Struct DiskCache 

pub struct DiskCache { /* private fields */ }

Disk persistence helper for one cached catalogue file.

Implementations

impl DiskCache

pub fn new(cache_file: PathBuf) -> Self

Bind a cache to a specific catalogue path. Path is created lazily on first write — readers tolerate the parent dir not existing yet.

pub fn path(&self) -> &Path

Logical cache file path (no I/O).

pub async fn read_any(&self) -> Result<Option<CachedCatalogue>, CacheError>

Read the cached snapshot regardless of staleness. Returns:

• Ok(Some(snap)) — file existed AND parsed cleanly.
• Ok(None) — file missing OR parse failed (latter emits a tracing::warn for ops triage).
• Err(CacheError::Io) — only for non-NotFound I/O errors (permission denied, EIO, etc).

pub async fn read_fresh( &self, now_ms: u64, ttl_ms: u64, ) -> Result<Option<CachedCatalogue>, CacheError>

Read only when the snapshot is fresh (younger than ttl_ms relative to now_ms). Stale entries return Ok(None); the caller normally falls through to a network refresh and a subsequent Self::write_atomic.

pub async fn write_atomic( &self, snap: &CachedCatalogue, ) -> Result<(), CacheError>

Persist a snapshot. Implementation:

1. mkdir -p the parent dir (idempotent).
2. Write to a sibling .tmp file in the same dir so rename stays on one filesystem (atomic on POSIX).
3. rename(tmp, final) swaps the live snapshot in one step — readers always see either the prior snapshot or the new one, never a half-written file.
4. On error any partial .tmp is best-effort removed.

pub async fn invalidate(&self) -> Result<(), CacheError>

Forget the cache. Returns Ok(()) when file missing (idempotent) — matches the operator-facing “refresh” RPC’s expected semantics.

Trait Implementations

impl Clone for DiskCache

fn clone(&self) -> DiskCache

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for DiskCache

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

Formats the value using the given formatter.