use nonblock for request() ack

DESCRIPTION

@@ -1,7 +1,7 @@
 Package: nanonext
 Type: Package
 Title: NNG (Nanomsg Next Gen) Lightweight Messaging Library
-Version: 0.10.2.9018
+Version: 0.10.2.9019
 Description: R binding for NNG (Nanomsg Next Gen), a successor to ZeroMQ. NNG is
     a socket library implementing 'Scalability Protocols', a reliable,
     high-performance standard for common communications patterns including

NEWS.md

@@ -1,4 +1,4 @@
-# nanonext 0.10.2.9018 (development)
+# nanonext 0.10.2.9019 (development)
 
 #### New Features
 
@@ -10,6 +10,7 @@
 * `lock()` supplying 'cv' has improved behaviour which locks the socket whilst allowing for both initial connections and re-connections (when the 'cv' is registered for both add and remove pipe events).
 * Improves listener / dialer logic for TLS connections, allowing *inter alia* synchronous dials.
 * `pipe_notify()` arguments 'add', 'remove' and 'flag' now default to FALSE instead of TRUE for easier selective specification of the events to signal.
+* `request()` argument 'ack' behaviour is more robust.
 * Fixes memory leaks detected with valgrind.
 * Upgrades bundled 'libmbedtls' to v 3.5.0.
 

src/aio.c

@@ -256,7 +256,7 @@ static void raio_complete_ack(void *arg) {
 #else
 
   if (nng_msg_alloc(&msg, 0) == 0) {
-    if (nng_ctx_sendmsg(*ctx, msg, 0))
+    if (nng_ctx_sendmsg(*ctx, msg, NNG_FLAG_NONBLOCK))
       nng_msg_free(msg);
   }
   raio->result = res - !res;