Module engine_state_snapshot 

Persistent engine state snapshots for fast restart recovery.

After journal replay the engine writes a snapshot of its core state (orderbooks, counters, expired instruments) to disk. On the next restart the snapshot is loaded first, and only the delta since the snapshot’s last_command_id needs to be replayed from the journal.

File format: [msgpack payload][4-byte CRC32 LE]

Atomic write: temp → fsync → rename (same as journal checkpoint writes).

Structs

EngineStateSnapshot

Persistent engine state snapshot for fast restart recovery.

LegacyEngineStateSnapshot 🔒

Pre-CALL-1707 snapshot layout without last_balance_update_seq.

LegacyEngineStateSnapshotPreAppendOnlyV2 🔒

Older v2 layout from before snapshot fields were made append-only.

OrderSnapshotEntry

A single order in the snapshot, matching OrderBook::get_all_orders() output.

VolatilitySurfaceSnapshot

Constants

LEGACY_BALANCE_UPDATE_SEQ_MIGRATION_EPOCH 🔒

LEGACY_SNAPSHOT_VERSION_V1 🔒

LEGACY_SNAPSHOT_VERSION_V2 🔒

SNAPSHOT_CRC 🔒

SNAPSHOT_VERSION 🔒

Current snapshot format version.

Functions

build_snapshot

Build a snapshot from current engine state, tagged with the checkpoint boundary.

decode_legacy_engine_state_snapshot 🔒

msgpack_array_start 🔒

msgpack_map_start 🔒

msgpack_str_at 🔒

msgpack_u32_at 🔒

read_snapshot

Read a snapshot from disk with CRC32 integrity verification.

snapshot_order_count

Count total orders across all orderbooks in a snapshot.

snapshot_path_from_wal_path

Derive the snapshot file path from the WAL path.

snapshot_payload_version 🔒

write_snapshot

Write a snapshot atomically: temp → fsync → rename → dir sync.