Day 091 — Week 1 Review + Recall

Month 4 · Week 1 · ⬅ Day 090 · Day 092 ➡ · Journal index

🎯 Learning Objective

Consolidate Week 1 (net/http, routing, middleware, JSON, server lifecycle) with closed-book recall, then capture lessons in the weekly review.

📚 Topics

• Spaced recall across Days 085–090
• Gaps to carry into Week 2 (databases)

📖 Reading / Sources

• Re-read my own Days 085–090 notes (closed-book first)
• net/http overview — skim to confirm recall

📝 Notes

• The whole stack rests on one interface, http.Handler, with HandlerFunc as the function adapter → [[http-handler]].
• Go 1.22's ServeMux does method + wildcard routing and auto 404/405; chi adds nested routers and groups when the tree grows → [[router-choice]].
• Middleware = func(http.Handler) http.Handler; Chain composes outermost-first; Recoverer goes near the top → [[panic-recover]].
• JSON helpers: header before WriteHeader, DisallowUnknownFields, MaxBytesReader, map decode errors to status codes → [[error-wrapping]].
• Lifecycle: server timeouts + Shutdown(ctx); ErrServerClosed is success → [[http-timeouts]] / [[context]].

🏋️ Exercises / Practice

Exercise	Status	Link
All Week 1 exercises green (go test ./...)	✅	exercises/month-04/week-1

Full write-up, re-quiz, and metrics: week-1-review.md

🐛 Mistakes Made

• On recall I blanked on the exact Chain loop direction — re-derived it from the "outermost-first" rule rather than memorising the index math.

❓ Open Questions

• How much of this stays the same once a real database and database/sql enter the picture next week? (The handler/JSON/middleware layers shouldn't change.)

🧠 Active Recall (answer without looking)

1. Q: Which status does the stdlib mux send for a known path hit with an unregistered method?

A

`405 Method Not Allowed`, with an `Allow` header listing the registered methods.

1. Q: How should a handler treat http.ErrServerClosed from ListenAndServe?

A

As the expected success signal after `Shutdown` — match it with `errors.Is` and ignore it.

🪶 Feynman Reflection

A Go web service is layers around one interface: route to a handler, wrap it in middleware, decode/encode JSON at the edges, and manage the server's life with timeouts and graceful shutdown. Almost none of it needs a framework.

🕳️ Knowledge Gaps

• Forwarding optional ResponseWriter interfaces (Flusher/Hijacker) through wrappers — carry into a later streaming day.

✅ Summary

Week 1 is solid: I can build, route, wrap, and gracefully run a stdlib HTTP service, and I've logged the fuzzy spots for spaced repetition.

⏭️ Next Steps / Prep for Tomorrow

• Day 092: database/sql — connections, queries, and the standard DB API.

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Time spent	Difficulty	Confidence
75 min	🟦⬜⬜⬜⬜	🟦🟦🟦🟦⬜

Suggested commit: docs(journal): month 4 week 1 review + recall (day 091)