Give the held-message flow one owner

AGENTS.md

@@ -50,7 +50,7 @@ src/
 	dlr-merger.ts        DlrMerger: per-segment receipts counted into one MessageDlr
 	error-from.ts        An untyped value as error material: errorFrom() an Error, namedValue() a name
 	expiring-groups.ts   ExpiringGroups: the capped, weighed, expiring store DlrMerger, HeldMessages and Reassembler share
-	held-messages.ts     HeldMessages: capped, expiring messages the application has not answered, one MessageHold each
+	held-messages.ts     HeldMessages: a message from its `sms` event to its answer, capped and expiring, one MessageHold each
 	idle-waiters.ts      IdleWaiters: waiting for a count to fall to zero, and what is left of a budget
 	incoming-requests.ts Every request the peer sends: messages, receipts, links, unknown commands
 	link-life.ts         LinkLife: whether the link lives, and where a request waits for the next one
@@ -87,7 +87,7 @@ src/
 
 Imports point one way: `defs` knows nothing above it but `result.ts`, `pdu` uses `defs`, `session`
 uses `pdu`, and `client`/`server` use `session`. The ways back up are the `Session` handed to
-`createSms()` and `IncomingRequests`, which call back into it, and to `OnRequest` and `onConnected`
+`createSms()`, `HeldMessages` and `IncomingRequests`, which call back into it, and to `OnRequest` and `onConnected`
 in `session-options.ts`, all imported as a type only.
 
 **Parameter order is wire order.** The key order inside `cmds.*.params` is the order the fields are

src/held-messages.ts

@@ -1,15 +1,28 @@
-import type { PduObject } from './pdu.ts';
+import type { LinkLife } from './link-life.ts';
+import type { PduObject, PduObjectInput } from './pdu.ts';
+import type { Result } from './result.ts';
+import type { Session } from './session.ts';
+import type { SmsHandlers } from './sms.ts';
 import type { SmppLog } from './log.ts';
 import { ExpiringGroups } from './expiring-groups.ts';
 import { IdleWaiters } from './idle-waiters.ts';
+import { createSms } from './sms.ts';
+import { decodeSegments } from './reassembly.ts';
+import { paramText } from './defs/types.ts';
 import { retainedOctets } from './retained-pdu.ts';
 
+type Send = (input: PduObjectInput) => Promise<Result<{ pduObj: PduObject }>>;
+
 export type HeldMessagesOptions = {
+	link: LinkLife;
 	log: SmppLog;
 	max: number;
 	maxOctets: number;
 	/** Injected so expiry can be exercised without a wall clock. */
 	now?: (() => number) | undefined;
+	/** Past a drain's refusal, for a receipt the drain is itself waiting for. */
+	sendPastDrain: Send;
+	session: Session;
 	timeout: number;
 };
 
@@ -20,33 +33,40 @@ function keyOf(pduObjs: PduObject[]): string | undefined {
 	return first ? String(first.seqNr) : undefined;
 }
 
-type HoldEntry = {
+type HoldRoute = Pick<HeldMessagesOptions, 'link' | 'sendPastDrain' | 'session'>;
-	isHeld: () => boolean;
-	release: () => void;
-};
 
 /**
  * One message offered to the application. A drain waits on it until the first of: `answered()`,
  * every listener that took it rejecting, no listener taking it or one throwing, a later message on
  * its sequence number, its deadline, or the link going.
  */
-export class MessageHold {
+export class MessageHold implements SmsHandlers {
-	private readonly entry: HoldEntry;
+	private readonly generation: number;
+	private readonly pduObjs: PduObject[];
+	private readonly route: HoldRoute;
+	private readonly store: HeldMessages;
 	private working: number;
 
-	constructor(entry: HoldEntry, listeners: number) {
+	constructor(store: HeldMessages, route: HoldRoute, pduObjs: PduObject[], listeners: number) {
-		this.entry = entry;
+		this.generation = route.link.generation();
+		this.pduObjs = pduObjs;
+		this.route = route;
+		this.store = store;
 		this.working = listeners;
 	}
 
 	/** Whether a drain is still waiting for this message to be answered. */
 	isHeld(): boolean {
-		return this.entry.isHeld();
+		return this.store.holds(this.pduObjs);
 	}
 
 	/** A turn later, so a listener sending its receipt straight after the response still holds. */
 	answered(): void {
-		setImmediate(() => { this.entry.release(); });
+		setImmediate(() => { this.release(); });
+	}
+
+	lostLink(): boolean {
+		return this.route.link.generation() !== this.generation;
 	}
 
 	/** A rejection leaves the other listeners running, so only the last one to fail gives the message up. */
@@ -58,7 +78,12 @@ export class MessageHold {
 
 	/** At once, for a message nobody took or a listener threw on: that is not work a shutdown can wait for. */
 	release(): void {
-		this.entry.release();
+		this.store.release(this.pduObjs);
+	}
+
+	/** A receipt for a message still held is what a drain waits for, so it goes out past the drain. */
+	send(input: PduObjectInput): Promise<Result<{ pduObj: PduObject }>> {
+		return this.isHeld() ? this.route.sendPastDrain(input) : this.route.session.send(input);
 	}
 }
 
@@ -70,6 +95,7 @@ export class HeldMessages {
 	private readonly maxOctets: number;
 	/** A rejecting listener hands the message back as an `unknown`, so its hold is found by identity. */
 	private readonly offered = new WeakMap<object, MessageHold>();
+	private readonly route: HoldRoute;
 
 	constructor(options: HeldMessagesOptions) {
 		this.held = new ExpiringGroups({
@@ -80,6 +106,7 @@ export class HeldMessages {
 		});
 		this.log = options.log;
 		this.maxOctets = options.maxOctets;
+		this.route = { link: options.link, sendPastDrain: options.sendPastDrain, session: options.session };
 	}
 
 	get octetsHeld(): number {
@@ -98,10 +125,7 @@ export class HeldMessages {
 	}
 
 	private hold(pduObjs: PduObject[], listeners: number): MessageHold {
-		const hold = new MessageHold({
+		const hold = new MessageHold(this, this.route, pduObjs, listeners);
-			isHeld: () => this.has(pduObjs),
-			release: () => { this.release(pduObjs); },
-		}, listeners);
 		const key = keyOf(pduObjs);
 
 		if (key === undefined) return hold;
@@ -118,18 +142,25 @@ export class HeldMessages {
 		return hold;
 	}
 
-	offer<T extends object>(
+	/** Hands a whole message to the application as an `sms` event, held until it is answered. */
-		pduObjs: PduObject[],
+	offer(pduObjs: PduObject[], answeredAs?: string): MessageHold | undefined {
-		listeners: number,
+		const first = pduObjs[0];
-		build: (hold: MessageHold) => T,
-		emit: (message: T) => boolean,
-	): MessageHold {
-		const hold = this.hold(pduObjs, listeners);
-		const message = build(hold);
 
-		this.offered.set(message, hold);
+		if (!first) return undefined;
 
-		if (!emit(message)) hold.release();
+		const hold = this.hold(pduObjs, this.route.session.listenerCount('sms'));
+		const sms = createSms({
+			answeredAs,
+			from: paramText(first.params.source_addr),
+			message: decodeSegments(pduObjs),
+			pduObjs,
+			session: this.route.session,
+			to: paramText(first.params.destination_addr),
+		}, hold);
+
+		this.offered.set(sms, hold);
+
+		if (!this.route.session.emit('sms', sms)) hold.release();
 
 		return hold;
 	}
@@ -141,13 +172,13 @@ export class HeldMessages {
 		this.offered.get(message)?.listenerGaveUp();
 	}
 
-	private has(pduObjs: PduObject[]): boolean {
+	holds(pduObjs: PduObject[]): boolean {
 		const key = keyOf(pduObjs);
 
 		return key !== undefined && this.held.get(key) === pduObjs;
 	}
 
-	private release(pduObjs: PduObject[]): void {
+	release(pduObjs: PduObject[]): void {
 		const key = keyOf(pduObjs);
 
 		// Identity, not the key: a wrapped sequence number must not release someone else's message.

src/incoming-requests.ts

@@ -10,13 +10,11 @@ import type { Session } from './session.ts';
 import type { SmppLog } from './log.ts';
 import type { SmsIdFormat } from './sms-id.ts';
 import { HeldMessages } from './held-messages.ts';
-import { Reassembler, decodeSegments } from './reassembly.ts';
+import { Reassembler } from './reassembly.ts';
 import { bindCommands, defaults, standsInFor } from './session-options.ts';
 import { concatOf } from './concat.ts';
-import { createSms } from './sms.ts';
 import { detach } from './retained-pdu.ts';
 import { dlrFromPdu } from './dlr.ts';
-import { paramText } from './defs/types.ts';
 import { respIdParams, segmentId } from './sms-id.ts';
 import { respNameFor } from './defs/commands.ts';
 
@@ -67,7 +65,6 @@ export class IncomingRequests {
 	private readonly log: SmppLog;
 	private readonly onRequest: OnRequest | undefined;
 	private readonly reassembler: Reassembler;
-	private readonly sendPastDrain: IncomingRequestsOptions['sendPastDrain'];
 	private readonly session: Session;
 	private readonly smsIdFormat: SmsIdFormat;
 	private readonly systemId: string;
@@ -76,9 +73,12 @@ export class IncomingRequests {
 	constructor(options: IncomingRequestsOptions) {
 		this.dlrMerger = options.dlrMerger;
 		this.held = new HeldMessages({
+			link: options.link,
 			log: options.log,
 			max: defaults.maxHeldMessages,
 			maxOctets: defaults.maxHeldOctets,
+			sendPastDrain: options.sendPastDrain,
+			session: options.session,
 			timeout: defaults.heldMessageTimeout,
 		});
 		this.link = options.link;
@@ -91,7 +91,6 @@ export class IncomingRequests {
 			onLost: lost => { this.reportLost(lost); },
 			timeout: options.reassemblyTimeout ?? defaults.reassemblyTimeout,
 		});
-		this.sendPastDrain = options.sendPastDrain;
 		this.session = options.session;
 		this.smsIdFormat = options.smsIdFormat ?? {};
 		this.systemId = options.systemId ?? defaults.systemId;
@@ -254,7 +253,7 @@ export class IncomingRequests {
 		const concat = concatOf(pduObj);
 
 		if (!concat) {
-			this.emitSms([detach(pduObj)]);
+			this.held.offer([detach(pduObj)]);
 
 			return;
 		}
@@ -276,7 +275,7 @@ export class IncomingRequests {
 			respIdParams(pduObj.cmdName, segmentId(collected.smsId, concat.part - 1, concat.total)),
 		);
 
-		if (collected.whole) this.emitSms(collected.whole, collected.smsId);
+		if (collected.whole) this.held.offer(collected.whole, collected.smsId);
 	}
 
 	private reportLost(lost: LostGroup): void {
@@ -284,25 +283,4 @@ export class IncomingRequests {
 			`Gave up ${String(lost.parts)} of ${String(lost.total)} segments of an incomplete concatenated message: ${lostReasons[lost.reason]}`,
 		));
 	}
-
-	private emitSms(pduObjs: PduObject[], answeredAs?: string): void {
-		const first = pduObjs[0];
-
-		if (!first) return;
-
-		const generation = this.link.generation();
-
-		this.held.offer(pduObjs, this.session.listenerCount('sms'), hold => createSms({
-			answeredAs,
-			from: paramText(first.params.source_addr),
-			message: decodeSegments(pduObjs),
-			pduObjs,
-			session: this.session,
-			to: paramText(first.params.destination_addr),
-		}, {
-			lostLink: () => this.link.generation() !== generation,
-			onAnswered: () => { hold.answered(); },
-			send: input => (hold.isHeld() ? this.sendPastDrain(input) : this.session.send(input)),
-		}), sms => this.session.emit('sms', sms));
-	}
 }

src/sms.ts

@@ -68,8 +68,8 @@ export type SmsInput = {
 
 /** What the session's incoming side gives a message so it can be answered and accounted for. */
 export type SmsHandlers = {
+	answered: () => void;
 	lostLink: () => boolean;
-	onAnswered: () => void;
 	send: (input: PduObjectInput) => Promise<Result<{ pduObj: PduObject }>>;
 };
 
@@ -107,7 +107,7 @@ export function createSms(input: SmsInput, handlers: SmsHandlers): Sms {
 /** Every segment went out answered, so the call is what the shutdown waits for and nothing else. */
 function answeredOnArrival(
 	options: SendRespOptions,
-	handlers: Pick<SmsHandlers, 'onAnswered'>,
+	handlers: Pick<SmsHandlers, 'answered'>,
 ): Promise<VoidResult> {
 	if (options.smsId !== undefined) {
 		return Promise.resolve({
@@ -121,7 +121,7 @@ function answeredOnArrival(
 		});
 	}
 
-	handlers.onAnswered();
+	handlers.answered();
 
 	return Promise.resolve({});
 }
@@ -131,7 +131,7 @@ async function sendResp(
 	session: Session,
 	answered: { smsId: string },
 	options: SendRespOptions,
-	handlers: Pick<SmsHandlers, 'lostLink' | 'onAnswered'>,
+	handlers: Pick<SmsHandlers, 'answered' | 'lostLink'>,
 ): Promise<VoidResult> {
 	const total = sms.pduObjs.length;
 
@@ -158,7 +158,7 @@ async function sendResp(
 
 	const failure = results.find(result => result.err);
 
-	if (!failure) handlers.onAnswered();
+	if (!failure) handlers.answered();
 
 	return failure ?? {};
 }

test/session-extras.test.ts

@@ -5,7 +5,7 @@ import type { Collected, LostGroup } from '../src/reassembly.ts';
 import type { Dlr } from '../src/dlr.ts';
 import type { ErrorName } from '../src/defs/errors.ts';
 import type { IncomingRequestsOptions } from '../src/incoming-requests.ts';
-import type { MessageHold } from '../src/held-messages.ts';
+import type { HeldMessagesOptions, MessageHold } from '../src/held-messages.ts';
 import type { MessageState } from '../src/defs/constants.ts';
 import type { MessageDlr } from '../src/session.ts';
 import type { PduObject, PduObjectInput } from '../src/pdu.ts';
@@ -1543,11 +1543,34 @@ describe('held message bounds', () => {
 	}
 
 	function offer(held: HeldMessages, seqNr: number): MessageHold {
-		return held.offer(message(seqNr), 1, () => ({}), () => true);
+		const hold = held.offer(message(seqNr));
+
+		assert.ok(hold);
+
+		return hold;
 	}
 
-	test('is full at its count, and a re-used sequence number replaces rather than adding', () => {
+	/** Offers to a session with a listener, so an offer is held rather than released as untaken. */
-		const held = new HeldMessages({ log: silentLog, max: 2, maxOctets: 1_000_000, timeout: 10_000 });
+	function heldOn(
+		t: TestContext,
+		options: Pick<HeldMessagesOptions, 'max' | 'maxOctets' | 'now' | 'timeout'>,
+	): HeldMessages {
+		const session = new Session({ sock: new net.Socket() });
+
+		closeAfter(t, session);
+		session.on('sms', () => undefined);
+
+		return new HeldMessages({
+			...options,
+			link: new LinkLife({ log: silentLog, reconnects: false, timeout: 100 }),
+			log: silentLog,
+			sendPastDrain: () => Promise.resolve({ err: new Error('never sent') }),
+			session,
+		});
+	}
+
+	test('is full at its count, and a re-used sequence number replaces rather than adding', t => {
+		const held = heldOn(t, { max: 2, maxOctets: 1_000_000, timeout: 10_000 });
 		const first = offer(held, 1);
 		const replaced = offer(held, 2);
 
@@ -1563,9 +1586,9 @@ describe('held message bounds', () => {
 	});
 
 	// submitPdu() holds 1026 octets by the maxOctets charge: its object, and the three text fields.
-	test('is full at its octet cap, until a message leaves by any way out', () => {
+	test('is full at its octet cap, until a message leaves by any way out', t => {
 		let now = 0;
-		const held = new HeldMessages({ log: silentLog, max: 10, maxOctets: 2000, now: () => now, timeout: 10_000 });
+		const held = heldOn(t, { max: 10, maxOctets: 2000, now: () => now, timeout: 10_000 });
 		const answered = offer(held, 1);
 
 		assert.equal(held.full(), false);
@@ -1658,9 +1681,9 @@ describe('held message bounds', () => {
 		incoming.clear();
 	});
 
-	test('gives up on a message the application never answers', () => {
+	test('gives up on a message the application never answers', t => {
 		let now = 0;
-		const held = new HeldMessages({ log: silentLog, max: 10, maxOctets: 1_000_000, now: () => now, timeout: 60 });
+		const held = heldOn(t, { max: 10, maxOctets: 1_000_000, now: () => now, timeout: 60 });
 
 		offer(held, 1);
 		now = 61;
@@ -1674,9 +1697,9 @@ describe('held message bounds', () => {
 	});
 
 	// Without this the drain sits out its whole budget before returning what a sweep already settled.
-	test('wakes a waiting drain when the last message expires', async () => {
+	test('wakes a waiting drain when the last message expires', async t => {
 		let now = 0;
-		const held = new HeldMessages({ log: silentLog, max: 10, maxOctets: 1_000_000, now: () => now, timeout: 60 });
+		const held = heldOn(t, { max: 10, maxOctets: 1_000_000, now: () => now, timeout: 60 });
 
 		offer(held, 1);
 
@@ -1708,7 +1731,7 @@ describe('sendResp()', () => {
 			to: '46709771337',
 		}, {
 			lostLink: () => false,
-			onAnswered: () => { answered++; },
+			answered: () => { answered++; },
 			send: () => Promise.resolve({ err: new Error('never sent') }),
 		});
 
@@ -1733,7 +1756,7 @@ describe('sendDlr()', () => {
 			to: '46709771337',
 		}, {
 			lostLink: () => false,
-			onAnswered: () => undefined,
+			answered: () => undefined,
 			send: () => {
 				call++;
 

todo.md

@@ -209,14 +209,6 @@ hardest, and the held-message flow across `incoming-requests.ts`, `held-messages
 - [ ] **Lift Locality to 7, and confirm it with a scoring run.** A run reading 7.0 or above also
       retires the #30, #46 and #48 decision.
 
-- [ ] **Give the held-message flow one owner — next, the condition #48 merged under.** Whether a
-      message is still held, and so whether its receipt may pass the drain, is decided across
-      `IncomingRequests.emitSms()`, `HeldMessages.offer()`/`MessageHold`, `createSms()`'s handlers in
-      `sms.ts` and `Session`'s rejection handler, which finds the hold again through a `WeakMap`
-      keyed on the `Sms`; `MessageHold.answered()` defers its release a `setImmediate` so a
-      `sendDlr()` straight after `sendResp()` still counts as held. All four seats of the #48 run
-      ranked it second hardest; the inherited architect put it at about two days.
-
 ### Correctness
 
 - [ ] **Refuse to open a link that dropped while its rebind was answered.** A peer sending