🐛 Automatically expire idle db connections after one minute

[fabianvf]

Summary by CodeRabbit

• New Features
  • None.
• Bug Fixes
  • None.
• Chores
  • Apply consistent database session settings for new connections: short idle timeouts and an application identifier to reduce lingering sessions, improve resource usage, and enhance stability and observability under load.
• Documentation
  • None.
• Refactor
  • None.
• Tests
  • None.
• Style
  • None.
• Revert
  • None.

[coderabbitai]

Walkthrough

Adds a SQLAlchemy engine connect-event listener to set PostgreSQL session parameters (idle_session_timeout, idle_in_transaction_session_timeout, application_name) on each new connection. No public interfaces changed.

Changes

Cohort / File(s)	Summary
DB connection session settings kai_mcp_solution_server/src/kai_mcp_solution_server/db/dao.py	Introduces an engine.connect event listener to execute SET statements for idle_session_timeout, idle_in_transaction_session_timeout, and application_name on every new PostgreSQL connection. No API surface changes.

Sequence Diagram(s)

sequenceDiagram
    actor App
    participant Engine as SQLAlchemy Engine
    participant PG as PostgreSQL

    App->>Engine: Acquire connection
    activate Engine
    Engine-->>PG: Open connection
    activate PG
    Note right of Engine: on_connect event fires
    Engine->>PG: SET idle_session_timeout = '1min'
    Engine->>PG: SET idle_in_transaction_session_timeout = '1min'
    Engine->>PG: SET application_name = 'kai-solution-server'
    PG-->>Engine: OK
    deactivate PG
    Engine-->>App: Connection ready
    deactivate Engine

    alt Error setting parameters
        PG-->>Engine: Error
        Engine-->>App: Propagate connection error
    end

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Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Poem

I twitch my ears at timeout’s tune,
One minute naps for idle swoon—
Transactions too must not daydream,
Our name declared in server stream.
Hop, set, connect—so clean and clever,
A tidy warren, humming ever. 🐇⏱️

Pre-merge checks and finishing touches

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	You can run @coderabbitai generate docstrings to improve docstring coverage.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title Check	✅ Passed	The title succinctly and accurately summarizes the primary change: automatically expiring idle database connections after one minute. It reflects the code change that configures session idle timeouts and is specific enough for a reviewer scanning the PR to understand the main intent.

✨ Finishing touches

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[JonahSussman]

LGTM

[fabianvf]

/cherry-pick release-0.8

[fabianvf]

/cherrypick release-0.8

[coderabbitai]

Actionable comments posted: 0

🧹 Nitpick comments (1)

kai_mcp_solution_server/src/kai_mcp_solution_server/db/dao.py (1)

143-143: Remove unused parameter to clean up the function signature.

The conn_record parameter is not used in the function. While SQLAlchemy event listeners often have standardized signatures where not all parameters are used, removing unused parameters improves code clarity.

-        def _set_pg_timeouts(dbapi_conn: Any, conn_record: Any) -> None:
+        def _set_pg_timeouts(dbapi_conn: Any, _conn_record: Any) -> None:

Alternatively, if the parameter is truly unnecessary:

-        def _set_pg_timeouts(dbapi_conn: Any, conn_record: Any) -> None:
+        def _set_pg_timeouts(dbapi_conn: Any, *_: Any) -> None:

📜 Review details

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📥 Commits

Reviewing files that changed from the base of the PR and between 8068840 and 210a15f.

📒 Files selected for processing (1)

• kai_mcp_solution_server/src/kai_mcp_solution_server/db/dao.py (1 hunks)

🧰 Additional context used

🪛 Ruff (0.13.1)

kai_mcp_solution_server/src/kai_mcp_solution_server/db/dao.py

143-143: Unused function argument: conn_record

(ARG001)

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🔇 Additional comments (2)

kai_mcp_solution_server/src/kai_mcp_solution_server/db/dao.py (2)

142-148: LGTM! Good connection timeout configuration for PostgreSQL.

The event listener properly sets PostgreSQL session timeouts to prevent idle connections from consuming resources. The 1-minute timeout aligns with the PR objective and will help maintain database health.

---

142-148: Verify PostgreSQL-specific settings don't affect other database types.

The event listener is registered for all non-SQLite databases, but the SQL commands (SET idle_session_timeout, etc.) are PostgreSQL-specific. This could cause errors with MySQL, MariaDB, or other database types.

Run this script to check if the codebase supports multiple database types: