singleflight

Documentation

Overview

Package singleflight provides a duplicate function call suppression mechanism. 包 singleflight 提供了重复的函数调用抑制机制。单航模式

Index

• type Group
  • func (g *Group) Do(key string, fn func() (interface{}, error)) (v interface{}, err error, shared bool)
  • func (g *Group) DoChan(key string, fn func() (interface{}, error)) (<-chan Result, bool)
  • func (g *Group) ForgetUnshared(key string) bool
• type Result

Types

type Group

type Group struct {
	// contains filtered or unexported fields
}

Group represents a class of work and forms a namespace in which units of work can be executed with duplicate suppression. Group 代表一类工作，并形成一个命名空间，在该命名空间中可以重复执行工作单元。

func (*Group) Do

func (g *Group) Do(key string, fn func() (interface{}, error)) (v interface{}, err error, shared bool)

Do executes and returns the results of the given function, making sure that only one execution is in-flight for a given key at a time. If a duplicate comes in, the duplicate caller waits for the original to complete and receives the same results. The return value shared indicates whether v was given to multiple callers. Do 执行并返回给定函数 fn 的结果，确保一次仅对给定 key 进行一次执行。 如果出现重复，则重复的调用者将等待原始呼叫完成并收到相同的结果。 返回值中的 shared 表示是否将 v 分配给多个调用方。 阻塞调用

func (*Group) DoChan

func (g *Group) DoChan(key string, fn func() (interface{}, error)) (<-chan Result, bool)

DoChan is like Do but returns a channel that will receive the results when they are ready. The second result is true if the function will eventually be called, false if it will not (because there is a pending request with this key). DoChan 和 Do 类似，但是返回一个 channel 来接收返回值。如果 fn 函数最终会调用，则返回 true ，否则返回 false 。 非阻塞调用， 需要自己来处理 channel

func (*Group) ForgetUnshared

func (g *Group) ForgetUnshared(key string) bool

ForgetUnshared tells the singleflight to forget about a key if it is not shared with any other goroutines. Future calls to Do for a forgotten key will call the function rather than waiting for an earlier call to complete. Returns whether the key was forgotten or unknown--that is, whether no other goroutines are waiting for the result. ForgetUnshared 遗忘没有多个 goroutines 执行此 key 的调用的 key 。将来调用已经遗忘了的 key 是会调用传递的函数，而不是等待之前调用的返回。 返回是否 key 被遗忘了， 也就是：如果没有其它的 goroutine 等待返回结果，返回 true ， 否则返回 false 。

type Result

type Result struct {
	Val    interface{} // 值
	Err    error       // 错误
	Shared bool        // 返回的 Result 是否共享
}

Result holds the results of Do, so they can be passed on a channel. Result 保存 singleflight.Do 的结果，因此可以在通道上传递它们。