Rearrange sources (#4997)

include/xrpl/beast/clock/basic_seconds_clock.h

@@ -0,0 +1,56 @@
+//------------------------------------------------------------------------------
+/*
+    This file is part of Beast: https://github.com/vinniefalco/Beast
+    Copyright 2013, Vinnie Falco <vinnie.falco@gmail.com>
+
+    Permission to use, copy, modify, and/or distribute this software for any
+    purpose  with  or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+
+    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+#ifndef BEAST_CHRONO_BASIC_SECONDS_CLOCK_H_INCLUDED
+#define BEAST_CHRONO_BASIC_SECONDS_CLOCK_H_INCLUDED
+
+#include <chrono>
+
+namespace beast {
+
+/** A clock whose minimum resolution is one second.
+
+    The purpose of this class is to optimize the performance of the now()
+    member function call. It uses a dedicated thread that wakes up at least
+    once per second to sample the requested trivial clock.
+
+    @tparam Clock A type meeting these requirements:
+        http://en.cppreference.com/w/cpp/concept/Clock
+*/
+class basic_seconds_clock
+{
+public:
+    using Clock = std::chrono::steady_clock;
+
+    explicit basic_seconds_clock() = default;
+
+    using rep = typename Clock::rep;
+    using period = typename Clock::period;
+    using duration = typename Clock::duration;
+    using time_point = typename Clock::time_point;
+
+    static bool const is_steady = Clock::is_steady;
+
+    static time_point
+    now();
+};
+
+}  // namespace beast
+
+#endif