精简版StringBuilder,提速字符串拼接
编写目的
在频繁的字符串拼接中,为了提升程序的性能,我们往往会用StringBuilder代替String+=String这样的操作;
而我在实际编码中发现,大部分情况下我用到的只是StringBuilder的Append方法;
一些极端的情况下,我希望我的程序性能更高,这时从StringBuilder入手是一个不错的主意;
所以我希望用一种简单的方案代替StringBuilder,我将这个方案命名为QuickStringWriter;
方案定义
对于StringBuilder来说他除了Append之外还会有更多的方法,比如Insert,AppendFormat等
而QuickStringWriter这个方案,仅仅是用来代替简单的字符串+=这样的操作,所以我不会考虑他们,只需要重新实现Append,并让他们比StringBuilder更快
初步设计
class QuickStringWriter : IDisposable
{
public QuickStringWriter Append(bool val);
public QuickStringWriter Append(byte val);
public QuickStringWriter Append(char val);
public QuickStringWriter Append(DateTime val);
public QuickStringWriter Append(DateTime val, string format);
public QuickStringWriter Append(decimal val);
public QuickStringWriter Append(double val);
public QuickStringWriter Append(Guid val);
public QuickStringWriter Append(Guid val, string format);
public QuickStringWriter Append(short val);
public QuickStringWriter Append(int val);
public QuickStringWriter Append(long val);
public QuickStringWriter Append(sbyte val);
public QuickStringWriter Append(float val);
public QuickStringWriter Append(string val);
public QuickStringWriter Append(ushort val);
public QuickStringWriter Append(uint val);
public QuickStringWriter Append(ulong val);
public QuickStringWriter Clear();
void Dispose();
string ToString();
}
结构
QuickStringWriter将使用一个Char数组作为缓冲区(Buff)
使用一个属性Position作为当前字符位置,或者说是当前字符数
重写ToString方法,将当前缓冲区中的内容,从0到Position转为string对象输出
char[] Buff;
int Position; public override string ToString()
{
return new string(Buff, , Position);
}
设置缓冲区
既然有缓冲区,那么就要考虑缓冲区不足时的处理
我设计2个方法解决这个问题
//设置缓冲区容量
void SetCapacity(int capacity)
{
if (capacity > Buff.Length)
{
if (capacity > * ) //6000W
{
throw new OutOfMemoryException("QuickStringWriter容量不能超过6000万个字符");
}
}
var newbuff = new char[capacity];
Array.Copy(Buff, , newbuff, , Math.Min(Position, capacity));
Buff = newbuff;
Position = Math.Min(Position, Buff.Length);
}
//翻倍空间
void ToDouble()
{
SetCapacity(Math.Min(Buff.Length * , * ));
}
第一个方法SetCapacity,我预留了一个缩小当前缓冲区的处理,虽然现在不会使用
第二个方法就是翻倍缓冲区,这里也是有个条件的,如果当前缓冲区大于5W,最多一次也只能扩容10W字符的容量
//当容量不足的时候,尝试翻倍空间
void Try()
{
if (Position >= Buff.Length)
{
ToDouble();
}
}
//测试剩余空间大小,如果不足,则扩展至可用大小后再翻倍
void Check(int count)
{
var pre = Position + count;
if (pre >= Buff.Length)
{
SetCapacity(pre * );
}
}
这里还需要2个方法可以方面的调用
比如在追加单个字符的时候可以调用Try
在追加指定长度字符之前可以调用Check
性能
在性能上,我只要考虑每一个方法的性能都能快StringBuilder就可以了,这点其实并不是非常困难
public QuickStringWriter Append(Boolean val)
{
if (val)
{
Check();
Buff[Position++] = 't';
Buff[Position++] = 'r';
Buff[Position++] = 'u';
Buff[Position++] = 'e';
}
else
{
Check();
Buff[Position++] = 'f';
Buff[Position++] = 'a';
Buff[Position++] = 'l';
Buff[Position++] = 's';
Buff[Position++] = 'e';
}
return this;
}
bool类型处理
百万次追加 false
StringBuilder 19ms
QuickStringWriter 9ms
ps:系统的bool转换为String后首字母都是大小,这里我为了使用更方面直接转为小写的了
public QuickStringWriter Append(DateTime val)
{
Check();
if (val.Year < )
{
Buff[Position++] = '';
if (val.Year < )
{
Buff[Position++] = '';
if (val.Year < )
{
Buff[Position++] = '';
}
}
}
Append((long)val.Year);
Buff[Position++] = '-'; if (val.Month < )
{
Buff[Position++] = '';
}
Append((long)val.Month);
Buff[Position++] = '-'; if (val.Day < )
{
Buff[Position++] = '';
}
Append((long)val.Day);
Buff[Position++] = ' '; if (val.Hour < )
{
Buff[Position++] = '';
}
Append((long)val.Hour);
Buff[Position++] = ':'; if (val.Minute < )
{
Buff[Position++] = '';
}
Append((long)val.Minute);
Buff[Position++] = ':'; if (val.Second < )
{
Buff[Position++] = '';
}
Append((long)val.Minute);
return this;
}
DateTime类型处理
十万次追加 DateTime.Now
StringBuilder 90ms
QuickStringWriter 55ms
Char[] NumberBuff;
public QuickStringWriter Append(Int64 val)
{
if (val == )
{
Buff[Position++] = '';
return this;
} var pos = ;
if (val < )
{
Buff[Position++] = '-';
NumberBuff[pos] = (char)(~(val % ) + '');
if (val < -)
{
val = val / -;
NumberBuff[--pos] = (char)(val % + '');
}
}
else
{
NumberBuff[pos] = (char)(val % + '');
}
while ((val = val / 10L) != 0L)
{
NumberBuff[--pos] = (char)(val % 10L + '');
}
var length = - pos;
Check(length);
Array.Copy(NumberBuff, pos, Buff, Position, length);
Position += length;
return this;
}
整数类型的处理
百万次追加 long.MaxValue sbyte.MaxValue
StringBuilder 190ms 120ms
QuickStringWriter 115ms 33ms
public QuickStringWriter Append(Char val)
{
Try();
Buff[Position++] = val;
return this;
}
char类型处理
百万次追加 'a'
StringBuilder 7ms
QuickStringWriter 4ms
public QuickStringWriter Append(String val)
{
if (val == null || val.Length == )
{
return this;
}
else if (val.Length <= )
{
Check(val.Length);
Buff[Position++] = val[];
if (val.Length > )
{
Buff[Position++] = val[];
if (val.Length > )
{
Buff[Position++] = val[];
}
}
}
else
{
Check(val.Length);
val.CopyTo(, Buff, Position, val.Length);
Position += val.Length;
}
return this;
}
String处理
嗯..这个和StringBuilder几乎相同
然后其他的类型就直接按照调用Append(string str) 的处理方式就可以了
public QuickStringWriter Append(Guid val)
{
Append(val.ToString());
return this;
} public QuickStringWriter Append(Decimal val)
{
Append(val.ToString(System.Globalization.NumberFormatInfo.InvariantInfo));
return this;
}
其他类型处理
全部完成了之后 我把他加入到之前的JsonBuilder中试试
//protected StringBuilder Buff = new StringBuilder(4096);
protected QuickStringWriter Buff = new QuickStringWriter();//字符缓冲区
调用需要修改一个地方
public string ToJsonString(object obj)
{
//Buff.Length = 0; //StringBuilder清空方法
Buff.Clear();//QuickStringWriter清空方法
AppendObject(obj);
return Buff.ToString();
}
再来看看前后的差距
- 原StringBuilder缓冲
211ms | 166ms | 162ms | 164ms | 164ms | 160ms | 163ms | 160ms | 179ms | 156ms |
- 更换为QuickStringWriter后
167ms | 134ms | 134ms | 134ms | 135ms | 134ms | 134ms | 133ms | 134ms | 134ms |
ps:在公司的破电脑上也测了,发现配置越差差距越大,在公司的酷睿双核上差距应该是40%左右
完整代码
using System;
using System.Collections.Generic;
using System.Text; namespace blqw
{
public class QuickStringWriter : IDisposable
{
public QuickStringWriter() : this() { }
/// <summary>
/// 实例化新的对象,并且指定初始容量
/// </summary>
/// <param name="capacity"></param>
public QuickStringWriter(int capacity)
{
NumberBuff = new Char[];
Buff = new Char[capacity];
} //设置缓冲区容量
void SetCapacity(int capacity)
{
if (capacity > Buff.Length)
{
if (capacity > * ) //6000W
{
throw new OutOfMemoryException("QuickStringWriter容量不能超过6000万个字符");
}
}
var newbuff = new char[capacity];
Array.Copy(Buff, , newbuff, , Math.Min(Position, capacity));
Buff = newbuff;
Position = Math.Min(Position, Buff.Length);
}
//当容量不足的时候,尝试翻倍空间
void ToDouble()
{
SetCapacity(Math.Min(Buff.Length * , * ));
} Char[] NumberBuff;
Char[] Buff;
int Position; public void Dispose()
{
NumberBuff = null;
Buff = null;
} public QuickStringWriter Append(Boolean val)
{
if (val)
{
Check();
Buff[Position++] = 't';
Buff[Position++] = 'r';
Buff[Position++] = 'u';
Buff[Position++] = 'e';
}
else
{
Check();
Buff[Position++] = 'f';
Buff[Position++] = 'a';
Buff[Position++] = 'l';
Buff[Position++] = 's';
Buff[Position++] = 'e';
}
return this;
}
public QuickStringWriter Append(DateTime val)
{
Check();
if (val.Year < )
{
Buff[Position++] = '';
if (val.Year < )
{
Buff[Position++] = '';
if (val.Year < )
{
Buff[Position++] = '';
}
}
}
Append((long)val.Year);
Buff[Position++] = '-'; if (val.Month < )
{
Buff[Position++] = '';
}
Append((long)val.Month);
Buff[Position++] = '-'; if (val.Day < )
{
Buff[Position++] = '';
}
Append((long)val.Day);
Buff[Position++] = ' '; if (val.Hour < )
{
Buff[Position++] = '';
}
Append((long)val.Hour);
Buff[Position++] = ':'; if (val.Minute < )
{
Buff[Position++] = '';
}
Append((long)val.Minute);
Buff[Position++] = ':'; if (val.Second < )
{
Buff[Position++] = '';
}
Append((long)val.Minute);
return this;
} public QuickStringWriter Append(Guid val)
{
Append(val.ToString());
return this;
} public QuickStringWriter Append(DateTime val, string format)
{ Append(val.ToString(format));
return this;
}
public QuickStringWriter Append(Guid val, string format)
{
Append(val.ToString(format));
return this;
} public QuickStringWriter Append(Decimal val)
{
Append(val.ToString());
return this;
}
public QuickStringWriter Append(Double val)
{
Append(Convert.ToString(val));
return this;
}
public QuickStringWriter Append(Single val)
{
Append(Convert.ToString(val));
return this;
} public QuickStringWriter Append(SByte val)
{
Append((Int64)val);
return this;
}
public QuickStringWriter Append(Int16 val)
{
Append((Int64)val);
return this;
}
public QuickStringWriter Append(Int32 val)
{
Append((Int64)val);
return this;
} public override string ToString()
{
return new string(Buff, , Position);
} public QuickStringWriter Append(Int64 val)
{
if (val == )
{
Buff[Position++] = '';
return this;
} var pos = ;
if (val < )
{
Buff[Position++] = '-';
NumberBuff[pos] = (char)(~(val % ) + '');
if (val < -)
{
val = val / -;
NumberBuff[--pos] = (char)(val % + '');
}
}
else
{
NumberBuff[pos] = (char)(val % + '');
}
while ((val = val / 10L) != 0L)
{
NumberBuff[--pos] = (char)(val % 10L + '');
}
var length = - pos;
Check(length);
Array.Copy(NumberBuff, pos, Buff, Position, length);
Position += length;
return this;
}
public QuickStringWriter Append(Char val)
{
Try();
Buff[Position++] = val;
return this;
}
public QuickStringWriter Append(String val)
{
if (val == null || val.Length == )
{
return this;
}
else if (val.Length <= )
{
Check(val.Length);
Buff[Position++] = val[];
if (val.Length > )
{
Buff[Position++] = val[];
if (val.Length > )
{
Buff[Position++] = val[];
}
}
}
else
{
Check(val.Length);
val.CopyTo(, Buff, Position, val.Length);
Position += val.Length;
}
return this;
} public QuickStringWriter Append(Byte val)
{
Append((UInt64)val);
return this;
}
public QuickStringWriter Append(UInt16 val)
{
Append((UInt64)val);
return this;
}
public QuickStringWriter Append(UInt32 val)
{
Append((UInt64)val);
return this;
}
public QuickStringWriter Append(UInt64 val)
{
if (val == )
{
Buff[Position++] = '';
return this;
}
var pos = ; NumberBuff[pos] = (char)(val % + ''); while ((val = val / 10L) != 0L)
{
NumberBuff[--pos] = (char)(val % 10L + '');
}
var length = - pos;
Check(length);
Array.Copy(NumberBuff, pos, Buff, Position, length);
Position += length;
return this;
} public QuickStringWriter Clear()
{
Position = ;
return this;
} //当容量不足的时候,尝试翻倍空间
void Try()
{
if (Position >= Buff.Length)
{
ToDouble();
}
}
//测试剩余空间大小,如果不足,则扩展至可用大小后再翻倍
void Check(int count)
{
var pre = Position + count;
if (pre >= Buff.Length)
{
SetCapacity(pre * );
}
} }
}
QuickStringWriter完整代码
这样就OK了,在很多时间他就是一个完全可以满足需求的精简提速版的StringBuilder!
包括以后如果机会放出个人用的简易ORM也会发现里面的字符串拼接也是用的这个对象
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