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restic/internal/repository/parallel.go
2017-09-10 11:00:07 +02:00

76 lines
1.7 KiB
Go

package repository
import (
"context"
"sync"
"github.com/restic/restic/internal/debug"
"github.com/restic/restic/internal/restic"
)
// ParallelWorkFunc gets one file ID to work on. If an error is returned,
// processing stops. When the contect is cancelled the function should return.
type ParallelWorkFunc func(ctx context.Context, id string) error
// ParallelIDWorkFunc gets one restic.ID to work on. If an error is returned,
// processing stops. When the context is cancelled the function should return.
type ParallelIDWorkFunc func(ctx context.Context, id restic.ID) error
// FilesInParallel runs n workers of f in parallel, on the IDs that
// repo.List(t) yield. If f returns an error, the process is aborted and the
// first error is returned.
func FilesInParallel(ctx context.Context, repo restic.Lister, t restic.FileType, n uint, f ParallelWorkFunc) error {
wg := &sync.WaitGroup{}
ch := repo.List(ctx, t)
errors := make(chan error, n)
for i := 0; uint(i) < n; i++ {
wg.Add(1)
go func() {
defer wg.Done()
for {
select {
case id, ok := <-ch:
if !ok {
return
}
err := f(ctx, id)
if err != nil {
errors <- err
return
}
case <-ctx.Done():
return
}
}
}()
}
wg.Wait()
select {
case err := <-errors:
return err
default:
break
}
return nil
}
// ParallelWorkFuncParseID converts a function that takes a restic.ID to a
// function that takes a string. Filenames that do not parse as a restic.ID
// are ignored.
func ParallelWorkFuncParseID(f ParallelIDWorkFunc) ParallelWorkFunc {
return func(ctx context.Context, s string) error {
id, err := restic.ParseID(s)
if err != nil {
debug.Log("invalid ID %q: %v", id, err)
return nil
}
return f(ctx, id)
}
}