mirror of https://github.com/restic/restic.git
72 lines
1.3 KiB
Go
72 lines
1.3 KiB
Go
package repository
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import (
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"sync"
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"github.com/restic/restic/backend"
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)
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func closeIfOpen(ch chan struct{}) {
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// only close ch when it is not already closed, in which the case statement runs.
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select {
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case <-ch:
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return
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default:
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close(ch)
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}
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}
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// ParallelWorkFunc gets one file ID to work on. If an error is returned,
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// processing stops. If done is closed, the function should return.
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type ParallelWorkFunc func(id string, done <-chan struct{}) error
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// FilesInParallel runs n workers of f in parallel, on the IDs that
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// repo.List(t) yield. If f returns an error, the process is aborted and the
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// first error is returned.
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func FilesInParallel(repo backend.Lister, t backend.Type, n uint, f ParallelWorkFunc) error {
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done := make(chan struct{})
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defer closeIfOpen(done)
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wg := &sync.WaitGroup{}
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ch := repo.List(t, done)
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errors := make(chan error, n)
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for i := 0; uint(i) < n; i++ {
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wg.Add(1)
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go func() {
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defer wg.Done()
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for {
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select {
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case id, ok := <-ch:
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if !ok {
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return
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}
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err := f(id, done)
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if err != nil {
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closeIfOpen(done)
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errors <- err
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return
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}
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case <-done:
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return
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}
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}
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}()
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}
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wg.Wait()
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select {
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case err := <-errors:
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return err
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default:
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break
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}
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return nil
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}
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