Module sync_index 

Maintains a persistent index of files that have been previously synced.

The index maps local file paths to their checksums, modification times, and target album IDs. A sharded design (ShardedSyncIndex) distributes entries across multiple segment files for lock-free concurrent reads during parallel scans. On startup, unchanged files are skipped entirely by comparing stored checksums against the current state.

Structs

Shard 🔒

A single shard of the sync index, holding a subset of entries.

ShardedSyncIndex

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.

SyncIndexData 🔒

Inner serialized structure representing the index files list.

SyncIndexDataRef 🔒

Borrowed reference of the serialized index for zero-copy writes.

SyncTarget

Describes the intended album target for a file during sync operations.

SyncedFileRecord

Represents a record stored on disk for a synced file, including the last associated album target.

Enums

SyncDecision

Indicates the result of comparing a file on disk with the saved sync index.

Constants

SHARD_COUNT 🔒

Number of shards for distributing sync index entries.

Functions

fingerprint_from_metadata 🔒

Helper to calculate the size and modification timestamp fingerprint of a file.

load_entries 🔒

Helper to load all stored sync records from the file.

migrate_from_cache_dir 🔒

Migrate legacy cache-dir synced indices on first launch.

shard_for 🔒

Determine which shard index a path belongs to.