polybar-dwm/include/modules/meta/timer_module.hpp
Patrick Ziegler 82ebad5e7a
fix(timer_module): Ensure that interval > 0 (#2274)
Since 3.5.0, we use m_interval for a modulo operation, this crashes the
bar if the interval is 0. A non-positive interval shouldn't be allowed
anyway, so we now throw an exception in that case.

Fixes #2273
2020-12-05 22:58:38 +01:00

78 lines
2.3 KiB
C++

#pragma once
#include "modules/meta/base.hpp"
POLYBAR_NS
namespace modules {
using interval_t = chrono::duration<double>;
template <class Impl>
class timer_module : public module<Impl> {
public:
using module<Impl>::module;
void start() {
this->m_mainthread = thread(&timer_module::runner, this);
}
protected:
/**
* Loads and sets the interval for this module.
*
* Will throw an exception if a non-positive (<= 0) number is given.
*/
void set_interval(interval_t def) {
m_interval = this->m_conf.template get<decltype(m_interval)>(this->name(), "interval", def);
if (m_interval <= 0s) {
throw module_error(
this->name() + ": 'interval' must be larger than 0 (got '" + to_string(m_interval.count()) + "s')");
}
}
void runner() {
this->m_log.trace("%s: Thread id = %i", this->name(), concurrency_util::thread_id(this_thread::get_id()));
const auto check = [&]() -> bool {
std::unique_lock<std::mutex> guard(this->m_updatelock);
return CAST_MOD(Impl)->update();
};
try {
// warm up module output before entering the loop
check();
CAST_MOD(Impl)->broadcast();
while (this->running()) {
if (check()) {
CAST_MOD(Impl)->broadcast();
}
// wait until next full interval to avoid drifting clocks
using clock = chrono::system_clock;
using sys_duration_t = clock::time_point::duration;
auto sys_interval = chrono::duration_cast<sys_duration_t>(m_interval);
clock::time_point now = clock::now();
sys_duration_t adjusted = sys_interval - (now.time_since_epoch() % sys_interval);
// The seemingly arbitrary addition of 500ms is due
// to the fact that if we wait the exact time our
// thread will be woken just a tiny bit prematurely
// and therefore the wrong time will be displayed.
// It is currently unknown why exactly the thread gets
// woken prematurely.
CAST_MOD(Impl)->sleep_until(now + adjusted + 500ms);
}
} catch (const exception& err) {
CAST_MOD(Impl)->halt(err.what());
}
}
protected:
interval_t m_interval{1.0};
};
} // namespace modules
POLYBAR_NS_END