关于java:黑马精品Java架构师实战训练营wumi

download:【黑马精品】Java 架构师实战训练营

package main
import (

"fmt"
"math/rand"
"time"

)
var (

Web   = fakeSearch("web")
Image = fakeSearch("image")
Video = fakeSearch("video")

)
type Result string
type Search func(query string) Result
func fakeSearch(kind string) Search {

return func(query string) Result {time.Sleep(time.Duration(rand.Intn(100)) * time.Millisecond)
    return Result(fmt.Sprintf("%s result for %q\n", kind, query))
}

}
func Google(query string) (results []Result) {

results = append(results, Web(query))
results = append(results, Image(query))
results = append(results, Video(query))
return

}
func main() {

rand.Seed(time.Now().UnixNano())
start := time.Now()
results := Google("golang")
elapsed := time.Since(start)
fmt.Println(results)
fmt.Println(elapsed)

}
运行后果如下:

[web result for “golang”
image result for “golang”
video result for “golang”
]
153.365484ms

谷歌搜寻 2.0

同时运行网页、图像和视频搜寻，并等待所有后果。没有锁，没有条件变量，没有回调。

代码如下，关注 Google 函数。

package main
import (

"fmt"
"math/rand"
"time"

)
var (

Web   = fakeSearch("web")
Image = fakeSearch("image")
Video = fakeSearch("video")

)
type Result string
type Search func(query string) Result
func fakeSearch(kind string) Search {

return func(query string) Result {time.Sleep(time.Duration(rand.Intn(100)) * time.Millisecond)
    return Result(fmt.Sprintf("%s result for %q\n", kind, query))
}

}
func Google(query string) (results []Result) {

c := make(chan Result)
go func() { c <- Web(query) } ()
go func() { c <- Image(query) } ()
go func() { c <- Video(query) } ()
for i := 0; i < 3; i++ {
    result := <-c
    results = append(results, result)
}
return

}
func main() {

rand.Seed(time.Now().UnixNano())
start := time.Now()
results := Google("golang")
elapsed := time.Since(start)
fmt.Println(results)
fmt.Println(elapsed)

}

谷歌搜寻 2.1 不要等待缓慢的服务器。没有锁，无条件变量，没有回调。通过 select 的超时实现，需要把 time.After 定义的超时通道放在 for 循环外层。

package main
import (

"fmt"
"math/rand"
"time"

)
var (

Web   = fakeSearch("web")
Image = fakeSearch("image")
Video = fakeSearch("video")

)
type Result string
type Search func(query string) Result
func fakeSearch(kind string) Search {

return func(query string) Result {time.Sleep(time.Duration(rand.Intn(100)) * time.Millisecond)
    return Result(fmt.Sprintf("%s result for %q\n", kind, query))
}

}
func Google(query string) (results []Result) {

c := make(chan Result)
go func() { c <- Web(query) } ()
go func() { c <- Image(query) } ()
go func() { c <- Video(query) } ()
timeout := time.After(80 * time.Millisecond)
for i := 0; i < 3; i++ {
    select {
    case result := <-c:
        results = append(results, result)
    case <-timeout:
        fmt.Println("timed out")
        return
    }
}
return

}
func main() {

rand.Seed(time.Now().UnixNano())
start := time.Now()
results := Google("golang")
elapsed := time.Since(start)
fmt.Println(results)
fmt.Println(elapsed)

}