Struct WriteLedger 

pub struct WriteLedger { /* private fields */ }

A turn-scoped copy-on-first-write ledger: the record that lets retry revert a fabricated file to the state it had before the turn began.

The first time a path is written during a turn, its prior bytes are captured (Some = the file existed; None = it did not). Later writes to the same path in the same turn do not overwrite that entry — the pre-turn state is the revert target, never an intermediate write. The rig instrument reverted with a bare rm (sound only because its corpus files never pre-existed); in the real loop a flagged file may be an edit of a tracked file, so the ledger restores bytes rather than deleting. Git-independent by design — newt gates non-git trees too (docs/design/retry-technique.md).

Implementations

impl WriteLedger

pub fn new() -> Self

An empty ledger for a fresh turn.

pub fn note_before_write(&mut self, path: impl Into<PathBuf>)

Record path’s pre-turn state the first time it is written this turn. Call this before the write lands. A no-op on any subsequent write to the same path — the pre-turn snapshot is preserved.

Only a genuine NotFound records the “did-not-exist” marker (None) that makes revert delete the path. Any other read error (EACCES, a transient NFS hiccup, the path being a directory) leaves the path untracked — conflating “unreadable” with “absent” would let revert delete a pre-existing file whose note-time read merely failed. Untracked ⇒ revert returns false and refuses to touch it.

pub fn revert(&self, path: &Path) -> Result<bool>

Restore path to its recorded pre-turn state: write the captured bytes back, or remove the file if it did not exist pre-turn. Returns true iff the path had a ledger entry (so the caller can warn on a gate-flagged path the ledger never saw — a bug, not a silent delete of an untracked file).

Errors

Propagates I/O errors from the restore write or remove (a NotFound on remove is treated as already-reverted, not an error).

pub fn is_empty(&self) -> bool

Whether nothing has been written this turn.

pub fn len(&self) -> usize

How many distinct paths were written this turn.

Trait Implementations

impl Clone for WriteLedger

fn clone(&self) -> WriteLedger

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for WriteLedger

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for WriteLedger

fn default() -> WriteLedger

Returns the “default value” for a type.