Documentation
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Overview ¶
Package activator implements scale-to-zero (ADR-0016): an in-process data-path component backing a gateway route's upstream. For a request to a scaled-to-zero function it buffers the request, single-flights a wake (Scaler.ScaleTo(fn,1)), waits for a ready upstream to appear, then forwards the held request (or 503s on timeout, or at once for a Failed function); and it runs a periodic idle-reclaim pass that scales idle functions to zero. It emits a scale INTENT through two seams (Endpoints read / Scaler write); it does not provision workers (that is the P-M Function reconciler) and it does not register a Function reconciler (one-reconciler-per-gvk, ADR-0015).
Index ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func FailedFault ¶ added in v0.2.1
FailedFault is the fault.Unavailable a call to f is answered with when f is Failed, naming its Ready reason, else nil. A wake does not leave Failed (ADR-0016 C2) and the reconciler does not restart a ShapeInvalid worker (ADR-0142), so a held call could only time out (issue #142).
func KeepEdgeHeaders ¶ added in v0.2.3
func KeepEdgeHeaders(rp *httputil.ReverseProxy, w http.ResponseWriter)
KeepEdgeHeaders makes rp put the headers w carries now back before the final response or the error response: httputil.ReverseProxy clears the whole header map after it relays an upstream 1xx, which would drop the X-Request-Id and CORS headers the edge set before proxying (#417). It sets rp.ModifyResponse and wraps rp.ErrorHandler, which must be set first.
func WithFunction ¶
func WithFunction(r *http.Request, fn FunctionRef) *http.Request
WithFunction returns r carrying fn for ServeHTTP. The gateway route wiring (P-I) sets it from the matched route; tests set it directly.
Types ¶
type Activator ¶
type Activator struct {
// contains filtered or unexported fields
}
Activator is the scale-to-zero data path + idle-reclaim component.
func (*Activator) ReclaimIdle ¶
ReclaimIdle scales to zero every minReplicas==0 function whose last activity is older than its IdleTimeout, that has no call in flight and no wake in progress. Functions with recent activity, MinReplicas != 0, or a zero IdleTimeout (reclaim disabled) are skipped. A function not yet seen, or with a call in flight, is given a full grace window from the current time. Entries for functions that no longer exist are dropped.
func (*Activator) Run ¶
Run calls ReclaimIdle every ReclaimInterval until ctx is cancelled. On return it ends every in-flight activation (its waiters get Unavailable) and waits for them.
func (*Activator) ServeHTTP ¶
func (a *Activator) ServeHTTP(w http.ResponseWriter, r *http.Request)
ServeHTTP serves one request: warm → proxy now; cold → single-flight ScaleTo(1), wait for a ready upstream (bounded by ActivationTimeout), then forward. On activation timeout or for a Failed function → 503 problem+json; a request with no FunctionRef in context → 500 problem+json.
func (*Activator) Wake ¶
Wake returns fn's ready upstream, single-flight-activating (ScaleTo(1) + poll, bounded by ActivationTimeout) if it is cold — the shared wake primitive (ADR-0033) used by both the data-plane cold path (ServeHTTP) and the eventing trigger path. It records activity (touch, feeding idle reclaim); an Endpoints error → fault.Unavailable; a ready function returns its upstream immediately; a not-ready one is woken via the existing per-fn singleflight.
type CallTracker ¶ added in v0.1.4
type CallTracker struct {
// contains filtered or unexported fields
}
CallTracker counts the calls made to each worker, keyed by the upstream's host:port, so the Function reconciler can tell when a worker of a demoted revision is drained (ADR-0143). Every caller that reaches workers — the activator's proxy, the workflow dispatcher, the Sensor invoker — sends through Wrap, and the resolver records each hand-out. Safe for concurrent use.
func NewCallTracker ¶ added in v0.1.4
func NewCallTracker(c clock.Clock) *CallTracker
NewCallTracker builds a tracker on c (the system clock when nil).
func (*CallTracker) HandedOut ¶ added in v0.1.4
func (t *CallTracker) HandedOut(upstream string)
HandedOut records that the resolver returned upstream to a caller.
func (*CallTracker) Idle ¶ added in v0.1.4
func (t *CallTracker) Idle(upstream string, settle time.Duration) bool
Idle reports whether no call to upstream is in flight and it was not handed out within settle. An idle upstream is forgotten.
func (*CallTracker) Wrap ¶ added in v0.1.4
func (t *CallTracker) Wrap(rt http.RoundTripper) http.RoundTripper
Wrap returns a RoundTripper that counts each request to its URL's host:port from RoundTrip until the response body is closed, or until RoundTrip fails. A nil rt wraps http.DefaultTransport.
type Deps ¶
type Deps struct {
Store store.Store // lists Functions for idle reclaim; read for a Failed phase while activating
Endpoints Endpoints // ready-upstream resolver (required)
Scaler Scaler // scale-intent writer (required)
Clock clock.Clock // default clock.System()
Logger *slog.Logger // default slog.Default()
ActivationTimeout time.Duration // cold-start hold bound; default 30s
PollInterval time.Duration // ready-poll cadence; default 25ms
ReclaimInterval time.Duration // idle-reclaim cadence for Run; default 30s
Calls *CallTracker // counts the calls to each worker (ADR-0143), which idle reclaim also reads; nil ⇒ uncounted
}
Deps configures the activator (internal component, ADR-0002 §1).
type Endpoints ¶
type Endpoints interface {
// Upstream returns the ready upstream URL for fn and whether one exists. The URL's path, if
// any, is where fn's worker serves it (a pool worker's /function/<name>, ADR-0046).
Upstream(ctx context.Context, fn FunctionRef) (upstream string, ready bool, err error)
}
Endpoints resolves a function's currently-ready upstream. P-M/scheduler provide the production driver (from the provisioned replica set); tests inject a fake.
type FunctionRef ¶
type FunctionRef struct {
Namespace v1.NamespaceName
Name v1.ObjectName
}
FunctionRef identifies the function a request / scale-decision targets.
Source Files
Directories
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Package storescaler is the V1 store-backed activator.Scaler driver (ADR-0016): it records a function's scale intent as its partitioned status Phase — the wake edge Idle→Deploying for replicas>=1, the reclaim edge *→Idle for replicas==0 — via store.Update.
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Package storescaler is the V1 store-backed activator.Scaler driver (ADR-0016): it records a function's scale intent as its partitioned status Phase — the wake edge Idle→Deploying for replicas>=1, the reclaim edge *→Idle for replicas==0 — via store.Update. |