Bug 222746 – IDBTransaction is closed prematurely if a microtask is awaited after opening the transaction under some circumstances

• Component: WebCore Misc.
• Status: RESOLVED DUPLICATE

[Bruno Windels]

Created attachment 422245 [details]
a small test case reproducing the problem

I'm encountering an issue with IndexedDB which I can reproduce on several webkit based browsers (Safari on iOS 13.4, Safari TP 121 on macOS 10.15, and WebKitGTK 2.30.5 on Linux).
The issue is that under some circumstances, an IDBTransaction can get closed if you wait a single microtask (e.g. await Promise.resolve()) to queue your first IDBRequest (as opposed to a macrotask, which is expected).

In the web app where I encountered the issue, it happens easily if I have optional async code path after opening a transaction (async because they use indexeddb, no other macro tasks).

I've attached a test case that reproduces the problem, where scheduling a macro task in between two transactions seems to trigger the bug.
I have reduced it as much as possible, so every step is essential to reproduce the problem AFAIK.

[Chris Dumez]

The IDBTransaction constructor uses this:
 vm.whenIdle([protectedThis = makeRef(*this)]() {
            protectedThis->deactivate();
        });

It seems our lambda is getting called prematurely here because the JS is using await on a setTimeout.

[Sihui Liu]

Seem the same as https://bugs.webkit.org/show_bug.cgi?id=216769

[Chris Dumez]

Interesting part of the repro case:
```
            try {
                const db = await openDatabase(dbName, db => {
                    db.createObjectStore("test", {keyPath: "key"});
                }, 1);
                const readTxn = db.transaction(["test"], "readonly");
                await reqAsPromise(readTxn.objectStore("test").get("somekey"));
                // schedule a macro task in between the two txns
                await new Promise(r => setTimeout(r, 0));
                const writeTxn = db.transaction(["test"], "readwrite");
                await Promise.resolve();
                writeTxn.objectStore("test").add({key: "somekey", value: "foo"});
                await txnAsPromise(writeTxn);
            } catch (err) {
                if (err.name === "TransactionInactiveError") {
                    return true; // BUG
                }
```

So it looks like whenIdle called our lambda before the call to:
writeTxn.objectStore("test").add()

Calling our lambda deactivated the writeTxn, which is why we reject the promise with a TransactionInactiveError.

[Radar WebKit Bug Importer]

<rdar://problem/75320436>

[Sihui Liu]

*** This bug has been marked as a duplicate of bug 216769 ***