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[T any] struct
func NewChannel[T any]() *Channel[T]

例子:

package main

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

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

Bridge

将多个channel链接到一个channel，直到取消上下文。

函数签名:

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

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[int]()
	genVals := func() <-chan <-chan int {
		out := make(chan (<-chan int))
		go func() {
			defer close(out)
			for i := 1; i <= 5; i++ {
				stream := make(chan int, 1)
				stream <- i
				close(stream)
				out <- stream
			}
		}()
		return out
	}

	for v := range c.Bridge(ctx, genVals()) {
		fmt.Println(v)
	}

	// Output:
	// 1
	// 2
	// 3
	// 4
	// 5
}

FanIn

将多个channel合并为一个channel，直到取消上下文。

函数签名:

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

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[int]()
	channels := make([]<-chan int, 2)

	for i := 0; i < 2; i++ {
		channels[i] = c.Take(ctx, c.Repeat(ctx, i), 2)
	}

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

	for v := range chs {
		fmt.Println(v) //1 1 0 0 or 0 0 1 1
	}
}

Generate

根据传入的值，生成channel.

函数签名:

func (c *Channel[T]) Generate(ctx context.Context, values ...T) <-chan T

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[int]()
	intStream := c.Generate(ctx, 1, 2, 3)

	fmt.Println(<-intStream)
	fmt.Println(<-intStream)
	fmt.Println(<-intStream)

	// Output:
	// 1
	// 2
	// 3
}

Repeat

返回一个channel，将参数`values`重复放入channel，直到取消上下文。

函数签名:

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

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[int]()
	intStream := c.Take(ctx, c.Repeat(ctx, 1, 2), 4)

	for v := range intStream {
		fmt.Println(v)
	}

	// Output:
	// 1
	// 2
	// 1
	// 2
}

RepeatFn

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

函数签名:

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

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() string {
		return "hello"
	}

	c := concurrency.NewChannel[string]()
	intStream := c.Take(ctx, c.RepeatFn(ctx, fn), 3)

	for v := range intStream {
		fmt.Println(v)
	}
	// Output:
	// hello
	// hello
	// hello
}

Or

将一个或多个channel读取到一个channel中，当任何读取channel关闭时将结束读取。

函数签名:

func (c *Channel[T]) Or(channels ...<-chan T) <-chan T

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 any)
		go func() {
			defer close(c)
			time.Sleep(after)
		}()
		return c
	}

	start := time.Now()

	c := concurrency.NewChannel[any]()
	<-c.Or(
		sig(1*time.Second),
		sig(2*time.Second),
		sig(3*time.Second),
	)

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

OrDone

将一个channel读入另一个channel，直到取消上下文。

函数签名:

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

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[int]()
	intStream := c.Take(ctx, c.Repeat(ctx, 1), 3)

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

	// Output:
	// 1
	// 1
	// 1
}

Take

返回一个channel，其值从另一个channel获取，直到取消上下文。

函数签名:

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

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 int, 5)
	numbers <- 1
	numbers <- 2
	numbers <- 3
	numbers <- 4
	numbers <- 5
	defer close(numbers)

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

	for v := range intStream {
		fmt.Println(v)
	}

	// Output:
	// 1
	// 2
	// 3
}

Tee

将一个channel分成两个channel，直到取消上下文。

函数签名:

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

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[int]()
	intStream := c.Take(ctx, c.Repeat(ctx, 1), 2)

	ch1, ch2 := c.Tee(ctx, intStream)

	for v := range ch1 {
		fmt.Println(v)
		fmt.Println(<-ch2)
	}
	// Output:
	// 1
	// 1
	// 1
	// 1
}