Instrumentor.h

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/// @file Instrumentor.h
/// @author TheCherno
/// @author Damon S. Green II
/// @brief Provides instrumentation and profiling utilities.
 
//Copyright © TheCherno
//Modifications Copyright © 2025 Damon S.Green II(nomad_ii_damon)
//
//Licensed under the Apache License, Version 2.0 (the "License");
//you may not use this file except in compliance with the License.
//You may obtain a copy of the License at
//
//[Apache](http://www.apache.org/licenses/LICENSE-2.0)
 
#pragma once
 
#include "Vesper/Core/Log.h"
 
#include <algorithm>
#include <chrono>
#include <fstream>
#include <iomanip>
#include <string>
#include <thread>
#include <mutex>
#include <sstream>
 
namespace Vesper {
 
    using FloatingPointMicroseconds = std::chrono::duration<double, std::micro>;
 
 
    struct ProfileResult
    {
        std::string Name;
        long long Start, End;
        uint32_t ThreadID;
    };
 
    struct InstrumentationSession
    {
        std::string Name;
    };
 
    class Instrumentor
    {
    private:
        InstrumentationSession* m_CurrentSession;
        std::ofstream m_OutputStream;
        std::mutex m_Mutex;
    public:
        Instrumentor()
            : m_CurrentSession(nullptr)
        {
        }
 
        void BeginSession(const std::string& name, const std::string& filepath = "results.json")
        {
            std::lock_guard lock(m_Mutex);
            if (m_CurrentSession) {
                // If there is already a current session, end it and start new one
                if (Log::GetCoreLogger())
                {
                    VZ_CORE_ERROR("Instrumentor::BeginSession('{0}') when session '{1}' already open.", name, m_CurrentSession->Name);
                }
                InternalEndSession();
            }
            m_OutputStream.open(filepath);
            if (m_OutputStream.is_open()) {
                m_CurrentSession = new InstrumentationSession{ name };
                WriteHeader();
            }
            else {
                if (Log::GetCoreLogger())
                {
                    VZ_CORE_ERROR("Instrumentor could not open results file '{0}'.", filepath);
                }
            }
            WriteHeader();
            m_CurrentSession = new InstrumentationSession{ name };
        }
 
        void EndSession()
        {
            std::lock_guard lock(m_Mutex);
            InternalEndSession();
        }
 
        void WriteProfile(const ProfileResult& result)
        {
            m_OutputStream << ",";
 
            std::string name = result.Name;
            std::replace(name.begin(), name.end(), '"', '\'');
 
            m_OutputStream << "{";
            m_OutputStream << "\"cat\":\"function\",";
            m_OutputStream << "\"dur\":" << (result.End - result.Start) << ',';
            m_OutputStream << "\"name\":\"" << name << "\",";
            m_OutputStream << "\"ph\":\"X\",";
            m_OutputStream << "\"pid\":0,";
            m_OutputStream << "\"tid\":" << result.ThreadID << ",";
            m_OutputStream << "\"ts\":" << result.Start;
            m_OutputStream << "}";
 
            std::lock_guard lock(m_Mutex);
            if (m_CurrentSession)
            {
                //m_OutputStream << json.str();
                m_OutputStream.flush();
            }
        }
 
        void WriteHeader()
        {
            m_OutputStream << "{\"otherData\": {},\"traceEvents\":[";
            m_OutputStream.flush();
        }
 
        void WriteFooter()
        {
            m_OutputStream << "]}";
            m_OutputStream.flush();
        }
 
        void InternalEndSession()
        {
            if (m_CurrentSession)
            {
                WriteFooter();
                m_OutputStream.close();
                delete m_CurrentSession;
                m_CurrentSession = nullptr;
            }
        }
 
        static Instrumentor& Get()
        {
            static Instrumentor instance;
            return instance;
        }
    };
 
    class InstrumentationTimer
    {
    public:
        InstrumentationTimer(const char* name)
            : m_Name(name), m_Stopped(false)
        {
            m_StartTimepoint = std::chrono::high_resolution_clock::now();
        }
 
        ~InstrumentationTimer()
        {
            if (!m_Stopped)
                Stop();
        }
 
        void Stop()
        {
            auto endTimepoint = std::chrono::high_resolution_clock::now();
 
            long long start = std::chrono::time_point_cast<std::chrono::microseconds>(m_StartTimepoint).time_since_epoch().count();
            long long end = std::chrono::time_point_cast<std::chrono::microseconds>(endTimepoint).time_since_epoch().count();
 
            uint32_t threadID = std::hash<std::thread::id>{}(std::this_thread::get_id());
            Instrumentor::Get().WriteProfile({ m_Name, start, end, threadID });
 
            m_Stopped = true;
        }
    private:
        const char* m_Name;
        std::chrono::time_point<std::chrono::high_resolution_clock> m_StartTimepoint;
        bool m_Stopped;
    };
 
 
}
 
namespace InstrumentorUtils {
 
    template <size_t N>
    struct ChangeResult
    {
        char Data[N];
    };
 
    template <size_t N, size_t K>
    constexpr auto CleanupOutputString(const char(&expr)[N], const char(&remove)[K])
    {
        ChangeResult<N> result = {};
 
        size_t srcIndex = 0;
        size_t dstIndex = 0;
        while (srcIndex < N)
        {
            size_t matchIndex = 0;
            while (matchIndex < K - 1 && srcIndex + matchIndex < N - 1 && expr[srcIndex + matchIndex] == remove[matchIndex])
                matchIndex++;
            if (matchIndex == K - 1)
                srcIndex += matchIndex;
            result.Data[dstIndex++] = expr[srcIndex] == '"' ? '\'' : expr[srcIndex];
            srcIndex++;
        }
        return result;
    }
}
 
 
#define VZ_PROFILE 1
#if VZ_PROFILE
    // Resolve which function signature macro will be used. Note that this only
    // is resolved when the (pre)compiler starts, so the syntax highlighting
    // could mark the wrong one in your editor!
    #if defined(__GNUC__) || (defined(__MWERKS__) && (__MWERKS__ >= 0x3000)) || (defined(__ICC) && (__ICC >= 600)) || defined(__ghs__)
    #define VZ_FUNC_SIG __PRETTY_FUNCTION__
    #elif defined(__DMC__) && (__DMC__ >= 0x810)
    #define VZ_FUNC_SIG __PRETTY_FUNCTION__
    #elif (defined(__FUNCSIG__) || (_MSC_VER))
    #define VZ_FUNC_SIG __FUNCSIG__
    #elif (defined(__INTEL_COMPILER) && (__INTEL_COMPILER >= 600)) || (defined(__IBMCPP__) && (__IBMCPP__ >= 500))
    #define VZ_FUNC_SIG __FUNCTION__
    #elif defined(__BORLANDC__) && (__BORLANDC__ >= 0x550)
    #define VZ_FUNC_SIG __FUNC__
    #elif defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 199901)
    #define VZ_FUNC_SIG __func__
    #elif defined(__cplusplus) && (__cplusplus >= 201103)
    #define VZ_FUNC_SIG __func__
    #else
    #define VZ_FUNC_SIG "VZ_FUNC_SIG unknown!"
    #endif
 
    #define VZ_PROFILE_BEGIN_SESSION(name, filepath) ::Vesper::Instrumentor::Get().BeginSession(name, filepath)
    #define VZ_PROFILE_END_SESSION() ::Vesper::Instrumentor::Get().EndSession()
    #define VZ_PROFILE_SCOPE_LINE2(name, line) constexpr auto fixedName##line = InstrumentorUtils::CleanupOutputString(name, "__cdecl ");
                                                   ::Vesper::InstrumentationTimer timer##line(fixedName##line.Data)
    #define VZ_PROFILE_SCOPE_LINE(name, line) VZ_PROFILE_SCOPE_LINE2(name, line)
    #define VZ_PROFILE_SCOPE(name) VZ_PROFILE_SCOPE_LINE(name, __LINE__)
    #define VZ_PROFILE_FUNCTION() VZ_PROFILE_SCOPE(VZ_FUNC_SIG)
#else
    #define VZ_PROFILE_BEGIN_SESSION(name, filepath)
    #define VZ_PROFILE_END_SESSION()
    #define VZ_PROFILE_FUNCTION()
    #define VZ_PROFILE_SCOPE(name)
#endif