Added custom error handler support to async sink

include/spdlog/details/err_helper.h

@@ -18,6 +18,5 @@ public:
     void handle_unknown_ex(const std::string& origin, const source_loc& loc) const noexcept;
     void set_err_handler(err_handler handler);
 };
-
+} // namespace details
-
+} // namespace spdlog
-}} // namespace spdlog::details

include/spdlog/sinks/async_sink.h

@@ -42,7 +42,7 @@ public:
         err_handler custom_err_handler = nullptr;
     };
 
-    explicit async_sink(config async_config);
+    explicit async_sink(const config &async_config);
 
     // create an async_sink with one backend sink
     template <typename Sink, typename... SinkArgs>

src/sinks/async_sink.cpp

@@ -14,11 +14,15 @@
 namespace spdlog {
 namespace sinks {
 
-async_sink::async_sink(config async_config)
+async_sink::async_sink(const config &async_config)
-    : config_(std::move(async_config)) {
+    : config_(async_config) {
     if (config_.queue_size == 0 || config_.queue_size > max_queue_size) {
         throw spdlog_ex("async_sink: invalid queue size");
     }
+    if (config_.custom_err_handler) {
+        err_helper_.set_err_handler(config_.custom_err_handler);
+    }
+
     q_ = std::make_unique<queue_t>(config_.queue_size);
     worker_thread_ = std::thread([this] {
         if (config_.on_thread_start) config_.on_thread_start();

tests/test_async.cpp

@@ -295,3 +295,17 @@ TEST_CASE("backend_ex", "[async]") {
     REQUIRE_NOTHROW(logger->info("Hello message"));
     REQUIRE_NOTHROW(logger->flush());
 }
+
+// test async custom error handler. trigger it using a backend exception and make sure it's called
+TEST_CASE("custom_err_handler", "[async]") {
+    bool error_called = false;
+    auto test_sink = std::make_shared<test_sink_mt>();
+    test_sink->set_exception(std::runtime_error("test backend exception"));
+    async_sink::config config;
+    config.sinks.push_back(std::move(test_sink));
+    config.custom_err_handler = [&error_called](const std::string &) { error_called = true;};
+    auto asink = std::make_shared<async_sink>(config);
+    spdlog::logger ("async_logger", std::move(asink)).info("Test");
+    // lvalue logger so will be destructed here already so all messages were processed
+    REQUIRE(error_called);
+}