fixes #334 Separate context for state machines from sockets

This provides context support for REQ and REP sockets.
More discussion around this is in the issue itself.

Optionally we would like to extend this to the surveyor pattern.

Note that we specifically do not support pollable descriptors
for non-default contexts, and the results of using file descriptors
for polling (NNG_OPT_SENDFD and NNG_OPT_RECVFD) is undefined.

In the future, it might be nice to figure out how to factor in
optional use of a message queue for users who want more buffering,
but we think there is little need for this with cooked mode.

1 files changed, 101 insertions, 0 deletions

diff --git a/src/core/pollable.c b/src/core/pollable.c
new file mode 100644
index 00000000..b5cecf37
--- /dev/null
+++ b/src/core/pollable.c
@@ -0,0 +1,101 @@
+//
+// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2018 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 "core/nng_impl.h"
+
+struct nni_pollable {
+	int     p_rfd;
+	int     p_wfd;
+	nni_mtx p_lock;
+	bool    p_raised;
+	bool    p_open;
+};
+
+int
+nni_pollable_alloc(nni_pollable **pp)
+{
+	nni_pollable *p;
+	if ((p = NNI_ALLOC_STRUCT(p)) == NULL) {
+		return (NNG_ENOMEM);
+	}
+	p->p_open   = false;
+	p->p_raised = false;
+	nni_mtx_init(&p->p_lock);
+	*pp = p;
+	return (0);
+}
+
+void
+nni_pollable_free(nni_pollable *p)
+{
+	if (p == NULL) {
+		return;
+	}
+	if (p->p_open) {
+		nni_plat_pipe_close(p->p_rfd, p->p_wfd);
+	}
+	nni_mtx_fini(&p->p_lock);
+	NNI_FREE_STRUCT(p);
+}
+
+void
+nni_pollable_raise(nni_pollable *p)
+{
+	if (p == NULL) {
+		return;
+	}
+	nni_mtx_lock(&p->p_lock);
+	p->p_raised = true;
+	if (p->p_open) {
+		nni_mtx_unlock(&p->p_lock);
+		nni_plat_pipe_raise(p->p_wfd);
+		return;
+	}
+	nni_mtx_unlock(&p->p_lock);
+}
+
+void
+nni_pollable_clear(nni_pollable *p)
+{
+	if (p == NULL) {
+		return;
+	}
+	nni_mtx_lock(&p->p_lock);
+	p->p_raised = false;
+	if (p->p_open) {
+		nni_mtx_unlock(&p->p_lock);
+		nni_plat_pipe_clear(p->p_rfd);
+		return;
+	}
+	nni_mtx_unlock(&p->p_lock);
+}
+
+int
+nni_pollable_getfd(nni_pollable *p, int *fdp)
+{
+	if (p == NULL) {
+		return (NNG_EINVAL);
+	}
+	nni_mtx_lock(&p->p_lock);
+	if (!p->p_open) {
+		int rv;
+		if ((rv = nni_plat_pipe_open(&p->p_wfd, &p->p_rfd)) != 0) {
+			nni_mtx_unlock(&p->p_lock);
+			return (rv);
+		}
+		p->p_open = true;
+		if (p->p_raised) {
+			nni_plat_pipe_raise(p->p_wfd);
+		}
+	}
+	nni_mtx_unlock(&p->p_lock);
+	*fdp = p->p_rfd;
+	return (0);
+}