asyncutil

README

asyncutil

A collection of utilities for concurrent programming in Go.

Usage

godoc

Collect

func someWork(id int) chan error {
    errs := make(chan error)
    go func(result *Result) {
        // ...
        errs <- err
    }(&Result{ID: id})
    return errs
}

for err := range asyncutil.Collect(
    someWork(1),
    someWork(2),
) {
    if err != nil {
        fmt.Println("Error:", err)
    }
}

Benchmarks

$ go test -bench . -count 1 .
goos: darwin
goarch: amd64
pkg: github.com/sanggonlee/asyncutil

Collect

5 functions running, each taking 50 milliseconds:

BenchmarkCollect_5_functions_of_50_milliseconds_each-8                21          52155152 ns/op
BenchmarkSequential_5_functions_of_50_milliseconds_each-8              4         262524126 ns/op

2 functions running, each taking 30 milliseconds:

BenchmarkCollect_2_functions_of_30_milliseconds_each-8                38          32424379 ns/op
BenchmarkSequential_2_functions_of_30_milliseconds_each-8             18          64462037 ns/op

5 functions running, each taking 200 milliseconds:

BenchmarkCollect_5_functions_of_200_milliseconds_each-8                5         202613911 ns/op
BenchmarkSequential_5_functions_of_200_milliseconds_each-8             1        1012167372 ns/op

Documentation

Index

• func Collect(errchans ...<-chan error) <-chan error
• func CollectContext(ctx context.Context, errchans ...<-chan error) <-chan error

Examples

• Collect

Functions

func Collect

func Collect(errchans ...<-chan error) <-chan error

Collect takes error channels and returns a new error channel where all non-nil errors from input error channels are funneled into.

Example

package main

import (
	"fmt"
	"net/http"

	"github.com/sanggonlee/asyncutil"
)

func main() {
	doWork := func(url string) chan error {
		errs := make(chan error)
		go func(url string) {
			// Some expensive work..
			_, err := http.Get(url)
			if err != nil {
				errs <- err
			}
		}(url)
		return errs
	}

	for err := range asyncutil.Collect(
		doWork("1"),
		doWork("2"),
	) {
		if err != nil {
			fmt.Println("Error:", err)
		}
	}
}

func CollectContext

func CollectContext(ctx context.Context, errchans ...<-chan error) <-chan error

CollectContext is same as Collect, except it takes a context. If the context exceeds deadline or is cancelled, the resulting error channel receives the corresponding error, in addition to the errors collected by errchans. If the context was already cancelled by the time CollectContext is executed, the resulting error channel will only contain the context error, and not the errors collected by errchans.