From 9fccd5f81db046a83e0e3f450c10457d54522890 Mon Sep 17 00:00:00 2001
From: jordi fita mas <jordi@tandem.blog>
Date: Wed, 26 Jul 2023 00:48:58 +0200
Subject: [PATCH] Acquire the database connection in App.ServeHTTP with cookie
 set

Almost all request will need the database connection, either because
they will perform queries or because they need to check if the user is
logged in, for instance, so it should be acquired as far above as
possible to avoid acquiring multiple connections.

This is specially true since i have to pass the cookie to the database
to switch role and set request.user.email and request.user.cookie
config variables.  I do not want to do that many times per request.
---
 pkg/app/app.go     | 42 +++++++++++++++++++++++++-----------------
 pkg/app/login.go   | 11 +++++++++--
 pkg/database/db.go |  5 ++++-
 3 files changed, 38 insertions(+), 20 deletions(-)

diff --git a/pkg/app/app.go b/pkg/app/app.go
index c80b0b2..f5915f7 100644
--- a/pkg/app/app.go
+++ b/pkg/app/app.go
@@ -57,24 +57,32 @@ func New(db *database.DB) http.Handler {
 func (h *App) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	var head string
 	head, r.URL.Path = shiftPath(r.URL.Path)
-	switch head {
-	case "static":
+	if head == "static" {
 		h.fileHandler.ServeHTTP(w, r)
-	case "login":
-		switch r.Method {
-		case http.MethodPost:
-			h.handleLogin(w, r)
-		default:
-			methodNotAllowed(w, r, http.MethodPost)
+	} else {
+		cookie := getSessionCookie(r)
+		conn := h.db.MustAcquire(r.Context(), cookie)
+		defer conn.Release()
+
+		if head == "login" {
+			switch r.Method {
+			case http.MethodPost:
+				h.handleLogin(w, r, conn)
+			default:
+				methodNotAllowed(w, r, http.MethodPost)
+			}
+		} else {
+			switch head {
+			case "":
+				switch r.Method {
+				case http.MethodGet:
+					h.handleGet(w, r)
+				default:
+					methodNotAllowed(w, r, http.MethodGet)
+				}
+			default:
+				http.NotFound(w, r)
+			}
 		}
-	case "":
-		switch r.Method {
-		case http.MethodGet:
-			h.handleGet(w, r)
-		default:
-			methodNotAllowed(w, r, http.MethodGet)
-		}
-	default:
-		http.NotFound(w, r)
 	}
 }
diff --git a/pkg/app/login.go b/pkg/app/login.go
index 3f24ea5..9646ceb 100644
--- a/pkg/app/login.go
+++ b/pkg/app/login.go
@@ -10,6 +10,7 @@ import (
 	"net/http"
 	"time"
 
+	"dev.tandem.ws/tandem/camper/pkg/database"
 	"dev.tandem.ws/tandem/camper/pkg/form"
 	httplib "dev.tandem.ws/tandem/camper/pkg/http"
 	"dev.tandem.ws/tandem/camper/pkg/locale"
@@ -65,7 +66,7 @@ func (h *App) matchLocale(r *http.Request) *locale.Locale {
 	return locale.Match(r, h.locales, h.defaultLocale, h.languageMatcher)
 }
 
-func (h *App) handleLogin(w http.ResponseWriter, r *http.Request) {
+func (h *App) handleLogin(w http.ResponseWriter, r *http.Request, conn *database.Conn) {
 	login := newLoginForm()
 	if err := login.Parse(r); err != nil {
 		http.Error(w, err.Error(), http.StatusBadRequest)
@@ -73,7 +74,6 @@ func (h *App) handleLogin(w http.ResponseWriter, r *http.Request) {
 	}
 	l := h.matchLocale(r)
 	if login.Valid(l) {
-		conn := h.db.MustAcquire(r.Context())
 		cookie := conn.MustGetText(r.Context(), "select login($1, $2, $3)", login.Email, login.Password, httplib.RemoteAddr(r))
 		if cookie != "" {
 			setSessionCookie(w, cookie)
@@ -92,6 +92,13 @@ func setSessionCookie(w http.ResponseWriter, cookie string) {
 	http.SetCookie(w, createSessionCookie(cookie, 8766*24*time.Hour))
 }
 
+func getSessionCookie(r *http.Request) string {
+	if cookie, err := r.Cookie(sessionCookie); err == nil {
+		return cookie.Value
+	}
+	return ""
+}
+
 func createSessionCookie(value string, duration time.Duration) *http.Cookie {
 	return &http.Cookie{
 		Name:     sessionCookie,
diff --git a/pkg/database/db.go b/pkg/database/db.go
index 3f8fe25..14e8d8a 100644
--- a/pkg/database/db.go
+++ b/pkg/database/db.go
@@ -53,11 +53,14 @@ func (db *DB) Acquire(ctx context.Context) (*Conn, error) {
 	return &Conn{conn}, nil
 }
 
-func (db *DB) MustAcquire(ctx context.Context) *Conn {
+func (db *DB) MustAcquire(ctx context.Context, cookie string) *Conn {
 	conn, err := db.Acquire(ctx)
 	if err != nil {
 		panic(err)
 	}
+	if _, err = conn.Exec(ctx, "select set_cookie($1)", cookie); err != nil {
+		panic(false)
+	}
 	return conn
 }