Struct Journal 

pub struct Journal { /* private fields */ }

What: The records of one migration. BTreeMap<String, String> is a text-to-text dictionary kept in key order (sibling HashMap has no order). Why: A sorted map writes the same file text for the same records.

In TS you’d write (pseudocode):

type Journal = { path: string; started: string; steps: Record<string, { state: string; at: string }> };

Implementations

impl Journal

pub fn load(path: &Path) -> Result<Journal, MigrateError>

What: Load the journal at path, or start an empty one when there is no file. Why: A file that exists but is not a journal of this format is an error naming the file: guessing would resume or skip steps on a false record.

In TS you’d write (pseudocode):

const journal = await Journal.load(path);

pub fn started(&self) -> &str

When the migration began, as toISOString text; unique to the migration and kept by a resumed run.

pub fn path(&self) -> &Path

The journal file’s path.

pub fn is_persisted(&self) -> bool

Whether any step has been recorded on disk.

pub fn seconds_of(&self, step: &str) -> Option<i64>

The time, in whole seconds after the epoch, at which the step got its current state; nothing for a step with no record or a record written without a time.

pub fn state(&self, step: &str) -> Option<&str>

The recorded state of a step, if any.

pub fn is_done(&self, step: &str) -> bool

Whether the step finished.

pub fn has_begun(&self, step: &str) -> bool

Whether the step began (finished or not).

pub fn mark(&mut self, step: &str, state: &str) -> Result<(), MigrateError>

What: Record a step’s state and write the file. Why: The file is written to a sibling created exclusively (under a name of its own, never one an earlier run or another user could have planted a link at) and renamed over the journal, with the data synced first, so a kill leaves either the old or the new journal.

In TS you’d write (pseudocode):

await journal.mark('copy', 'done');

pub fn delete(&mut self) -> Result<(), MigrateError>

What: Delete the journal file. Why: A rolled-back or fully removed migration leaves no record, so the next migration starts clean.

In TS you’d write (pseudocode):

await rm(journal.path, { force: true });

Trait Implementations

impl Clone for Journal

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Journal

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

Formats the value using the given formatter.

impl Eq for Journal

impl PartialEq for Journal

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for Journal