package main import ( "database/sql" ) func (db *database) cachePersistently(key string, data []byte) error { _, err := db.exec("insert or replace into persistent_cache(key, data, date) values(@key, @data, @date)", sql.Named("key", key), sql.Named("data", data), sql.Named("date", utcNowString())) return err } func (db *database) retrievePersistentCache(key string) (data []byte, err error) { d, err, _ := db.pc.Do(key, func() (interface{}, error) { if row, err := db.queryRow("select data from persistent_cache where key = @key", sql.Named("key", key)); err == sql.ErrNoRows { return nil, nil } else if err != nil { return nil, err } else { err = row.Scan(&data) return data, err } }) if err != nil { return nil, err } return d.([]byte), nil } func (db *database) clearPersistentCache(pattern string) error { _, err := db.exec("delete from persistent_cache where key like @pattern", sql.Named("pattern", pattern)) return err }