95 lines
2.1 KiB
Go
95 lines
2.1 KiB
Go
package physical
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import (
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"context"
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"errors"
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"strings"
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)
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var ErrRelativePath = errors.New("relative paths not supported")
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// View represents a prefixed view of a physical backend
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type View struct {
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backend Backend
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prefix string
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}
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// Verify View satisfies the correct interfaces
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var _ Backend = (*View)(nil)
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// NewView takes an underlying physical backend and returns
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// a view of it that can only operate with the given prefix.
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func NewView(backend Backend, prefix string) *View {
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return &View{
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backend: backend,
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prefix: prefix,
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}
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}
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// List the contents of the prefixed view
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func (v *View) List(ctx context.Context, prefix string) ([]string, error) {
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if err := v.sanityCheck(prefix); err != nil {
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return nil, err
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}
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return v.backend.List(ctx, v.expandKey(prefix))
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}
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// Get the key of the prefixed view
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func (v *View) Get(ctx context.Context, key string) (*Entry, error) {
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if err := v.sanityCheck(key); err != nil {
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return nil, err
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}
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entry, err := v.backend.Get(ctx, v.expandKey(key))
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if err != nil {
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return nil, err
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}
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if entry == nil {
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return nil, nil
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}
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entry.Key = v.truncateKey(entry.Key)
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return &Entry{
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Key: entry.Key,
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Value: entry.Value,
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}, nil
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}
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// Put the entry into the prefix view
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func (v *View) Put(ctx context.Context, entry *Entry) error {
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if err := v.sanityCheck(entry.Key); err != nil {
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return err
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}
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nested := &Entry{
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Key: v.expandKey(entry.Key),
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Value: entry.Value,
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}
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return v.backend.Put(ctx, nested)
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}
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// Delete the entry from the prefix view
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func (v *View) Delete(ctx context.Context, key string) error {
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if err := v.sanityCheck(key); err != nil {
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return err
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}
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return v.backend.Delete(ctx, v.expandKey(key))
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}
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// sanityCheck is used to perform a sanity check on a key
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func (v *View) sanityCheck(key string) error {
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if strings.Contains(key, "..") {
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return ErrRelativePath
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}
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return nil
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}
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// expandKey is used to expand to the full key path with the prefix
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func (v *View) expandKey(suffix string) string {
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return v.prefix + suffix
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}
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// truncateKey is used to remove the prefix of the key
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func (v *View) truncateKey(full string) string {
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return strings.TrimPrefix(full, v.prefix)
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}
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