InMemoryCache
Defined in: src/cache/InMemoryCache.ts:20
Generic distributed-cache abstraction — used by HTTP middleware
(response-cache, rate-limit, idempotency-key) and the optional
CachedSnapshotStore decorator. Three implementations ship:
InMemoryCache— single-process Map; default, ideal for tests/dev.RedisCache— wrapsioredis(optional peer dependency).MemcachedCache— wrapsmemjs(optional peer dependency).
The surface is intentionally small. Seven operations cover ~95% of the
real cases in this codebase; we deliberately exclude pattern-scans
(anti-pattern at scale) and pub/sub (already provided by the cluster
layer). Bulk mget / mset (#14) cut round-trips for the hot
sharded-entity-hydration path after a rebalance.
Failure model: a cache is opportunistic by definition. Backends
are encouraged to return a sensible default rather than throw on
transient connection errors — get returning None on network failure
is fine, since the caller’s job is to fall back to the source of
truth anyway. Exceptions are reserved for misuse (invalid TTL, etc).
Implements
Section titled “Implements”Constructors
Section titled “Constructors”Constructor
Section titled “Constructor”new InMemoryCache():
InMemoryCache
Returns
Section titled “Returns”InMemoryCache
Methods
Section titled “Methods”close()
Section titled “close()”close():
Promise<void>
Defined in: src/cache/InMemoryCache.ts:102
Best-effort teardown. Idempotent.
Returns
Section titled “Returns”Promise<void>
Implementation of
Section titled “Implementation of”delete()
Section titled “delete()”delete(…
keys):Promise<void>
Defined in: src/cache/InMemoryCache.ts:73
Delete one or many keys. Idempotent — missing keys are a no-op.
Parameters
Section titled “Parameters”…string[]
Returns
Section titled “Returns”Promise<void>
Implementation of
Section titled “Implementation of”get<
V>(key):Promise<Option<V>>
Defined in: src/cache/InMemoryCache.ts:23
Get a value; returns None on miss, expiry, or transient backend failure.
Type Parameters
Section titled “Type Parameters”V
Parameters
Section titled “Parameters”string
Returns
Section titled “Returns”Promise<Option<V>>
Implementation of
Section titled “Implementation of”incr()
Section titled “incr()”incr(
key,ttlMs?):Promise<number>
Defined in: src/cache/InMemoryCache.ts:41
Atomic increment by 1 — returns the new value. When ttlMs is
supplied AND the key was newly created (counter value is 1 after
the call), the TTL is set; subsequent increments do not refresh it.
This is the right semantics for a fixed-window rate-limiter.
Parameters
Section titled “Parameters”string
ttlMs?
Section titled “ttlMs?”number
Returns
Section titled “Returns”Promise<number>
Implementation of
Section titled “Implementation of”mget()
Section titled “mget()”mget<
V>(keys):Promise<Map<string,V>>
Defined in: src/cache/InMemoryCache.ts:77
Bulk get (#14) — fetch multiple keys in a single round-trip when
the backend supports it. Returns a Map keyed by the input
keys; misses (no entry, expired, malformed payload, transient
backend failure) are simply absent from the result rather than
mapped to undefined. Map.get(k) therefore returns V | undefined with the same “missing key” semantics as the
single-key get.
Order of the returned Map matches the order of the input keys for backends that support it (Redis MGET); backends that fall back to parallel single-key reads (Memcached) may surface a different iteration order — don’t rely on it.
Type Parameters
Section titled “Type Parameters”V
Parameters
Section titled “Parameters”readonly string[]
Returns
Section titled “Returns”Promise<Map<string, V>>
Implementation of
Section titled “Implementation of”mset()
Section titled “mset()”mset<
V>(entries,ttlMs?):Promise<void>
Defined in: src/cache/InMemoryCache.ts:92
Bulk set (#14) — write multiple key/value pairs with a shared
TTL. The atomicity guarantee is per backend: Redis emits a
single MSET (no-TTL) or pipelined SET ... PX (with-TTL);
Memcached has no native bulk write so the calls go out in
parallel. Single-process backends (InMemory) trivially see
the whole bag at once. ttlMs applies to every entry.
Type Parameters
Section titled “Type Parameters”V
Parameters
Section titled “Parameters”entries
Section titled “entries”ReadonlyMap<string, V>
ttlMs?
Section titled “ttlMs?”number
Returns
Section titled “Returns”Promise<void>
Implementation of
Section titled “Implementation of”set<
V>(key,value,ttlMs?):Promise<void>
Defined in: src/cache/InMemoryCache.ts:33
Set a value with optional TTL (milliseconds). Omitting ttlMs means no expiry.
Type Parameters
Section titled “Type Parameters”V
Parameters
Section titled “Parameters”string
V
ttlMs?
Section titled “ttlMs?”number
Returns
Section titled “Returns”Promise<void>
Implementation of
Section titled “Implementation of”setIfAbsent()
Section titled “setIfAbsent()”setIfAbsent<
V>(key,value,ttlMs?):Promise<boolean>
Defined in: src/cache/InMemoryCache.ts:61
Set only if the key does not yet exist. Returns true on success (the value was stored), false on collision (someone else got there first). Used as the kernel of idempotency-key dedup.
Type Parameters
Section titled “Type Parameters”V
Parameters
Section titled “Parameters”string
V
ttlMs?
Section titled “ttlMs?”number
Returns
Section titled “Returns”Promise<boolean>
Implementation of
Section titled “Implementation of”sizeForTest()
Section titled “sizeForTest()”sizeForTest():
number
Defined in: src/cache/InMemoryCache.ts:107
Test hook — current entry count, including expired-but-not-cleaned entries.
Returns
Section titled “Returns”number