634 lines
17 KiB
JavaScript
634 lines
17 KiB
JavaScript
/*---------------------------------------------------------------------------*/
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/* Unification */
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var __ = new Object(); /* wildcard marker */
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__.__ = "__";
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function unificationFailed() {
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throw {unificationFailed: true};
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}
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function unify1(a, b) {
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var i;
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if (a === __) return b;
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if (b === __) return a;
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if (a === b) return a;
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if (Array.isArray(a) && Array.isArray(b)) {
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if (a.length !== b.length) unificationFailed();
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var result = new Array(a.length);
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for (i = 0; i < a.length; i++) {
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result[i] = unify1(a[i], b[i]);
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}
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return result;
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}
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if (typeof a === "object" && typeof b === "object") {
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/* TODO: consider other kinds of matching. I've chosen to
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require any field mentioned by either side to be present in
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both. Does that make sense? */
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var result = ({});
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for (i in a) { if (a.hasOwnProperty(i)) result[i] = true; }
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for (i in b) { if (b.hasOwnProperty(i)) result[i] = true; }
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for (i in result) {
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if (result.hasOwnProperty(i)) {
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result[i] = unify1(a[i], b[i]);
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}
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}
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return result;
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}
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unificationFailed();
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}
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function unify(a, b) {
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try {
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// console.log("unify", JSON.stringify(a), JSON.stringify(b));
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return {result: unify1(a, b)};
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} catch (e) {
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if (e.unificationFailed) return undefined;
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throw e;
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}
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}
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function anyUnify(aa, bb) {
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for (var i = 0; i < aa.length; i++) {
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for (var j = 0; j < bb.length; j++) {
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if (unify(aa[i], bb[j])) return true;
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}
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}
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return false;
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}
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/*---------------------------------------------------------------------------*/
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/* Events and Actions */
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function Route(isSubscription, pattern, metaLevel, level) {
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this.isSubscription = isSubscription;
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this.pattern = pattern;
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this.metaLevel = (metaLevel === undefined) ? 0 : metaLevel;
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this.level = (level === undefined) ? 0 : level;
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}
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Route.prototype.drop = function () {
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if (this.metaLevel === 0) { return null; }
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return new Route(this.isSubscription, this.pattern, this.metaLevel - 1, this.level);
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};
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Route.prototype.lift = function () {
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return new Route(this.isSubscription, this.pattern, this.metaLevel + 1, this.level);
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};
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Route.prototype.toJSON = function () {
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return [this.isSubscription ? "sub" : "pub", this.pattern, this.metaLevel, this.level];
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};
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Route.fromJSON = function (j) {
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switch (j[0]) {
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case "sub": return new Route(true, j[1], j[2], j[3]);
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case "pub": return new Route(false, j[1], j[2], j[3]);
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default: throw { message: "Invalid JSON-encoded route: " + JSON.stringify(j) };
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}
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};
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function sub(pattern, metaLevel, level) {
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return new Route(true, pattern, metaLevel, level);
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}
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function pub(pattern, metaLevel, level) {
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return new Route(false, pattern, metaLevel, level);
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}
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function spawn(behavior, initialRoutes) {
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return { type: "spawn",
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behavior: behavior,
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initialRoutes: (initialRoutes === undefined) ? [] : initialRoutes };
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}
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function updateRoutes(routes) {
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return { type: "routes", routes: routes };
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}
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function sendMessage(m, metaLevel, isFeedback) {
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return { type: "message",
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metaLevel: (metaLevel === undefined) ? 0 : metaLevel,
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message: m,
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isFeedback: (isFeedback === undefined) ? false : isFeedback };
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}
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function shutdownWorld() {
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return { type: "shutdownWorld" };
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}
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/*---------------------------------------------------------------------------*/
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/* Metafunctions */
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function dropRoutes(routes) {
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var result = [];
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for (var i = 0; i < routes.length; i++) {
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var r = routes[i].drop();
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if (r) { result.push(r); }
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}
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return result;
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}
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function liftRoutes(routes) {
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var result = [];
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for (var i = 0; i < routes.length; i++) {
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result.push(routes[i].lift());
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}
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return result;
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}
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function intersectRoutes(rs1, rs2, ignoreLevels) {
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var result = [];
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for (var i = 0; i < rs1.length; i++) {
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for (var j = 0; j < rs2.length; j++) {
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var ri = rs1[i];
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var rj = rs2[j];
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if (ri.isSubscription === !rj.isSubscription
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&& ri.metaLevel === rj.metaLevel
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&& (ignoreLevels || (ri.level < rj.level)))
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{
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var u = unify(ri.pattern, rj.pattern);
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if (u) {
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var rk = new Route(ri.isSubscription, u.result, ri.metaLevel, ri.level);
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result.push(rk);
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}
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}
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}
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}
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return result;
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}
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function filterEvent(e, routes) {
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switch (e.type) {
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case "routes":
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return updateRoutes(intersectRoutes(e.routes, routes));
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case "message":
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for (var i = 0; i < routes.length; i++) {
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var r = routes[i];
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if (e.metaLevel === r.metaLevel
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&& e.isFeedback === !r.isSubscription
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&& unify(e.message, r.pattern))
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{
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return e;
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}
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}
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return null;
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default:
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throw { message: "Event type " + e.type + " not filterable",
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event: e };
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}
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}
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/*---------------------------------------------------------------------------*/
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/* Configurations */
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function World(bootFn) {
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this.nextPid = 0;
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this.eventQueue = [];
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this.processTable = {};
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this.downwardRoutes = [];
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this.processActions = [];
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this.activePid = null;
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this.stepperId = null;
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this.asChild(-1, bootFn, true);
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}
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/* Class state / methods */
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World.stack = [];
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World.current = function () {
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return World.stack[World.stack.length - 1];
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};
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World.send = function (m, metaLevel, isFeedback) {
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World.current().enqueueAction(sendMessage(m, metaLevel, isFeedback));
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};
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World.updateRoutes = function (routes) {
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World.current().enqueueAction(updateRoutes(routes));
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};
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World.spawn = function (behavior, initialRoutes) {
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World.current().enqueueAction(spawn(behavior, initialRoutes));
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};
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World.exit = function (exn) {
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World.current().killActive(exn);
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};
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World.shutdownWorld = function () {
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World.current().enqueueAction(shutdownWorld());
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};
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World.withWorldStack = function (stack, f) {
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var oldStack = World.stack;
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World.stack = stack;
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var result = null;
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try {
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result = f();
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} catch (e) {
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World.stack = oldStack;
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throw e;
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}
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World.stack = oldStack;
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return result;
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};
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World.wrap = function (f) {
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var savedStack = World.stack.slice();
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var savedPid = World.current().activePid;
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return function () {
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var actuals = arguments;
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return World.withWorldStack(savedStack, function () {
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var result = World.current().asChild(savedPid, function () {
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return f.apply(null, actuals);
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});
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World.stack[0].startStepping();
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return result;
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});
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};
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};
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/* Instance methods */
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World.prototype.killActive = function (exn) {
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this.kill(this.activePid, exn);
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};
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World.prototype.enqueueAction = function (action) {
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this.processActions.push([this.activePid, action]);
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};
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World.prototype.isQuiescent = function () {
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return this.eventQueue.length === 0 && this.processActions.length === 0;
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};
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World.prototype.step = function () {
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this.dispatchEvents();
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this.performActions();
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return this.stepChildren() || !this.isQuiescent();
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};
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World.prototype.startStepping = function () {
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var self = this;
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if (this.stepperId) return;
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if (this.step()) {
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this.stepperId = setTimeout(function () {
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self.stepperId = null;
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self.startStepping();
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}, 0);
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}
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};
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World.prototype.stopStepping = function () {
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if (this.stepperId) {
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clearTimeout(this.stepperId);
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this.stepperId = null;
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}
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};
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World.prototype.asChild = function (pid, f, omitLivenessCheck) {
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if (!(pid in this.processTable) && !omitLivenessCheck) {
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console.warn("World.asChild eliding invocation of dead process", pid);
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return;
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}
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World.stack.push(this);
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var result = null;
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this.activePid = pid;
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try {
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result = f();
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} catch (e) {
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this.kill(pid, e);
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}
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this.activePid = null;
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if (World.stack.pop() !== this) {
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throw { message: "Internal error: World stack imbalance" };
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}
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return result;
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};
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World.prototype.kill = function (pid, exn) {
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if (exn && exn.stack) {
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console.log("Process exited", pid, exn, exn.stack);
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} else {
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console.log("Process exited", pid, exn);
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}
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var p = this.processTable[pid];
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if (p && p.behavior.trapexit) {
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this.asChild(pid, function () { return p.behavior.trapexit(exn); });
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}
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delete this.processTable[pid];
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this.issueRoutingUpdate();
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};
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World.prototype.stepChildren = function () {
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var someChildBusy = false;
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for (var pid in this.processTable) {
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var p = this.processTable[pid];
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if (p.behavior.step /* exists, haven't called it yet */) {
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var childBusy = this.asChild(pid, function () { return p.behavior.step() });
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someChildBusy = someChildBusy || childBusy;
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}
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}
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return someChildBusy;
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};
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World.prototype.performActions = function () {
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var queue = this.processActions;
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this.processActions = [];
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var item;
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while ((item = queue.shift())) {
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this.performAction(item[0], item[1]);
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}
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};
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World.prototype.dispatchEvents = function () {
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var queue = this.eventQueue;
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this.eventQueue = [];
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var item;
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while ((item = queue.shift())) {
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this.dispatchEvent(item);
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}
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};
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World.prototype.performAction = function (pid, action) {
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switch (action.type) {
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case "spawn":
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var pid = this.nextPid++;
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this.processTable[pid] = { routes: action.initialRoutes, behavior: action.behavior };
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if (action.behavior.boot) { this.asChild(pid, function () { action.behavior.boot() }); }
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this.issueRoutingUpdate();
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break;
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case "routes":
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if (pid in this.processTable) {
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// it may not be: this might be the routing update from a
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// kill of the process
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this.processTable[pid].routes = action.routes;
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}
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this.issueRoutingUpdate();
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break;
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case "message":
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if (action.metaLevel === 0) {
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this.eventQueue.push(action);
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} else {
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World.send(action.message, action.metaLevel - 1, action.isFeedback);
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}
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break;
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case "shutdownWorld":
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World.exit();
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break;
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default:
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throw { message: "Action type " + action.type + " not understood",
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action: action };
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}
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};
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World.prototype.aggregateRoutes = function (base) {
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var acc = base.slice();
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for (var pid in this.processTable) {
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var p = this.processTable[pid];
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for (var i = 0; i < p.routes.length; i++) {
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acc.push(p.routes[i]);
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}
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}
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return acc;
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};
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World.prototype.issueLocalRoutingUpdate = function () {
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this.eventQueue.push(updateRoutes(this.aggregateRoutes(this.downwardRoutes)));
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};
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World.prototype.issueRoutingUpdate = function () {
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this.issueLocalRoutingUpdate();
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World.updateRoutes(dropRoutes(this.aggregateRoutes([])));
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};
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World.prototype.dispatchEvent = function (e) {
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for (var pid in this.processTable) {
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var p = this.processTable[pid];
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var e1 = filterEvent(e, p.routes);
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// console.log("filtering", e, p.routes, e1);
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if (e1) { this.asChild(pid, function () { p.behavior.handleEvent(e1) }); }
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}
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};
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World.prototype.handleEvent = function (e) {
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switch (e.type) {
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case "routes":
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this.downwardRoutes = liftRoutes(e.routes);
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this.issueLocalRoutingUpdate();
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break;
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case "message":
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this.eventQueue.push(sendMessage(e.message, e.metaLevel + 1, e.isFeedback));
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break;
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default:
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throw { message: "Event type " + e.type + " not understood",
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event: e };
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}
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};
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/*---------------------------------------------------------------------------*/
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/* Utilities: detecting presence/absence events via routing events */
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function PresenceDetector(initialRoutes) {
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this.state = this._digestRoutes(initialRoutes === undefined ? [] : initialRoutes);
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}
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PresenceDetector.prototype._digestRoutes = function (routes) {
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var newState = {};
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for (var i = 0; i < routes.length; i++) {
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newState[JSON.stringify(routes[i].toJSON())] = routes[i];
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}
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return newState;
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};
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PresenceDetector.prototype.getRouteList = function () {
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var rs = [];
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for (var k in this.state) { rs.push(this.state[k]); }
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return rs;
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};
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PresenceDetector.prototype.handleRoutes = function (routes) {
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var added = [];
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var removed = [];
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var newState = this._digestRoutes(routes);
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for (var k in newState) {
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if (!(k in this.state)) {
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added.push(newState[k]);
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} else {
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delete this.state[k];
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}
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}
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for (var k in this.state) {
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removed.push(this.state[k]);
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}
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this.state = newState;
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return { added: added, removed: removed };
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};
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PresenceDetector.prototype.presenceExistsFor = function (probeRoute) {
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for (var k in this.state) {
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var existingRoute = this.state[k];
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if (probeRoute.isSubscription === !existingRoute.isSubscription
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&& probeRoute.metaLevel === existingRoute.metaLevel
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&& probeRoute.level === existingRoute.level
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&& unify(probeRoute.pattern, existingRoute.pattern))
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{
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return true;
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}
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}
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return false;
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};
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/*---------------------------------------------------------------------------*/
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/* Utilities: matching demand for some service */
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function DemandMatcher(pattern, metaLevel, options) {
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options = $.extend({
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demandLevel: 0,
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supplyLevel: 0,
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demandSideIsSubscription: true
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}, options);
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this.pattern = pattern;
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this.metaLevel = metaLevel;
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this.demandLevel = options.demandLevel;
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this.supplyLevel = options.supplyLevel;
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this.demandSideIsSubscription = options.demandSideIsSubscription;
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this.onDemandIncrease = function (r) {
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console.error("Unhandled increase in demand for route", r);
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};
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this.onSupplyDecrease = function (r) {
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console.error("Unhandled decrease in supply for route", r);
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};
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this.state = new PresenceDetector();
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}
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DemandMatcher.prototype.boot = function () {
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World.updateRoutes([this.computeDetector(true),
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this.computeDetector(false)]);
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};
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DemandMatcher.prototype.handleEvent = function (e) {
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if (e.type === "routes") {
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this.handleRoutes(e.routes);
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}
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};
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DemandMatcher.prototype.computeDetector = function (demandSide) {
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var maxLevel = (this.demandLevel > this.supplyLevel ? this.demandLevel : this.supplyLevel);
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return new Route(this.demandSideIsSubscription ? !demandSide : demandSide,
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this.pattern,
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this.metaLevel,
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maxLevel + 1);
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};
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DemandMatcher.prototype.handleRoutes = function (routes) {
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var changes = this.state.handleRoutes(routes);
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this.incorporateChanges(true, changes.added);
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this.incorporateChanges(false, changes.removed);
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};
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DemandMatcher.prototype.incorporateChanges = function (isArrivals, routeList) {
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var relevantChangeDetector = this.computeDetector(isArrivals);
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var expectedChangeLevel = isArrivals ? this.demandLevel : this.supplyLevel;
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var expectedPeerLevel = isArrivals ? this.supplyLevel : this.demandLevel;
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for (var i = 0; i < routeList.length; i++) {
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var changed = routeList[i];
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if (changed.level != expectedChangeLevel) continue;
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var relevantChangedN = intersectRoutes([changed], [relevantChangeDetector]);
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if (relevantChangedN.length === 0) continue;
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var relevantChanged = relevantChangedN[0]; /* there can be only one */
|
|
var peerDetector = new Route(relevantChanged.isSubscription,
|
|
relevantChanged.pattern,
|
|
relevantChanged.metaLevel,
|
|
expectedPeerLevel + 1);
|
|
var peerRoutes = intersectRoutes(this.state.getRouteList(), [peerDetector]);
|
|
var peerExists = false;
|
|
for (var j = 0; j < peerRoutes.length; j++) {
|
|
if (peerRoutes[j].level == expectedPeerLevel) {
|
|
peerExists = true;
|
|
break;
|
|
}
|
|
}
|
|
if (isArrivals && !peerExists) { this.onDemandIncrease(relevantChanged); }
|
|
if (!isArrivals && peerExists) { this.onSupplyDecrease(relevantChanged); }
|
|
}
|
|
};
|
|
|
|
/*---------------------------------------------------------------------------*/
|
|
/* Utilities: deduplicator */
|
|
|
|
function Deduplicator(ttl_ms) {
|
|
this.ttl_ms = ttl_ms || 10000;
|
|
this.queue = [];
|
|
this.map = {};
|
|
this.timerId = null;
|
|
}
|
|
|
|
Deduplicator.prototype.accept = function (m) {
|
|
var s = JSON.stringify(m);
|
|
if (s in this.map) return false;
|
|
var entry = [(+new Date()) + this.ttl_ms, s, m];
|
|
this.map[s] = entry;
|
|
this.queue.push(entry);
|
|
|
|
if (this.timerId === null) {
|
|
var self = this;
|
|
this.timerId = setInterval(function () { self.expireMessages(); },
|
|
this.ttl_ms > 1000 ? 1000 : this.ttl_ms);
|
|
}
|
|
return true;
|
|
};
|
|
|
|
Deduplicator.prototype.expireMessages = function () {
|
|
var now = +new Date();
|
|
while (this.queue.length > 0 && this.queue[0][0] <= now) {
|
|
var entry = this.queue.shift();
|
|
delete this.map[entry[1]];
|
|
}
|
|
if (this.queue.length === 0) {
|
|
clearInterval(this.timerId);
|
|
this.timerId = null;
|
|
}
|
|
};
|
|
|
|
/*---------------------------------------------------------------------------*/
|
|
/* Ground interface */
|
|
|
|
function Ground(bootFn) {
|
|
var self = this;
|
|
this.stepperId = null;
|
|
this.state = new PresenceDetector();
|
|
World.withWorldStack([this], function () {
|
|
self.world = new World(bootFn);
|
|
});
|
|
}
|
|
|
|
Ground.prototype.step = function () {
|
|
var self = this;
|
|
return World.withWorldStack([this], function () {
|
|
return self.world.step();
|
|
});
|
|
};
|
|
|
|
Ground.prototype.startStepping = World.prototype.startStepping;
|
|
Ground.prototype.stopStepping = World.prototype.stopStepping;
|
|
|
|
Ground.prototype.enqueueAction = function (action) {
|
|
if (action.type === 'routes') {
|
|
var added = this.state.handleRoutes(action.routes).added;
|
|
if (added.length > 0) {
|
|
console.error("You have subscribed to a nonexistent event source.", added);
|
|
}
|
|
} else {
|
|
console.error("You have sent a message into the outer void.", action);
|
|
}
|
|
};
|