lancet/docs/concurrency_zh-CN.md

Concurrency

并发包包含一些支持并发编程的功能。例如：goroutine, channel, async等。

源码:

• https://github.com/duke-git/lancet/blob/main/concurrency/channel.go

用法:

import (
    "github.com/duke-git/lancet/v2/concurrency"
)

目录

Channel

• NewChannel
• Bridge
• FanIn
• Generate
• Or
• OrDone
• Repeat
• RepeatFn
• Take
• Tee

文档

Channel

NewChannel

返回一个 Channel 指针实例

函数签名:

type Channel struct {}
func NewChannel() *Channel

例子:

package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/concurrency"
)

func main() {
    c := concurrency.NewChannel()
}

Bridge

将多个通道链接到一个通道，直到取消上下文。

函数签名:

func (c *Channel) Bridge(ctx context.Context, chanStream <-chan <-chan any) <-chan any

例子:

package main

import (
    "context"
    "fmt"
    "github.com/duke-git/lancet/v2/concurrency"
)

func main() {
    ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	c := concurrency.NewChannel()
	genVals := func() <-chan <-chan any {
		chanStream := make(chan (<-chan any))
		go func() {
			defer close(chanStream)
			for i := 0; i < 10; i++ {
				stream := make(chan any, 1)
				stream <- i
				close(stream)
				chanStream <- stream
			}
		}()
		return chanStream
	}

	index := 0
	for val := range c.Bridge(ctx, genVals()) {
		fmt.Printf("%v ", val) //0 1 2 3 4 5 6 7 8 9
	}
}

FanIn

将多个通道合并为一个通道，直到取消上下文

函数签名:

func (c *Channel) FanIn(ctx context.Context, channels ...<-chan any) <-chan any

例子:

package main

import (
    "context"
    "fmt"
    "github.com/duke-git/lancet/v2/concurrency"
)

func main() {
    ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	c := concurrency.NewChannel()
	channels := make([]<-chan any, 3)

	for i := 0; i < 3; i++ {
		channels[i] = c.Take(ctx, c.Repeat(ctx, i), 3)
	}

	mergedChannel := c.FanIn(ctx, channels...)

	for val := range mergedChannel {
		fmt.Println("\t%d\n", val) //1,2,1,0,0,1,0,2,2 (order not for sure)
	}
}

Repeat

返回一个chan，将参数`values`重复放入chan，直到取消上下文。

函数签名:

func (c *Channel) Repeat(ctx context.Context, values ...any) <-chan any

例子:

package main

import (
    "context"
    "fmt"
    "github.com/duke-git/lancet/v2/concurrency"
)

func main() {
    ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	c := concurrency.NewChannel()
	intStream := c.Take(ctx, c.Repeat(ctx, 1, 2), 5)

	for v := range intStream {
     	fmt.Println(v) //1, 2, 1, 2, 1
	}
}

RepeatFn

返回一个chan，重复执行函数fn，并将结果放入返回的chan，直到取消上下文。

函数签名:

func (c *Channel) RepeatFn(ctx context.Context, fn func() any) <-chan any

例子:

package main

import (
    "context"
    "fmt"
    "github.com/duke-git/lancet/v2/concurrency"
)

func main() {
    ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	fn := func() any {
		s := "a"
		return s
	}
	c := concurrency.NewChannel()
	dataStream := c.Take(ctx, c.RepeatFn(ctx, fn), 3)

	for v := range dataStream {
	    fmt.Println(v) //a, a, a
	}
}

Or

将一个或多个通道读取到一个通道中，当任何读取通道关闭时将结束读取。

函数签名:

func (c *Channel) Or(channels ...<-chan any) <-chan any

例子:

package main

import (
    "context"
    "fmt"
    "github.com/duke-git/lancet/v2/concurrency"
)

func main() {
    sig := func(after time.Duration) <-chan any {
		c := make(chan interface{})
		go func() {
			defer close(c)
			time.Sleep(after)
		}()
		return c
	}

	start := time.Now()

	c := concurrency.NewChannel()
	<-c.Or(
		sig(1*time.Second),
		sig(2*time.Second),
		sig(3*time.Second),
		sig(4*time.Second),
		sig(5*time.Second),
	)

	fmt.Println("done after %v", time.Since(start)) //1.003s
}

OrDone

将一个通道读入另一个通道，直到取消上下文。

函数签名:

func (c *Channel) OrDone(ctx context.Context, channel <-chan any) <-chan any

例子:

package main

import (
    "context"
    "fmt"
    "github.com/duke-git/lancet/v2/concurrency"
)

func main() {
    ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	c := concurrency.NewChannel()
	intStream := c.Take(ctx, c.Repeat(ctx, 1), 3)

	for val := range c.OrDone(ctx, intStream) {
		fmt.Println(val)  //1
	}
}

Take

返回一个chan，其值从另一个chan获取，直到取消上下文。

函数签名:

func (c *Channel) Take(ctx context.Context, valueStream <-chan any, number int) <-chan any

例子:

package main

import (
    "context"
    "fmt"
    "github.com/duke-git/lancet/v2/concurrency"
)

func main() {
    ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	numbers := make(chan any, 5)
	numbers <- 1
	numbers <- 2
	numbers <- 3
	numbers <- 4
	numbers <- 5
	defer close(numbers)

	c := concurrency.NewChannel()
	intStream := c.Take(ctx, numbers, 3)

	for val := range intStream {
        fmt.Println(val) //1, 2, 3
	}
}

Tee

将一个通道分成两个通道，直到取消上下文。

函数签名:

func (c *Channel) Tee(ctx context.Context, in <-chan any) (<-chan any, <-chan any)

例子:

package main

import (
    "context"
    "fmt"
    "github.com/duke-git/lancet/v2/concurrency"
)

func main() {
    ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	c := concurrency.NewChannel()
	inStream := c.Take(ctx, c.Repeat(ctx, 1, 2), 4)

	out1, out2 := c.Tee(ctx, inStream)
	for val := range out1 {
        fmt.Println(val) //1
        fmt.Println(<-out2) //1
	}
}