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.

6 files changed, 12 insertions, 23 deletions

diff --git a/src/platform/windows/win_iocp.c b/src/platform/windows/win_iocp.c
index c4cdcb8a..9c3343b7 100644
--- a/src/platform/windows/win_iocp.c
+++ b/src/platform/windows/win_iocp.c
@@ -174,17 +174,14 @@ nni_win_iocp_register(HANDLE h)
 int
 nni_win_event_init(nni_win_event *evt, nni_win_event_ops *ops, void *ptr)
 {
-	int rv;
-
 	ZeroMemory(&evt->olpd, sizeof(evt->olpd));
 	evt->olpd.hEvent = CreateEvent(NULL, TRUE, TRUE, NULL);
 	if (evt->olpd.hEvent == NULL) {
 		return (nni_win_error(GetLastError()));
 	}
-	if (((rv = nni_mtx_init(&evt->mtx)) != 0) ||
-	    ((rv = nni_cv_init(&evt->cv, &evt->mtx)) != 0)) {
-		return (rv); // NB: This will never happen on Windows.
-	}
+	nni_mtx_init(&evt->mtx);
+	nni_cv_init(&evt->cv, &evt->mtx);
+
 	evt->ops  = *ops;
 	evt->aio  = NULL;
 	evt->ptr  = ptr;
@@ -240,9 +237,7 @@ nni_win_iocp_sysinit(void)
 			goto fail;
 		}
 	}
-	if ((rv = nni_mtx_init(&nni_win_iocp_mtx)) != 0) {
-		goto fail;
-	}
+	nni_mtx_init(&nni_win_iocp_mtx);
 	for (i = 0; i < NNI_WIN_IOCP_NTHREADS; i++) {
 		nni_thr_run(&nni_win_iocp_thrs[i]);
 	}
diff --git a/src/platform/windows/win_ipc.c b/src/platform/windows/win_ipc.c
index c9eb20ec..a60815fa 100644
--- a/src/platform/windows/win_ipc.c
+++ b/src/platform/windows/win_ipc.c
@@ -566,10 +566,9 @@ nni_win_ipc_sysinit(void)
 	NNI_LIST_INIT(&worker->workers, nni_plat_ipc_ep, node);
 	NNI_LIST_INIT(&worker->waiters, nni_plat_ipc_ep, node);
 
-	if (((rv = nni_mtx_init(&worker->mtx)) != 0) ||
-	    ((rv = nni_cv_init(&worker->cv, &worker->mtx)) != 0)) {
-		return (rv);
-	}
+	nni_mtx_init(&worker->mtx);
+	nni_cv_init(&worker->cv, &worker->mtx);
+
 	rv = nni_thr_init(&worker->thr, nni_win_ipc_conn_thr, worker);
 	if (rv != 0) {
 		return (rv);
diff --git a/src/platform/windows/win_net.c b/src/platform/windows/win_net.c
index 63295a71..80e3724d 100644
--- a/src/platform/windows/win_net.c
+++ b/src/platform/windows/win_net.c
@@ -680,8 +680,6 @@ int
 nni_win_tcp_sysinit(void)
 {
 	WSADATA data;
-	WORD    ver;
-	ver = MAKEWORD(2, 2);
 	if (WSAStartup(MAKEWORD(2, 2), &data) != 0) {
 		NNI_ASSERT(LOBYTE(data.wVersion) == 2);
 		NNI_ASSERT(HIBYTE(data.wVersion) == 2);
diff --git a/src/platform/windows/win_pipe.c b/src/platform/windows/win_pipe.c
index 861fbc76..edc4df3f 100644
--- a/src/platform/windows/win_pipe.c
+++ b/src/platform/windows/win_pipe.c
@@ -19,9 +19,9 @@
 int
 nni_plat_pipe_open(int *wfdp, int *rfdp)
 {
-	SOCKET afd = INVALID_SOCKET;
 	SOCKET rfd = INVALID_SOCKET;
 	SOCKET wfd = INVALID_SOCKET;
+	SOCKET afd;
 
 	struct sockaddr_in addr;
 	socklen_t          alen;
diff --git a/src/platform/windows/win_resolv.c b/src/platform/windows/win_resolv.c
index a01dc123..4ce12d84 100644
--- a/src/platform/windows/win_resolv.c
+++ b/src/platform/windows/win_resolv.c
@@ -254,9 +254,8 @@ nni_win_resolv_sysinit(void)
 {
 	int rv;
 
-	if ((rv = nni_mtx_init(&nni_win_resolv_mtx)) != 0) {
-		return (rv);
-	}
+	nni_mtx_init(&nni_win_resolv_mtx);
+
 	if ((rv = nni_taskq_init(&nni_win_resolv_tq, 4)) != 0) {
 		nni_mtx_fini(&nni_win_resolv_mtx);
 		return (rv);
diff --git a/src/platform/windows/win_thread.c b/src/platform/windows/win_thread.c
index c01ec782..879cd772 100644
--- a/src/platform/windows/win_thread.c
+++ b/src/platform/windows/win_thread.c
@@ -30,12 +30,11 @@ nni_free(void *b, size_t z)
 	HeapFree(GetProcessHeap(), 0, b);
 }
 
-int
+void
 nni_plat_mtx_init(nni_plat_mtx *mtx)
 {
 	InitializeSRWLock(&mtx->srl);
 	mtx->init = 1;
-	return (0);
 }
 
 void
@@ -56,12 +55,11 @@ nni_plat_mtx_unlock(nni_plat_mtx *mtx)
 	ReleaseSRWLockExclusive(&mtx->srl);
 }
 
-int
+void
 nni_plat_cv_init(nni_plat_cv *cv, nni_plat_mtx *mtx)
 {
 	InitializeConditionVariable(&cv->cv);
 	cv->srl = &mtx->srl;
-	return (0);
 }
 
 void