ryanmaclean bop O(N) — keep loops linear
When adding behavior to a per-card loop (dispatcher, merge-gate, reap, status), never introduce per-item syscalls. The loop body should do O(1) memory work per card; all I/O flushes once per iteration.
Approved patterns
1. Collect then flush
let mut events: Vec<Event> = Vec::new();
for card in cards {
process(card); // existing work
events.push(build_event(card)); // O(1) memory, no I/O
}
flush_events(&events); // one write, one POST
2. Opt-in gate
let enabled = lineage::is_enabled(); // check once
for card in cards {
process(card);
if enabled {
events.push(...); // zero work when disabled
}
}
3. Defer to background
let (tx, rx) = mpsc::channel();
std::thread::spawn(move || { for ev in rx { write(ev); } });
for card in cards {
process(card);
let _ = tx.send(build_event(card)); // non-blocking
}
Anti-patterns — reject these in review
| Anti-pattern | Why it's O(2N) | Fix |
|---|---|---|
| File append per card in loop | N extra fsync calls | Collect → flush |
Command::spawn per card |
N fork+exec calls | Batch or defer |
| Serialize JSON per card unconditionally | N allocs when no consumer | Opt-in gate |
| HTTP POST per card | N network round-trips | Batch POST |
| Re-read config file per card | N file reads | Cache at loop top |
Where this applies in bop
run_dispatcher()— processes up tomax_workerscards per iterationrun_merge_gate()— processes all done/ cards per iterationreap_orphans()— scans all running/ cardsprint_state_group()— reads all cards in a state dir forbop statuscmd_doctor()acceptance criteria lint — iterates pending/ cards
COW note
fs::rename is metadata-only on APFS/ext4/btrfs — no bytes copied, COW reflinks preserved. It's already O(1). Don't wrap it in anything that adds O(N) I/O.