Abstract backend worker class

include/spdlog/details/backend_worker.h

@@ -0,0 +1,22 @@
+// Copyright(c) 2015-present, Gabi Melman & spdlog contributors.
+// Distributed under the MIT License (http://opensource.org/licenses/MIT)
+
+#pragma once
+
+
+namespace spdlog {
+
+namespace details {
+
+class thread_pool;
+
+class backend_worker : public std::enable_shared_from_this<backend_worker> {
+    friend class thread_pool;
+
+protected:
+    virtual void backend_sink_it_(const details::log_msg &msg) = 0;
+    virtual void backend_flush_() = 0;
+};
+
+}  // namespace details
+}  // namespace spdlog