RT-Thread 堆内存 检查命令 free 实现及介绍

在RT-Thread系统中，通常可以通过rt_memory_info函数获取当前的堆内存使用信息，然后你可以包装这个函数来显示剩余的堆空间。rt_memory_info实现见：
rt-thread/src/mem.c:

void rt_memory_info(rt_uint32_t *total,
                    rt_uint32_t *used,
                    rt_uint32_t *max_used)
{
    if (total != RT_NULL)
        *total = mem_size_aligned;
    if (used  != RT_NULL)
        *used = used_mem;
    if (max_used != RT_NULL)
        *max_used = max_mem;
}

rt-thread 中其实已经实现了cmd_free 函数，可以使用这个函数来查看当前堆的使用情况：

#ifdef RT_USING_HEAP
int cmd_free(int argc, char **argv)
{
    rt_uint32_t total = 0, used = 0, max_used = 0;

    rt_memory_info(&total, &used, &max_used);
    rt_kprintf("total   : %d\n", total);
    rt_kprintf("used    : %d\n", used);
    rt_kprintf("maximum : %d\n", max_used);
    return 0;
}
MSH_CMD_EXPORT_ALIAS(cmd_free, free, Show the memory usage in the system.);
#endif /* RT_USING_HEAP */

所以在终端执行free 命令即可查看堆的使用情况：

msh >help
RT-Thread shell commands:
list             - list all commands in system
list_timer       - list timer in system
list_mempool     - list memory pool in system
list_memheap     - list memory heap in system
list_msgqueue    - list message queue in system
list_mailbox     - list mail box in system
list_mutex       - list mutex in system
list_event       - list event in system
list_sem         - list semaphore in system
list_thread      - list thread
version          - show RT - Thread version information
clear            - clear the terminal screen
hello            - say hello world
free             - Show the memory usage in the system.
ps               - List threads in the system.
help             - RT - Thread shell help.

rt_memory_info 函数验证

如下实现了一个测试函数，在函数开始的时候查看当前堆使用了多少，然后再进行rt_malloc(1024) 之后再查看下堆使用了多少，通过前后对比可以看出rt_memory_info函数获取的信息是否正确。

#include <rtthread.h>
#include <pthread.h>

#define TEST_MALLOC_SIZE        1024

static int mem_check_test(void)
{
        char *ptr = RT_NULL;
        rt_uint32_t total = 0, used_pre = 0, max_used = 0;
        rt_uint32_t used_next = 0;

        rt_memory_info(&total, &used_pre, &max_used);

        ptr = (char *)rt_malloc(TEST_MALLOC_SIZE);
        if (ptr == RT_NULL) {
                rt_kprintf("mem check test failed\n");
                return -RT_ENOMEM;
        }

        rt_memory_info(&total, &used_next, &max_used);

        if ((used_next - used_pre) != TEST_MALLOC_SIZE + 16) {
                rt_kprintf("mem check test failed\n"
                           "mem used_pre: %d, mem used_next:%d\n",
                           used_pre, used_next);

                rt_free(ptr);

                return -RT_ERROR;
        }

        rt_kprintf("mem check test ok\n");

        rt_free(ptr);

	return RT_EOK;
}
INIT_APP_EXPORT(mem_check_test);

关于free命令的本地测试如下：

通过执行free命令之后可以看到一共有多少heap和已经使用了多少。

通常需要在跑完测试用例后不能影响heap的大小，简单点说就是你的测试case不能导致内存泄露。