Module engine_journal_batcher 

WAL-first journal batcher for durable ACKs in the engine hot path.

The engine pushes JournalEntry values into a bounded channel. This task drains entries, appends them to a local WAL, calls fdatasync, and only then allows ACK/event emission via commit_ack.

PostgreSQL replication runs asynchronously after WAL durability so client-visible latency is decoupled from network/database I/O.

Modules

rsm_block_persistence 🔒

Structs

EngineJournalBatcher

The batcher that runs in the background and appends to local WAL first, then replicates to PostgreSQL asynchronously.

EventPayload

Pre-serialized event payload ready for DB storage. Contains wire-format bytes (version byte + msgpack) so no further serialization is needed.

JournalBatcherConfig

Configuration for the journal batcher

JournalCashWithdrawalSideEffect

Journal-only side effect for a CashWithdrawalUpdate command.

JournalEntry

A journal entry to be batched and durably appended.

JournalFillSideEffect

Journal-only accounting deltas for a single OrderFilled event.

PreparedWalBlock 🔒

ReplicationProgress 🔒

RsmBatchRoots 🔒

RsmWalWriterState 🔒

WalBlockRecordWithRoots 🔒

WalDurableBlockEntry 🔒

WalJournalRecord 🔒

WalRecordWithOffset 🔒

WalState 🔒

Enums

JournalMessage

Messages sent to the journal batcher.

ReplicationMessage 🔒

WalWriterMessage 🔒

Messages sent from the batcher task to the dedicated WAL writer thread.

Constants

DEFAULT_CHANNEL_CAPACITY

Default channel capacity

REPLICATION_RETRY_DELAY 🔒

WAL_PREALLOC_CHUNK 🔒

Pre-allocate WAL file in 64 MiB chunks to avoid extent allocation stalls.

Functions

append_command_delta 🔒

append_intent_delta 🔒

append_obligation_delta 🔒

apply_recovered_rsm_commitment_blocks 🔒

engine_command_identity_hashes 🔒

engine_journal_entry_insert 🔒

next_replication_chunk_len 🔒

Returns the number of records for the next replication chunk.

rsm_batch_roots_from_wal 🔒

rsm_event_payload_hash 🔒

rsm_global_leaf 🔒

rsm_hash_with_domain 🔒

rsm_state_delta_from_entries 🔒

rsm_state_delta_from_parts 🔒

rsm_state_supported_command 🔒

should_defer_replay_record 🔒

wal_fsync_io_uring 🔒

Submit IORING_OP_FSYNC with DATASYNC flag via io_uring.

wal_writer_thread_main 🔒

Dedicated WAL writer OS thread.

Type Aliases

JournalBatchSender

Sender half for pushing journal entries

SharedJournalBatchSender

Shared sender that can be cloned and used from the engine.

WalBlockEntry 🔒

WalBlockRecord 🔒