Cache the full book counter

lib/database/books.go

@@ -3,6 +3,8 @@ package database
 import (
 	"strings"
 	"time"
+
+	log "github.com/cihub/seelog"
 )
 
 // Book metadata
@@ -84,7 +86,10 @@ func (db *pgDB) getBooks(active bool, query string, length int, start int) (book
 		OrderExpr(order, rankParams...).
 		Offset(start).
 		Limit(length).
-		SelectAndCountEstimate(100)
+		SelectAndCountEstimate(1000)
+	if query == "" && active {
+		num = db.bookCount
+	}
 	return books, num, err
 }
 
@@ -158,6 +163,28 @@ func (db *pgDB) IsBookActive(id string) bool {
 	return active[0]
 }
 
+func (db *pgDB) updateCounter() {
+	var count int
+	err := db.sql.Model(&Book{}).
+		ColumnExpr("count(*)").
+		Where("active = true").
+		Select(&count)
+	if err != nil {
+		log.Error("Error updating count: ", err)
+	} else {
+		db.bookCount = count
+	}
+}
+
+func (db *pgDB) countUpdater() {
+	periodicity := 61 * time.Minute
+
+	for true {
+		db.updateCounter()
+		time.Sleep(periodicity)
+	}
+}
+
 type columnq struct {
 	column string
 	value  string

lib/database/database.go

@@ -31,8 +31,9 @@ const (
 )
 
 type pgDB struct {
-	sql  *pg.DB
+	sql       *pg.DB
-	tags []string
+	tags      []string
+	bookCount int
 }
 
 // Options for the database
@@ -58,8 +59,10 @@ func Init(options Options) (DB, error) {
 	})
 	// TODO: create db
 
-	db := pgDB{sql, []string{}}
+	var db pgDB
+	db.sql = sql
 	go db.tagUpdater()
+	go db.countUpdater()
 
 	return &db, nil
 }