Some minor cleanup of PRs

CHANGELOG.md

@@ -38,6 +38,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Completely reformat the sources and added a .clang-format file (a project master and a slightly-different one for headers).
 - Added GitHub CI Action, removing legacy Travis and Appveyor files
 - [#503](https://github.com/eclipse-paho/paho.mqtt.cpp/issues/503) Fixed issue that generated docs were empty.
+- [#518](https://github.com/eclipse-paho/paho.mqtt.cpp/pull/518) Add function for checking async consumer event queue size
+- [#519](https://github.com/eclipse-paho/paho.mqtt.cpp/pull/519) Fix potential deadlock in set_callback
 
 
 ## [Version 1.4.1](https://github.com/eclipse/paho.mqtt.cpp/compare/v1.4.0..v1.4.1) - (2024-07-09)

include/mqtt/async_client.h

@@ -822,11 +822,8 @@ class async_client : public virtual iasync_client
      * as the event count may change between checking the size and actual retrieval.
      * @return the number of events in the queue.
      */
-    std::size_t consumer_events_available() const override {
-        if (que_)
-            return que_->size();
-        else
-            return 0;
+    std::size_t consumer_queue_size() const override {
+        return (que_) ? que_->size() : 0;
     }
     /**
      * Read the next message from the queue.

include/mqtt/iasync_client.h

@@ -483,7 +483,7 @@ class iasync_client
      * as the event count may change between checking the size and actual retrieval.
      * @return the number of events in the queue.
      */
-    virtual std::size_t consumer_events_available() const { return 0; }
+    virtual std::size_t consumer_queue_size() const { return 0; }
     /**
      * Read the next message from the queue.
      * This blocks until a new message arrives.

src/async_client.cpp

@@ -327,10 +327,9 @@ void async_client::set_callback(callback& cb)
             nullptr /*&async_client::on_delivery_complete*/
         );
     }
-    else
+    else {
         MQTTAsync_setConnected(cli_, nullptr, nullptr);
 
-    if (rc != MQTTASYNC_SUCCESS) {
         guard g(lock_);
         userCallback_ = nullptr;
         throw exception(rc);

test/unit/test_async_client.cpp

@@ -1008,21 +1008,21 @@ TEST_CASE("async_client consumer timeout", "[client]")
     cli.try_consume_message_until(std::chrono::steady_clock::now());
 }
 
-TEST_CASE("async_client consumer events available", "[client]")
+TEST_CASE("async_client consumer queue size", "[client]")
 {
     async_client cli{GOOD_SERVER_URI, CLIENT_ID};
     cli.start_consuming();
-    REQUIRE(0 == cli.consumer_events_available());
+    REQUIRE(0 == cli.consumer_queue_size());
 
     token_ptr conn_tok{cli.connect()};
     REQUIRE(conn_tok);
     conn_tok->wait();
     REQUIRE(cli.is_connected());
     // expect connected_event to be in the queue now
-    REQUIRE(1 == cli.consumer_events_available());
+    REQUIRE(1 == cli.consumer_queue_size());
     event e;
     REQUIRE(cli.try_consume_event(&e));
-    REQUIRE(0 == cli.consumer_events_available());
+    REQUIRE(0 == cli.consumer_queue_size());
 
     cli.stop_consuming();
     cli.disconnect()->wait();