Struct EngineJournalWriter 

pub struct EngineJournalWriter {
    pool: DbPool,
    event_persistence_mode: EventPersistenceMode,
    critical_event_types: HashSet<String>,
}

Durable engine journal writer

Fields

pool: DbPool

event_persistence_mode: EventPersistenceMode

Event persistence mode (controls latency/durability tradeoff)

critical_event_types: HashSet<String>

Implementations

impl EngineJournalWriter

pub fn new(pool: DbPool) -> Self

Create a new journal writer with the given database pool

pub fn new_with_mode(pool: DbPool, mode: EventPersistenceMode) -> Self

Create a new journal writer with explicit event persistence mode

pub fn from_database_url_with_config( database_url: &str, pool_max: u32, config: &JournalRuntimeConfig, ) -> Result<Self, EngineJournalError>

pub fn from_auth_config( auth: &DbAuthConfig, pool_max: u32, config: &JournalRuntimeConfig, ) -> Result<Self, EngineJournalError>

pub fn event_persistence_mode(&self) -> EventPersistenceMode

Get the current event persistence mode

pub fn append_transition( &self, received_ts_ms: u64, command_data: &[u8], response_data: Option<&[u8]>, order_id: Option<i64>, pre_digest: &EngineStateDigest, post_digest: &EngineStateDigest, duration_ms: u64, events: &[EngineMessage], request_uuid: DbUuid, command_type_enum: Option<CommandType>, ) -> Result<JournalAppendResult, EngineJournalError>

Append a state transition to the journal.

This is transactional and provides idempotency:

• If request_id already exists, returns the existing record (no new inserts)
• If request_id is new, inserts command, events, and digests atomically

Arguments

• received_ts_ms - When the command was received
• command_data - Wire-format bytes (version byte + msgpack)
• response_data - Optional response wire bytes for idempotent returns
• order_id - Extracted order_id for indexed column
• pre_digest - State digest before applying
• post_digest - State digest after applying
• duration_ms - Processing duration
• events - Events generated by applying the command
• request_uuid - Unique request UUID for idempotency
• command_type_enum - Command type enum

fn append_transition_internal( &self, received_ts_ms: u64, command_data: &[u8], response_data: Option<&[u8]>, order_id: Option<i64>, pre_digest: &EngineStateDigest, post_digest: &EngineStateDigest, duration_ms: u64, events: &[EngineMessage], fill_side_effects: &[JournalFillSideEffect], balance_updates: &[BalanceUpdate], request_uuid: DbUuid, command_type_enum: Option<CommandType>, ) -> Result<JournalAppendResult, EngineJournalError>

pub fn get_by_request_id( &self, request_id: &Uuid, ) -> Result<Option<JournalFullRecord>, EngineJournalError>

Get a journal record by request_id

fn get_by_request_id_internal( &self, conn: &mut PgConnection, request_id: &Uuid, ) -> Result<Option<JournalFullRecord>, EngineJournalError>

pub fn get_recent( &self, limit: usize, ) -> Result<Vec<JournalCommandSummary>, EngineJournalError>

Get recent journal command summaries

pub fn get_recent_request_ids( &self, since_hours: i64, ) -> Result<HashSet<Uuid>, EngineJournalError>

Get recent request_ids for idempotency cache warm-up. Returns request_ids from commands received in the last since_hours hours. This is used at startup to populate the in-memory HashSet for fast idempotency checks.

pub fn request_id_exists( &self, request_id: &Uuid, ) -> Result<bool, EngineJournalError>

Check if a request_id exists in the journal (lightweight existence check). Returns true if the request_id has been processed before.

Trait Implementations

impl JournalWriter for EngineJournalWriter

fn is_durable(&self) -> bool

Whether writes through this writer survive process restart.

fn append_transition( &self, received_ts_ms: u64, command_data: &[u8], response_data: Option<&[u8]>, order_id: Option<i64>, pre_digest: &EngineStateDigest, post_digest: &EngineStateDigest, duration_ms: u64, events: &[EngineMessage], request_uuid: DbUuid, command_type_enum: Option<CommandType>, ) -> Result<JournalAppendResult, EngineJournalError>

Append a state transition to the journal. Returns existing record if request_id already exists (idempotency).

fn append_transition_with_fill_side_effects( &self, received_ts_ms: u64, command_data: &[u8], response_data: Option<&[u8]>, order_id: Option<i64>, pre_digest: &EngineStateDigest, post_digest: &EngineStateDigest, duration_ms: u64, events: &[EngineMessage], fill_side_effects: &[JournalFillSideEffect], balance_updates: &[BalanceUpdate], request_uuid: DbUuid, command_type_enum: Option<CommandType>, ) -> Result<JournalAppendResult, EngineJournalError>

Append a transition while atomically materializing any fill side-effects.

fn get_by_request_id( &self, request_id: &Uuid, ) -> Result<Option<JournalFullRecord>, EngineJournalError>

Get a journal record by request_id

fn request_id_exists( &self, request_id: &Uuid, ) -> Result<bool, EngineJournalError>

Check if a request_id exists in the journal (lightweight existence check)

fn get_recent_request_ids( &self, since_hours: i64, ) -> Result<HashSet<Uuid>, EngineJournalError>

Get recent request_ids for idempotency cache warm-up

fn get_recent( &self, limit: usize, ) -> Result<Vec<JournalCommandSummary>, EngineJournalError>

Get recent journal command summaries (for monitoring)