update and change how we build with spdlog

third_party/spdlog/include/spdlog/details/backtracer.h

@@ -0,0 +1,46 @@
+// Copyright(c) 2015-present, Gabi Melman & spdlog contributors.
+// Distributed under the MIT License (http://opensource.org/licenses/MIT)
+
+#pragma once
+
+#include "spdlog/details/log_msg_buffer.h"
+#include "spdlog/details/circular_q.h"
+
+#include <atomic>
+#include <mutex>
+#include <functional>
+
+// Store log messages in circular buffer.
+// Useful for storing debug data in case of error/warning happens.
+
+namespace spdlog {
+namespace details {
+class backtracer
+{
+    mutable std::mutex mutex_;
+    std::atomic<bool> enabled_{false};
+    circular_q<log_msg_buffer> messages_;
+
+public:
+    backtracer() = default;
+    backtracer(const backtracer &other);
+
+    backtracer(backtracer &&other) SPDLOG_NOEXCEPT;
+    backtracer &operator=(backtracer other);
+
+    void enable(size_t size);
+    void disable();
+    bool enabled() const;
+    explicit operator bool() const;
+    void push_back(const log_msg &msg);
+
+    // pop all items in the q and apply the given fun on each of them.
+    void foreach_pop(std::function<void(const details::log_msg &)> fun);
+};
+
+} // namespace details
+} // namespace spdlog
+
+#ifdef SPDLOG_HEADER_ONLY
+#include "backtracer-inl.h"
+#endif