Crate kevy_embedded

Expand description

kevy-embedded — kevy without the network.

In-process Redis-compatible key–value store: load + reply directly from your own threads, no TCP, no shards, no reactor. Use this when you want kevy’s data structures + persistence in the same address space as your app — caches, embedded databases, WASM blobs, sidecar tools.

Zero crates.io dependencies: only kevy-store (the keyspace) and kevy-persist (snapshot + AOF). The whole network layer (kevy-rt, kevy-sys, kevy-uring) is intentionally NOT pulled in.

§Quick start

use kevy_embedded::{Store, Config};

let s = Store::open(Config::default())?;
s.set(b"greeting", b"hello")?;
assert_eq!(s.get(b"greeting")?, Some(b"hello".to_vec()));

§With persistence

with_persist(dir) enables AOF auto-append on every write and replays on open — restart-safe out of the box. Snapshot (dump-0.rdb) is loaded first if present; AOF (aof-0.aof) is replayed on top.

use kevy_embedded::{Store, Config};

let s = Store::open(Config::default().with_persist("./data"))?;
s.set(b"counter", b"42")?;
drop(s); // flushes AOF on drop

// Next process: state survives.
let s2 = Store::open(Config::default().with_persist("./data"))?;
assert_eq!(s2.get(b"counter")?, Some(b"42".to_vec()));

§When NOT to use this crate

You want a Redis-protocol TCP server → use the kevy crate’s serve instead.
You need cross-process concurrency → kevy-embedded is single-process (one mutex). Multi-process needs the network layer.

Structs§

AnnSpec: v2.8 — HNSW declaration (immutable once created; RFC D2).
AtomicAllShards: Context handed to the atomic_all_shards closure body. Methods route to the right shard by hashing the key.
AtomicCtx: Handle passed to the atomic closure body. Methods mirror the equivalent Store ops but operate on the already-held write lock, so reads inside the block see the closure’s own writes.
Change: One mutation delivered by Store::changes_since.
ChangeBatch: A batch of changes plus the cursor to resume from.
Config: Embedded-store config. Build by chaining with_* methods on Config::default.
ExpireStats: What Store::tick_expire saw and did. Surfaced for tests, INFO keyspace, and (eventually) Wave 2 task #4’s crash-safe verifier.
GroupStats: One group’s live statistics.
IndexCursor: Opaque pagination cursor: the last (value, key) served. Encoded by the runtime into the wire cursor; None = start.
IndexStats: Sizing + health counters (IDX.LIST / memory formula).
KevyInfo: Snapshot of a store’s runtime counters, returned by Store::info. A cheap aggregate (one mutex lock); fields mirror the individual accessors.
Pipeline: Builder-style write queue. Returned by Store::pipeline; call fluent methods to enqueue + commit() to apply with batched AOF fsync.
PrefixInfo: Per-prefix keyspace stats from Store::info_prefix.
RewriteStats: Result of an Aof::rewrite_from call. Surfaced by BGREWRITEAOF / INFO persistence.
ScoreBound: A score-range endpoint for ZRANGEBYSCORE/ZCOUNT (inclusive or exclusive). Use value = ±INFINITY for -inf/+inf.
Snapshot: A frozen, consistent point-in-time view of the whole store.
SnapshotEntry: One entry from Snapshot::each_prefix / Snapshot::keys_prefix.
Store: The embedded keyspace.
Subscription: A handle to one subscription — owns the receive end of the bus channel.
ViewLeaf: One leaf: a declared index + the shape it contributes.
WeakStore: Weak handle to a Store — does not keep the underlying keyspace alive.
ZaddFlags: Parsed ZADD condition flags. CH only changes the reply (changed count instead of added count) — callers read ZaddReport::changed when set; the engine behavior is identical.
ZaddReport: Outcome of a flags-aware ZADD.

Enums§

AggBy: Ranking metric for AggSegment::top_groups.
AppendFsync: When to fsync the AOF to disk.
BitOp: Operator for Store::bitop.
EvictionPolicy: Maxmemory eviction policy. Mirror of kevy_config::EvictionPolicy — duplicated here so kevy-store stays a leaf crate (no kevy-config dep).
FeedError: Why a feed read could not be served.
HExpireCond: Condition flags for HEXPIRE (NX/XX/GT/LT; at most one).
IndexKind: Index kind (KIND range|unique).
IndexValType: Declared scalar type of an index (TYPE i64|f64|str).
IndexValue: One indexed scalar. Ordering is total within a type; the catalog guarantees a segment only ever holds one variant.
KevyMetric: A persistence event worth observing. More variants may be added; match non-exhaustively (_ => {}) to stay forward-compatible.
PubsubFrame: One pub/sub event delivered to a Subscription.
StoreError: Operation errors surfaced to the command layer.
TtlReaperMode: How the active TTL reaper runs.
ViewMode: View mode.
ViewTree: The composition tree. Depth ≤ 3, leaves ≤ 4 (declarative caps, enforced at CREATE).
ZAggregate: AGGREGATE mode for inter/union (Redis 6.2; default Sum).

Type Aliases§

HExpireCode: Per-field reply codes for HEXPIRE-family calls (Redis 7.4): -2 key or field missing, 0 condition (NX/XX/GT/LT) not met, 1 deadline set, 2 field deleted (deadline already due).
IndexPage: One page of index hits plus the cursor to resume from.
ViewPage: One page of view members plus the resume cursor.