profile_timer.cpp

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#ifdef BUILD_PROFILED
 
#include <cstdlib>
#include <cstring>
#include "profile_timer.hpp"
 
std::chrono::steady_clock::time_point Profiler::start_point;
 
Profiler& Profiler::get_instance(){
        static Profiler inst;
        static std::mutex mut;
        std::lock_guard<std::mutex> lock(mut);
        if(inst.start_point.time_since_epoch() == std::chrono::steady_clock::duration::zero()){
                inst.start_point = std::chrono::steady_clock::now();
        }
        return inst;
}
 
void Profiler::write_events(const std::vector<Profile_event>& events){
        if(!active)
                return;
 
        std::lock_guard<std::mutex> lock(io_mut);
        for(const auto& event : events){
 
                auto ts = event.start;
                auto end = event.end;
                out_file << "{ \"name\": \"" << event.name << "\""
                        << ", \"cat\": \"function\""
                        << ", \"ph\": \"X\""
                        << ", \"pid\": \"" << pid << "\""
                        << ", \"tid\": \"" << event.thread_id << "\""
                        << ", \"ts\": \"" << ts << "\""
                        << ", \"dur\": \"" << end - ts << "\""
                        << ", \"dbg_end\": \"" << end << "\""
                        << "},\n ";
        }
}
 
Profiler::Profiler(){
        const char *env_p = std::getenv("UG_PROFILE");
        active = env_p && env_p[0] != '\0';
        if(!active){
                return;
        }
 
        std::string filename = "ug_";
        filename += env_p;
        filename += ".json";
 
        pid = std::this_thread::get_id();
        out_file.open(filename);
 
        out_file << "[ ";
}
 
Profiler_thread_inst::Profiler_thread_inst(Profiler& profiler) : profiler(profiler) {
        thread_events.reserve(THREAD_EVENT_BUF_SIZE);
        c_timers.reserve(20);
}
 
Profiler_thread_inst& Profiler_thread_inst::get_instance(){
        static thread_local Profiler_thread_inst inst(Profiler::get_instance());
        return inst;
}
 
Profiler_thread_inst::~Profiler_thread_inst(){
        profiler.write_events(thread_events);
}
 
void Profiler_thread_inst::add_event(Profile_event&& event){
        if(thread_events.size() == THREAD_EVENT_BUF_SIZE){
                profiler.write_events(thread_events);
                thread_events.clear();
        }
 
        thread_events.emplace_back(std::move(event));
}
 
void Profiler_thread_inst::push_timer(const char *name){
        c_timers.emplace_back(std::ref(*this), std::string(name));
}
 
void Profiler_thread_inst::pop_timer(){
        c_timers.pop_back();
}
 
Profile_timer::Profile_timer(Profiler_thread_inst& profiler, std::string name) :
        profiler(profiler),
        event(name, std::this_thread::get_id())
{
        auto ts = std::chrono::duration_cast<std::chrono::microseconds>(std::chrono::steady_clock::now() - profiler.profiler.get_start_point()).count();
 
        /* Chromium has problems if two events within the same thread have
         * the same start time. To work around this we just add a microsecond
         * if the start time would be the same as the previous one
         */
        if(ts <= profiler.last_ts){
                ts = profiler.last_ts + 1;
        }
 
        event.start = ts;
        profiler.last_ts = ts;
}
 
Profile_timer::Profile_timer(Profile_timer&& o) :
        profiler(o.profiler)
{
        std::swap(event, o.event);
}
 
Profile_timer::~Profile_timer(){
        commit();
}
 
Profile_timer& Profile_timer::operator=(Profile_timer&& rhs) {
        std::swap(event, rhs.event);
        std::swap(profiler, rhs.profiler);
        return *this;
}
 
void Profile_timer::commit(){
        if(event.name.empty())
                return;
 
        event.end = std::chrono::duration_cast<std::chrono::microseconds>(std::chrono::steady_clock::now() - profiler.get().profiler.get_start_point()).count();
        profiler.get().add_event(std::move(event));
}
 
void push_prof_timer(const char *name){
        Profiler_thread_inst::get_instance().push_timer(name);
}
 
void pop_prof_timer(){
        Profiler_thread_inst::get_instance().pop_timer();
}
 
#endif //BUILD_PROFILED