AdguardTeam / AdguardTeam/ContentBlocker

updateFilterEnabled() performs synchronous SQLite writes on the UI thread, causing UI freezes

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Description

**Description:**
The `updateFilterEnabled()` method is invoked directly inside a View `FilterViewAdapter.onClick()` callback, which always runs on the main (UI) thread. However, this method performs **synchronous SQLite write operations**, including:

* `db.beginTransaction()`
* `db.update(...)`
* `db.setTransactionSuccessful()`
* `db.endTransaction()`

These calls involve **disk I/O**, **database locking**, and **fsync operations**, all executed synchronously.
Executing them on the main thread can lead to noticeable UI jank or freezes, especially on:

* devices with slower storage
* devices under heavy I/O load
* large or fragmented database files

Because this logic is triggered inside a click handler, the UI freeze is visible as delayed button response or stuttering.

Additionally, `ApplyAndRefreshTask` is executed **after** the blocking database operations have already completed, so it does **not** prevent the UI thread from stalling.

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### **Why this is a problem**

Android documentation explicitly warns:

> Do not access SQLiteDatabase on the main thread.
> Disk I/O can block the UI thread and cause ANRs.

This implementation violates that guideline and introduces potential jank every time a filter is enabled/disabled.

---

### **Suggested Fix**

Move the database write operation off the UI thread. After the write completes, post back to the UI thread to update the checkbox state.

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