
+			arg.did  = 0;
+			arg.when = 10000;
+			nni_thr_run(&thr);
+
+			nni_mtx_lock(&arg.mx);
+			if (!arg.did) {
+				nni_cv_wait(&arg.cv);
+			}
+			nni_mtx_unlock(&arg.mx);
+			nni_thr_wait(&thr);
+			So(arg.did == 1);
+		});
+
+		Convey("Timeout works", {
+			arg.did  = 0;
+			arg.when = 200000;
+			nni_thr_run(&thr);
+			nni_mtx_lock(&arg.mx);
+			if (!arg.did) {
+				nni_cv_until(&arg.cv, nni_clock() + 10000);
+			}
+			So(arg.did == 0);
+			nni_mtx_unlock(&arg.mx);
+			nni_thr_wait(&thr);
+		});
+
+		Convey("Empty timeout is EAGAIN", {
+			nni_mtx_lock(&arg.mx);
+			So(nni_cv_until(&arg.cv, 0) == NNG_EAGAIN);
+			nni_mtx_unlock(&arg.mx);
+		});
+
+		Convey("Not running works", {
+			arg.did  = 0;
+			arg.when = 1;
+			nni_mtx_lock(&arg.mx);
+			if (!arg.did) {
+				nni_cv_until(&arg.cv, nni_clock() + 10000);
+			}
+			So(arg.did == 0);
+			nni_mtx_unlock(&arg.mx);
+		});
+	});
+}
+
+#if SYNC_FALLBACK
+extern int nni_plat_sync_fallback;
+
+#define ConveyFB(x, y) Convey(x, y)
+
+static void
+test_sync_fallback(void)
+{
+	nni_plat_sync_fallback = 1;
+	Convey("Mutexes work", {
+		nni_mtx mx;
+		int     rv;
+
+		nni_mtx_init(&mx);
+
+		Convey("We can lock a mutex", {
+			nni_mtx_lock(&mx);
+			So(1);
+			Convey("And we can unlock it", {
+				nni_mtx_unlock(&mx);
+				So(1);
+				Convey("And then lock it again", {
+					nni_mtx_lock(&mx);
+					So(1);
+					nni_mtx_unlock(&mx);
+					So(1);
+				});
+			});
+			Convey("Things block properly", {
+
+				nni_mtx_init(&arg.mx);
+				nni_cv_init(&arg.cv, &arg.mx);
+				So(nni_thr_init(&thr, notifyafter, &arg) == 0);
+				arg.did  = 0;
+				arg.when = 0;
+				nni_mtx_lock(&arg.mx);
+				nni_thr_run(&thr);
+				nng_usleep(10000);
+				So(arg.did == 0);
+				nni_mtx_unlock(&arg.mx);
+				nng_usleep(10000);
+				nni_mtx_lock(&arg.mx);
+				while (!arg.did) {
+					nni_cv_wait(&arg.cv);
+				}
+				So(arg.did != 0);
+				nni_mtx_unlock(&arg.mx);
+				nni_thr_fini(&thr);
+				nni_cv_fini(&arg.cv);
+				nni_mtx_fini(&arg.mx);
+			})
+		});
+		Convey("We can finalize it", { nni_mtx_fini(&mx); });
+	});
+
+	Convey("Condition variables work", {
+
+		nni_mtx_init(&arg.mx);
+		nni_cv_init(&arg.cv, &arg.mx);
+		So(nni_thr_init(&thr, notifyafter, &arg) == 0);
+
+		Reset({
+			nni_cv_fini(&arg.cv);
+			nni_mtx_fini(&arg.mx);
+			nni_thr_fini(&thr);
+		});
+
+		Convey("Notification works", {
+			arg.did  = 0;
+			arg.when = 10000;
+			nni_thr_run(&thr);
+
+			nni_mtx_lock(&arg.mx);
+			if (!arg.did) {
+				nni_cv_wait(&arg.cv);
+			}
+			nni_mtx_unlock(&arg.mx);
+			nni_thr_wait(&thr);
+			So(arg.did == 1);
+		});
+
+		Convey("Timeout works", {
+			arg.did  = 0;
+			arg.when = 200000;
+			nni_thr_run(&thr);
+			nni_mtx_lock(&arg.mx);
+			if (!arg.did) {
+				nni_cv_until(&arg.cv, nni_clock() + 10000);
+			}
+			So(arg.did == 0);
+			nni_mtx_unlock(&arg.mx);
+			nni_thr_wait(&thr);
+		});
+
+		Convey("Empty timeout is EAGAIN", {
+			nni_mtx_lock(&arg.mx);
+			So(nni_cv_until(&arg.cv, 0) == NNG_EAGAIN);
+			nni_mtx_unlock(&arg.mx);
+		});
+
+		Convey("Not running works", {
+			arg.did  = 0;
+			arg.when = 1;
+			nni_mtx_lock(&arg.mx);
+			if (!arg.did) {
+				nni_cv_until(&arg.cv, nni_clock() + 10000);
+			}
+			So(arg.did == 0);
+			nni_mtx_unlock(&arg.mx);
+		});
+	});
+}
+#else
+#define ConveyFB(x, y)
+#endif
+
+TestMain("Synchronization", {
+	nni_init();
+
+	Convey("Synchronization works", { test_sync(); });
+
+	ConveyFB("Fallback synchronization works", { test_sync_fallback(); });
+
+	ConveyFB("Transform works", {
+		nni_plat_sync_fallback = 0;
+		nni_mtx_init(&arg.mx);
+		nni_plat_sync_fallback = 1;
+		nni_cv_init(&arg.cv, &arg.mx);
+		So(nni_thr_init(&thr, notifyafter, &arg) == 0);
+
+		arg.did  = 0;
+		arg.when = 10000;
+		nni_thr_run(&thr);
+
+		nni_mtx_lock(&arg.mx);
+		if (!arg.did) {
+			nni_cv_wait(&arg.cv);
+		}
+		nni_mtx_unlock(&arg.mx);
+		nni_thr_wait(&thr);
+		So(arg.did == 1);
+	});
+})