mirror of
https://github.com/tailscale/tailscale.git
synced 2025-03-13 17:03:52 +00:00
ipn/store: improve FileStore.WriteState atomicity
If an error occurs with FileStore.WriteState, it should not record the provided value as this results in an inconsistency between what is cached in memory and what is stored on disk. Also, update the documentation of StateStore.ReadState to indicate that the returned value should be treated as immutable. This property is assumed by the fact that FileStore.ReadState returns the same slice of bytes for repeated calls to the same key. Updates #cleanup Signed-off-by: Joe Tsai <joetsai@digital-static.net>
This commit is contained in:
parent
60e768fd14
commit
2ad040db3b
@ -68,8 +68,9 @@ func CurrentProfileKey(userID string) StateKey {
|
||||
|
||||
// StateStore persists state, and produces it back on request.
|
||||
type StateStore interface {
|
||||
// ReadState returns the bytes associated with ID. Returns (nil,
|
||||
// ErrStateNotExist) if the ID doesn't have associated state.
|
||||
// ReadState returns the bytes associated with ID.
|
||||
// It returns (nil, ErrStateNotExist) if the ID doesn't have associated state.
|
||||
// The returned value must not be mutated.
|
||||
ReadState(id StateKey) ([]byte, error)
|
||||
// WriteState saves bs as the state associated with ID.
|
||||
//
|
||||
|
@ -173,16 +173,22 @@ func (s *FileStore) ReadState(id ipn.StateKey) ([]byte, error) {
|
||||
}
|
||||
|
||||
// WriteState implements the StateStore interface.
|
||||
func (s *FileStore) WriteState(id ipn.StateKey, bs []byte) error {
|
||||
func (s *FileStore) WriteState(id ipn.StateKey, bs []byte) (err error) {
|
||||
s.mu.Lock()
|
||||
defer s.mu.Unlock()
|
||||
if bytes.Equal(s.cache[id], bs) {
|
||||
bs0 := s.cache[id]
|
||||
if bytes.Equal(bs0, bs) {
|
||||
return nil
|
||||
}
|
||||
defer func() {
|
||||
if err != nil {
|
||||
s.cache[id] = bs0
|
||||
}
|
||||
}()
|
||||
s.cache[id] = bytes.Clone(bs)
|
||||
bs, err := json.MarshalIndent(s.cache, "", " ")
|
||||
b, err := json.MarshalIndent(s.cache, "", " ")
|
||||
if err != nil {
|
||||
return err
|
||||
}
|
||||
return atomicfile.WriteFile(s.path, bs, 0600)
|
||||
return atomicfile.WriteFile(s.path, b, 0600)
|
||||
}
|
||||
|
Loading…
x
Reference in New Issue
Block a user