[juliasilge]

The first step toward #16709!

With Data Connections enabled (the default since #16288), Positron disconnects the database connections that R and Python code opens. This PR stops that:

It does not yet show these connections in the Data Connections pane but I'll do an additional PR to add them there.

Cause

PositronConnectionsService closed every connection comm when it arrived, because the old Connections pane is not registered when Data Connections is on. A close from the frontend runs the disconnect function of the connection itself in the kernel:

1. client.dispose() sends comm_close to the kernel.
2. In R, Ark receives the close and calls .ps.connection_close(id), which calls con$disconnect().
3. In Python, _on_comm_close calls _close_connection, which closes the object (for example, sqlite3 calls conn.close()).

As a result, a connection from connections::connection_open() (or from an odbc connection in R) was not valid after the next call. In Python, %connection_show con closed con.

Change

• PositronConnectionsService now keeps comms whose metadata language_id is r or python open, until the runtime closes them or the session ends. It closes all other comms as before (for example, ggsql comms).
• The service still records the code of each comm for getSessionConnectionCode; that behavior does not change.
• A comm that is open at startup can time out before it sends its metadata. Ark answers get_metadata only when R is idle, so a window reload during a long computation could cause this. Such a comm now takes the language of its session. The same rule applies when the metadata request fails. Before, the service closed these comms, and R then disconnected the user's object when it became idle.
• With Data Connections off, the old Connections pane path does not change.

Release Notes

New Features

• N/A

Bug Fixes

• With Data Connections enabled, R and Python database connections stay open (Connections opened from R code no longer appear after Data Connections became the default #16709)

Validation Steps

@:connections

Unit tests are in positronConnectionsService.vitest.ts and runtimeDataConnections.vitest.ts.

To test this out manually, use a build with Data Connections enabled (the default).

R (needs the connections and RSQLite packages):

con <- connections::connection_open(RSQLite::SQLite(), tempfile())

Check that you have a con object and then run:

DBI::dbIsValid(con@con)

The result is now TRUE. Before this fix, it is FALSE. (connection_open() returns a wrapper, so the DBI connection is in its con slot.)

Python:

import sqlite3
con = sqlite3.connect(":memory:")

%connection_show con

Then run:

con.execute("select 1").fetchone()

The result is (1,). Before this fix, Python shows sqlite3.ProgrammingError: Cannot operate on a closed database.

[github-actions]

E2E Tests 🚀
This PR will run tests tagged with: @:critical @:connections

Why these tags?

Tag	Source
@:critical	Always runs (required)
@:connections	PR description

More on automatic tags from changed files.

Test count: Linux: 100 tests.

^{readme  valid tags}