factor db creation to its own package

cmd/gonic/main.go

@@ -2,14 +2,13 @@ package main
 
 import (
 	"flag"
-	"fmt"
 	"log"
 	"os"
 
-	"github.com/jinzhu/gorm"
 	_ "github.com/jinzhu/gorm/dialects/sqlite"
 	"github.com/peterbourgon/ff"
 
+	"github.com/sentriz/gonic/db"
 	"github.com/sentriz/gonic/server"
 )
 
@@ -43,10 +42,7 @@ func main() {
 	if _, err := os.Stat(*musicPath); os.IsNotExist(err) {
 		log.Fatal("please provide a valid music directory")
 	}
-	db, err := gorm.Open("sqlite3", fmt.Sprintf(
-		"%s?cache=shared&_busy_timeout=%d",
-		*dbPath, 2000,
-	))
+	db, err := db.New(*dbPath)
 	if err != nil {
 		log.Fatalf("error opening database: %v\n", err)
 	}

cmd/gonicscan/main.go

@@ -2,14 +2,13 @@ package main
 
 import (
 	"flag"
-	"fmt"
 	"log"
 	"os"
 
-	"github.com/jinzhu/gorm"
 	_ "github.com/jinzhu/gorm/dialects/sqlite"
 	"github.com/peterbourgon/ff"
 
+	"github.com/sentriz/gonic/db"
 	"github.com/sentriz/gonic/scanner"
 )
 
@@ -29,14 +28,10 @@ func main() {
 	if _, err := os.Stat(*musicPath); os.IsNotExist(err) {
 		log.Fatal("please provide a valid music directory")
 	}
-	db, err := gorm.Open("sqlite3", fmt.Sprintf(
-		"%s?cache=shared&_busy_timeout=%d",
-		*dbPath, 2000,
-	))
+	db, err := db.New(*dbPath)
 	if err != nil {
 		log.Fatalf("error opening database: %v\n", err)
 	}
-	db.SetLogger(log.New(os.Stdout, "gorm ", 0))
 	s := scanner.New(
 		db,
 		*musicPath,

db/db.go

@@ -0,0 +1,34 @@
+package db
+
+import (
+	"fmt"
+	"log"
+	"net/url"
+	"os"
+
+	"github.com/jinzhu/gorm"
+	"github.com/pkg/errors"
+)
+
+var (
+	dbMaxOpenConns = 1
+	dbOptions      = url.Values{
+		// with this, multiple connections share a single data and schema cache.
+		// see https://www.sqlite.org/sharedcache.html
+		"cache": []string{"shared"},
+		// with this, the db sleeps for a little while when locked. can prevent
+		// a SQLITE_BUSY. see https://www.sqlite.org/c3ref/busy_timeout.html
+		"_busy_timeout": []string{"30000"},
+	}
+)
+
+func New(path string) (*gorm.DB, error) {
+	pathAndArgs := fmt.Sprintf("%s?%s", path, dbOptions.Encode())
+	db, err := gorm.Open("sqlite3", pathAndArgs)
+	if err != nil {
+		return nil, errors.Wrap(err, "with gorm")
+	}
+	db.DB().SetMaxOpenConns(dbMaxOpenConns)
+	db.SetLogger(log.New(os.Stdout, "gorm ", 0))
+	return db, nil
+}