Enum StreamMode 

#[non_exhaustive]
pub enum StreamMode {
    Durable,
    DurableSummary {
        patch_kind: PatchKind,
    },
    BestEffortLive {
        config: BestEffortLiveConfig,
    },
}

Per-call durability mode for [EngineBackend::append_frame].

RFC-015 §1. Mode is per-call — workers routinely mix frame types (tokens + progress + final summary) in a single attempt and the right durability differs per frame type. See RFC-015 §5 for the caveat on mixed-mode streams.

#[non_exhaustive]: new modes land additively (the v0.6 PR deliberately excludes KeepAllDeltas, dropped by owner adjudication; a future mode for e.g. per-frame-replicated streams would land here).

Doc-comment contract on Self::Durable

If the same stream also receives Self::BestEffortLive frames, Durable frames are subject to the best-effort MAXLEN trim (see RFC-015 §5). Callers that need strict retention for Durable frames alongside best-effort telemetry must not mix modes on one stream or should place the durable frames on a sibling stream.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

Durable

Current default — every frame XADDs as a durable entry.

DurableSummary

Server-side rolling-summary collapse. Each frame’s payload is a delta/patch applied atomically to a summary Hash (per PatchKind); the delta is also XADDed to the stream with mode=summary fields so live tailers continue to observe change events. RFC-015 §3.

Fields

patch_kind: PatchKind

BestEffortLive

Short-lived frame. XADDed with mode=best_effort; per-stream MAXLEN rolls it off and the stream key gets a TTL refresh only when the stream has never held a durable frame (RFC-015 §4.1).

The per-stream MAXLEN is computed dynamically in Lua from an EMA of observed append rate (RFC-015 §4.2). See BestEffortLiveConfig for the tunable knobs.

Fields

config: BestEffortLiveConfig

Implementations

impl StreamMode

pub fn durable() -> StreamMode

The v0.6 default — Self::Durable. Provided for symmetry with the other constructors (the enum is #[non_exhaustive] so cross-crate consumers cannot construct variants by name).

pub fn durable_summary() -> StreamMode

Self::DurableSummary with PatchKind::JsonMergePatch — the only supported PatchKind in v0.6.

pub fn best_effort_live(ttl_ms: u32) -> StreamMode

Self::BestEffortLive with the caller-supplied ttl_ms and default BestEffortLiveConfig knobs. RFC-015 §4 guidance: 5_000..=30_000 ms. Below ~1000 ms a live tailer may not connect in time; above ~60_000 ms the memory argument against plain Self::Durable weakens.

pub fn best_effort_live_with_config(config: BestEffortLiveConfig) -> StreamMode

Self::BestEffortLive with a fully-specified BestEffortLiveConfig. Use for per-workload tuning of α, the MAXLEN clamp, or the TTL — defaults are wired from BestEffortLiveConfig::with_ttl.

pub fn wire_str(&self) -> &'static str

Stable wire-level token for this mode, written to the XADD entry mode field (RFC-015 §6.1). Tail filters compare against these string values server-side.

Trait Implementations

impl Clone for StreamMode

fn clone(&self) -> StreamMode

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for StreamMode

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl Default for StreamMode

fn default() -> StreamMode

Returns the “default value” for a type.

impl Hash for StreamMode

fn hash<__H>(&self, state: &mut __H)

where __H: Hasher,

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for StreamMode

fn eq(&self, other: &StreamMode) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Copy for StreamMode

impl Eq for StreamMode

impl StructuralPartialEq for StreamMode