5 changed files with 178 additions and 9 deletions
@ -0,0 +1,83 @@ |
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package main |
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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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// 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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// 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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// 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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// 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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// 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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// 分块写入,因为一次写入可能超过令牌桶的 burst size
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remaining := len(p) |
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written := 0 |
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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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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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// 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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// 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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