5 changed files with 178 additions and 9 deletions
			
			
		@ -0,0 +1,83 @@ | 
				
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package main | 
				
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 | 
				
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import ( | 
				
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	"context" | 
				
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	"golang.org/x/time/rate" | 
				
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	"net" | 
				
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) | 
				
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 | 
				
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// ThrottledConn 包装了一个 net.Conn,并对其读写速率进行限制
 | 
				
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type ThrottledConn struct { | 
				
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	net.Conn | 
				
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	readerLimiter *rate.Limiter | 
				
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	writerLimiter *rate.Limiter | 
				
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} | 
				
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 | 
				
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// NewThrottledConn 创建一个新的限流连接
 | 
				
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func NewThrottledConn(conn net.Conn, readLimiter, writeLimiter *rate.Limiter) *ThrottledConn { | 
				
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	return &ThrottledConn{ | 
				
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		Conn:          conn, | 
				
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		readerLimiter: readLimiter, | 
				
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		writerLimiter: writeLimiter, | 
				
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	} | 
				
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} | 
				
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 | 
				
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// Read 方法被重写,增加了速率限制
 | 
				
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func (c *ThrottledConn) Read(p []byte) (n int, err error) { | 
				
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	if c.readerLimiter == nil { | 
				
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		return c.Conn.Read(p) // 如果没有读限制器,则直接读取
 | 
				
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	} | 
				
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 | 
				
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	// 读取数据
 | 
				
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	n, err = c.Conn.Read(p) | 
				
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	if n > 0 { | 
				
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		// [核心] 等待,直到令牌桶允许 n 字节的数据通过
 | 
				
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		if waitErr := c.readerLimiter.WaitN(context.Background(), n); waitErr != nil { | 
				
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			return n, waitErr // 如果等待出错,返回错误
 | 
				
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		} | 
				
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	} | 
				
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	return n, err | 
				
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} | 
				
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 | 
				
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// Write 方法被重写,增加了速率限制
 | 
				
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func (c *ThrottledConn) Write(p []byte) (n int, err error) { | 
				
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	if c.writerLimiter == nil { | 
				
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		return c.Conn.Write(p) // 如果没有写限制器,则直接写入
 | 
				
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	} | 
				
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 | 
				
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	// 分块写入,因为一次写入可能超过令牌桶的 burst size
 | 
				
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 | 
				
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	remaining := len(p) | 
				
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	written := 0 | 
				
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 | 
				
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	for remaining > 0 { | 
				
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		// 计算本次可以写入多少
 | 
				
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		// WaitN 会阻塞,直到桶里有足够的令牌,或者 context 被取消
 | 
				
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		// 一次最多等待一个桶大小 (burst size) 的令牌
 | 
				
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		burst := c.writerLimiter.Burst() | 
				
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		toWrite := min(remaining, burst) | 
				
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 | 
				
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		if err := c.writerLimiter.WaitN(context.Background(), toWrite); err != nil { | 
				
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			return written, err | 
				
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		} | 
				
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 | 
				
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		// 写入数据
 | 
				
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		n, err := c.Conn.Write(p[written : written+toWrite]) | 
				
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		if n > 0 { | 
				
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			written += n | 
				
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			remaining -= n | 
				
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		} | 
				
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		if err != nil { | 
				
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			return written, err | 
				
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		} | 
				
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	} | 
				
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	return written, nil | 
				
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} | 
				
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 | 
				
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// min 辅助函数
 | 
				
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func min(a, b int) int { | 
				
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	if a < b { | 
				
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		return a | 
				
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	} | 
				
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	return b | 
				
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} | 
				
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