perf.h

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#ifndef ZTH_PERF_H
#define ZTH_PERF_H
/*
 * Zth (libzth), a cooperative userspace multitasking library.
 * Copyright (C) 2019-2022  Jochem Rutgers
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at https://mozilla.org/MPL/2.0/.
 */
 
#include <libzth/macros.h>
 
#ifdef __cplusplus
 
#       include <libzth/allocator.h>
#       include <libzth/config.h>
#       include <libzth/time.h>
#       include <libzth/util.h>
 
#       include <cstdio>
#       include <cstdlib>
#       include <cstring>
 
namespace zth {
 
int perf_init();
void perf_deinit();
 
class Fiber;
 
UniqueID<Fiber> const& currentFiberID() noexcept;
 
class Backtrace {
        ZTH_CLASS_NEW_DELETE(Backtrace)
public:
        typedef vector_type<void*>::type bt_type;
 
        explicit Backtrace(size_t skip = 0, size_t maxDepth = 128);
        Fiber* fiber() const noexcept
        {
                return m_fiber;
        }
 
        uint64_t fiberId() const noexcept
        {
                return m_fiberId;
        }
 
        bt_type const& bt() const noexcept
        {
                return m_bt;
        }
 
        bool truncated() const noexcept
        {
                return m_truncated;
        }
 
        Timestamp const& t0() const noexcept
        {
                return m_t0;
        }
 
        Timestamp const& t1() const noexcept
        {
                return m_t1;
        }
 
        void printPartial(size_t start, ssize_t end = -1, int color = -1) const;
        void print(int color = -1) const;
        void printDelta(Backtrace const& other, int color = -1) const;
 
private:
        Timestamp m_t0;
        Timestamp m_t1;
        Fiber* m_fiber;
        uint64_t m_fiberId;
        bt_type m_bt;
        bool m_truncated;
};
 
template <bool Enable = Config::EnablePerfEvent>
struct PerfEvent {
        enum Type { Nothing, FiberName, FiberState, Log, Marker };
 
        constexpr PerfEvent() noexcept
                : fiber()
                , type(Nothing)
                , unused()
        {}
 
        explicit PerfEvent(UniqueID<Fiber> const& fiber)
                : fiber(fiber.id())
                , type(FiberName)
                , str(strdup(fiber.name().c_str()))
        {}
 
        PerfEvent(
                UniqueID<Fiber> const& fiber, int state,
                Timestamp const& t = Timestamp::now()) noexcept
                : t(t)
                , fiber(fiber.id())
                , type(FiberState)
                , fiberState(state)
        {}
 
        PerfEvent(
                UniqueID<Fiber> const& fiber, string const& str,
                Timestamp const& t = Timestamp::now())
                : t(t)
                , fiber(fiber.id())
                , type(Log)
                , str(strdup(str.c_str()))
        {}
 
        PerfEvent(
                UniqueID<Fiber> const& fiber, char const* marker,
                Timestamp const& t = Timestamp::now()) noexcept
                : t(t)
                , fiber(fiber.id())
                , type(Marker)
                , c_str(marker)
        {}
 
        __attribute__((format(ZTH_ATTR_PRINTF, 4, 5)))
        PerfEvent(UniqueID<Fiber> const& fiber, Timestamp const& t, char const* fmt, ...)
                : t(t)
                , fiber(fiber.id())
                , type(Log)
        {
                va_list args;
                va_start(args, fmt);
                if(vasprintf(&str, fmt, args) == -1)
                        str = nullptr;
                va_end(args);
        }
 
        __attribute__((format(ZTH_ATTR_PRINTF, 4, 0)))
        PerfEvent(UniqueID<Fiber> const& fiber, Timestamp const& t, char const* fmt, va_list args)
                : t(t)
                , fiber(fiber.id())
                , type(Log)
        {
                if(vasprintf(&str, fmt, args) == -1)
                        str = nullptr;
        }
 
        // Use default copy/move-ctor and copy/move-assignment, which
        // duplicate the allocated string pointers.  In that case, only
        // one of the copies must be release()d later on.
 
        // release() is called by PerfFiber (see perf.cpp), not by the dtor of PerfEvent.
        void release() const
        {
                switch(type) {
                case FiberName:
                case Log:
                        free(str);
                        break;
                default:;
                }
        }
 
        Timestamp t;
        uint64_t fiber;
        Type type;
 
        union {
                void* unused;
                char* str;
                char const* c_str;
                int fiberState;
        };
};
 
#       pragma GCC diagnostic push
#       pragma GCC diagnostic ignored "-Wunused-parameter"
template <>
struct PerfEvent<false> {
        enum Type { Nothing, FiberName, FiberState, Log, Marker };
 
        constexpr PerfEvent() noexcept
                : unused()
        {}
 
        constexpr explicit PerfEvent(UniqueID<Fiber> const& fiber) noexcept
                : unused()
        {}
 
        constexpr PerfEvent(
                UniqueID<Fiber> const& fiber, int state, Timestamp const& t = Timestamp()) noexcept
                : unused()
        {}
 
        constexpr PerfEvent(
                UniqueID<Fiber> const& fiber, string const& str,
                Timestamp const& t = Timestamp()) noexcept
                : unused()
        {}
 
        constexpr PerfEvent(
                UniqueID<Fiber> const& fiber, char const* marker,
                Timestamp const& t = Timestamp()) noexcept
                : unused()
        {}
 
        __attribute__((format(ZTH_ATTR_PRINTF, 4, 5))) constexpr PerfEvent(
                UniqueID<Fiber> const& fiber, Timestamp const& t, char const* fmt, ...) noexcept
                : unused()
        {}
 
        __attribute__((format(ZTH_ATTR_PRINTF, 4, 0))) PerfEvent(
                UniqueID<Fiber> const& fiber, Timestamp const& t, char const* fmt,
                va_list args) noexcept
                : unused()
        {}
 
        void release() const noexcept {}
 
        union {
                void* unused;
                struct timespec t;
                uint64_t fiber;
                Type type;
                char* str;
                char const* c_str;
                int fiberState;
        };
};
#       pragma GCC diagnostic pop
 
typedef vector_type<PerfEvent<> >::type perf_eventBuffer_type;
ZTH_TLS_DECLARE(perf_eventBuffer_type*, perf_eventBuffer)
 
void perf_flushEventBuffer() noexcept;
 
#       if __cplusplus >= 201103L
// Construct PerfEvent in-place in buffer.
template <typename... Args>
inline void perf_event(Args&&... args) noexcept
{
        if(!Config::EnablePerfEvent || unlikely(!perf_eventBuffer)) {
                // Drop, as there is no event buffer...
                return;
        }
 
        try {
                perf_eventBuffer->emplace_back(std::forward<Args>(args)...);
        } catch(...) {
                // Cannot allocate buffer. Drop.
                return;
        }
 
        zth_assert(perf_eventBuffer->size() <= Config::PerfEventBufferSize);
 
        if(unlikely(perf_eventBuffer->size() >= Config::PerfEventBufferThresholdToTriggerVCDWrite))
                perf_flushEventBuffer();
}
 
#               define zth_perf_event(...) zth::perf_event(__VA_ARGS__)
#       else
// Copy PerfEvent into buffer.
inline void perf_event(PerfEvent<> const& event) noexcept
{
        if(!Config::EnablePerfEvent || unlikely(!perf_eventBuffer)) {
                // Release now, as there is no event buffer...
                event.release();
                return;
        }
 
        try {
                perf_eventBuffer->push_back(event);
        } catch(...) {
                // Cannot allocate buffer. Release now and drop.
                event.release();
                return;
        }
 
        zth_assert(perf_eventBuffer->size() <= Config::PerfEventBufferSize);
 
        if(unlikely(perf_eventBuffer->size() >= Config::PerfEventBufferThresholdToTriggerVCDWrite))
                perf_flushEventBuffer();
}
 
#               define zth_perf_event(...) zth::perf_event(PerfEvent<>(__VA_ARGS__))
#       endif
 
ZTH_EXPORT inline void perf_mark(char const* marker)
{
        if(Config::EnablePerfEvent)
                zth_perf_event(currentFiberID(), marker);
}
 
ZTH_EXPORT __attribute__((format(ZTH_ATTR_PRINTF, 1, 2))) inline void perf_log(char const* fmt, ...)
{
        if(!Config::EnablePerfEvent)
                return;
 
        va_list args;
        va_start(args, fmt);
        zth_perf_event(currentFiberID(), Timestamp::now(), fmt, args);
        va_end(args);
}
 
ZTH_EXPORT __attribute__((format(ZTH_ATTR_PRINTF, 1, 0))) inline void
perf_logv(char const* fmt, va_list args)
{
        if(Config::EnablePerfEvent)
                zth_perf_event(currentFiberID(), Timestamp::now(), fmt, args);
}
 
inline void perf_syscall(char const* syscall, Timestamp const& t = Timestamp())
{
        if(Config::EnablePerfEvent && zth_config(PerfSyscall))
                zth_perf_event(currentFiberID(), syscall, t.isNull() ? Timestamp::now() : t);
}
 
template <typename T = float>
class Load {
        ZTH_CLASS_NEW_DELETE(Load)
public:
        typedef T type;
 
        explicit Load(type rc = 1) noexcept
                : m_rc(rc)
                , m_active()
                , m_current(Timestamp::now())
                , m_load()
        {}
 
        type rc() const noexcept
        {
                return m_rc;
        }
 
        void setRc(type rc) noexcept
        {
                m_rc = rc;
        }
 
        void start(Timestamp const& now = Timestamp::now()) noexcept
        {
                if(isActive())
                        return;
 
                idle((type)(now - m_current).s());
                m_current = now;
                m_active = true;
        }
 
        void stop(Timestamp const& now = Timestamp::now()) noexcept
        {
                if(!isActive())
                        return;
 
                active((type)(now - m_current).s());
                m_current = now;
                m_active = false;
        }
 
        bool isActive() const noexcept
        {
                return m_active;
        }
 
        type load() const noexcept
        {
                return m_load;
        }
 
        type load(Timestamp const& now) const noexcept
        {
                type dt_s = (type)(now - m_current).s();
                if(isActive())
                        return active(load(), dt_s);
                else
                        return idle(load(), dt_s);
        }
 
        void idle(type dt_s) noexcept
        {
                m_load = idle(load(), dt_s);
        }
 
        void active(type dt_s) noexcept
        {
                m_load = active(load(), dt_s);
        }
 
protected:
        type idle(type load, type dt_s) const noexcept
        {
                if(dt_s <= 0)
                        return load;
 
                return ((type)1 - alpha(dt_s)) * load;
        }
 
        type active(type load, type dt_s) const noexcept
        {
                if(dt_s <= 0)
                        return load;
 
                type a = alpha(dt_s);
                return a + ((type)1 - a) * load;
        }
 
        type alpha(type dt_s) const noexcept
        {
                return dt_s / (rc() + dt_s);
        }
 
private:
        type m_rc;
        bool m_active;
        Timestamp m_current;
        type m_load;
};
 
template <typename T = float, size_t Bins = 2, typename Count = uint_fast32_t>
class EventRate {
        ZTH_CLASS_NEW_DELETE(EventRate)
public:
        typedef T type;
        typedef Count count_type;
 
        explicit EventRate(type window = 1) noexcept
                : m_window_s(window)
                , m_window(window)
                , m_binStart()
                , m_bins()
                , m_current()
        {
                static_assert(std::numeric_limits<decltype(m_current)>::max() >= Bins, "");
        }
 
        void event(Timestamp const& now = Timestamp::now()) noexcept
        {
                size_t b = 0;
                for(; m_binStart + m_window < now && b < Bins; b++) {
                        // Proceed to next bin.
                        m_current = (m_current + 1U) % Bins;
                        m_bins[m_current] = 0;
                        m_binStart += m_window;
                }
 
                if(unlikely(b == Bins)) {
                        // Cleared all bins. Apparently, m_binStart was a long time ago.
                        m_binStart = now;
                }
 
                m_bins[m_current]++;
        }
 
        void operator()(Timestamp const& now = Timestamp::now()) noexcept
        {
                event(now);
        }
 
        type rate(Timestamp const& now = Timestamp::now()) const noexcept
        {
                type w = (type)(now - m_binStart).s() / m_window_s;
 
                if(unlikely(w > 1)) {
                        if(w > 2)
                                return 0; // We are really late.
 
                        w = 1;
                }
 
                // Scale the first bin, such that it is gradually removed from the average.
                type first_bin = ((type)1 - w) * (type)m_bins[(m_current + 1U) % Bins];
                // Last bin only holds events from [m_binStart,now[, no scaling required.
                type last_bin = (type)m_bins[m_current];
 
                // Sum all intermediate bins.
                type sum = first_bin + last_bin;
                for(decltype(m_current + 0) i = 2; i < Bins; i++)
                        sum += (type)m_bins[(m_current + i) % Bins];
 
                // As the first and last one are both partial, divide by Bins - 1.
                return sum * ((type)1 / (type)(Bins - 1)) / m_window_s;
        }
 
        operator type() const noexcept
        {
                return rate();
        }
 
private:
        type m_window_s;
        TimeInterval m_window;
        Timestamp m_binStart;
        count_type m_bins[Bins];
        uint8_t m_current;
};
 
} // namespace zth
 
EXTERN_C ZTH_EXPORT ZTH_INLINE void zth_perf_mark_(char const* marker)
{
        zth::perf_mark(marker);
}
 
EXTERN_C ZTH_EXPORT ZTH_INLINE __attribute__((format(ZTH_ATTR_PRINTF, 1, 2))) void
zth_perf_log(char const* fmt, ...)
{
        va_list args;
        va_start(args, fmt);
        zth::perf_logv(fmt, args);
        va_end(args);
}
 
EXTERN_C ZTH_EXPORT ZTH_INLINE __attribute__((format(ZTH_ATTR_PRINTF, 1, 0))) void
zth_perf_logv(char const* fmt, va_list args)
{
        zth::perf_logv(fmt, args);
}
 
#else // !__cplusplus
 
#       include <stdarg.h>
 
ZTH_EXPORT void zth_perf_mark_(char const* marker);
ZTH_EXPORT __attribute__((format(ZTH_ATTR_PRINTF, 1, 2))) void zth_perf_log(char const* fmt, ...);
ZTH_EXPORT __attribute__((format(ZTH_ATTR_PRINTF, 1, 0))) void
zth_perf_logv(char const* fmt, va_list args);
 
#endif // __cplusplus
 
#define zth_perf_mark(marker) zth_perf_mark_("" marker)
 
#endif // ZTH_PERF_H