PROMISE
Introduction
promise allows you to write async code in sync fashion
- First class context.Context support
- Automatic panic recovery
- Generics support
- Goroutine pool support
- sourcegraph/conc
- panjf2000/ants
- Your own!
Install
$ go get github.com/chebyrash/promise
Quickstart
package main
import (
"context"
"encoding/json"
"fmt"
"net/http"
"github.com/chebyrash/promise"
)
func main() {
p1 := promise.New(func(resolve func(int), reject func(error)) {
factorial := findFactorial(20)
resolve(factorial)
})
p2 := promise.New(func(resolve func(string), reject func(error)) {
ip, err := fetchIP()
if err != nil {
reject(err)
} else {
resolve(ip)
}
})
factorial, _ := p1.Await(context.Background())
fmt.Println(*factorial)
IP, _ := p2.Await(context.Background())
fmt.Println(*IP)
}
func findFactorial(n int) int {
if n == 1 {
return 1
}
return n * findFactorial(n-1)
}
func fetchIP() (string, error) {
resp, err := http.Get("https://httpbin.org/ip")
if err != nil {
return "", err
}
defer resp.Body.Close()
type Response struct {
Origin string `json:"origin"`
}
var response Response
err = json.NewDecoder(resp.Body).Decode(&response)
return response.Origin, err
}Pool
-
Promise execution can be dispatched to distinct pools, providing granular control over task distribution and concurrency.
-
Better performance can be achieved by allowing different stages of a Promise chain to be executed on different goroutine pools, optimizing for the specific requirements of each task.
package main
import (
"context"
"github.com/chebyrash/promise"
)
func main() {
ctx := context.Background()
// fetches data from API, runs on ioOptimizedPool
dataPromise := promise.NewWithPool(func(resolve func(string), reject func(error)) {
data, err := fetchDataFromAPI()
if err != nil {
reject(err)
} else {
resolve(data)
}
}, ioOptimizedPool)
// computes result based on the fetched data, runs on cpuOptimizedPool
resultPromise := promise.ThenWithPool(dataPromise, ctx, func(data string) (string, error) {
result, err := computeResult(data)
return result, err
}, cpuOptimizedPool)
}