Module journal 

Available on crate feature alloc only.

Append-only session operation log and its CRC-framed encoding.

This module provides the building blocks for durable session state. It is organised as a sans-io toolkit with no knowledge of files or async:

• JournaledSession wraps an InMemorySession and records every mutation as a SessionOp. The persistence layer decides how to store those ops: framed bytes for a file, rows for a SQL store.
• encode_frames turns recorded ops into CRC-framed bytes.
• JournalReader decodes those bytes one frame at a time, either streaming from external storage or in-memory.
• Header is the file-level header that identifies the on-disk format version, written once before any frames.

Modules

crc32 🔒

CRC-32/ISO-HDLC (IEEE 802.3) checksum.

encode 🔒

frame 🔒

header 🔒

reader 🔒

Sans-io journal replay.

Structs

Header

A parsed, supported journal file header.

JournalReader

Decodes CRC-framed journal records one frame at a time.

JournaledSession

A SessionState wrapper that records every mutation as a SessionOp.

Enums

Demand

Describes what the I/O layer should do next.

HeaderError

Why a byte sequence is not a valid, supported journal file header.

JournalFrameError

Error returned when a journal frame cannot be decoded.

Step

Reports the result of feeding a chunk to the reader.

Functions

encode_frames

Encodes ops as a single CRC frame, appending it to out.

snapshot_ops

Encodes the entire current state of session as a sequence of “store” ops.