Files
xahaud/src/ripple/beast/clock/basic_seconds_clock.cpp
Howard Hinnant 32a26a65d9 Make basic_seconds_clock::time_point atomic
* Just the rep is made atomic to workaround older compilers
2021-12-14 17:47:04 -08:00

107 lines
2.8 KiB
C++

//------------------------------------------------------------------------------
/*
This file is part of Beast: https://github.com/vinniefalco/Beast
Copyright 2021, Howard Hinnant <howard.hinnant@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.
*/
//==============================================================================
#include <ripple/beast/clock/basic_seconds_clock.h>
#include <atomic>
#include <cassert>
#include <chrono>
#include <condition_variable>
#include <mutex>
#include <thread>
namespace beast {
namespace {
// Updates the clock
class seconds_clock_thread
{
using Clock = basic_seconds_clock::Clock;
bool stop_;
std::mutex mut_;
std::condition_variable cv_;
std::thread thread_;
std::atomic<Clock::time_point::rep> tp_;
public:
~seconds_clock_thread();
seconds_clock_thread();
Clock::time_point
now();
private:
void
run();
};
static_assert(std::atomic<std::chrono::steady_clock::rep>::is_always_lock_free);
seconds_clock_thread::~seconds_clock_thread()
{
assert(thread_.joinable());
{
std::lock_guard lock(mut_);
stop_ = true;
} // publish stop_ asap so if waiting thread times-out, it will see it
cv_.notify_one();
thread_.join();
}
seconds_clock_thread::seconds_clock_thread()
: stop_{false}, tp_{Clock::now().time_since_epoch().count()}
{
thread_ = std::thread(&seconds_clock_thread::run, this);
}
seconds_clock_thread::Clock::time_point
seconds_clock_thread::now()
{
return Clock::time_point{Clock::duration{tp_.load()}};
}
void
seconds_clock_thread::run()
{
std::unique_lock lock(mut_);
while (true)
{
using namespace std::chrono;
auto now = Clock::now();
tp_ = now.time_since_epoch().count();
auto const when = floor<seconds>(now) + 1s;
if (cv_.wait_until(lock, when, [this] { return stop_; }))
return;
}
}
} // unnamed namespace
basic_seconds_clock::time_point
basic_seconds_clock::now()
{
static seconds_clock_thread clk;
return clk.now();
}
} // namespace beast