winter @ OS X 10.11.6 MacBook Pro (Retina, 13-inch, Early 2015)

// 20170224 11:58

// gcc winter.c
// ./a.out

#include 
#include 
#include 
#include 

#define NUM_THREADS 3 // 75% CPU on [ OS X 10.11.6 MacBook Pro (Retina, 13-inch, Early 2015) ]
#define NUM_SECONDS 60

static int g_run = 1;

//          Charging: No
//      Charging: No

// 说明：用于判断是否已经在充电了。
static int is_charging()
{
    int ret = 0;
    FILE* fstream = NULL;

    char buff[1024];
    memset(buff, 0, sizeof(buff));

    if ( NULL == (fstream = popen("system_profiler SPPowerDataType | grep 'Charging: '","r")) )
    {
        return -1;
    }

    while ( NULL != fgets(buff, sizeof(buff), fstream) )
    {
        if ( strlen(buff) > 20 ) // 因为有两行符合条件的，这里只选择一行判断即可。
        {
            printf("%s", buff);

            if ( NULL != strstr(buff,"Yes") )
            {
                ret = 1; // 正在充电
            }
        }

        memset(buff, 0, sizeof(buff));
    }

    pclose(fstream);
    fstream = NULL;

    return ret;
}

static void* cpu(void* args)
{
    int i = 0;
    float j = 0;

    while (g_run)
    {
        i += 5;
        i -= 3;
        i *= 5;
        i /= 3;

        j += 5.1;
        j -= 3.2;
        j *= 5.3;
        j /= 3.4;
    }

    return NULL;
}

// 冬天MBP经常充不进电，原因是温度太低。平时喜欢通过运行flash程序让电脑发热，比如看看优酷视频什么的，但是如果是在公司上班时间呢？看片总不太好吧……

int main(void)
{
    pthread_t threads[NUM_THREADS];

    int t = 0;

    g_run = 1;
    for (t = 0; t < NUM_THREADS; ++t)
    {
        if ( 0 != pthread_create(&threads[t], NULL, cpu, NULL) ) // CPU动起来，温度升上来。
        {
            return -1;
        }
    }

    while ( 1 != is_charging() ) // 如果温度够了，电池已经在充电了，那就退出这个程序吧。否则间隔 NUM_SECONDS 秒之后再检测一次。
    {
        sleep(NUM_SECONDS);
    }

    g_run = 0;
    for (t = 0; t < NUM_THREADS; ++t)
    {
        pthread_join(threads[t], NULL);
    }

    return 0;
}