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gabime
Windows: flush_every stops working when adjusting system clock backwards
Tested using VS2017.
To reproduce:
#include <iostream>
#include <spdlog/spdlog.h>
#include <spdlog/sinks/basic_file_sink.h>
#include <windows.h>
int main()
{
// use Bash from Git for Windows
//
// $ touch app.log
// $ tail -f app.log
auto file_logger = spdlog::basic_logger_mt("default", "app.log");
spdlog::set_default_logger(file_logger);
spdlog::flush_every(std::chrono::seconds(1));
spdlog::info("first");
// change system time to an earlier point, then press enter
//
// C:\>time 10:00
getchar();
// then you won't see this line
spdlog::info("second");
for (;;) { Sleep(1000); }
return 0;
}
Similar to issue #609. But caused by MSVC's buggy implementation of std::condition_variable::wait_for. (According to cppreference, this function must use a steady clock.)
File periodic_worker-inl.h:
SPDLOG_INLINE periodic_worker::periodic_worker(const std::function<void()> &callback_fun, std::chrono::seconds interval)
{
active_ = (interval > std::chrono::seconds::zero());
if (!active_)
{
return;
}
worker_thread_ = std::thread([this, callback_fun, interval]() {
for (;;)
{
std::unique_lock<std::mutex> lock(this->mutex_);
// ↓ THIS LINE
if (this->cv_.wait_for(lock, interval, [this] { return !this->active_; }))
{
return; // active_ == false, so exit this thread
}
callback_fun();
}
});
}
I try to replace std::mutex & std::condition_variable to CRITICAL_SECTION & CONDITION_VARIABLE, then the problem disappears.
Possible (quick and dirty) fix:
- ~~https://github.com/kbridge/spdlog/blob/v1.x/include/spdlog/details/periodic_worker.h~~
- ~~https://github.com/kbridge/spdlog/blob/v1.x/include/spdlog/details/periodic_worker-inl.h~~
↓ See below
Yes. Can't believe g++ has the same issue. These buggy standard libraries... :disappointed:
@gabime Would you like to add a workaround, or leave this to standard library implementors?
Lets leave it - it will never end if spdlog try to reimplement buggy standard lib features. I think it out of spdlog’s scope..
Of course this is out of spdlog's scope!
To be helpful, let me post my workaround here, for people who suffer. Then we can close this issue.
Sure. Thanks. if you could make it portable to gcc as well, it would be super!
spdlog periodic_worker workaround for MSVC
https://gist.github.com/kbridge/251808f0cb7411782c3a2ce5f4877287
I think I will try someday, or maybe someone else. I'm a Windows programmer. Haven't been working with pthreads for a long time.
Related SO: https://stackoverflow.com/questions/47349751/stdconditional-variablewait-for-stdthreadsleep-for-on-windows-are-affec
