429Enjoyer
130 lines
2.6 KiB
Go
130 lines
2.6 KiB
Go
package backend
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import (
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"context"
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"errors"
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"fmt"
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"sync"
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"time"
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)
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var ErrDownloadCancelled = errors.New("download cancelled")
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var downloadCancelState = struct {
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sync.Mutex
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ctx context.Context
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cancel context.CancelFunc
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active int
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stopping bool
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}{}
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func BeginDownloadCancellationScope() (context.Context, func()) {
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downloadCancelState.Lock()
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defer downloadCancelState.Unlock()
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if downloadCancelState.ctx == nil || downloadCancelState.active == 0 {
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downloadCancelState.ctx, downloadCancelState.cancel = context.WithCancel(context.Background())
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downloadCancelState.stopping = false
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}
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downloadCancelState.active++
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ctx := downloadCancelState.ctx
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once := sync.Once{}
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return ctx, func() {
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once.Do(func() {
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downloadCancelState.Lock()
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defer downloadCancelState.Unlock()
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if downloadCancelState.active > 0 {
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downloadCancelState.active--
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}
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if downloadCancelState.active == 0 {
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if downloadCancelState.cancel != nil {
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downloadCancelState.cancel()
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}
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downloadCancelState.ctx = nil
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downloadCancelState.cancel = nil
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downloadCancelState.stopping = false
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}
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})
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}
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}
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func ActiveDownloadContext() context.Context {
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downloadCancelState.Lock()
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defer downloadCancelState.Unlock()
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if downloadCancelState.ctx == nil {
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return context.Background()
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}
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return downloadCancelState.ctx
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}
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func ForceStopActiveDownloads() {
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downloadCancelState.Lock()
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cancel := downloadCancelState.cancel
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if cancel != nil {
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downloadCancelState.stopping = true
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}
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downloadCancelState.Unlock()
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if cancel != nil {
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cancel()
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}
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CancelQueuedAndDownloadingItems()
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SetDownloading(false)
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}
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func IsDownloadForceStopRequested() bool {
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downloadCancelState.Lock()
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defer downloadCancelState.Unlock()
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return downloadCancelState.stopping
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}
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func CheckDownloadCancelled() error {
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ctx := ActiveDownloadContext()
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select {
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case <-ctx.Done():
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return ErrDownloadCancelled
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default:
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return nil
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}
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}
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func SleepWithDownloadContext(delay time.Duration) error {
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if delay <= 0 {
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return CheckDownloadCancelled()
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}
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ctx := ActiveDownloadContext()
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timer := time.NewTimer(delay)
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defer timer.Stop()
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select {
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case <-ctx.Done():
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return ErrDownloadCancelled
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case <-timer.C:
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return nil
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}
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}
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func IsDownloadCancelledError(err error) bool {
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if err == nil {
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return false
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}
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return errors.Is(err, ErrDownloadCancelled) || errors.Is(err, context.Canceled)
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}
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func WrapDownloadCancelled(err error) error {
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if err == nil {
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return nil
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}
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if IsDownloadForceStopRequested() || errors.Is(err, context.Canceled) {
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return fmt.Errorf("%w", ErrDownloadCancelled)
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}
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return err
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}
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