boxmaker/docs/plans/M4b/14-gatewayd-serve-approvals.md

M4b task 14: the serve loop posts approvals and marks them

Branch: m4b (run git switch m4b; git status --short must be empty, otherwise stop) Commit subject: gatewayd: serve, posting approvals, marking them, and the listener

Goal

The serve loop does what gateway.sock connections ask (M4b spec, sections 6 and 8):

• Show: place the approval (its session's turn in flight: that thread; otherwise the first approver's direct messages, as a new thread), post its parts in order, record the posts in the state file, register it for answers (task 11), and reply with the post ids, or why it could not be posted.
• Ended: forget it, and add how it ended to its last post, naming who answered.
• At the first connection after a start, the approval posts the last run left behind are marked: their last post is replaced by its title and the restart line.
• run opens gateway.sock before connecting; a failure stops gatewayd at start (Stop::Start, pointer gatewayd-start-failed).

Files

• Copy: the skeleton crates/gatewayd/src/serve/approvals.rs, crates/gatewayd/tests/serve_approvals.rs, crates/gatewayd/tests/support/brokerd_client.rs, and a new version of the given crates/gatewayd/tests/support/fake_mm.rs (it gains post edits, user names, and refusing posts)
• Modify: crates/gatewayd/src/serve/mod.rs, docs/implementer-log.md

The skeleton

Written: Open, gateway_requests (drain the channel, never blocking) and show (read both first). To fill, each with its steps in its comment: place, ended, mark_left_behind, mark.

serve/mod.rs, exactly

1. mod approvals; before mod handle;. Imports: use std::collections::HashMap;, use crate::approvals::Registry;, use crate::gateway::{self, ToLoop};.
2. Three fields at the end of struct Gateway:

    /// The approvals posted here, shared with the turns (for the notice) and judged by commands.
    registry: Arc<Registry>,
    /// What `gateway.sock` connections ask of the loop.
    gateway_rx: Receiver<ToLoop>,
    /// The last post of each approval posted here and not yet ended.
    open: HashMap<u64, approvals::Open>,

3. Gateway::new gains a last parameter gateway_rx: Receiver<ToLoop>, and sets registry: Arc::new(Registry::new()), gateway_rx, open: HashMap::new(),.
4. In run, right before let client = Arc::new(Client::new(…));:

    let listener = match gateway::listen(&config.gateway_socket()) {
        Ok(listener) => listener,
        Err(why) => return Stop::Start(why),
    };
    let (gateway_tx, gateway_rx) = mpsc::channel();
    if let Err(e) = gateway::serve(
        listener,
        gateway_tx,
        gateway::Timing::default(),
        Arc::clone(&log),
    ) {
        return Stop::Start(format!("cannot start the gateway.sock thread: {e}"));
    }

and Gateway::new(config, client, state, log) becomes Gateway::new(config, client, state, log, gateway_rx). 5. In connected, inside if !self.restarted { … }, after the take_in_flight loop: self.mark_left_behind()?; 6. In event_loop, after self.finished()?;: self.gateway_requests()?;

Steps

• 1. Copy. git switch m4b, then cp docs/plans/M4b/files/crates/gatewayd/src/serve/approvals.rs crates/gatewayd/src/serve/ && cp docs/plans/M4b/files/crates/gatewayd/tests/serve_approvals.rs crates/gatewayd/tests/ && cp docs/plans/M4b/files/crates/gatewayd/tests/support/brokerd_client.rs docs/plans/M4b/files/crates/gatewayd/tests/support/fake_mm.rs crates/gatewayd/tests/support/
• 2. Make the six serve/mod.rs changes. cargo build -p gatewayd must succeed.
• 3. See it fail. cargo test -p gatewayd --test serve_approvals. Expected: 4 fail, 1 passes (the socket is there while gatewayd runs).
• 4. Fill mark, place, ended, mark_left_behind, cargo check -p gatewayd after each.
• 5. See it pass. cargo test -p gatewayd --test serve_approvals, three times: 5 passed. Then cargo test -p gatewayd: every suite passes.
• 6. Run the gate. cargo fmt --all, then make gate. Expected last line: gate: ok.
• 7. Log and commit. git add crates/gatewayd docs/implementer-log.md Cargo.lock && git commit

Done when

• cargo test -p gatewayd passes; make gate prints gate: ok.

Stop and report if

• A comment above a todo!() does not fit its function, or contradicts a test: quote it.
• show or gateway_requests seems to need a change: they are given.