Video Decode Worker

app.application.managers.video_decode_worker

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Centralizes video decode worker activation and deactivation per session.

See Also

• VideoDecodeWorker — performs frame decoding
• SessionInitializer — attaches decoding resources to a session

Layer: Application. Context: Coordinates session-scoped lifecycles for application workers and resources.

VideoDecodeWorkerManager

Manages VideoDecodeWorker activation and deactivation on a per-session basis.

Responsibilities

• Activate a session's decode worker (start buffering frames from the current playback position).
• Deactivate a session's decode worker (stop buffering, free memory).

This manager centralises the worker-toggle logic that previously lived inside SessionService._activate_video_decode_worker_for_session_id and SessionService._deactivate_video_decode_worker_for_session_id, giving SessionService a narrower single responsibility.

ValueError exceptions from set_active() are intentionally swallowed here to preserve the original silent-return behaviour: they indicate that the worker is in a transient view_state (e.g. not yet started) where the toggle cannot be applied.

The session repository is injected, so the manager is independently unit-testable without a live Application instance.

PARAMETER	DESCRIPTION
session_repo	Interface used to resolve sessions and coordinate their decode workers. TYPE: UIApplicationInterface

__init__(session_repo: UIApplicationInterface) -> None

activate(s_id: SessionId) -> None

Resume the video decode worker for s_id (start buffering frames).

Seeks to the session's current playback position so the ring buffer is filled with the frames the user is about to see.

PARAMETER	DESCRIPTION
s_id	Session ID of the target session. TYPE: SessionId

Note

Silently returns if the worker raises ValueError (transient worker view_state — mirrors the original SessionService behaviour).

deactivate(s_id: SessionId) -> None

Pause the video decode worker for s_id (stop buffering, free RAM).

Clears the ring buffer immediately to reclaim the memory used by pre-decoded frames.

PARAMETER	DESCRIPTION
s_id	Session ID of the target session. TYPE: SessionId

Note

Silently returns if the worker raises ValueError (transient worker view_state — mirrors the original SessionService behaviour).

switch_active_session(old_s_id: SessionId | None, new_s_id: SessionId) -> None

Perform the canonical old→new active-session decode-worker transition.

Pauses the old session's decode worker (if any) then resumes the new one. The method is a no-op when old_s_id == new_s_id so that callers do not need to guard against redundant switches themselves.

PARAMETER	DESCRIPTION
old_s_id	Previously active session ID, or None on first open. TYPE: SessionId | None
new_s_id	Newly active session ID. TYPE: SessionId

Note

Individual activate / deactivate calls preserve their existing ValueError tolerance semantics.