[webkit-changes] [WebKit/WebKit] e96507: Keep track of LocalStorage size in memory for quot...

[Sihui]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: e9650775a43554b06d3406b3a9a750451fbdc4a5
      https://github.com/WebKit/WebKit/commit/e9650775a43554b06d3406b3a9a750451fbdc4a5
  Author: Sihui Liu <sihui_liu at apple.com>
  Date:   2023-02-07 (Tue, 07 Feb 2023)

  Changed paths:
    M Source/WebKit/NetworkProcess/storage/SQLiteStorageArea.cpp
    M Source/WebKit/NetworkProcess/storage/SQLiteStorageArea.h

  Log Message:
  -----------
  Keep track of LocalStorage size in memory for quota computation
https://bugs.webkit.org/show_bug.cgi?id=251800
rdar://problem/105085248

Reviewed by Chris Dumez.

As stated in 259571 at main, StorageAreaMap in web process performs quota check differently from SQLiteStorageArea in
network process. StorageAreaMap uses item (Strings) size and compares size with quota before write operation, while
SQLiteStorageArea sets size limit of database, and relies on SQLite to perform check of database size on write
operation. Also, SQLiteStorageArea stores item value (String) as blob in database, so characters will be upconverted and
take more space. Because of this difference, the two processes can have different result on quota check. For example,
web process might think a write operation passes quota check and sends request to network process, and network process
thinks it fails quota check.

The problem is SQLiteStorageArea currently tries to batch write operations in transaction for performance and SQLite
could roll back transaction automatically when there is a quota error (see https://www.sqlite.org/lang_transaction.html
and SQLITE_FULL). This means when quota error occurs, we might lose all changes in the same transaction and will need to
read all items from database again (to sync cache in SQLiteStorageArea amd StorageAreaMap), which can be costly and lead
to flakiness in tests like imported/w3c/web-platform-tests/webstorage/storage_local_setitem_quotaexceedederr.window.html.
Therefore, this patch makes makes SQLiteStorageArea perform quota check the same way as StorageAreaMap by keeping track
of items size and use it for quota computation. This will make write request that passes quota check in web process less
likely to fail due to quota error and thus makes transaction less likely to be rolled back.

* Source/WebKit/NetworkProcess/storage/SQLiteStorageArea.cpp:
(WebKit::SQLiteStorageArea::close):
(WebKit::SQLiteStorageArea::prepareDatabase):
(WebKit::SQLiteStorageArea::getItem):
(WebKit::SQLiteStorageArea::allItems):
(WebKit::SQLiteStorageArea::setItem):
(WebKit::SQLiteStorageArea::removeItem):
(WebKit::SQLiteStorageArea::clear):
(WebKit::SQLiteStorageArea::handleDatabaseCorruptionIfNeeded):
(WebKit::SQLiteStorageArea::updateCacheIfNeeded):
(WebKit::SQLiteStorageArea::requestSpace):
* Source/WebKit/NetworkProcess/storage/SQLiteStorageArea.h:

Canonical link: https://commits.webkit.org/259995@main