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, 0, 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 > 6000 * 10000) //6000W { throw new OutOfMemoryException("QuickStringWriter容量不能超过6000万个字符"); } } var newbuff = new char[capacity]; Array.Copy(Buff, 0, newbuff, 0, Math.Min(Position, capacity)); Buff = newbuff; Position = Math.Min(Position, Buff.Length);}//翻倍空间void ToDouble(){ SetCapacity(Math.Min(Buff.Length * 2, 10 * 10000));}
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 * 2); }}
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(4); Buff[Position++] = 't'; Buff[Position++] = 'r'; Buff[Position++] = 'u'; Buff[Position++] = 'e'; } else { Check(5); Buff[Position++] = 'f'; Buff[Position++] = 'a'; Buff[Position++] = 'l'; Buff[Position++] = 's'; Buff[Position++] = 'e'; } return this;} 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(18); if (val.Year < 1000) { Buff[Position++] = '0'; if (val.Year < 100) { Buff[Position++] = '0'; if (val.Year < 10) { Buff[Position++] = '0'; } } } Append((long)val.Year); Buff[Position++] = '-'; if (val.Month < 10) { Buff[Position++] = '0'; } Append((long)val.Month); Buff[Position++] = '-'; if (val.Day < 10) { Buff[Position++] = '0'; } Append((long)val.Day); Buff[Position++] = ' '; if (val.Hour < 10) { Buff[Position++] = '0'; } Append((long)val.Hour); Buff[Position++] = ':'; if (val.Minute < 10) { Buff[Position++] = '0'; } Append((long)val.Minute); Buff[Position++] = ':'; if (val.Second < 10) { Buff[Position++] = '0'; } Append((long)val.Minute); return this;} 十万次追加 DateTime.Now
StringBuilder 90ms
QuickStringWriter 55ms
Char[] NumberBuff;public QuickStringWriter Append(Int64 val){ if (val == 0) { Buff[Position++] = '0'; return this; } var pos = 63; if (val < 0) { Buff[Position++] = '-'; NumberBuff[pos] = (char)(~(val % 10) + '1'); if (val < -10) { val = val / -10; NumberBuff[--pos] = (char)(val % 10 + '0'); } } else { NumberBuff[pos] = (char)(val % 10 + '0'); } while ((val = val / 10L) != 0L) { NumberBuff[--pos] = (char)(val % 10L + '0'); } var length = 64 - pos; Check(length); Array.Copy(NumberBuff, pos, Buff, Position, length); Position += length; return this;} 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;} 百万次追加 'a'
StringBuilder 7ms
QuickStringWriter 4ms
public QuickStringWriter Append(String val){ if (val == null || val.Length == 0) { return this; } else if (val.Length <= 3) { Check(val.Length); Buff[Position++] = val[0]; if (val.Length > 1) { Buff[Position++] = val[1]; if (val.Length > 2) { Buff[Position++] = val[2]; } } } else { Check(val.Length); val.CopyTo(0, Buff, Position, val.Length); Position += val.Length; } return this;} 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;} 代入
全部完成了之后 我把他加入到之前的中试试
//protected StringBuilder Buff = new StringBuilder(4096);protected QuickStringWriter Buff = new QuickStringWriter(4096);//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(2048) { } /// /// 实例化新的对象,并且指定初始容量 /// /// public QuickStringWriter(int capacity) { NumberBuff = new Char[64]; Buff = new Char[capacity]; } //设置缓冲区容量 void SetCapacity(int capacity) { if (capacity > Buff.Length) { if (capacity > 6000 * 10000) //6000W { throw new OutOfMemoryException("QuickStringWriter容量不能超过6000万个字符"); } } var newbuff = new char[capacity]; Array.Copy(Buff, 0, newbuff, 0, 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 * 2, 10 * 10000)); } Char[] NumberBuff; Char[] Buff; int Position; public void Dispose() { NumberBuff = null; Buff = null; } public QuickStringWriter Append(Boolean val) { if (val) { Check(4); Buff[Position++] = 't'; Buff[Position++] = 'r'; Buff[Position++] = 'u'; Buff[Position++] = 'e'; } else { Check(5); Buff[Position++] = 'f'; Buff[Position++] = 'a'; Buff[Position++] = 'l'; Buff[Position++] = 's'; Buff[Position++] = 'e'; } return this; } public QuickStringWriter Append(DateTime val) { Check(18); if (val.Year < 1000) { Buff[Position++] = '0'; if (val.Year < 100) { Buff[Position++] = '0'; if (val.Year < 10) { Buff[Position++] = '0'; } } } Append((long)val.Year); Buff[Position++] = '-'; if (val.Month < 10) { Buff[Position++] = '0'; } Append((long)val.Month); Buff[Position++] = '-'; if (val.Day < 10) { Buff[Position++] = '0'; } Append((long)val.Day); Buff[Position++] = ' '; if (val.Hour < 10) { Buff[Position++] = '0'; } Append((long)val.Hour); Buff[Position++] = ':'; if (val.Minute < 10) { Buff[Position++] = '0'; } Append((long)val.Minute); Buff[Position++] = ':'; if (val.Second < 10) { Buff[Position++] = '0'; } 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, 0, Position); } public QuickStringWriter Append(Int64 val) { if (val == 0) { Buff[Position++] = '0'; return this; } var pos = 63; if (val < 0) { Buff[Position++] = '-'; NumberBuff[pos] = (char)(~(val % 10) + '1'); if (val < -10) { val = val / -10; NumberBuff[--pos] = (char)(val % 10 + '0'); } } else { NumberBuff[pos] = (char)(val % 10 + '0'); } while ((val = val / 10L) != 0L) { NumberBuff[--pos] = (char)(val % 10L + '0'); } var length = 64 - 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 == 0) { return this; } else if (val.Length <= 3) { Check(val.Length); Buff[Position++] = val[0]; if (val.Length > 1) { Buff[Position++] = val[1]; if (val.Length > 2) { Buff[Position++] = val[2]; } } } else { Check(val.Length); val.CopyTo(0, 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 == 0) { Buff[Position++] = '0'; return this; } var pos = 63; NumberBuff[pos] = (char)(val % 10 + '0'); while ((val = val / 10L) != 0L) { NumberBuff[--pos] = (char)(val % 10L + '0'); } var length = 64 - pos; Check(length); Array.Copy(NumberBuff, pos, Buff, Position, length); Position += length; return this; } public QuickStringWriter Clear() { Position = 0; 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 * 2); } } }} 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