实用的无锁队列(二)

上次的修改一下

链接在此：[无锁队列一]

//c_buffer.h
class c_data
{
private:
	s_memory v_root = NULL;
	s_memory *v_r = NULL;
	s_memory *v_w = NULL;
	int v_num = 0;
public:
	~c_data()
	{
		s_memory_block * pos = v_root.v_next;
		int num = 0;
		while (1) {
			int flag = pos->flag;
			s_memory_block * tmp = pos->v_next;
			delete pos;
			pos = tmp;
			if (++num == v_num) //cycle must be out
				break;
		}
	}
	int func_mem_create(int pagesize, int num = 200)
	{
		s_memory_block * pos = NULL;
		s_memory_block * smb = new s_memory_block(pagesize);
		v_root.v_next = smb; //the first 
		smb->flag = 0;
		pos = smb;
		for (int i = 1; i flag = i;
			pos->v_next = smb;
			pos = smb;
		}
		pos->v_next = v_root.v_next;
		v_w = &v_root;
		v_r = &v_root;
		v_num = num;
		return 0;
	}



	s_memory  *func_mem_write_get()
	{
		while (1)
		{
			char m = v_w->v_next->v_lock.load(std::memory_order_relaxed);
			if(m != en_read)
			{
				size_t pack_num = v_w->v_pack_num;
				v_w = v_w->v_next;
				v_w->v_lock.store(en_write, std::memory_order_relaxed);
				//v_w->v_lock = en_write;
				v_w->v_pack_num = pack_num +1;
				return v_w;
			}
			else {
				//give up the left cpu time let read to do what to do
				std::this_thread::yield();
			}
		}
	}
	//this function will end the memory barriar
	void func_mem_write_fin(s_memory * w)
	{
		w->v_lock = en_middle;
	}
	s_memory * func_mem_read_get()
	{
		char m = v_r->v_next->v_lock.load(std::memory_order_relaxed);
		if (m == en_middle)//en_middle can read , en_write can not read
		{
			v_r->v_next->v_lock = en_read;
			v_r = v_r->v_next;
			return v_r;
		}
		return NULL;
	}
	void func_mem_read_fin(s_memory *r)
	{
		r->v_lock.store(en_middle, std::memory_order_relaxed);
	}
};

测试：

#include "c_buffer.h"
#include 
using namespace std;
int main()
{

	c_data mdata;
	mdata.func_mem_create(M_MTU);
#if 1
	std::thread thd([&mdata]() {
		for (;;)
		{
			s_memory * r = mdata.func_mem_read_get();
			//this is the exit condition
			if (r && r->v_pack_num == 999)
			{
				cout