goroutine

Documentation

Overview

Package goroutine helps to manage goroutines safely.

It recovers panic with panichandle.

Index

• func CancelWait(ctx context.Context, f func(ctx context.Context)) (cancelWait func())
• func Iter[In, Out any](ctx context.Context, in iter.Seq[In], workers int, ...) iter.Seq[Out]
• func IterOrdered[In, Out any](ctx context.Context, in iter.Seq[In], workers int, ...) iter.Seq[Out]
• func Map[MIn ~map[K]In, MOut map[K]Out, K comparable, In, Out any](ctx context.Context, in MIn, workers int, ...) MOut
• func MapError[MIn ~map[K]In, MOut map[K]Out, K comparable, In, Out any](ctx context.Context, in MIn, workers int, ...) (MOut, error)
• func N(ctx context.Context, n int, f func(ctx context.Context))
• func Services(ctx context.Context, services map[string]func(context.Context) error) error
• func Slice[SIn ~[]In, SOut []Out, In, Out any](ctx context.Context, in SIn, workers int, ...) SOut
• func SliceError[SIn ~[]In, SOut []Out, In, Out any](ctx context.Context, in SIn, workers int, ...) (SOut, error)
• func Start(ctx context.Context, f func(ctx context.Context))
• func Wait(ctx context.Context, f func(ctx context.Context)) (wait func())
• func WaitGroup(ctx context.Context, wg *sync.WaitGroup, f func(ctx context.Context))
• func WithError[In, Out any](f func(context.Context, In) (Out, error)) func(context.Context, In) ValErr[Out]
• type ValErr

Examples

• Iter
• IterOrdered
• Map
• MapError
• Services
• Slice
• SliceError
• WithError

Functions

func CancelWait

func CancelWait(ctx context.Context, f func(ctx context.Context)) (cancelWait func())

CancelWait executes a function in a new goroutine. It returns a function that cancels the context and blocks until the goroutine is terminated. The caller must call this function.

func Iter

func Iter[In, Out any](ctx context.Context, in iter.Seq[In], workers int, f func(context.Context, In) Out) iter.Seq[Out]

Iter runs a function for each values of an input iterator with concurrent workers. It returns an iterator with the unordered output values. For an ordered version, see IterOrdered.

If the context is canceled, it stops reading values from the input iterator. If the caller stops iterating the output iterator, the context is canceled.

Example

ctx := context.Background()
in := slices.Values([]int{1, 2, 3, 4, 5})
out := Iter(ctx, in, 2, func(ctx context.Context, v int) int {
	return v * 2
})
for v := range out {
	fmt.Println(v)
}

Output:

2
4
6
8
10

func IterOrdered

func IterOrdered[In, Out any](ctx context.Context, in iter.Seq[In], workers int, f func(context.Context, In) Out) iter.Seq[Out]

IterOrdered is like Iter but it keeps the order of the output values.

Example

ctx := context.Background()
in := slices.Values([]int{1, 2, 3, 4, 5})
out := IterOrdered(ctx, in, 2, func(ctx context.Context, v int) int {
	return v * 2
})
for v := range out {
	fmt.Println(v)
}

Output:

2
4
6
8
10

func Map

func Map[MIn ~map[K]In, MOut map[K]Out, K comparable, In, Out any](ctx context.Context, in MIn, workers int, f func(ctx context.Context, k K, v In) Out) MOut

Map is a Iter wrapper for maps.

Example

ctx := context.Background()
out := Map(ctx, map[int]int{
	1: 1,
	2: 2,
	3: 3,
	4: 4,
	5: 5,
}, 2, func(ctx context.Context, k int, v int) int {
	return v * 2
})
fmt.Println(out)

Output:

map[1:2 2:4 3:6 4:8 5:10]

func MapError

func MapError[MIn ~map[K]In, MOut map[K]Out, K comparable, In, Out any](ctx context.Context, in MIn, workers int, f func(ctx context.Context, k K, v In) (Out, error)) (MOut, error)

MapError is a Map wrapper that returns an error.

Example

ctx := context.Background()
out, err := MapError(ctx, map[int]int{
	1: 1,
	2: 2,
	3: 3,
	4: 4,
	5: 5,
}, 2, func(ctx context.Context, k int, v int) (int, error) {
	if v == 3 {
		return 0, errors.New("error")
	}
	return v * 2, nil
})
fmt.Println(out)
fmt.Println(err)

Output:

map[1:2 2:4 3:0 4:8 5:10]
error

func N

func N(ctx context.Context, n int, f func(ctx context.Context))

N executes a function with multiple goroutines. It blocks until all goroutines are terminated.

func Services

func Services(ctx context.Context, services map[string]func(context.Context) error) error

Services runs multiple services in goroutines.

It waits for all services to finish.

If a service returns an error, it cancels the context. All errors are joined and returned.

Example

ctx := context.Background()
fmt.Println("start")
err := Services(ctx, map[string]func(context.Context) error{
	"a": func(ctx context.Context) error {
		fmt.Println("service A")
		return nil
	},
	"b": func(ctx context.Context) error {
		fmt.Println("service B")
		return nil
	},
})
if err != nil {
	panic(err)
}
fmt.Println("stop")

Output:

start
service A
service B
stop

func Slice

func Slice[SIn ~[]In, SOut []Out, In, Out any](ctx context.Context, in SIn, workers int, f func(ctx context.Context, i int, v In) Out) SOut

Slice is a Iter wrapper for slices.

Example

ctx := context.Background()
out := Slice(ctx, []int{1, 2, 3, 4, 5}, 2, func(ctx context.Context, i int, v int) int {
	return v * 2
})
fmt.Println(out)

Output:

[2 4 6 8 10]

func SliceError

func SliceError[SIn ~[]In, SOut []Out, In, Out any](ctx context.Context, in SIn, workers int, f func(ctx context.Context, i int, v In) (Out, error)) (SOut, error)

SliceError is a Slice wrapper that returns an error.

Example

ctx := context.Background()
out, err := SliceError(ctx, []int{1, 2, 3, 4, 5}, 2, func(ctx context.Context, i int, v int) (int, error) {
	if v == 3 {
		return 0, errors.New("error")
	}
	return v * 2, nil
})
fmt.Println(out)
fmt.Println(err)

Output:

[2 4 0 8 10]
error

func Start

func Start(ctx context.Context, f func(ctx context.Context))

Start executes a function in a new goroutine.

func Wait

func Wait(ctx context.Context, f func(ctx context.Context)) (wait func())

Wait executes a function in a new goroutine. It returns a function that blocks until the goroutine is terminated. The caller must call this function.

func WaitGroup

func WaitGroup(ctx context.Context, wg *sync.WaitGroup, f func(ctx context.Context))

WaitGroup executes a function in a new goroutine with a sync.WaitGroup. It calls sync.WaitGroup.Add before starting it, and sync.WaitGroup.Done when the goroutine is terminated.

func WithError

func WithError[In, Out any](f func(context.Context, In) (Out, error)) func(context.Context, In) ValErr[Out]

WithError transforms a function that returns an error into a function that returns a ValErr.

Example

ctx := context.Background()
in := slices.Values([]int{1, 2, 3, 4, 5})
out := Iter(ctx, in, 2, WithError(func(ctx context.Context, v int) (int, error) {
	if v == 3 {
		return 0, errors.New("error")
	}
	return v * 2, nil
}))
for v := range out {
	if v.Err != nil {
		fmt.Println(v.Err)
	} else {
		fmt.Println(v.Val)
	}
}

Output:

2
4
error
8
10

Types

type ValErr

type ValErr[T any] struct {
	Val T
	Err error
}

ValErr is a value with an error.