capsite/toybox: mount lookups in SQL, not a scan in JS

Each request parsed every mount's labels and searched them in JS. Labels
now sit one per row in mount_label, indexed on (key, value): a lookup
joins the request's labels (json_each) on the index and keeps the vat
whose every label matched. The overlap check at registration is SQL too.

mount.labels keeps the whole set as JSON; mounts stored before
mount_label get their rows filled in when the schema runs. The SQL lives
in mounts-sql.js, tested on node:sqlite, old-shape state included.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

toybox/labels.js

@@ -51,23 +51,3 @@ export const checkUrl = (labels, url) => {
 	}
 };
 
-/**
- * Do `a` and `b` give some key different values? Flower refuses to register
- * a target that doesn't conflict with every other: lookups stay unambiguous.
- *
- * @param {Record<string, string>} a
- * @param {Record<string, string>} b
- */
-export const conflict = (a, b) => Object.entries(a).some(([k, v]) => k in b && b[k] !== v);
-
-/**
- * Does `request` carry every label of `mount`, with the same values?
- *
- * Stricter than Flower's match (no conflict): an ingress client holds no
- * constrained handle, so a label it omits must not match, or a secret
- * label would protect nothing.
- *
- * @param {Record<string, string>} mount
- * @param {Record<string, string>} request
- */
-export const carries = (mount, request) => Object.entries(mount).every(([k, v]) => request[k] === v);

toybox/mounts-sql.js

@@ -0,0 +1,53 @@
+/**
+ * @file The ingress's mounts, in SQL: which vat serves which label set.
+ *
+ * Labels sit one per row, so a lookup can use an index; `mount.labels`
+ * keeps the whole set as JSON. Request and mount labels arrive as JSON
+ * objects, split into rows by `json_each`.
+ */
+
+export const MOUNT_SCHEMA = [
+	"CREATE TABLE IF NOT EXISTS mount (vat TEXT PRIMARY KEY, labels TEXT)",
+	"CREATE TABLE IF NOT EXISTS mount_label (vat TEXT, key TEXT, value TEXT, PRIMARY KEY (vat, key))",
+	"CREATE INDEX IF NOT EXISTS mount_label_kv ON mount_label (key, value)",
+	// mounts made before mount_label existed
+	`INSERT OR IGNORE INTO mount_label
+	 SELECT m.vat, j.key, j.value FROM mount m, json_each(m.labels) j
+	 WHERE NOT EXISTS (SELECT 1 FROM mount_label l WHERE l.vat = m.vat)`,
+];
+
+/**
+ * Another mount (than ?2's) whose labels conflict with none of ?1's.
+ * Flower's registration rule: every mount must conflict with every other.
+ */
+export const OVERLAP = `
+	SELECT 1 FROM mount m WHERE m.vat != ?2 AND NOT EXISTS (
+		SELECT 1 FROM mount_label l JOIN json_each(?1) r ON r.key = l.key
+		WHERE l.vat = m.vat AND l.value != r.value)
+	LIMIT 1`;
+
+export const MOUNT = "INSERT OR REPLACE INTO mount VALUES (?1, ?2)";
+export const MOUNT_LABELS = "INSERT INTO mount_label SELECT ?1, key, value FROM json_each(?2)";
+export const UNMOUNT = "DELETE FROM mount WHERE vat = ?1";
+export const UNMOUNT_LABELS = "DELETE FROM mount_label WHERE vat = ?1";
+
+/**
+ * The mount whose every label ?1 (the request's labels) carries, with the
+ * same value: the labels that match, counted per vat, against how many
+ * the vat has. A mount with no labels matches any request.
+ *
+ * Stricter than Flower's match (no conflict): an ingress client holds no
+ * constrained handle, so a label it omits must not match, or a secret
+ * label would protect nothing.
+ */
+export const LOOKUP = `
+	SELECT m.vat, m.labels FROM mount m JOIN (
+		SELECT l.vat, count(*) AS hits
+		FROM json_each(?1) r JOIN mount_label l ON l.key = r.key AND l.value = r.value
+		GROUP BY l.vat
+	) h ON h.vat = m.vat
+	WHERE h.hits = (SELECT count(*) FROM mount_label WHERE vat = m.vat)
+	UNION ALL
+	SELECT m.vat, m.labels FROM mount m
+	WHERE NOT EXISTS (SELECT 1 FROM mount_label l WHERE l.vat = m.vat)
+	LIMIT 1`;

toybox/supervisor.js

@@ -4,7 +4,8 @@ import { DurableObject, WorkerEntrypoint } from "cloudflare:workers";
 import { RpcTarget, newWebSocketRpcSession, newWorkersRpcResponse } from "capnweb";
 import { E, Far } from "@endo/far";
 import { makeClient, swissnumFromBytes } from "@endo/ocapn";
-import { carries, conflict, mergeLabels, urlLabels } from "./labels.js";
+import { mergeLabels, urlLabels } from "./labels.js";
+import { LOOKUP, MOUNT, MOUNT_LABELS, MOUNT_SCHEMA, OVERLAP, UNMOUNT, UNMOUNT_LABELS } from "./mounts-sql.js";
 import { locationOf, makeRpcNetLayer } from "./netlayer.js";
 import VAT_RUNTIME from "vat-runtime.txt";
 
@@ -282,14 +283,7 @@ export class Router extends WorkerEntrypoint {
 export class Directory extends DurableObject {
 	constructor(ctx, env) {
 		super(ctx, env);
-		ctx.storage.sql.exec("CREATE TABLE IF NOT EXISTS mount (vat TEXT PRIMARY KEY, labels TEXT)");
-	}
-
-	#mounts() {
-		return this.ctx.storage.sql
-			.exec("SELECT vat, labels FROM mount")
-			.toArray()
-			.map(({ vat, labels }) => ({ vat, labels: JSON.parse(labels) }));
+		for (const statement of MOUNT_SCHEMA) ctx.storage.sql.exec(statement);
 	}
 
 	/**
@@ -299,22 +293,28 @@ export class Directory extends DurableObject {
 	 * @param {Record<string, string> | null} labels
 	 */
 	mount(vat, labels) {
-		if (labels) {
-			const overlap = this.#mounts().find((m) => m.vat !== vat && !conflict(m.labels, labels));
-			if (overlap) throw new Error("mount overlaps another: add a label whose value tells them apart");
-			this.ctx.storage.sql.exec("INSERT OR REPLACE INTO mount VALUES (?, ?)", vat, JSON.stringify(labels));
-		} else {
-			this.ctx.storage.sql.exec("DELETE FROM mount WHERE vat = ?", vat);
-		}
+		const { sql } = this.ctx.storage;
+		this.ctx.storage.transactionSync(() => {
+			sql.exec(UNMOUNT_LABELS, vat);
+			if (!labels) return void sql.exec(UNMOUNT, vat);
+			const json = JSON.stringify(labels);
+			if (sql.exec(OVERLAP, json, vat).toArray().length) {
+				throw new Error("mount overlaps another: add a label whose value tells them apart");
+			}
+			sql.exec(MOUNT, vat, json);
+			sql.exec(MOUNT_LABELS, vat, json);
+		});
 	}
 
 	/**
-	 * The mount whose labels `request` carries, if any.
+	 * The mount whose labels `request` carries, if any. Registration keeps
+	 * mounts pairwise conflicting, so at most one can match.
 	 *
 	 * @param {Record<string, string>} request
 	 */
 	lookup(request) {
-		return this.#mounts().find((m) => carries(m.labels, request)) ?? null;
+		const [row] = this.ctx.storage.sql.exec(LOOKUP, JSON.stringify(request)).toArray();
+		return row ? { vat: row.vat, labels: JSON.parse(row.labels) } : null;
 	}
 }
 

toybox/test/mounts-sql.test.js

@@ -0,0 +1,53 @@
+/** @file The ingress's mount SQL, on node:sqlite: lookup, overlap, and mounts stored before mount_label. */
+import { DatabaseSync } from "node:sqlite";
+import { test } from "node:test";
+import assert from "node:assert/strict";
+import { LOOKUP, MOUNT, MOUNT_LABELS, MOUNT_SCHEMA, OVERLAP } from "../mounts-sql.js";
+
+const makeDb = () => {
+	const db = new DatabaseSync(":memory:");
+	for (const statement of MOUNT_SCHEMA) db.exec(statement);
+	const mount = (vat, labels) => {
+		const json = JSON.stringify(labels);
+		db.prepare(MOUNT).run(vat, json);
+		db.prepare(MOUNT_LABELS).run(vat, json);
+	};
+	const lookup = (request) => db.prepare(LOOKUP).get(JSON.stringify(request))?.vat ?? null;
+	const overlaps = (vat, labels) => !!db.prepare(OVERLAP).get(JSON.stringify(labels), vat);
+	return { db, mount, lookup, overlaps };
+};
+
+test("a request reaches the mount whose every label it carries", () => {
+	const { mount, lookup } = makeDb();
+	mount("a", { vat: "alice", key: "s3cret" });
+	mount("b", { vat: "bob" });
+	assert.equal(lookup({ vat: "alice", key: "s3cret", page: "2" }), "a");
+	assert.equal(lookup({ vat: "alice" }), null);
+	assert.equal(lookup({ vat: "alice", key: "wrong" }), null);
+	assert.equal(lookup({ vat: "bob" }), "b");
+	assert.equal(lookup({}), null);
+});
+
+test("a mount with no labels matches any request", () => {
+	const { mount, lookup } = makeDb();
+	mount("only", {});
+	assert.equal(lookup({ anything: "x" }), "only");
+});
+
+test("overlap: a mount must conflict with every other", () => {
+	const { mount, overlaps } = makeDb();
+	mount("a", { vat: "alice" });
+	assert.equal(overlaps("b", { vat: "alice", n: "2" }), true);
+	assert.equal(overlaps("b", { app: "x" }), true);
+	assert.equal(overlaps("b", { vat: "bob" }), false);
+	assert.equal(overlaps("a", { vat: "alice", n: "2" }), false, "a vat's own mount doesn't count");
+});
+
+test("mounts stored before mount_label are filled in when the schema runs", () => {
+	const db = new DatabaseSync(":memory:");
+	db.exec("CREATE TABLE mount (vat TEXT PRIMARY KEY, labels TEXT)");
+	db.prepare("INSERT INTO mount VALUES (?, ?)").run("old", JSON.stringify({ vat: "old" }));
+	for (const statement of MOUNT_SCHEMA) db.exec(statement);
+	assert.equal(db.prepare(LOOKUP).get(JSON.stringify({ vat: "old" }))?.vat, "old");
+	assert.equal(db.prepare(LOOKUP).get(JSON.stringify({ vat: "other" })), undefined);
+});