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Use Go Channels as Promises and Async/Await
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| // Javascript. | |
| const one = async () => { | |
| // Simulate a workload. | |
| sleep(Math.floor(Math.random() * Math.floor(2000))) | |
| return 1 | |
| } | |
| const two = async () => { | |
| // Simulate a workload. | |
| sleep(Math.floor(Math.random() * Math.floor(1000))) | |
| sleep(Math.floor(Math.random() * Math.floor(1000))) | |
| return 2 | |
| } | |
| const r = await Promise.race(one(), two()) | |
| console.log(r) |
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| // Go. | |
| package main | |
| import ( | |
| "fmt" | |
| "math/rand" | |
| "time" | |
| ) | |
| func timeout3s(data) <-chan int32 { | |
| r := make(chan int32) | |
| go func() { | |
| defer close(r) | |
| // Simulate a workload. | |
| time.Sleep(time.Millisecond * time.Duration(3000)) | |
| r <- data | |
| }() | |
| return r | |
| } | |
| func callUpstream() <-chan int32 { | |
| r := make(chan int32) | |
| go func() { | |
| defer close(r) | |
| data, err = fetchData() | |
| writeToDb(data) | |
| r <- data | |
| }() | |
| return r | |
| } | |
| // 4s | |
| func main() { | |
| var r int32 | |
| fromDB, err = readFromDB() | |
| if(fromDB.createdAt < 60*1000) { // old = false | |
| return fromDB | |
| } | |
| select { | |
| case r = <-timeout3s(fromDB): | |
| case r = <-callUpstream(): | |
| } | |
| return r | |
| } |
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