Remove Old Mutex

[stevensJourney]

Overview

The very first version of the JS SDK used a shared mutex instance for read and write locks. Future versions moved the locking to the DBAdapter interface.

The AbstractPowerSyncDatabase still contained the shared mutex code which was used in the common readLock and writeLock implementations.

Using the same mutex for readLock and writeLock breaks concurrency. The React native SDK had an override for the readLock and writeLock method which avoided this issue. Web only has a single connection, so concurrency wasn't an issue there. The Node.js SDK however would rely on the common implementation and would therefore have some concurrency issues. Luckily the individual get, getAll and getOptional methods go through the DBAdapter and not the readLock API. Currency was only partially broken for the Node.js SDK.

This PR removes the old mutex entirely.

[changeset-bot]

🦋 Changeset detected

Latest commit: 88fbaf8

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 7 packages

Name	Type
@powersync/node	Patch
@powersync/common	Patch
@powersync/op-sqlite	Patch
@powersync/react-native	Patch
@powersync/tanstack-react-query	Patch
@powersync/web	Patch
@powersync/diagnostics-app	Patch

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[rkistner]

What was affected by this?

[stevensJourney]

The only affect I can think of is in the Node.js SDK: calls to readLock and writeLock would be wrapped in a shared mutex. Calling readLock in a writeLock and vice-versa would hang. Calls would also be executed sequentially.