Struct KeyValue

pkg/sorted/sqlkv/sqlkv.go:35–66

KeyValue implements the sorted.KeyValue interface using an *sql.DB.

// KeyValue implements the sorted.KeyValue interface using an *sql.DB.
type KeyValue struct {
	DB *sql.DB

	// SetFunc is an optional func to use when REPLACE INTO does not exist
	SetFunc      func(*sql.DB, string, string) error
	BatchSetFunc func(*sql.Tx, string, string) error

	// PlaceHolderFunc optionally replaces ? placeholders
	// with the right ones for the rdbms in use.
	PlaceHolderFunc func(string) string

	// Gate optionally limits concurrent access.
	//
	// This originally existed just for SQLite, whose driver likes
	// to return "the database is locked"
	// (perkeep.org/issue/114), so this keeps some pressure
	// off. But we still trust SQLite to deal with concurrency in
	// most cases.
	//
	// It's also used to limit the number of MySQL connections.
	Gate *syncutil.Gate

	// TablePrefix optionally provides a prefix for SQL table
	// names. This is typically "dbname.", ending in a period.
	TablePrefix string

	queriesInitOnce sync.Once // guards initialization of both queries and replacer
	replacer        *strings.Replacer

	queriesMu sync.RWMutex
	queries   map[string]string
}

// sql returns the query, replacing placeholders using PlaceHolderFunc,
// and /*TPRE*/ with TablePrefix.