From 56faa3dc8de3189d8c415c6b9fe91385e549a2fc Mon Sep 17 00:00:00 2001
From: Takatoshi Kondo <redboltz@gmail.com>
Date: Mon, 11 Oct 2021 17:26:43 +0900
Subject: [PATCH] Used compare_exchange_weak for decriment and comparison.

---
 example/bench.cpp | 21 ++++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

diff --git a/example/bench.cpp b/example/bench.cpp
index 2c9cea017..8f4851c2c 100644
--- a/example/bench.cpp
+++ b/example/bench.cpp
@@ -18,6 +18,15 @@
 
 namespace as = boost::asio;
 
+template <typename T>
+bool compare_decrement(std::atomic<T>& val, T comp) {
+    T old = val.load();
+    do {
+        if (old == comp) return true;
+    } while (!val.compare_exchange_weak(old, old - 1));
+    return false;
+}
+
 int main(int argc, char **argv) {
     try {
         boost::program_options::options_description desc;
@@ -568,9 +577,7 @@ int main(int argc, char **argv) {
                             async_wait_pub(ci);
                         }
 
-                        if (--rest_times == 0) {
-                            finish_proc();
-                        }
+                        if (compare_decrement(rest_times, std::uint64_t(1))) finish_proc();
                         return true;
                     };
 
@@ -585,7 +592,7 @@ int main(int argc, char **argv) {
                         [&]
                         (bool /*sp*/, MQTT_NS::connect_return_code connack_return_code) {
                             if (connack_return_code == MQTT_NS::connect_return_code::accepted) {
-                                if (--rest_connect == 0) sub_proc();
+                                if (compare_decrement(rest_connect, std::size_t(1))) sub_proc();
                             }
                             else {
                                 std::cout << "connack error:" << connack_return_code << std::endl;
@@ -597,7 +604,7 @@ int main(int argc, char **argv) {
                         [&]
                         (bool /*sp*/, MQTT_NS::v5::connect_reason_code reason_code, MQTT_NS::v5::properties /*props*/) {
                             if (reason_code == MQTT_NS::v5::connect_reason_code::success) {
-                                if (--rest_connect == 0) sub_proc();
+                                if (compare_decrement(rest_connect, std::size_t(1))) sub_proc();
                             }
                             else {
                                 std::cout << "connack error:" << reason_code << std::endl;
@@ -613,7 +620,7 @@ int main(int argc, char **argv) {
                             if (results.front() == MQTT_NS::suback_return_code::success_maximum_qos_0 ||
                                 results.front() == MQTT_NS::suback_return_code::success_maximum_qos_1 ||
                                 results.front() == MQTT_NS::suback_return_code::success_maximum_qos_2) {
-                                if (--rest_sub == 0) pub_proc();
+                                if (compare_decrement(rest_sub, std::size_t(1))) pub_proc();
                             }
                             return true;
                         }
@@ -627,7 +634,7 @@ int main(int argc, char **argv) {
                             if (reasons.front() == MQTT_NS::v5::suback_reason_code::granted_qos_0 ||
                                 reasons.front() == MQTT_NS::v5::suback_reason_code::granted_qos_1 ||
                                 reasons.front() == MQTT_NS::v5::suback_reason_code::granted_qos_2) {
-                                if (--rest_sub == 0) pub_proc();
+                                if (compare_decrement(rest_sub, std::size_t(1))) pub_proc();
                             }
                             return true;
                         }