364 lines
12 KiB
TypeScript
364 lines
12 KiB
TypeScript
import { Actor, Assertion, Entity, Handle, Ref, Turn } from './actor.js';
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import { BytesLike, canonicalString, Decoder, encode, FlexMap, IdentityMap, mapPointers, underlying, Value } from '@preserves/core';
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import {
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EncodedAttenuation,
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EntityMessage,
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IO,
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Oid,
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TurnMessage,
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WireRef,
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WireSymbol,
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_Assert,
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_Message,
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_Retract,
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_Sync,
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decodeAttenuation,
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encodeAttenuation,
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myRef,
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yourRef,
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} from './protocol.js';
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import { queueTask } from './task.js';
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import { attenuate } from './rewrite.js';
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export class SyncPeerEntity implements Entity {
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readonly relay: Relay;
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readonly peer: Ref;
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readonly handleMap = new IdentityMap<Handle, Handle>();
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e: WireSymbol | null = null;
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constructor(relay: Relay, peer: Ref) {
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this.relay = relay;
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this.peer = peer;
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}
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assert(turn: Turn, assertion: Assertion, handle: Handle): void {
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this.handleMap.set(handle, turn.assert(this.peer, assertion));
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}
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retract(turn: Turn, handle: Handle): void {
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turn.retract(this.handleMap.get(handle)!);
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this.handleMap.delete(handle);
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}
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message(turn: Turn, body: Assertion): void {
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// We get to vanish from the indexes now
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this.relay.releaseRefOut(this.e!);
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turn.message(this.peer, body);
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}
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sync(turn: Turn, peer: Ref): void {
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turn._sync(this.peer, peer);
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}
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}
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export class RelayEntity implements Entity {
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readonly relay: Relay;
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readonly oid: Oid;
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constructor(relay: Relay, oid: Oid) {
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this.relay = relay;
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this.oid = oid;
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}
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send(m: EntityMessage<WireRef>): void {
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this.relay.send(this.oid, m);
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}
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assert(_turn: Turn, assertion: Assertion, handle: Handle): void {
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this.send(IO.Assert(this.relay.register(assertion, handle), handle));
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}
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retract(_turn: Turn, handle: Handle): void {
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this.relay.deregister(handle);
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this.send(IO.Retract(handle));
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}
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message(_turn: Turn, body: Assertion): void {
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this.send(IO.Message(this.relay.register(body, null)));
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}
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sync(turn: Turn, peer: Ref): void {
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const peerEntity = new SyncPeerEntity(this.relay, peer);
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const exported: Array<WireSymbol> = [];
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const ior = this.relay.rewriteRefOut(turn.ref(peerEntity), false, exported);
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peerEntity.e = exported[0];
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this.send(IO.Sync(ior));
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}
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}
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export class Membrane {
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readonly byOid = new IdentityMap<Oid, WireSymbol>();
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readonly byRef = new IdentityMap<Ref, WireSymbol>();
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grab<Table extends "byOid" | "byRef">(table: Table,
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key: Parameters<Membrane[Table]['get']>[0],
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transient: boolean,
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f: () => WireSymbol): WireSymbol
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{
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let e = this[table].get(key as any);
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if (e === void 0) {
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e = f();
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this.byRef.set(e.ref, e);
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this.byOid.set(e.oid, e);
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}
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if (!transient) e.count++;
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return e;
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}
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drop(e: WireSymbol): void {
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e.count--;
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if (e.count === 0) {
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this.byOid.delete(e.oid);
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this.byRef.delete(e.ref);
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}
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}
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}
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export const INERT_REF: Ref = {
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relay: (() => {
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const a = new Actor();
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a.exitReason = { ok: true };
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return a;
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})(),
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target: {},
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};
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export type PacketWriter = (bs: Uint8Array) => void;
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export interface RelayOptions {
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packetWriter: PacketWriter;
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setup(t: Turn, r: Relay): void;
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debug?: boolean;
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trustPeer?: boolean;
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}
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export class Relay {
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readonly actor: Actor;
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readonly w: PacketWriter;
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readonly inboundAssertions = new IdentityMap<Handle, {
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localHandle: Handle,
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imported: Array<WireSymbol>,
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}>();
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readonly outboundAssertions = new IdentityMap<Handle, Array<WireSymbol>>();
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readonly exported = new Membrane();
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readonly imported = new Membrane();
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nextLocalOid: Oid = 0;
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pendingTurn: TurnMessage<WireRef> = [];
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debug: boolean;
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trustPeer: boolean;
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readonly decoder = new Decoder<WireRef>(void 0, {
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includeAnnotations: false,
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decodePointer: v => {
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function complain(): never {
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throw new Error(
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`Received invalid object reference ${v.asPreservesText()} from peer`);
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}
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if (!(Array.isArray(v) && v.length >= 2 && typeof v[1] === 'number')) {
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complain();
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}
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const oid = v[1] as Oid;
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switch (v[0]) {
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case 0:
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if (v.length > 2) complain();
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return myRef(oid);
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case 1:
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// TODO: check EncodedAttenuation
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return yourRef(oid, v.slice(2) as EncodedAttenuation);
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default:
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complain();
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}
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},
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});
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constructor(t: Turn, options: RelayOptions) {
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this.actor = t.actor;
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this.w = options.packetWriter;
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this.debug = options.debug ?? false;
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this.trustPeer = options.trustPeer ?? true;
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options.setup(t, this);
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}
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rewriteOut(assertion: Assertion, transient: boolean): [Value<WireRef>, Array<WireSymbol>]
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{
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const exported: Array<WireSymbol> = [];
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const rewritten = mapPointers(assertion, r => this.rewriteRefOut(r, transient, exported));
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return [rewritten, exported];
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}
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rewriteIn(t: Turn, a: Value<WireRef>): [Assertion, Array<WireSymbol>]
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{
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const imported: Array<WireSymbol> = [];
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const rewritten = mapPointers(a, r => this.rewriteRefIn(t, r, imported));
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return [rewritten, imported];
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}
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register(assertion: Assertion, handle: Handle | null): Value<WireRef> {
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const [rewritten, exported] = this.rewriteOut(assertion, handle === null);
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if (handle !== null) this.outboundAssertions.set(handle, exported);
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return rewritten;
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}
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deregister(handle: Handle): void {
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(this.outboundAssertions.get(handle) ?? []).forEach(e => this.releaseRefOut(e));
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}
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rewriteRefOut(r: Ref, transient: boolean, exported: Array<WireSymbol>): WireRef {
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if (r.target instanceof RelayEntity && r.target.relay === this) {
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if (r.attenuation === void 0 || r.attenuation.length === 0) {
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// No extra conditions on this reference since it was sent to us.
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return yourRef(r.target.oid, []);
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} else {
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// This reference has been attenuated since it was sent to us.
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// Do we trust the peer to enforce such attenuation on our behalf?
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if (this.trustPeer) {
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return yourRef(r.target.oid, encodeAttenuation(r.attenuation));
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} else {
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// fall through: treat the attenuated ref as a local ref, and re-export it.
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}
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}
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}
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const e = this.exported.grab(
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"byRef", r, transient, () => {
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if (transient) throw new Error("Cannot send transient reference");
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return { oid: this.nextLocalOid++, ref: r, count: 0 };
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});
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exported.push(e);
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return myRef(e.oid);
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}
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releaseRefOut(e: WireSymbol) {
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this.exported.drop(e);
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}
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rewriteRefIn(t: Turn, n: WireRef, imported: Array<WireSymbol>): Ref {
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switch (n.loc) {
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case 'your': {
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const r = this.lookupLocal(n.oid);
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if (n.attenuation.length === 0 || r === INERT_REF) {
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return r;
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} else {
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type AttenuatedRef = Ref & { __attenuations?: FlexMap<EncodedAttenuation, Ref> };
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const ar = r as AttenuatedRef;
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if (ar.__attenuations === void 0) {
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ar.__attenuations = new FlexMap(canonicalString);
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}
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return ar.__attenuations.getOrSet(n.attenuation, () =>
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attenuate(r, ... decodeAttenuation(n.attenuation)));
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}
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}
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case 'mine': {
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const e = this.imported.grab("byOid", n.oid, false, () =>
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({ oid: n.oid, ref: t.ref(new RelayEntity(this, n.oid)), count: 0 }));
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imported.push(e);
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return e.ref;
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}
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}
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}
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send(remoteOid: Oid, m: EntityMessage<WireRef>): void {
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if (this.pendingTurn.length === 0) {
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queueTask(() => {
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if (this.debug) console.log('OUT', this.pendingTurn.asPreservesText());
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this.w(underlying(encode<WireRef>(this.pendingTurn, {
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canonical: true,
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encodePointer: n => {
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switch (n.loc) {
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case 'mine': return [0, n.oid];
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case 'your': return [1, n.oid, ... n.attenuation];
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}
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},
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})));
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this.pendingTurn = [];
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});
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}
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this.pendingTurn.push([remoteOid, m]);
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}
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lookupLocal(localOid: Oid): Ref {
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return this.exported.byOid.get(localOid)?.ref ?? INERT_REF;
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}
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accept(bs: BytesLike): void {
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Turn.for(this.actor, t => {
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this.decoder.write(bs);
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while (true) {
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const wireTurn = this.decoder.try_next() as (TurnMessage<WireRef> | undefined);
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if (wireTurn === void 0) break;
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// TODO: deep check that wireTurn really is a TurnMessage
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if (this.debug) console.log('IN', wireTurn.asPreservesText());
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wireTurn.forEach(v => {
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const [localOid, m] = v;
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this.handle(t, this.lookupLocal(localOid), m);
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});
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}
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});
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}
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handle(t: Turn, r: Ref, m: EntityMessage<WireRef>) {
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switch (m.label) {
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case _Assert: {
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const [a, imported] = this.rewriteIn(t, IO.Assert._.assertion(m));
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this.inboundAssertions.set(IO.Assert._.handle(m), {
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localHandle: t.assert(r, a),
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imported,
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});
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break;
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}
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case _Retract: {
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const remoteHandle = IO.Retract._.handle(m);
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const h = this.inboundAssertions.get(remoteHandle);
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if (h === void 0) throw new Error(`Peer retracted invalid handle ${remoteHandle}`);
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this.inboundAssertions.delete(remoteHandle);
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h.imported.forEach(e => this.imported.drop(e));
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t.retract(h.localHandle);
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break;
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}
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case _Message: {
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const [a, imported] = this.rewriteIn(t, IO.Message._.body(m));
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if (imported.length > 0) throw new Error("Cannot receive transient reference");
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t.message(r, a);
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break;
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}
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case _Sync: {
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const imported: Array<WireSymbol> = [];
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const k = this.rewriteRefIn(t, IO.Sync._.peer(m), imported);
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t.sync(r).then(t => {
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t.message(k, true);
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imported.forEach(e => this.imported.drop(e));
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});
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break;
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}
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}
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}
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}
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export interface RelayActorOptions extends RelayOptions {
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initialOid?: Oid;
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initialRef?: Ref;
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nextLocalOid?: Oid;
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}
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export function spawnRelay(t: Turn, options: RelayActorOptions & {initialOid: Oid}): Promise<Ref>;
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export function spawnRelay(t: Turn, options: Omit<RelayActorOptions, 'initialOid'>): Promise<null>;
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export function spawnRelay(t: Turn, options: RelayActorOptions): Promise<Ref | null>
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{
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return new Promise(resolve => {
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t.spawn(t => {
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const relay = new Relay(t, options);
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if (options.initialRef !== void 0) {
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relay.rewriteRefOut(options.initialRef, false, []);
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}
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if (options.initialOid !== void 0) {
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resolve(relay.rewriteRefIn(t, myRef(options.initialOid), []));
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} else {
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resolve(null);
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}
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if (options.nextLocalOid !== void 0) {
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relay.nextLocalOid = (options.nextLocalOid === 0) ? 1 : options.nextLocalOid;
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}
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});
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});
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}
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