ProcessMetrics.cpp

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#include "metrics/ProcessMetrics.hpp"
 
#include "utils/FileHelpers.hpp"
 
#include <spdlog/spdlog.h>
 
#include <dirent.h>
#include <sys/resource.h>
 
constexpr int SLEEP_INTERVAL_SEC = 1;
 
size_t ProcessMetrics::countDirectoryEntries(const std::string &path)
{
    DIR *dir = nullptr;
    size_t count = 0;
    if ((dir = opendir(path.c_str())) != nullptr)
    {
        while (readdir(dir) != nullptr) // NOLINT(concurrency-mt-unsafe)
        {
            ++count;
        }
        closedir(dir);
    }
 
    return count;
}
 
long int ProcessMetrics::getMemoryUsage()
{
    struct rusage r_usage {};
    getrusage(RUSAGE_SELF, &r_usage);
    return r_usage.ru_maxrss; // NOLINT(cppcoreguidelines-pro-type-union-access)
}
 
long int ProcessMetrics::getPageFaults()
{
    struct rusage r_usage {};
    getrusage(RUSAGE_SELF, &r_usage);
    return r_usage.ru_majflt; // NOLINT(cppcoreguidelines-pro-type-union-access)
}
 
double ProcessMetrics::getCpuUsage()
{
    if (_oldCpuTime == 0)
    {
        _oldCpuTime = times(&_oldCpu);
        if (_oldCpuTime == static_cast<clock_t>(-1))
        {
            _oldCpuTime = 0;
        }
        return 0.0;
    }
 
    struct tms nowCpu {};
    auto nowCpuTime = times(&nowCpu);
 
    const double usage = 100.0 * static_cast<double>(nowCpu.tms_utime - _oldCpu.tms_utime) /
                         static_cast<double>(nowCpuTime - _oldCpuTime);
 
    std::swap(_oldCpu, nowCpu);
    std::swap(_oldCpuTime, nowCpuTime);
 
    return usage;
}
 
std::pair<size_t, size_t> ProcessMetrics::getDiskIO()
{
    std::string buffer;
    findFromFile("/proc/self/io", "read_bytes", buffer);
    size_t readBytes = buffer.empty() ? 0 : std::stoull(buffer);
 
    buffer.clear();
    findFromFile("/proc/self/io", "write_bytes", buffer);
    size_t writeBytes = buffer.empty() ? 0 : std::stoull(buffer);
 
    std::pair<size_t, size_t> result = {readBytes - _oldReadBytes, writeBytes - _oldWriteBytes};
 
    std::swap(_oldReadBytes, readBytes);
    std::swap(_oldWriteBytes, writeBytes);
 
    return result;
}
 
size_t ProcessMetrics::getThreadCount() { return countDirectoryEntries("/proc/self/task"); }
 
size_t ProcessMetrics::getFileDescriptorCount() { return countDirectoryEntries("/proc/self/fd"); }
 
void ProcessMetrics::update()
{
    _pCurrentTime->SetToCurrentTime();
    _pMemory->Set(static_cast<double>(getMemoryUsage()));
    _pPageFaults->Set(static_cast<double>(getPageFaults()));
    _pCpuUsage->Set(getCpuUsage());
    auto [diskRead, diskWrite] = getDiskIO();
    _pDiskRead->Set(static_cast<double>(diskRead));
    _pDiskWrite->Set(static_cast<double>(diskWrite));
    _pThreadCount->Set(static_cast<double>(getThreadCount()));
    _pFileDescriptorCount->Set(static_cast<double>(getFileDescriptorCount()));
}
 
void ProcessMetrics::threadRunner() noexcept
{
    while (!_shouldStop._M_i)
    {
        try
        {
            update();
            if (_checkFlag)
            {
                _checkFlag->test_and_set();
            }
        }
        catch (const std::exception &e)
        {
            spdlog::error("Self monitoring failed: {}", e.what());
        }
 
        std::this_thread::sleep_for(std::chrono::seconds(SLEEP_INTERVAL_SEC));
    }
}
 
ProcessMetrics::ProcessMetrics(std::shared_ptr<std::atomic_flag> checkFlag,
                               const std::shared_ptr<prometheus::Registry> &reg)
    : _checkFlag(std::move(checkFlag))
{
    if (reg == nullptr)
    {
        throw std::invalid_argument("Registry is nullptr");
    }
 
    _pInitTime =
        &prometheus::BuildGauge().Name("init_time").Help("Initialization time of application").Register(*reg).Add({});
    _pCurrentTime =
        &prometheus::BuildGauge().Name("current_time").Help("Current time of application").Register(*reg).Add({});
    _pMemory =
        &prometheus::BuildGauge().Name("memory_usage").Help("Memory usage of application").Register(*reg).Add({});
    _pPageFaults =
        &prometheus::BuildGauge().Name("page_faults").Help("Page faults of application").Register(*reg).Add({});
    _pCpuUsage = &prometheus::BuildGauge().Name("cpu_usage").Help("CPU usage of application").Register(*reg).Add({});
    _pDiskRead = &prometheus::BuildGauge().Name("disk_read").Help("Disk read of application").Register(*reg).Add({});
    _pDiskWrite = &prometheus::BuildGauge().Name("disk_write").Help("Disk write of application").Register(*reg).Add({});
    _pThreadCount =
        &prometheus::BuildGauge().Name("thread_count").Help("Thread count of application").Register(*reg).Add({});
    _pFileDescriptorCount = &prometheus::BuildGauge()
                                 .Name("file_descriptor_count")
                                 .Help("File descriptor count of application")
                                 .Register(*reg)
                                 .Add({});
 
    _pInitTime->SetToCurrentTime();
 
    _thread = std::make_unique<std::thread>(&ProcessMetrics::threadRunner, this);
}
 
ProcessMetrics::~ProcessMetrics()
{
    _shouldStop.test_and_set();
    if (_thread && _thread->joinable())
    {
        _thread->join();
    }
}