Implement file based caching

1 files changed, 60 insertions, 0 deletions

diff --git a/modules/cache/sqlitestore.go b/modules/cache/sqlitestore.go
new file mode 100644
index 0000000..50c8007
--- /dev/null
+++ b/modules/cache/sqlitestore.go
@@ -0,0 +1,60 @@
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+package cache
+
+import (
+	"database/sql"
+	"fmt"
+	"log"
+	"os"
+
+	_ "github.com/mattn/go-sqlite3"
+)
+
+func NewSQLiteStore(file string) *SQLiteStore {
+	db, err := sql.Open("sqlite3", fmt.Sprintf("file:%s?_timeout=5000&_journal=WAL", file))
+	if err != nil {
+		log.Printf("cache: failed to create database file %q: %v\n", file, err)
+		os.Exit(1)
+	}
+
+	c := &SQLiteStore{db: db}
+	c.migrate()
+
+	return c
+}
+
+type SQLiteStore struct {
+	db *sql.DB
+}
+
+func (s *SQLiteStore) Get(key string) ([]byte, bool) {
+	var value []byte
+	if err := s.db.QueryRow(`SELECT value FROM cache WHERE key = ? LIMIT 1`, key).Scan(&value); err != nil {
+		return nil, false
+	}
+	return value, true
+}
+
+func (s *SQLiteStore) Set(key string, value []byte) {
+	if _, err := s.db.Exec(`INSERT INTO cache (key, value) VALUES (?, ?)`, key, value); err != nil {
+		log.Printf("cache: failed to insert cache key %q: %v\n", key, value)
+	}
+}
+
+func (s *SQLiteStore) Close() {
+	s.db.Close()
+}
+
+func (s *SQLiteStore) migrate() {
+	if _, err := s.db.Exec(`CREATE TABLE IF NOT EXISTS cache (key TEXT, value BLOB)`); err != nil {
+		log.Printf("cache: failed to create cache table: %v\n", err)
+		os.Exit(1)
+	}
+	if _, err := s.db.Exec(`CREATE UNIQUE INDEX IF NOT EXISTS cache_key_idx ON cache(key)`); err != nil {
+		log.Printf("cache: failed to create cache index: %v\n", err)
+		os.Exit(1)
+	}
+}