restic/internal/repository/parallel.go
2018-01-21 21:15:09 +01:00

65 lines
1.7 KiB
Go

package repository
import (
"context"
"github.com/restic/restic/internal/debug"
"github.com/restic/restic/internal/restic"
"golang.org/x/sync/errgroup"
)
// 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) yields. 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 int, f ParallelWorkFunc) error {
g, ctx := errgroup.WithContext(ctx)
ch := make(chan string, n)
g.Go(func() error {
defer close(ch)
return repo.List(ctx, t, func(fi restic.FileInfo) error {
select {
case <-ctx.Done():
case ch <- fi.Name:
}
return nil
})
})
for i := 0; i < n; i++ {
g.Go(func() error {
for name := range ch {
err := f(ctx, name)
if err != nil {
return err
}
}
return nil
})
}
return g.Wait()
}
// 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)
}
}