class Buffer{
public:
	Buffer();									//構(gòu)造
	~Buffer();	
	int init();									//分配緩沖區(qū)
private:
	char* m_s;									//緩沖區(qū)指針
	size_t m_read_index;						//讀指針位置
	size_t m_write_index;						//寫指針位置
	size_t m_max_size;							//緩沖區(qū)長(zhǎng)度
	size_t m_expand_par;						//擴(kuò)展因子
};

Buffer::Buffer()
	:m_read_index(0),m_write_index(0),m_max_size(10), m_expand_par(2),m_s(nullptr)
{}

Buffer::~Buffer()
{
	delete[] m_s;
}

int Buffer::init()
{
	m_s = new char[m_max_size]();
	if (m_s == nullptr) {
		cout << "分配m_s失敗\n";
		return -1;
	}
	return 0;
}

class Buffer {
public:
...
private:	
	void adjust_buffer();						//調(diào)整數(shù)據(jù)位置至緩沖區(qū)頭部頭
	void expand_buffer(size_t need_size);		//擴(kuò)展緩沖區(qū)長(zhǎng)度
...
}

void Buffer::adjust_buffer()
{
	if (m_read_index == 0)					//數(shù)據(jù)已經(jīng)在頭部，直接返回
		return;
	int used_size = m_write_index - m_read_index;
	if (used_size == 0) {					//緩沖區(qū)為空，重置讀寫指針
		m_write_index = 0;
		m_read_index = 0;
	}
	else {
		cout << "調(diào)整前read_index write_index" << m_read_index << " " << m_write_index << endl;
		memcpy(m_s, &m_s[m_read_index], used_size);		//將數(shù)據(jù)拷貝至頭部
		m_write_index -= m_read_index;						//寫指針也前移
		cout << "調(diào)整了" << used_size << "個(gè)字節(jié)" << endl;
		m_read_index = 0;								//讀指針置0
	}
	
	cout << "調(diào)整后read_index write_index" << m_read_index << " " << m_write_index << endl;
}

void Buffer::expand_buffer(size_t need_size)			//need_size需要寫入的字節(jié)數(shù)
{
	size_t used_size = m_write_index - m_read_index;	//used_size表示已經(jīng)存儲(chǔ)的字節(jié)數(shù)
	size_t remain_size = m_max_size - used_size;		//remain_size表示剩余空間
	size_t expand_size = m_max_size;					
	while (remain_size < need_size) {					//剩余空間不夠時(shí)擴(kuò)展，用while表示直到擴(kuò)展至夠用
		expand_size *= m_expand_par;
		remain_size = expand_size - used_size;
		//cout << "擴(kuò)展長(zhǎng)度中... 總剩余 總長(zhǎng)度 " << remain_size << "  " << expand_size << endl;
	}
	char* s1 = new char[expand_size]();					//申請(qǐng)新的空間
	memcpy(s1, m_s, m_max_size);
	free(m_s);
	m_s = s1;											//將新空間掛載到緩沖區(qū)
	m_max_size = expand_size;							//更新緩沖區(qū)總長(zhǎng)度
	//cout << "擴(kuò)展結(jié)束，總長(zhǎng)度為" << m_max_size << endl;
}

class Buffer {
public:
	void write_to_buffer(char* src);				//從src中寫數(shù)據(jù)
	size_t readable_bytes();						//存儲(chǔ)數(shù)據(jù)的字節(jié)數(shù)
	size_t read_from_buffer(char *dst,int bytes);	//讀數(shù)據(jù)
	size_t pop_bytes(size_t bytes);					//丟棄數(shù)據(jù)
}

void Buffer::write_to_buffer(char* src)
{
	size_t used_size = m_write_index - m_read_index;	//used_size表示已經(jīng)存儲(chǔ)的字節(jié)數(shù)
	size_t remain_size = m_max_size - used_size;		//remain_size表示剩余空間
	size_t cur_size = m_max_size - m_write_index;		//cur_size表示當(dāng)前能夠存儲(chǔ)的空間
	size_t size = init_random_write(&src);
	//printf("已經(jīng)使用%d,剩余總長(zhǎng)度%d,剩余當(dāng)前長(zhǎng)度%d\n", used_size, remain_size, cur_size);
	if (size > remain_size) {							//剩余空間不夠
		adjust_buffer();
		expand_buffer(size);
	}
	else if (size > cur_size) {							//剩余空間夠,當(dāng)前存不下
		adjust_buffer();
	}
	memcpy(&m_s[m_write_index], src, size);				//存儲(chǔ)數(shù)據(jù)
	m_write_index += size;
	delete[] src;

	//更新并打印log
	//used_size = m_write_index - m_read_index;			
	//remain_size = m_max_size - used_size;
	//cur_size = m_max_size - m_write_index;
	//printf("已經(jīng)使用%d,剩余總長(zhǎng)度%d,剩余當(dāng)前長(zhǎng)度%d\n", used_size, remain_size, cur_size);
}

static int get_random_len() {
	return rand() % 40;
}

static int get_random_ala() {
	return rand() % 26;
}

size_t Buffer::init_random_write(char** src)
{
	int size = get_random_len();
	char ala = get_random_ala();
	
	*src = new char[size];
	cout << "準(zhǔn)備寫入的長(zhǎng)度為" << size << " 值全是 " << (unsigned char)('a' + ala) << endl;
	for (int i = 0; i < size; i++) {
		(*src)[i] = 'a' + ala;
	}
	return size;
}

size_t Buffer::read_from_buffer(char*dst,int read_size)
{
	size_t read_max = m_write_index - m_read_index;			//read_max存儲(chǔ)的字節(jié)數(shù)
	if (read_size == 0 || read_max == 0)					//讀取0字節(jié)和空緩存區(qū)時(shí)直接返回
		return 0;	
	if (read_size == -1) {									//全讀走
		memcpy(dst, &m_s[m_read_index], read_max);
		m_read_index += read_max;
		cout << "讀取了" << read_max << "個(gè)字節(jié)" << endl;
	}
	else if (read_size > 0) {								//讀取指定字節(jié)
		if ((size_t)read_size > read_max)
			read_size = read_max;
		memcpy(dst, &m_s[m_read_index], read_size);
		m_read_index += read_size;
		cout << "讀取了" << read_size << "個(gè)字節(jié)" << endl;
	}
	return read_size;										//返回讀取的字節(jié)數(shù)
}

size_t Buffer::pop_bytes(size_t size)
{
	size_t read_max = m_write_index - m_read_index;		//存儲(chǔ)數(shù)據(jù)長(zhǎng)度
	//test random
	if (size == -2)
		size = get_random_len();

	if (size == 0 || read_max == 0)						//緩沖區(qū)為空或丟棄0字節(jié)返回
		return 0;
	if (size == -1) {									//全丟
		m_read_index += read_max;
		cout << "丟棄了" << read_max << "個(gè)字節(jié)" << endl;
		return read_max;
	}
	if (size > 0) {										//丟棄指定字節(jié)
		if (size > read_max)
			size = read_max;
		m_read_index += size;
		cout << "丟棄了" << size << "個(gè)字節(jié)" << endl;
	}
	return size;
}

	size_t peek_read();							//指向準(zhǔn)備讀的位置（調(diào)試用）
	size_t peek_write();						//指向準(zhǔn)備寫的位置（調(diào)試用）
	
	size_t Buffer::peek_write()
	{
		return m_write_index;
	}
	
	size_t Buffer::peek_read()
	{
		return m_read_index;
	}

#pragma once
class Buffer {
public:
	Buffer();									//構(gòu)造
	~Buffer();									//析構(gòu)
	int init();									//分配緩沖區(qū)
	void write_to_buffer(char* src);			//寫數(shù)據(jù)
	size_t pop_bytes(size_t bytes);				//丟棄數(shù)據(jù)
	size_t read_from_buffer(char *dst,int bytes);//讀數(shù)據(jù)
	size_t readable_bytes();					//得到存儲(chǔ)數(shù)據(jù)的字節(jié)數(shù)

	size_t peek_read();							//指向準(zhǔn)備讀的位置（調(diào)試用）
	size_t peek_write();						//指向準(zhǔn)備寫的位置（調(diào)試用）
private:	
	void adjust_buffer();						//調(diào)整數(shù)據(jù)位置至緩沖區(qū)頭
	void expand_buffer(size_t need_size);		//擴(kuò)展緩沖區(qū)長(zhǎng)度

	size_t init_random_write(char** src);			//隨機(jī)初始化一段數(shù)據(jù)（調(diào)試用）
private:
	char* m_s;									//緩沖區(qū)指針
	size_t m_read_index;						//讀指針位置
	size_t m_write_index;						//寫指針位置
	size_t m_max_size;							//緩沖區(qū)長(zhǎng)度
	size_t m_expand_par;						//擴(kuò)展因子
};

#include "Buffer.h"
#include<iostream>
#include<time.h>
using namespace std;
int total_write = 0;	//記錄總寫入
int total_read = 0;		//記錄總讀取
static int get_random_len() {
	return rand() % 40;
}

static int get_random_ala() {
	return rand() % 26;
}

Buffer::Buffer()
	:m_read_index(0),m_write_index(0),m_max_size(10), m_expand_par(2),m_s(nullptr)
{}

Buffer::~Buffer()
{
	delete[] m_s;
}

int Buffer::init()
{
	m_s = new char[m_max_size]();
	if (m_s == nullptr) {
		cout << "分配m_s失敗\n";
		return -1;
	}
	return 0;
}

size_t Buffer::read_from_buffer(char*dst,int read_size)
{
	size_t read_max = m_write_index - m_read_index;			//read_max存儲(chǔ)的字節(jié)數(shù)
	if (read_size == 0 || read_max == 0)					//讀取0字節(jié)和空緩存區(qū)時(shí)直接返回
		return 0;	
	if (read_size == -1) {									//全讀走
		memcpy(dst, &m_s[m_read_index], read_max);
		m_read_index += read_max;
		printf("讀取完成：\t讀取%d個(gè)字節(jié)\n", read_max); 
		total_read += read_max;
	}
	else if (read_size > 0) {								//讀取指定字節(jié)
		if ((size_t)read_size > read_max)
			read_size = read_max;
		memcpy(dst, &m_s[m_read_index], read_size);
		m_read_index += read_size;
		printf("讀取完成：\t讀取%d個(gè)字節(jié)\n", read_size);
		total_read += read_size;
	}
	return read_size;										//返回讀取的字節(jié)數(shù)
}

size_t Buffer::readable_bytes()
{
	return m_write_index - m_read_index;
}

size_t Buffer::peek_write()
{
	return m_write_index;
}

size_t Buffer::peek_read()
{
	return m_read_index;
}

void Buffer::write_to_buffer(char* src)
{
	size_t used_size = m_write_index - m_read_index;	//used_size表示已經(jīng)存儲(chǔ)的字節(jié)數(shù)
	size_t remain_size = m_max_size - used_size;		//remain_size表示剩余空間
	size_t cur_size = m_max_size - m_write_index;		//cur_size表示當(dāng)前能夠存儲(chǔ)的空間
	size_t size = init_random_write(&src);
	//printf("已經(jīng)使用%d,剩余總長(zhǎng)度%d,剩余當(dāng)前長(zhǎng)度%d\n", used_size, remain_size, cur_size);
	if (size > remain_size) {							//剩余空間不夠
		adjust_buffer();
		expand_buffer(size);
	}
	else if (size > cur_size) {							//剩余空間夠,當(dāng)前存不下
		adjust_buffer();
	}
	memcpy(&m_s[m_write_index], src, size);				//存儲(chǔ)數(shù)據(jù)
	m_write_index += size;
	delete[] src;

	//更新并打印log
	used_size = m_write_index - m_read_index;			
	remain_size = m_max_size - used_size;
	cur_size = m_max_size - m_write_index;
	printf("寫入完成：\t總存儲(chǔ)%d,剩余空間%d,剩余當(dāng)前空間%d\n", used_size, remain_size, cur_size);
}

size_t Buffer::pop_bytes(size_t size)
{
	size_t read_max = m_write_index - m_read_index;		//存儲(chǔ)數(shù)據(jù)長(zhǎng)度
	//test random
	if (size == -2)
		size = get_random_len();

	if (size == 0 || read_max == 0)						//緩沖區(qū)為空或丟棄0字節(jié)返回
		return 0;
	if (size == -1) {									//全丟
		m_read_index += read_max;
		cout << "丟棄了" << read_max << "個(gè)字節(jié)" << endl;
		total_read += read_max;
		return read_max;
	}
	if (size > 0) {										//丟棄指定字節(jié)
		if (size > read_max)
			size = read_max;
		m_read_index += size;
		cout << "丟棄了" << size << "個(gè)字節(jié)" << endl;
		total_read += size;
	}
	return size;
}

size_t Buffer::init_random_write(char** src)
{
	int size = get_random_len();
	total_write += size;
	*src = new char[size];
	char ala = get_random_ala();
	cout << "隨機(jī)寫入:\t長(zhǎng)度為" << size << " 值全是 " << (unsigned char)('a' + ala) << endl;
	for (int i = 0; i < size; i++) {
		(*src)[i] = 'a' + ala;
	}
	return size;
}

void Buffer::adjust_buffer()
{
	if (m_read_index == 0)								//數(shù)據(jù)已經(jīng)在頭部，直接返回
		return;
	int used_size = m_write_index - m_read_index;
	if (used_size == 0) {								//緩沖區(qū)為空，重置讀寫指針
		m_write_index = 0;
		m_read_index = 0;
	}
	else {
		cout << "調(diào)整前read_index write_index" << m_read_index << " " << m_write_index << endl;
		memcpy(m_s, &m_s[m_read_index], used_size);		//將數(shù)據(jù)拷貝至頭部
		m_write_index -= m_read_index;						//寫指針也前移
		cout << "調(diào)整了" << used_size << "個(gè)字節(jié)" << endl;
		m_read_index = 0;								//讀指針置0
	}
	
	cout << "調(diào)整后read_index write_index" << m_read_index << " " << m_write_index << endl;
}

void Buffer::expand_buffer(size_t need_size)			//need_size需要寫入的字節(jié)數(shù)
{
	size_t used_size = m_write_index - m_read_index;	//used_size表示已經(jīng)存儲(chǔ)的字節(jié)數(shù)
	size_t remain_size = m_max_size - used_size;		//remain_size表示剩余空間
	size_t expand_size = m_max_size;					
	while (remain_size < need_size) {					//剩余空間不夠時(shí)擴(kuò)展，用while表示直到擴(kuò)展至夠用
		expand_size *= m_expand_par;
		remain_size = expand_size - used_size;
		cout << "擴(kuò)展長(zhǎng)度中... 總剩余 總長(zhǎng)度 " << remain_size << "  " << expand_size << endl;
	}
	char* s1 = new char[expand_size]();					//申請(qǐng)新的空間
	memcpy(s1, m_s, m_max_size);
	free(m_s);
	m_s = s1;											//將新空間掛載到緩沖區(qū)
	m_max_size = expand_size;							//更新緩沖區(qū)總長(zhǎng)度
	cout << "擴(kuò)展結(jié)束，總長(zhǎng)度為" << m_max_size << endl;
}

int main() {
	srand((unsigned)time(NULL));		//調(diào)試需要初始化隨機(jī)種子
	Buffer* pbuffer = new Buffer();		//創(chuàng)建Buffer對(duì)象
	if (pbuffer->init() != 0)			//init函數(shù)分配緩沖區(qū)
		return 0;
	{
		char* s = nullptr;				//s是指向隨機(jī)數(shù)據(jù)的指針
		char* read = new char[1000];	//讀取時(shí)將數(shù)據(jù)存儲(chǔ)到的指針read
		size_t read_size = 0;			//本次讀取到的字節(jié)數(shù)
	
		pbuffer->write_to_buffer(s);
		read_size = pbuffer-> read_from_buffer(read, -1);
		pbuffer->write_to_buffer(s);
		pbuffer->pop_bytes(-2);
		read_size = read_size = pbuffer-> read_from_buffer(read, 0);
		pbuffer->write_to_buffer(s);
		cout << "總寫入\t" << total_write << endl;;
		cout << "總讀取\t" << total_read << endl;
		cout << "目前寫入" << total_write - total_read << endl;
		cout << "可讀取\t" << pbuffer->readable_bytes()<< endl;
		printf(" write %d read %d \n", pbuffer->peek_write(),pbuffer->peek_read());
		if (total_write - total_read != pbuffer->readable_bytes()) {	//根據(jù)總寫入-總讀取和一共存儲(chǔ)的字節(jié)數(shù)判斷是否存儲(chǔ)正確
			cout << "error!!!" << endl;
		}
		else
			cout << "test is ok\n\n\n";
	}
	delete s;
	delete[] read;
	delete pbuffer;
	return 0;
}

	int main() {
		srand((unsigned)time(NULL));		//調(diào)試需要初始化隨機(jī)種子
		Buffer* pbuffer = new Buffer();		//創(chuàng)建Buffer對(duì)象
		if (pbuffer->init() != 0)			//init函數(shù)分配緩沖區(qū)
			return 0;
		char* s = nullptr;				//s是指向隨機(jī)數(shù)據(jù)的指針
		char* read = new char[1000];	//讀取時(shí)將數(shù)據(jù)存儲(chǔ)到的指針read
		size_t read_size = 0;			//本次讀取到的字節(jié)數(shù)
		unsigned long long time = 0;	//調(diào)試的循環(huán)次數(shù)
		while (1) {
			pbuffer->write_to_buffer(s);
			read_size = pbuffer-> read_from_buffer(read, -1);
			pbuffer->write_to_buffer(s);
			pbuffer->write_to_buffer(s);
			pbuffer->pop_bytes(-2);
			read_size = read_size = pbuffer-> read_from_buffer(read, 0);
			pbuffer->write_to_buffer(s);
			pbuffer->pop_bytes(-2);
			pbuffer->write_to_buffer(s);
			read_size = pbuffer-> read_from_buffer(read, -1);
			pbuffer->write_to_buffer(s);
			pbuffer->write_to_buffer(s);
			read_size = pbuffer-> read_from_buffer(read, 22);
			pbuffer->write_to_buffer(s);
			pbuffer->write_to_buffer(s);
			read_size = pbuffer-> read_from_buffer(read, -1);
			pbuffer->pop_bytes(-2);
			pbuffer->pop_bytes(-2);
			pbuffer->write_to_buffer(s);
			pbuffer->write_to_buffer(s);
			read_size = pbuffer-> read_from_buffer(read, 2);
			pbuffer->write_to_buffer(s);
			read_size = pbuffer-> read_from_buffer(read, 17);
			pbuffer->write_to_buffer(s);
			pbuffer->pop_bytes(-2);
			pbuffer->write_to_buffer(s);
			pbuffer->write_to_buffer(s);
			pbuffer->read_from_buffer(read, 18);

			cout << "總寫入\t" << total_write << endl;;
			cout << "總讀取\t" << total_read << endl;
			cout << "目前寫入" << total_write - total_read << endl;
			cout << "可讀取\t" << pbuffer->readable_bytes()<< endl;
			printf(" write %d read %d \n", pbuffer->peek_write(),pbuffer->peek_read());
			if (total_write - total_read != pbuffer->readable_bytes()) {	//根據(jù)總寫入-總讀取和一共存儲(chǔ)的字節(jié)數(shù)判斷是否存儲(chǔ)正確
				cout << "error!!!" << endl;
				break;
			}
			if (time == 1000000)											//循環(huán)1000000次
			{
				cout << "1000000 ok!!!" << endl;
				break;
			}
			cout << time++ << " is ok\n\n\n";
		}
		delete s;
		delete[] read;
		delete pbuffer;
		return 0;
	}