这些天,Goroutines 和通道困扰着我。我正在查看https://github.com/adonovan/gopl.io/tree/master/ch9上的 memo5 代码。如果你看 memo5 的 memo.go,有func (e *entry) call(f Func, key string)和func (e *entry) deliver(response chan<- result)部分。// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.// License: https://creativecommons.org/licenses/by-nc-sa/4.0/// See page 278.// Package memo provides a concurrency-safe non-blocking memoization// of a function. Requests for different keys proceed in parallel.// Concurrent requests for the same key block until the first completes.// This implementation uses a monitor goroutine.package memo//!+Func// Func is the type of the function to memoize.type Func func(key string) (interface{}, error)// A result is the result of calling a Func.type result struct { value interface{} err error}type entry struct { res result ready chan struct{} // closed when res is ready}//!-Func//!+get// A request is a message requesting that the Func be applied to key.type request struct { key string response chan<- result // the client wants a single result}type Memo struct{ requests chan request }// New returns a memoization of f. Clients must subsequently call Close.func New(f Func) *Memo { memo := &Memo{requests: make(chan request)} go memo.server(f) return memo}func (memo *Memo) Get(key string) (interface{}, error) { response := make(chan result) memo.requests <- request{key, response} res := <-response return res.value, res.err}我不明白如何在 close(e.ready)这里 <-e.ready同步。就算看完书,也看不懂。请告诉我机制是什么。
1 回答
拉丁的传说
TA贡献1789条经验 获得超8个赞
e.ready
更多地被称为done
通道。这是一种通过关闭done
( e.ready
chan) 来告诉您的 ref 函数 dothing 已准备好的方法。<-e.ready
将阻塞直到它的done
( closed
)。
所以...阅读此代码意味着下一步。
deliver
等待红色信号。call
获取 e.res(
e.res.value 的数据,e.res.err = f(key)`)call
通过关闭它来释放完成的通道 (close(e.ready)
)deliver
可以通过块读取移动<-e.ready
并将数据发送到response
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