C++11统计CPU使用率、温度，内存使用率

本文的代码地址：https://github.com/BlueLeen/cpu_and_mem_monitor.git，代码已经在ubuntu18.04系统上编译通过，能够高效准确检测cpu、内存指标。

代码编译的详细步骤：

$ git clone https://github.com/BlueLeen/cpu_and_mem_monitor.git

$ cd cpu_and_mem_monitor

$ mkdir _build

$ cd _build

$ cmake ..

$ make

1、CPU使用率

主要是读取/proc/stat文件相关信息，进行解析。部分源代码如下：

#ifndef PROCDIR

#define PROCDIR "/proc"

#endif

#ifndef PROCSTATFILE

#define PROCSTATFILE PROCDIR "/stat"

#endif

bool CPUStats::UpdateCPUData()

{

unsigned long long int usertime, nicetime, systemtime, idletime;

unsigned long long int ioWait, irq, softIrq, steal, guest, guestnice;

int cpuid = -1;

if (!m_inited)

return false;

std::string line;

std::ifstream file (PROCSTATFILE);

bool ret = false;

if (!file.is_open()) {

std::cerr << "Failed to opening " << PROCSTATFILE << std::endl;

return false;

}

do {

if (!std::getline(file, line)) {

break;

} else if (!ret && sscanf(line.c_str(), "cpu %16llu %16llu %16llu %16llu %16llu %16llu %16llu %16llu %16llu %16llu",

&usertime, &nicetime, &systemtime, &idletime, &ioWait, &irq, &softIrq, &steal, &guest, &guestnice) == 10) {

ret = true;

calculateCPUData(m_cpuDataTotal, usertime, nicetime, systemtime, idletime, ioWait, irq, softIrq, steal, guest, guestnice);

} else if (sscanf(line.c_str(), "cpu%4d %16llu %16llu %16llu %16llu %16llu %16llu %16llu %16llu %16llu %16llu",

&cpuid, &usertime, &nicetime, &systemtime, &idletime, &ioWait, &irq, &softIrq, &steal, &guest, &guestnice) == 11) {

//std::cerr << "Parsing 'cpu" << cpuid << "' line:" << line << std::endl;

if (!ret) {

//std::cerr << "Failed to parse 'cpu' line" << std::endl;

std::cerr << "Failed to parse 'cpu' line:" << line << std::endl;

return false;

}

if (cpuid < 0 /* can it? */ || (size_t)cpuid > m_cpuData.size()) {

std::cerr << "Cpu id '" << cpuid << "' is out of bounds" << std::endl;

return false;

}

CPUData& cpuData = m_cpuData[cpuid];

calculateCPUData(cpuData, usertime, nicetime, systemtime, idletime, ioWait, irq, softIrq, steal, guest, guestnice);

cpuid = -1;

} else {

break;

}

} while(true);

m_cpuPeriod = (double)m_cpuData[0].totalPeriod / m_cpuData.size();

m_updatedCPUs = true;

return ret;

}

2、CPU温度

安装相关库：

$ sudo apt install lm-sensors libsensors4-dev

部分源代码如下：

void LMSensor::_update_feature_temp()

{

const sensors_subfeature *sf;

/*

* If the sensor is reporting a fault, we can't trust anything else

* it might tell us. Keep previous/default values.

*/

sf = sensors_get_subfeature(&m_name, &m_feature, SENSORS_SUBFEATURE_TEMP_FAULT);

if (sf && _get_value(sf))

return;

sf = sensors_get_subfeature(&m_name, &m_feature, SENSORS_SUBFEATURE_TEMP_INPUT);

m_value = sf ? _get_value(sf) : 0.0;

sf = sensors_get_subfeature(&m_name, &m_feature, SENSORS_SUBFEATURE_TEMP_ALARM);

m_alarm = sf && _get_value(sf);

sf = sensors_get_subfeature(&m_name, &m_feature, SENSORS_SUBFEATURE_TEMP_MAX_ALARM);

m_alarm |= sf && _get_value(sf);

sf = sensors_get_subfeature(&m_name, &m_feature, SENSORS_SUBFEATURE_TEMP_MIN_ALARM);

m_alarm |= sf && _get_value(sf);

}

3、内存使用率

部分源代码如下：

void update_meminfo(void) {

FILE *meminfo_fp;

static int reported = 0;

/* unsigned int a; */

char buf[256];

/* With multi-threading, calculations that require

* multple steps to reach a final result can cause havok

* if the intermediary calculations are directly assigned to the

* information struct (they may be read by other functions in the meantime).

* These variables keep the calculations local to the function and finish off

* the function by assigning the results to the information struct */

unsigned long long shmem = 0, sreclaimable = 0, curmem = 0, curbufmem = 0,

cureasyfree = 0, memavail = 0;

mem_info.memmax = mem_info.memdirty = mem_info.swap = mem_info.swapfree = mem_info.swapmax =

mem_info.memwithbuffers = mem_info.buffers = mem_info.cached = mem_info.memfree =

mem_info.memeasyfree = 0;

if (!(meminfo_fp = open_file("/proc/meminfo", &reported))) { }

while (!feof(meminfo_fp)) {

if (fgets(buf, 255, meminfo_fp) == nullptr) { break; }

if (strncmp(buf, "MemTotal:", 9) == 0) {

sscanf(buf, "%*s %llu", &mem_info.memmax);

} else if (strncmp(buf, "MemFree:", 8) == 0) {

sscanf(buf, "%*s %llu", &mem_info.memfree);

} else if (strncmp(buf, "SwapTotal:", 10) == 0) {

sscanf(buf, "%*s %llu", &mem_info.swapmax);

} else if (strncmp(buf, "SwapFree:", 9) == 0) {

sscanf(buf, "%*s %llu", &mem_info.swapfree);

} else if (strncmp(buf, "Buffers:", 8) == 0) {

sscanf(buf, "%*s %llu", &mem_info.buffers);

} else if (strncmp(buf, "Cached:", 7) == 0) {

sscanf(buf, "%*s %llu", &mem_info.cached);

} else if (strncmp(buf, "Dirty:", 6) == 0) {

sscanf(buf, "%*s %llu", &mem_info.memdirty);

} else if (strncmp(buf, "MemAvailable:", 13) == 0) {

sscanf(buf, "%*s %llu", &memavail);

} else if (strncmp(buf, "Shmem:", 6) == 0) {

sscanf(buf, "%*s %llu", &shmem);

} else if (strncmp(buf, "SReclaimable:", 13) == 0) {

sscanf(buf, "%*s %llu", &sreclaimable);

}

}

curmem = mem_info.memwithbuffers = mem_info.memmax - mem_info.memfree;

cureasyfree = mem_info.memfree;

mem_info.swap = mem_info.swapmax - mem_info.swapfree;

/* Reclaimable memory: does not include shared memory, which is part of cached

but unreclaimable. Includes the reclaimable part of the Slab cache though.

Note: when shared memory is swapped out, shmem decreases and swapfree

decreases - we want this.

*/

curbufmem = (mem_info.cached - shmem) + mem_info.buffers + sreclaimable;

curmem = mem_info.memmax - memavail;

cureasyfree += curbufmem;

/* Now that we know that every calculation is finished we can wrap up

* by assigning the values to the information structure */

mem_info.mem = curmem;

mem_info.bufmem = curbufmem;

mem_info.memeasyfree = cureasyfree;

memused = (float(mem_info.memmax) - float(mem_info.memeasyfree)) / (1024 * 1024);

memmax = float(mem_info.memmax) / (1024 * 1024);

fclose(meminfo_fp);

}

4、运行程序

$ ./cpumem_monitor #执行结果如下：