Increase database timeout and add logging to /api/v2/update

This is a stop-gap measure to help with issue #154 until a more scalable
solution is designed. The logging in /api/v2/update times how long it
takes to fetch the preload list from Chromium and how long it takes to
load preloaded domains from the database. The latter currently takes
around 15 seconds for approximately 50,000 entries.

api/update.go

@@ -3,6 +3,7 @@ package api
 import (
 	"fmt"
 	"net/http"
+	"time"
 
 	"github.com/chromium/hstspreload.org/database"
 	"github.com/chromium/hstspreload/chromium/preloadlist"
@@ -31,7 +32,9 @@ func (api API) Update(w http.ResponseWriter, r *http.Request) {
 	// In order to allow visiting the URL directly in the browser, we allow any method.
 
 	// Get preload list.
+	preloadListFetchStart := time.Now()
 	preloadList, listErr := api.preloadlist.NewFromLatest()
+	preloadListFetchDuration := time.Since(preloadListFetchStart)
 	if listErr != nil {
 		msg := fmt.Sprintf(
 			"Internal error: could not retrieve latest preload list. (%s)\n",
@@ -48,7 +51,9 @@ func (api API) Update(w http.ResponseWriter, r *http.Request) {
 	}
 
 	// Get domains currently recorded as preloaded.
+	preloadedDomainsFetchStart := time.Now()
 	preloadedDomains, dbErr := api.database.StatesWithStatus(database.StatusPreloaded)
+	preloadedDomainsFetchDuration := time.Since(preloadedDomainsFetchStart)
 	if dbErr != nil {
 		msg := fmt.Sprintf(
 			"Internal error: could not retrieve domain names previously marked as preloaded. (%s)\n",
@@ -120,6 +125,8 @@ func (api API) Update(w http.ResponseWriter, r *http.Request) {
 		len(removed),
 		len(selfRejected),
 	)
+	fmt.Fprintf(w, "Time spent fetching preload list: %s\n", preloadListFetchDuration)
+	fmt.Fprintf(w, "Time spent loading domains from database: %s\n", preloadedDomainsFetchDuration)
 
 	// Create log function to show progress.
 	written := false

database/database.go

@@ -14,7 +14,7 @@ const (
 	prodProjectID  = "hstspreload"
 
 	batchSize = 450
-	timeout   = 10 * time.Second
+	timeout   = 30 * time.Second
 
 	domainStateKind = "DomainState"
 )