Struct ShardedSyncIndex 

pub struct ShardedSyncIndex {
    index_file: PathBuf,
    shards: [RwLock<Shard>; 16],
}

Thread-safe sync index that distributes entries across 16 RwLock shards keyed by path hash. This eliminates the single-lock bottleneck when parallel producers (startup scan, watcher workers) and consumers (library UI sync-state lookups) all contend on the index simultaneously.

The public API is identical to the old SyncIndex but methods are inherent – callers no longer wrap this in Arc<Mutex<_>>.

Fields

index_file: PathBuf

Absolute path of index JSON on disk.

shards: [RwLock<Shard>; 16]

Array of RwLock-wrapped entry shards.

Implementations

impl ShardedSyncIndex

pub fn new() -> Self

Load existing indices from persistent path, migrating cache if necessary.

pub fn sync_decision( &self, path: &Path, target: &SyncTarget, ) -> Result<SyncDecision>

Decide whether a file is already current, needs a new upload, or only needs reassociation.

pub fn record_synced( &self, path: &str, checksum: &str, target: &SyncTarget, ) -> Result<()>

Save the latest synced fingerprint and album target for a file.

pub fn prune_missing(&self, seen_paths: &HashSet<String>) -> Result<()>

Drop records for files that no longer exist under any configured watch path.

pub fn stored_checksum(&self, path: &str) -> Option<String>

Reuse the previous checksum when a file only needs album reassociation.

pub fn fresh_checksum(&self, path: &Path) -> Option<String>

Return the cached checksum only if the file’s current size + mtime still match the stored fingerprint. Returns None when the file is missing, untracked, or has been modified since the last index update — callers must re-hash in that case.

pub fn record_for_path(&self, path: &str) -> Option<SyncedFileRecord>

Return a synced record for a specific path without touching the filesystem.

pub fn remove_path(&self, path: &str) -> Result<bool>

Remove one synced path from the index after a deliberate delete sync.

pub fn records_under_path(&self, root: &Path) -> Vec<(String, SyncedFileRecord)>

Return synced records rooted under a watch path.

pub fn paths_for_checksum(&self, checksum: &str) -> Vec<String>

All synced paths that share a checksum. Used to detect when an asset is referenced from more than one watch folder before trashing it.

pub fn local_path_for_checksum(&self, checksum: &str) -> Option<String>

Reverse-lookup a local path by checksum for library sync-state indicators.

pub fn flush(&self) -> Result<()>

Force a flush to disk if there are unwritten changes. Dirty markers are only cleared after a successful write, so a failed write leaves the data marked dirty for the next flush attempt.