fixes #419 want to nni_aio_stop without blocking (#428)

* fixes #419 want to nni_aio_stop without blocking

This actually introduces an nni_aio_close() API that causes
nni_aio_begin to return NNG_ECLOSED, while scheduling a callback
on the AIO to do an NNG_ECLOSED as well.  This should be called
in non-blocking close() contexts instead of nni_aio_stop(), and
the cases where we call nni_aio_fini() multiple times are updated
updated to add nni_aio_stop() calls on all "interlinked" aios before
finalizing them.

Furthermore, we call nni_aio_close() as soon as practical in the
close path.  This closes an annoying race condition where the
callback from a lower subsystem could wind up rescheduling an
operation that we wanted to abort.

1 files changed, 13 insertions, 6 deletions

diff --git a/src/protocol/reqrep0/req.c b/src/protocol/reqrep0/req.c
index bbb0b886..fc9d7271 100644
--- a/src/protocol/reqrep0/req.c
+++ b/src/protocol/reqrep0/req.c
@@ -186,6 +186,15 @@ req0_sock_fini(void *arg)
 }
 
 static void
+req0_pipe_stop(void *arg)
+{
+	req0_pipe *p = arg;
+
+	nni_aio_stop(p->aio_recv);
+	nni_aio_stop(p->aio_send);
+}
+
+static void
 req0_pipe_fini(void *arg)
 {
 	req0_pipe *p = arg;
@@ -243,17 +252,14 @@ req0_pipe_start(void *arg)
 }
 
 static void
-req0_pipe_stop(void *arg)
+req0_pipe_close(void *arg)
 {
 	req0_pipe *p = arg;
 	req0_sock *s = p->req;
 	req0_ctx * ctx;
 
-	nni_aio_stop(p->aio_recv);
-	nni_aio_stop(p->aio_send);
-
-	// At this point there should not be any further AIOs running.
-	// Further, any completion tasks have completed.
+	nni_aio_close(p->aio_recv);
+	nni_aio_close(p->aio_send);
 
 	nni_mtx_lock(&s->mtx);
 	// This removes the node from either busypipes or readypipes.
@@ -837,6 +843,7 @@ static nni_proto_pipe_ops req0_pipe_ops = {
 	.pipe_init  = req0_pipe_init,
 	.pipe_fini  = req0_pipe_fini,
 	.pipe_start = req0_pipe_start,
+	.pipe_close = req0_pipe_close,
 	.pipe_stop  = req0_pipe_stop,
 };