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async.go
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async.go
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package wallet
import (
"context"
"sync"
"time"
)
type Command func(context.Context) error
// FiniteCommand terminates when error is nil.
type FiniteCommand struct {
Interval time.Duration
Runable func(context.Context) error
}
func (c FiniteCommand) Run(ctx context.Context) error {
err := c.Runable(ctx)
if err == nil {
return nil
}
ticker := time.NewTicker(c.Interval)
for {
select {
case <-ctx.Done():
return ctx.Err()
case <-ticker.C:
err := c.Runable(ctx)
if err == nil {
return nil
}
}
}
}
// InfiniteCommand runs until context is closed.
type InfiniteCommand struct {
Interval time.Duration
Runable func(context.Context) error
}
func (c InfiniteCommand) Run(ctx context.Context) error {
_ = c.Runable(ctx)
ticker := time.NewTicker(c.Interval)
for {
select {
case <-ctx.Done():
return ctx.Err()
case <-ticker.C:
_ = c.Runable(ctx)
}
}
}
func NewGroup(parent context.Context) *Group {
ctx, cancel := context.WithCancel(parent)
return &Group{
ctx: ctx,
cancel: cancel,
}
}
type Group struct {
ctx context.Context
cancel func()
wg sync.WaitGroup
}
func (g *Group) Add(cmd Command) {
g.wg.Add(1)
go func() {
_ = cmd(g.ctx)
g.wg.Done()
}()
}
func (g *Group) Stop() {
g.cancel()
}
func (g *Group) Wait() {
g.wg.Wait()
}
func (g *Group) WaitAsync() <-chan struct{} {
ch := make(chan struct{})
go func() {
g.Wait()
close(ch)
}()
return ch
}
func NewAtomicGroup(parent context.Context) *AtomicGroup {
ctx, cancel := context.WithCancel(parent)
return &AtomicGroup{ctx: ctx, cancel: cancel}
}
// AtomicGroup terminates as soon as first goroutine terminates..
type AtomicGroup struct {
ctx context.Context
cancel func()
wg sync.WaitGroup
mu sync.Mutex
error error
}
// Go spawns function in a goroutine and stores results or errors.
func (d *AtomicGroup) Add(cmd Command) {
d.wg.Add(1)
go func() {
defer d.wg.Done()
err := cmd(d.ctx)
d.mu.Lock()
defer d.mu.Unlock()
if err != nil {
// do not overwrite original error by context errors
if d.error != nil {
return
}
d.error = err
d.cancel()
return
}
}()
}
// Wait for all downloaders to finish.
func (d *AtomicGroup) Wait() {
d.wg.Wait()
if d.Error() == nil {
d.mu.Lock()
defer d.mu.Unlock()
d.cancel()
}
}
func (d *AtomicGroup) WaitAsync() <-chan struct{} {
ch := make(chan struct{})
go func() {
d.Wait()
close(ch)
}()
return ch
}
// Error stores an error that was reported by any of the downloader. Should be called after Wait.
func (d *AtomicGroup) Error() error {
d.mu.Lock()
defer d.mu.Unlock()
return d.error
}
func (d *AtomicGroup) Stop() {
d.cancel()
}