实习的时候写的小练习程序：

VMSTAT.h

此代码用以从服务器获取运行状态信息

class VMSTAT
{
public:
	double stat[20];
	/*
	 *       Proc
	 *
	 * 0:r: The number of processes waiting for run time.
	 * 1:b: The number of processes in uninterruptible sleep.
	 *
	 *       Memory
	 *
	 * 2:swpd: the amount of virtual memory used.
	 * 3:free: the amount of idle memory.
	 * 4:buff: the amount of memory used as buffers.
	 * 5:cache: the amount of memory used as cache.
	 *
	 *       Swap
	 *
	 * 6:si: Amount of memory swapped in from disk (/s).
	 * 7:Amount of memory swapped to disk (/s).
	 *
	 *       IO
	 *
	 * 8:bi: Blocks received from a block device (blocks/s).
	 * 9:bo: Blocks sent to a block device (blocks/s).
	 *
	 *       System
	 *
	 * 10:in: The number of interrupts per second, including the clock.
	 * 11:cs: The number of context switches per second.
	 *
	 *       CPU
	 *
	 * 12:us: Time spent running non-kernel code. (user time, including nice time)
	 * 13:sy: Time spent running kernel code. (system time)
	 * 14:id: Time spent idle. Prior to Linux 2.5.41, this includes IO-wait time.
	 * 15:wa: Time spent waiting for IO. Prior to Linux 2.5.41, included in idle.
	 * 16:st: Time stolen from a virtual machine. Prior to Linux 2.6.11, unknown.
	 *
	 *       Add
	 *
	 * 17:Total Memory
	 * 18:Used Memory
	 * 19:CPU Usage
	 */

	void update()
	{

		//init array
		FILE *file = popen("vmstat", "r");
		char buf[300];
		fgets(buf, 300, file);
		fgets(buf, 300, file);
		fgets(buf, 300, file);

		int index = 0;
		for (int i = 0; i < 300; i++)
		{
			while (buf[i] < '0' || buf[i] > '9')
				i++;
			int tmp = 0;
			while (buf[i] >= '0' && buf[i] <= '9')
			{
				tmp = tmp * 10 + (buf[i] - '0');
				i++;
			}
			stat[index++] = tmp * 1.0;
			if (index == 17)
				break;
		}
		pclose(file);

		//total memory
		file = popen("cat /proc/meminfo", "r");
		double total = 0;
		fgets(buf, 300, file);
		char str[7];
		for (int i = 17; i < 24; i++)
			str[i - 17] = buf[i];

		for (int i = 0; i < 7; i++)
		{
			total = total * 10 + (str[i] == ' ' ? 0 : (str[i] - '0'));
		}

		//calculate all
		stat[17] = total;
		stat[18] = total - stat[3];
		stat[19] = 100 - stat[14];
		pclose(file);

	}

};

pshm.h

定义共享内存数据结构的结构体
定义主题ID

typedef struct tagMyStat
{
        int attche_count;
        int total;
        int avaliable;
        int used;
        int cpu_useage;
 
} MyStat;
 
#define CENTOS_PER   (4499)  //主题CENTOS_PER 由服务器发布 客户端进行订阅 服务器可发布多个主题，而客户端可以选择其中若干个感兴趣的进行订阅

shmClient.cpp

#include <stdio.h>
#include <time.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/shm.h>
#include  "VMSTAT.h"
#include "pshm.h"
int main()
{
	void *shm = NULL;
	MyStat *shared = NULL;
	int shmid = shmget((key_t) CENTOS_PER, sizeof(MyStat), IPC_CREAT);
	if (shmid == -1)
	{
		printf("%s\n", "shmget failed!");
		return 0;
	}
	shm = shmat(shmid, (void*) 0, 0);
	if (shm == (void*) -1)
	{
		printf("%s\n", "shmat failed!");
	}
	printf("Memory attached at %lx\n", (long) shm);
	shared = (MyStat*) shm;
	shared->attche_count++;
	time_t rawtime;
	struct tm *t;
	while (1)
	{
		time(&rawtime);
		t = localtime(&rawtime);
		printf(
				"Client@%d:%d:%d :Total: %d MB  Aviliable: %d MB  Used: %d MB  CPU: %d %\n",
				t->tm_hour, t->tm_min, t->tm_sec, shared->total,
				shared->avaliable, shared->used, shared->cpu_useage);
		sleep(1);
	}
	shared->attche_count--;
	if (shmdt(shm) == -1)
	{
		printf("%s\n", "shmdt failed!");
	}
	if (shmctl(shmid, IPC_RMID, 0) == -1)
	{
		printf("%s\n", "shmctl(IPC_RMID) failed!");
	}
	sleep(2);
	return 0;
}

shmServer.cpp

#include <stdio.h>
#include <time.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/shm.h>
#include "VMSTAT.h"
#include "pshm.h"

int main()
{
	void *shm = NULL;
	MyStat *shared = NULL;

	int shmid = shmget((key_t) CENTOS_PER, sizeof(MyStat), 0666 | IPC_CREAT);
	if (shmid == -1)
	{
		printf("%s\n", "shmget failed!");
		return 0;
	}
	shm = shmat(shmid, (void*) 0, 0);
	if (shm == (void*) -1)
	{
		printf("%s\n", "shmat failed!");
	}

	printf("Memory attached at %lx\n", (long) shm);

	shared = (MyStat*) shm;
	memset(shared, 0, sizeof(MyStat));
	shared->attche_count = 0;
	VMSTAT s;

	time_t rawtime;
	struct tm *t;

	while (1)
	{
		s.update();
		shared->total = int(s.stat[17] / 1000);
		shared->avaliable = int(s.stat[3] / 1000);
		shared->used = int(s.stat[18] / 1000);
		shared->cpu_useage = int(s.stat[19]);

		time(&rawtime);
		t = localtime(&rawtime);

		printf(
				"Server@%2d:%2d:%2d (%d):Total: %d MB  Aviliable: %d MB  Used: %d MB  CPU: %d %\n",
				t->tm_hour, t->tm_min, t->tm_sec, shared->attche_count,
				shared->total, shared->avaliable, shared->used,
				shared->cpu_useage);
		sleep(1);
	}

	if (shmdt(shm) == -1)
	{
		printf("%s\n", "shmdt failed!");
	}

	if (shmctl(shmid, IPC_RMID, 0) == -1)
	{
		printf("%s\n", "shmctl(IPC_RMID) failed!");
	}

	sleep(2);

	return 0;
}

服务器运行截图：

客户端运行截图：