doc: Document the coap_can_exit() function

include/coap3/net.h

@@ -483,7 +483,14 @@ int coap_handle_event(coap_context_t *context,
                       coap_session_t *session);
 /**
  * Returns 1 if there are no messages to send or to dispatch in the context's
- * queues. */
+ * queues.
+ *
+ * @param context The CoAP context to check.
+ *
+ * @return @c 0 if there are still pending transmits else @c 1 if nothing
+ *         queued for transmission.  Note that @c 0 does not mean there has
+ *         been a response to a transmitted request.
+ */
 int coap_can_exit(coap_context_t *context);
 
 /**

man/coap_io.txt.in

@@ -44,6 +44,8 @@ coap_tick_t _now_)*;
 *void coap_io_do_epoll(coap_context_t *_context_, struct epoll_event *_events_,
 size_t _nevents_)*;
 
+*int coap_can_exit(coap_context_t *_context_)*;
+
 For specific (D)TLS library support, link with
 *-lcoap-@LIBCOAP_API_VERSION@-notls*, *-lcoap-@LIBCOAP_API_VERSION@-gnutls*,
 *-lcoap-@LIBCOAP_API_VERSION@-openssl*, *-lcoap-@LIBCOAP_API_VERSION@-mbedtls*
@@ -73,6 +75,10 @@ processing. If _timeout_ms_ is set to COAP_IO_NO_WAIT, then *coap_io_process*()
 will return immediately after processing without waiting for any new input
 packets to arrive.
 
+*NOTE:* *coap_io_process*() should not be called from within a callback
+handler as defined using the coap_register_*_handler() as *coap_io_process*()
+will likely recursively call the same handler.
+
 There are two methods of how to call *coap_io_process*().
 
 1. Have *coap_io_process*() called from within a while() loop.  Under idle
@@ -161,6 +167,11 @@ as an event returned from a *epoll_wait*() call.  This file descriptor will get
 updated with information (read, write etc. available) whenever any of the
 internal to libcoap file descriptors (sockets) change state.
 
+The *coap_can_exit*() function checks to see if there are any outstanding
+PDUs to transmit associated with _context_ and returns 1 if there is nothing
+outstanding else 0. This function does not check that all requests transmitted
+have been responded to.
+
 RETURN VALUES
 -------------
 *coap_io_process*() and *coap_io_process_with_fds*() returns the time, in
@@ -173,6 +184,9 @@ descriptor to monitor, or -1 if epoll is not configured in libcoap.
 *coap_io_prepare_io*() and *coap_io_prepare_epoll*() returns the number of
 milli-seconds that need to be waited before the function should next be called.
 
+*coap_can_exit*() returns 1 if there is nothing outstanding to transmit else
+returns 0.
+
 EXAMPLES
 --------
 *Method One - use coap_io_process()*