Improve websocket message coalescing to handle thundering herds better

[bdraco]

Proposed change

When entities are added, we may add them in back-to-back tasks, which may return control to the event loop due to I/O or other suspension. This means that the WebSocket sender would run between each task, and the messages would not be coalesced, resulting in a thundering herd of messages to the browser, which would, in some cases, make the UI unresponsive.

To solve this, we now check if the queue has grown each time we are about to release the sender's future and reschedule the release of the queue for the next iteration of the event loop in the event the queue has grown in size. A safety value of PENDING_MSG_MAX_FORCE_READY is used to make sure we don't coalesce too many messages together to avoid the payload growing too large or the delay in sending becoming more than a few microseconds.

The auth code to delete the current refresh token (which closes the user's connection) expected it would always take one event loop iteration to send the response to deleting all the refresh tokens. Since it may take a few now, that code needed to be adjusted to have a longer delay to ensure the response could be sent before the user's own token was deleted.

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New integration (thank you!)
• New feature (which adds functionality to an existing integration)
• Deprecation (breaking change to happen in the future)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Additional information

• This PR fixes or closes issue: fixes #
• This PR is related to issue:
• Link to documentation pull request:

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• Tests have been added to verify that the new code works.

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[home-assistant]

Hey there @home-assistant/core, mind taking a look at this pull request as it has been labeled with an integration (websocket_api) you are listed as a code owner for? Thanks!

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[home-assistant]

Hey there @home-assistant/core, mind taking a look at this pull request as it has been labeled with an integration (auth) you are listed as a code owner for? Thanks!

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[bdraco]

@coderabbitai review

[coderabbitai]

Walkthrough

The changes introduce a delayed token deletion mechanism in the authentication component to avoid immediate connection closure and enhance the WebSocket API's message handling by managing queue sizes and future releases. Additionally, the tests are updated to reflect these changes, ensuring the new behaviors are correctly validated.

Changes

File	Change Summary
homeassistant/components/auth/__init__.py	Introduced _delete_current_token_soon() function to delete tokens after a delay.
homeassistant/components/websocket_api/const.py	Added PENDING_MSG_MAX_FORCE_READY constant and comments on browser limitations.
homeassistant/components/websocket_api/http.py	Enhanced WebSocketHandler with queue size management and future release handling.
tests/components/auth/test_init.py	Adjusted token deletion delay and added async block till done to ensure task completion.
tests/components/websocket_api/test_http.py	Removed assertion on message type before receiving a message from the websocket client.

Sequence Diagram(s) (Beta)

sequenceDiagram
    participant User
    participant HomeAssistant
    participant AuthComponent
    participant WebSocketAPI

    User->>HomeAssistant: Request Authentication
    HomeAssistant->>AuthComponent: Validate Token
    AuthComponent->>User: Token Validated

    User->>WebSocketAPI: Open WebSocket Connection
    WebSocketAPI->>WebSocketAPI: Manage Queue Size
    WebSocketAPI->>WebSocketAPI: Release Ready Future if Conditions Met

    User->>AuthComponent: Request Token Deletion
    AuthComponent->>AuthComponent: _delete_current_token_soon()
    AuthComponent->>HomeAssistant: Schedule Token Deletion Task (async)
    Note right of AuthComponent: Token deleted after delay

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[bdraco]

Thats a lot better.. I guess we need a fast path for bytes

[bdraco]

I tried doing 5 ms timer, but that increased the latency too much. Call_soon Seems to be the best way, since it balances the desired have low latency with not overloading the system

[bdraco]

The number of writes before

[bdraco]

after

[bdraco]

@coderabbitai review

[bdraco]

I've had the bootstrap test fail a few times today. I fixed it in #118285

[bdraco]

thanks