refactoring

cmd/db.go

@@ -0,0 +1,69 @@
+package cmd
+
+import (
+	"context"
+	"database/sql"
+	"time"
+
+	_ "modernc.org/sqlite"
+)
+
+type DB struct {
+	*sql.DB
+}
+
+type Cache DB
+
+var cacheAddr = "/tmp/turbomaps-er.db"
+
+func NewCache(ctx context.Context) Cache {
+	ctx, can := context.WithTimeout(ctx, 5*time.Second)
+	defer can()
+
+	db, err := sql.Open("sqlite", cacheAddr)
+	if err != nil {
+		panic(err)
+	}
+
+	if err := db.PingContext(ctx); err != nil {
+		panic(err)
+	}
+
+	return Cache(DB{DB: db})
+}
+
+func (db Cache) Get(ctx context.Context, k string) ([]byte, error) {
+	if err := db.init(ctx); err != nil {
+		return nil, err
+	}
+
+	row := db.QueryRowContext(ctx, `
+		SELECT v FROM cache WHERE k=$1
+	`, k)
+
+	var v []byte
+	if err := row.Scan(&v); err != nil {
+		return nil, err
+	}
+
+	return v, row.Err()
+}
+
+func (db Cache) Set(ctx context.Context, k string, v []byte) error {
+	if err := db.init(ctx); err != nil {
+		return err
+	}
+
+	_, err := db.ExecContext(ctx, `
+		INSERT INTO cache (k, v) VALUES ($1, $2)
+		ON CONFLICT DO UPDATE SET v=$2 WHERE k=$1
+	`, k, v)
+	return err
+}
+
+func (db Cache) init(ctx context.Context) error {
+	_, err := db.ExecContext(ctx, `
+		CREATE TABLE IF NOT EXISTS cache(k TEXT PRIMARY KEY, v TEXT)
+	`)
+	return err
+}