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#include "cpuload.h"
#include <chrono>
#include <numeric>
#include <libreichwein/file.h>
#include <libreichwein/stringhelper.h>
int get_number_of_cpus()
{
int result{};
std::string stat = Reichwein::File::getFile("/proc/stat");
std::vector<std::string> lines = Reichwein::Stringhelper::split(stat, "\n");
for (const auto& line: lines) {
std::vector<std::string> words = Reichwein::Stringhelper::split(line, " ");
// /proc/stat line, e.g.: cpu0 1132 34 1441 11311718 3675 127 438
if (words.size() >= 8) {
if (words[0].size() > 3 && words[0].substr(0, 3) == "cpu") {
++result;
}
}
}
return result;
}
// returns empty vector if no data is available yet
// Note: to be called several times, because data is generated differentially from /proc/stat
std::vector<int> get_cpu_loads()
{
using clock_type = std::chrono::high_resolution_clock;
static int number_of_cpus = get_number_of_cpus();
static std::vector<int> stat_cpus_sum(number_of_cpus);
static std::vector<int> stat_cpus_idle(number_of_cpus);
static std::chrono::time_point<clock_type> timestamp{};
std::string stat = Reichwein::File::getFile("/proc/stat");
std::vector<std::string> lines = Reichwein::Stringhelper::split(stat, "\n");
std::vector<int> result;
int i = 0;
for (const auto& line: lines) {
std::vector<std::string> words = Reichwein::Stringhelper::split(line, " ");
// /proc/stat line, e.g.: cpu0 1132 34 1441 11311718 3675 127 438
// idle value is at index 4
if (words.size() >= 8) {
if (words[0].size() > 3 && words[0].substr(0, 3) == "cpu") {
uint64_t sum = std::accumulate(words.begin() + 1, words.end(), uint64_t{}, [](uint64_t sum, const std::string& s){return sum + std::stoull(s);});
uint64_t idle = std::stoull(words[4]);
// previous data available
if (timestamp == std::chrono::time_point<clock_type>{})
{
uint64_t sum_diff = sum - stat_cpus_sum[i];
uint64_t idle_diff = idle - stat_cpus_idle[i];
int percentage = (sum_diff == 0) ? 0 : ((sum_diff - idle_diff) * 100 / sum_diff);
result.push_back(percentage);
}
stat_cpus_sum[i] = sum;
stat_cpus_idle[i] = idle;
++i;
}
}
}
return result;
}
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