cpu_memo.cpp

#include <iostream>
#include <thread>
#include <chrono>
#include <string.h>
 
#ifdef WIN32
#include <windows.h>  
#include <psapi.h>  
//#include <tlhelp32.h>
#include <direct.h>
#include <process.h>
#else
#include <sys/stat.h>
#include <sys/sysinfo.h>
#include <sys/time.h>
#include <unistd.h>
#endif
 
// get current process pid
inline int GetCurrentPid()
{
    return getpid();
}
 
// get specific process cpu occupation ratio by pid
#ifdef WIN32
// 
static uint64_t convert_time_format(const FILETIME* ftime)
{
    LARGE_INTEGER li;
 
    li.LowPart = ftime->dwLowDateTime;
    li.HighPart = ftime->dwHighDateTime;
    return li.QuadPart;
}
#else
// FIXME: can also get cpu and mem status from popen cmd
// the info line num in /proc/{pid}/status file
#define VMRSS_LINE 22
#define PROCESS_ITEM 14
 
static const char* get_items(const char* buffer, unsigned int item)
{
    // read from buffer by offset
    const char* p = buffer;
 
    int len = strlen(buffer);
    int count = 0;
 
    for (int i = 0; i < len; i++)
    {
        if (' ' == *p)
        {
            count++;
            if (count == item - 1)
            {
                p++;
                break;
            }
        }
        p++;
    }
 
    return p;
}
 
static inline unsigned long get_cpu_total_occupy()
{
    // get total cpu use time
 
    // different mode cpu occupy time
    unsigned long user_time;
    unsigned long nice_time;
    unsigned long system_time;
    unsigned long idle_time;
 
    FILE* fd;
    char buff[1024] = { 0 };
 
    fd = fopen("/proc/stat", "r");
    if (nullptr == fd)
        return 0;
 
    fgets(buff, sizeof(buff), fd);
    char name[64] = { 0 };
    sscanf(buff, "%s %ld %ld %ld %ld", name, &user_time, &nice_time, &system_time, &idle_time);
    fclose(fd);
 
    return (user_time + nice_time + system_time + idle_time);
}
 
static inline unsigned long get_cpu_proc_occupy(int pid)
{
    // get specific pid cpu use time
    unsigned int tmp_pid;
    unsigned long utime;  // user time
    unsigned long stime;  // kernel time
    unsigned long cutime; // all user time
    unsigned long cstime; // all dead time
 
    char file_name[64] = { 0 };
    FILE* fd;
    char line_buff[1024] = { 0 };
    sprintf(file_name, "/proc/%d/stat", pid);
 
    fd = fopen(file_name, "r");
    if (nullptr == fd)
        return 0;
 
    fgets(line_buff, sizeof(line_buff), fd);
 
    sscanf(line_buff, "%u", &tmp_pid);
    const char* q = get_items(line_buff, PROCESS_ITEM);
    sscanf(q, "%ld %ld %ld %ld", &utime, &stime, &cutime, &cstime);
    fclose(fd);
 
    return (utime + stime + cutime + cstime);
}
#endif
 
inline float GetCpuUsageRatio(int pid)
{
#ifdef WIN32
    static int64_t last_time = 0;
    static int64_t last_system_time = 0;
 
    FILETIME now;
    FILETIME creation_time;
    FILETIME exit_time;
    FILETIME kernel_time;
    FILETIME user_time;
    int64_t system_time;
    int64_t time;
    int64_t system_time_delta;
    int64_t time_delta;
 
    // get cpu num
    SYSTEM_INFO info;
    GetSystemInfo(&info);
    int cpu_num = info.dwNumberOfProcessors;
 
    float cpu_ratio = 0.0;
 
    // get process hanlde by pid
    HANDLE process = OpenProcess(PROCESS_ALL_ACCESS, FALSE, pid);
    // use GetCurrentProcess() can get current process and no need to close handle
 
    // get now time
    GetSystemTimeAsFileTime(&now);
 
    if (!GetProcessTimes(process, &creation_time, &exit_time, &kernel_time, &user_time))
    {
        // We don't assert here because in some cases (such as in the Task Manager)  
        // we may call this function on a process that has just exited but we have  
        // not yet received the notification.  
        printf("GetCpuUsageRatio GetProcessTimes failed\n");
        return 0.0;
    }
    // should handle the multiple cpu num
    system_time = (convert_time_format(&kernel_time) + convert_time_format(&user_time)) / cpu_num;
    time = convert_time_format(&now);
    if ((last_system_time == 0) || (last_time == 0))
    {
        // First call, just set the last values.  
        last_system_time = system_time;
        last_time = time;
        return 0.0;
    }
    system_time_delta = system_time - last_system_time;
    time_delta = time - last_time;
    CloseHandle(process);
    if (time_delta == 0)
    {
        printf("GetCpuUsageRatio time_delta is 0, error\n");
        return 0.0;
    }
    // We add time_delta / 2 so the result is rounded.  
    cpu_ratio = (int)((system_time_delta * 100 + time_delta / 2) / time_delta); // the % unit
    last_system_time = system_time;
    last_time = time;
    cpu_ratio /= 100.0; // convert to float number
    return cpu_ratio;
#else
    unsigned long totalcputime1, totalcputime2;
    unsigned long procputime1, procputime2;
    totalcputime1 = get_cpu_total_occupy();
    procputime1 = get_cpu_proc_occupy(pid);
    // FIXME: the 200ms is a magic number, works well
    usleep(200000); // sleep 200ms to fetch two time point cpu usage snapshots sample for later calculation
    totalcputime2 = get_cpu_total_occupy();
    procputime2 = get_cpu_proc_occupy(pid);
    float pcpu = 0.0;
    if (0 != totalcputime2 - totalcputime1)
        pcpu = (procputime2 - procputime1) / float(totalcputime2 - totalcputime1); // float number
    int cpu_num = get_nprocs();
    pcpu *= cpu_num; // should multiply cpu num in multiple cpu machine
    return pcpu;
#endif
}
// get specific process physical memeory occupation size by pid (MB)
inline float GetMemoryUsage(int pid)
{
#ifdef WIN32
    uint64_t mem = 0, vmem = 0;
    PROCESS_MEMORY_COUNTERS pmc;
    // get process hanlde by pid
    HANDLE process = OpenProcess(PROCESS_ALL_ACCESS, FALSE, pid);
    if (GetProcessMemoryInfo(process, &pmc, sizeof(pmc)))
    {
        mem = pmc.WorkingSetSize;
        vmem = pmc.PagefileUsage;
    }
    CloseHandle(process);
    // use GetCurrentProcess() can get current process and no need to close handle
    // convert mem from B to MB
    return mem / 1024.0 / 1024.0;
#else
    char file_name[64] = { 0 };
    FILE* fd;
    char line_buff[512] = { 0 };
    sprintf(file_name, "/proc/%d/status", pid);
    fd = fopen(file_name, "r");
    if (nullptr == fd)
        return 0;
    char name[64];
    int vmrss = 0;
    for (int i = 0; i < VMRSS_LINE - 1; i++)
        fgets(line_buff, sizeof(line_buff), fd);
    fgets(line_buff, sizeof(line_buff), fd);
    sscanf(line_buff, "%s %d", name, &vmrss);
    fclose(fd);
    // cnvert VmRSS from KB to MB
    return vmrss / 1024.0;
#endif
}
int main()
{
    // launch some task to occupy cpu and memory
    for (int i = 0; i < 5; i++)
        std::thread([]
            {
                std::this_thread::sleep_for(std::chrono::milliseconds(10));
            }).detach();
    int current_pid = GetCurrentPid(); // or you can set a outside program pid
    float cpu_usage_ratio = GetCpuUsageRatio(current_pid);
    float memory_usage = GetMemoryUsage(current_pid);
    while (true)
    {
        std::cout << "current pid: " << current_pid << std::endl;
        std::cout << "cpu usage ratio: " << cpu_usage_ratio * 100 << "%" << std::endl;
        std::cout << "memory usage: " << memory_usage << "MB" << std::endl;
        std::this_thread::sleep_for(std::chrono::milliseconds(1000));
    }
    return 0;
}