Module storage 

Persistent Storage with Journaling

Provides crash-resilient persistence for CRDTs using an append-only journal with automatic replay on mount and compaction support.

Architecture

The journal uses a simple binary format:

┌─────────────┬─────────────┬─────────────────┐
│ Length (4B) │ CRC32 (4B)  │ Payload (N B)   │
└─────────────┴─────────────┴─────────────────┘

Entries are either:

• Snapshot: Full state replacement (written during compaction)
• Delta: Incremental update (written on each mutation)

Recovery

On mount, the journal is replayed entry-by-entry:

• Snapshots replace the current state
• Deltas are merged via the CRDT’s Merge trait
• Truncated entries are ignored (WAL semantics)
• Checksum failures return an error

Features

Requires the persistence feature.

Example

use logicaffeine_system::storage::Persistent;
use logicaffeine_data::crdt::GCounter;

let vfs: Arc<dyn logicaffeine_system::fs::Vfs + Send + Sync> = Arc::new(NativeVfs::new("/data"));
let counter = Persistent::<GCounter>::mount(vfs, "counter.lsf").await?;

counter.mutate(|c| c.increment(5)).await?;
counter.compact().await?; // Reduce journal size

Structs

Persistent

A persistent CRDT wrapper with journaling (native platform).