Multiple Client Connection Locks #146
Merged
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
simolus3
reviewed
Mar 19, 2025
There was a problem hiding this comment.
The approach looks good to me.
I think we should also consider at least warning about the same database being opened multiple times alone (without any connect() issues). It wouldn't cause any corruption, but if one database is connected and another one isn't, update hooks wouldn't propagate changes. I think that's what one customer was seeing, so a warning may be appropriate. We can do that later too though.
core/src/commonMain/kotlin/com/powersync/db/PowerSyncDatabaseImpl.kt
Outdated
Show resolved
Hide resolved
core/src/commonMain/kotlin/com/powersync/db/PowerSyncDatabaseImpl.kt
Outdated
Show resolved
Hide resolved
core/src/commonMain/kotlin/com/powersync/db/PowerSyncDatabaseImpl.kt
Outdated
Show resolved
Hide resolved
simolus3
approved these changes
Mar 20, 2025
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Overview
Consumers might accidentally create multiple PowerSync clients for the same SQLite database. Calling
connecton these clients simultaneously could cause the shared SQLiteDB to reach an inconsistent state. Having multiple clients for the same database could also cause issues with watched queries since each database is only aware of changes made by it's own write connection.This PR adds static Mutex locks which prevent multiple clients of the same DB file from being connected at the same time. This also adds an internal mutex which queues multiple reconnect attempts on the same client.
A warning is logged if a PowerSync client tries to connect while the shared lock is held by another PowerSync client. In most cases consumers of this SDK should use this warning to fix multiple client instantiation issues.
Unit tests have been added to ensure the correct connect queueing behaviour. The Hello PowerSync demo has also been updated with buttons for connecting and disconnecting the client.