Add basic_seconds_clock, insight::Groups

beast/chrono/basic_seconds_clock.h

@@ -0,0 +1,237 @@
+//------------------------------------------------------------------------------
+/*
+    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 <algorithm>
+#include <chrono>
+
+#ifndef BEAST_BASIC_SECONDS_CLOCK_BOOST_WORKAROUND
+# ifdef _MSC_VER
+// Visual Studio 2012, 2013 have a bug in std::thread that
+// causes a hang on exit, in the library function atexit()
+#  if BEAST_USE_BOOST_FEATURES
+#   define BEAST_BASIC_SECONDS_CLOCK_BOOST_WORKAROUND 1
+#  else
+#   define BEAST_BASIC_SECONDS_CLOCK_BOOST_WORKAROUND 0
+#  endif
+# else
+#  define BEAST_BASIC_SECONDS_CLOCK_BOOST_WORKAROUND 0
+# endif
+#endif
+
+#if BEAST_BASIC_SECONDS_CLOCK_BOOST_WORKAROUND
+# include <boost/version.hpp>
+# if BOOST_VERSION >= 105500
+#  include <boost/thread/thread.hpp>
+#  include <boost/thread/mutex.hpp>
+#  include <boost/thread/condition_variable.hpp>
+#  include <boost/chrono.hpp>
+# else
+#  error "Boost version 1.55.0 or later is required"
+# endif
+#else
+# include <condition_variable>
+# include <mutex>
+# include <thread>
+#endif
+
+#include "../chrono/chrono_util.h"
+
+namespace beast {
+
+namespace detail {
+
+class seconds_clock_worker
+{
+public:
+    virtual void sample () = 0;
+};
+
+//------------------------------------------------------------------------------
+
+// Updates the clocks
+class seconds_clock_thread
+{
+public:
+#if BEAST_BASIC_SECONDS_CLOCK_BOOST_WORKAROUND
+    typedef boost::mutex mutex;
+    typedef boost::condition_variable cond_var;
+    typedef boost::lock_guard <mutex> lock_guard;
+    typedef boost::unique_lock <mutex> unique_lock;
+    typedef boost::chrono::steady_clock clock_type;
+    typedef boost::chrono::seconds seconds;
+    typedef boost::thread thread;
+#else
+    typedef std::mutex mutex;
+    typedef std::condition_variable cond_var;
+    typedef std::lock_guard <mutex> lock_guard;
+    typedef std::unique_lock <mutex> unique_lock;
+    typedef std::chrono::steady_clock clock_type;
+    typedef std::chrono::seconds seconds;
+    typedef std::thread thread;
+#endif
+    typedef std::vector <seconds_clock_worker*> workers;
+
+    bool m_stop;
+    mutex m_mutex;
+    cond_var m_cond;
+    workers m_workers;
+    thread m_thread;
+
+    seconds_clock_thread ()
+        : m_stop (false)
+    {
+        m_thread = thread (std::bind(
+            &seconds_clock_thread::run, this));
+    }
+
+    ~seconds_clock_thread ()
+    {
+        {
+            lock_guard lock (m_mutex);
+            m_stop = true;
+        }
+        m_cond.notify_all();
+        m_thread.join ();
+    }
+
+    void add (seconds_clock_worker& w)
+    {
+        lock_guard lock (m_mutex);
+        m_workers.push_back (&w);
+    }
+
+    void remove (seconds_clock_worker& w)
+    {
+        lock_guard lock (m_mutex);
+        m_workers.erase (std::find (
+            m_workers.begin (), m_workers.end(), &w));
+    }
+
+    void run ()
+    {
+        unique_lock lock (m_mutex);;
+
+        for (;;)
+        {
+            for (auto iter : m_workers)
+                iter->sample();
+
+            clock_type::time_point const when (
+                floor <seconds> (
+                    clock_type::now().time_since_epoch()) +
+                        seconds (1));
+
+            if (m_cond.wait_until (lock, when, [this]{ return m_stop; }))
+                return;
+        }
+    }
+
+    static seconds_clock_thread& instance ()
+    {
+        static seconds_clock_thread singleton;
+        return singleton;
+    }
+};
+
+}
+
+//------------------------------------------------------------------------------
+
+/** 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 TrivialClock The clock to sample.
+*/
+template <class TrivialClock>
+class basic_seconds_clock
+{
+public:
+    typedef std::chrono::seconds resolution;
+    typedef typename resolution::rep rep;
+    typedef typename resolution::period period;
+    typedef std::chrono::duration <rep, period> duration;
+    typedef std::chrono::time_point <basic_seconds_clock> time_point;
+
+    static bool const is_steady = TrivialClock::is_steady;
+
+    static time_point now ()
+    {
+        // Make sure the thread is constructed before the
+        // worker otherwise we will crash during destruction
+        // of objects with static storage duration.
+        struct initializer
+        {
+            initializer ()
+            {
+                detail::seconds_clock_thread::instance();
+            }
+        };
+        static initializer init;
+
+        struct worker : detail::seconds_clock_worker
+        {
+            typedef std::mutex mutex;
+            typedef std::lock_guard <mutex> lock_guard;
+
+            time_point m_now;
+            mutex m_mutex;
+
+            static time_point get_now ()
+            {
+                return time_point (floor <resolution> (
+                    TrivialClock::now().time_since_epoch()));
+            }
+
+            worker ()
+                : m_now (get_now ())
+            {
+                detail::seconds_clock_thread::instance().add (*this);
+            }
+
+            ~worker ()
+            {
+                detail::seconds_clock_thread::instance().remove (*this);
+            }
+
+            time_point now()
+            {
+                lock_guard lock (m_mutex);
+                return m_now;
+            }
+
+            void sample ()
+            {
+                lock_guard lock (m_mutex);
+                m_now = get_now ();
+            }
+        };
+
+        static worker w;
+
+        return w.now ();
+    }
+};
+
+}
+
+#endif