Web: IndexedDB puts and deletes resolve when their transaction commits (#1242)

apps/effectcraft-web/js/host.js

@@ -57,6 +57,26 @@ function req(r) {
   return new Promise((res, rej) => { r.onsuccess = () => res(r.result); r.onerror = () => rej(r.error); });
 }
 
+// Run `op` on `store` in a readwrite transaction of its own; resolves once the transaction has
+// committed. A request's success doesn't mean the write is stored: the transaction can still
+// abort afterwards (quota at commit, the browser closing), rolling it back, and a write
+// reported as saved then is never retried (#1242). A failed request aborts the transaction
+// with its error; an explicit abort leaves no error, hence the AbortError.
+function write(db, store, op) {
+  return new Promise((res, rej) => {
+    let tx = null;
+    try {
+      tx = db.transaction(store, "readwrite");
+      tx.oncomplete = () => res();
+      tx.onabort = () => rej(tx.error ?? new DOMException("the storage transaction was aborted", "AbortError"));
+      op(tx.objectStore(store));
+    } catch (e) {
+      try { tx?.abort(); } catch {}
+      rej(e);
+    }
+  });
+}
+
 async function idb() {
   if (!self.indexedDB) throw new Error("no IndexedDB");
   const open = indexedDB.open(DB, 1);
@@ -70,10 +90,10 @@ async function idb() {
       return all.map((r) => ({ key: r.key, data: new Uint8Array(r.data), modified: r.modified }));
     },
     async put(key, data, modified) {
-      await req(tx("readwrite").put({ key, data: data.slice().buffer, modified }));
+      await write(db, STORE, (s) => s.put({ key, data: data.slice().buffer, modified }));
     },
     async del(key) {
-      await req(tx("readwrite").delete(key));
+      await write(db, STORE, (s) => s.delete(key));
     },
   };
 }

apps/effectcraft-web/tests/storage.mjs

@@ -0,0 +1,180 @@
+// The IndexedDB storage backend of the web app (js/host.js) under Node with a fake IndexedDB, no
+// browser or Wasm build needed:
+//
+//   node apps/effectcraft-web/tests/storage.mjs
+//
+// A write is acknowledged only once its transaction has committed, not when its request
+// succeeded: a transaction that aborts afterwards rolls the write back, and the write must be
+// reported as failed so the flush keeps it for a retry (#1242). Exits non-zero on failure.
+import assert from "node:assert/strict";
+import { dirname, join } from "node:path";
+import { fileURLToPath, pathToFileURL } from "node:url";
+
+const here = dirname(fileURLToPath(import.meta.url));
+const tick = () => new Promise((r) => setTimeout(r, 0));
+globalThis.self = globalThis;
+
+// A small IndexedDB: requests succeed (or fail) one task after they're made, and a readwrite
+// transaction commits once its requests are done, unless it was aborted (which rolls back its
+// writes). `fault` makes the next request do something else.
+let fault = null; // "abortAfterSuccess" | "requestError" | "throw"
+const databases = new Map();
+
+class Request {
+  constructor(tx) {
+    this.transaction = tx;
+    this.result = undefined;
+    this.error = null;
+  }
+}
+
+class Store {
+  constructor(tx, rows) {
+    this.tx = tx;
+    this.rows = rows;
+  }
+  request(apply) {
+    const tx = this.tx;
+    if (tx.finished) throw new DOMException("the transaction has finished", "TransactionInactiveError");
+    const f = fault;
+    fault = null;
+    if (f === "throw") throw new DOMException("the value can't be cloned", "DataCloneError");
+    const r = new Request(tx);
+    tx.pending++;
+    setTimeout(() => {
+      tx.pending--;
+      if (tx.finished) return;
+      if (f === "requestError") {
+        r.error = new DOMException("the key already exists", "ConstraintError");
+        const e = { target: r, defaultPrevented: false, preventDefault() { this.defaultPrevented = true; } };
+        r.onerror?.(e);
+        tx.onerror?.(e);
+        if (!e.defaultPrevented) tx.fail(r.error);
+        return;
+      }
+      r.result = apply(tx.staged);
+      r.onsuccess?.({ target: r });
+      if (f === "abortAfterSuccess") tx.abort();
+      tx.maybeCommit();
+    }, 0);
+    return r;
+  }
+  put(v) {
+    return this.request((rows) => { rows.set(v[this.keyPath], structuredClone(v)); return v[this.keyPath]; });
+  }
+  delete(k) {
+    return this.request((rows) => { rows.delete(k); });
+  }
+  get(k) {
+    return this.request((rows) => rows.get(k));
+  }
+  getAll() {
+    return this.request((rows) => [...rows.values()]);
+  }
+}
+
+class Transaction {
+  constructor(db, name) {
+    this.db = db;
+    this.name = name;
+    this.staged = new Map(db.stores.get(name));
+    this.pending = 0;
+    this.finished = false;
+    this.error = null;
+    setTimeout(() => this.maybeCommit(), 0);
+  }
+  objectStore(name) {
+    const s = new Store(this, this.staged);
+    s.keyPath = this.db.keyPaths.get(name);
+    return s;
+  }
+  maybeCommit() {
+    if (this.finished || this.pending > 0) return;
+    this.finished = true;
+    this.db.stores.set(this.name, this.staged);
+    setTimeout(() => this.oncomplete?.(), 0);
+  }
+  fail(error) {
+    this.error = error;
+    this.abort();
+  }
+  abort() {
+    if (this.finished) throw new DOMException("the transaction has finished", "InvalidStateError");
+    this.finished = true;
+    setTimeout(() => this.onabort?.(), 0);
+  }
+}
+
+class Database {
+  constructor() {
+    this.stores = new Map();
+    this.keyPaths = new Map();
+  }
+  createObjectStore(name, { keyPath }) {
+    this.stores.set(name, new Map());
+    this.keyPaths.set(name, keyPath);
+  }
+  transaction(name) {
+    if (!this.stores.has(name)) throw new DOMException(`no store ${name}`, "NotFoundError");
+    return new Transaction(this, name);
+  }
+}
+
+globalThis.indexedDB = {
+  open(name) {
+    const r = new Request(null);
+    setTimeout(() => {
+      let db = databases.get(name);
+      if (!db) {
+        db = new Database();
+        databases.set(name, db);
+        r.result = db;
+        r.onupgradeneeded?.();
+      }
+      r.result = db;
+      r.onsuccess?.({ target: r });
+    }, 0);
+    return r;
+  },
+};
+
+const host = await import(pathToFileURL(join(here, "../js/host.js")));
+assert.equal(await host.storeOpen("indexeddb"), "indexeddb");
+const stored = (key) => databases.get("effectcraft").stores.get("entries").get(key);
+const bytes = (s) => new TextEncoder().encode(s);
+const text = (row) => row && new TextDecoder().decode(new Uint8Array(row.data));
+
+// A healthy write resolves once committed, and the store has it then.
+await host.storePut("project.json", bytes("v1"), 1);
+assert.equal(text(stored("project.json")), "v1", "a resolved put is committed");
+
+// The put's request succeeds, then the transaction aborts: the put fails, the old value stays.
+fault = "abortAfterSuccess";
+await assert.rejects(host.storePut("project.json", bytes("v2"), 2), { name: "AbortError" }, "an aborted put is reported");
+assert.equal(text(stored("project.json")), "v1", "the aborted put was rolled back");
+
+// The same for a delete: it fails and the entry stays.
+fault = "abortAfterSuccess";
+await assert.rejects(host.storeDelete("project.json"), { name: "AbortError" }, "an aborted delete is reported");
+assert.equal(text(stored("project.json")), "v1", "the aborted delete was rolled back");
+
+// A failed request aborts its transaction with the request's error.
+fault = "requestError";
+await assert.rejects(host.storePut("project.json", bytes("v3"), 3), { name: "ConstraintError" });
+assert.equal(text(stored("project.json")), "v1");
+
+// A request that throws at once (a value that can't be stored) fails the write.
+fault = "throw";
+await assert.rejects(host.storePut("project.json", bytes("v4"), 4), { name: "DataCloneError" });
+assert.equal(text(stored("project.json")), "v1");
+
+// The retry after a failure commits the latest value, and a later delete removes it.
+await host.storePut("project.json", bytes("v5"), 5);
+assert.equal(text(stored("project.json")), "v5");
+await host.storeDelete("project.json");
+assert.equal(stored("project.json"), undefined, "a resolved delete is committed");
+const all = await host.storeLoadAll();
+assert.deepEqual(all, [], "nothing else was written");
+
+await tick();
+console.log("storage: ok");