Buf网络缓冲区(C++)

Buf网络缓冲区

由于网络协议分包的需要,因此编写buf网络缓冲区,以便分包。

struct SBuf
{
	char* _base=nullptr;
	char* _b=nullptr;
	char* _e=nullptr;	
	size_t _size=0;

	SBuf(size_t size);
	SBuf();
	~SBuf();	
	char* data(){return _b;}
	void append(char* b, int32_t l);
	void consume(int32_t l);
	void clear(){ _b = _e = _base; }
	int32_t len(){return _e-_b;}
};

SBuf::SBuf(size_t size)
{
	_size = size;
	_b=_e=_base = new char[_size];	
	memset(_base,0,_size);
}
SBuf::SBuf()
{
	_size = getpagesize()/2;
	_b = _e = _base = new char[_size];
	memset(_base, 0, _size);
}

SBuf::~SBuf(){
	if (_base)(delete _base);
}
void SBuf::append(char* b, int32_t l)
{
	//_e后面的空间可以容纳当前追加数据
	if (_e + l < _base + _size){ 
		memcpy(_e,b,l);
		_e+=l;
	}else if(_e-_b+l<=_size){ //当前空间可以容纳追加的数据
		memcpy(_base,_b,_e-_b);
		_e = _base+len();
		_b=_base;

		memcpy(_e,b,l);
		_e+=l;
	}else{//空间不足
		char* newbuf = new char[(_size+l)*2];
		memset(newbuf,0, l * 2);
		_size = (_size + l) * 2;
		int32_t len = _e - _b;
		memcpy(newbuf, _b, len);
		memcpy(newbuf + len, b, l);
		delete _base;
		_b=_base=newbuf;
		_e = _b + len + l;
	}
}

void SBuf::consume(int32_t l)
{
	if (l >(_e-_b))
	{
		_b=_e=_base;
	}else{
		_b+=l;
	}	
}

测试用例

TEST(SBuf, append){
	SBuf buf(512);
	char b[5120] = {0};
	buf.append(b,sizeof(b));
	EXPECT_EQ(buf.len(),5120);
}


TEST(SBuf, append2){
	SBuf buf(5);
	char* b="123456";
	buf.append(b, strlen(b)+1);
	EXPECT_EQ(buf.len(), strlen(b) + 1);
	EXPECT_STREQ(buf._b,b);
}


TEST(SBuf, consume){
	SBuf buf(10);
	char* b = "123456";
	buf.append(b, strlen(b));
	buf.consume(3);
	string s;
	s.append(buf.data(), buf.len());
	EXPECT_EQ(buf.len(), strlen(b)-3);
	EXPECT_STREQ(s.c_str(),"456");

	buf.append(b, strlen(b));
	s.clear();
	s.append(buf.data(), buf.len());
	printf("buf data %s\n", s.c_str());

	buf.consume(8);
	buf.append(b, strlen(b));
	s.clear();
	s.append(buf.data(), buf.len());
	printf("buf data %s\n", s.c_str());
	EXPECT_STREQ(buf.data(), "6123456");
}

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