config

type Algorithm uint8

type BalancerConfig struct {
	// Algorithm define balancing algorithm
	Algorithm Algorithm

	// PreferLocal adds endpoint selection logic when local endpoints
	// are always used first.
	// When no alive local endpoints left other endpoints will be used.
	//
	// NOTE: some balancing methods (such as p2c) also may use knowledge of
	// endpoint's locality. Difference is that with PreferLocal local
	// endpoints selected separately from others. That is, if there at least
	// one local endpoint it will be used regardless of its performance
	// indicators.
	//
	// NOTE: currently driver (and even ydb itself) does not track load factor
	// of each endpoint properly. Enabling this Option may lead to the
	// situation, when all but one nodes in local datacenter become inactive
	// and all clients will overload this single instance very quickly. That
	// is, currently this Option may be called as experimental.
	// You have been warned.
	PreferLocal bool
}

type Config interface {
	// Endpoint is a required starting endpoint for connect
	Endpoint() string

	// Database is a required database name.
	Database() string

	// Secure() is an flag for secure connection
	Secure() bool

	// Credentials is an ydb client credentials.
	// In most cases Credentials are required.
	Credentials() credentials.Credentials

	// Trace contains driver tracing options.
	Trace() trace.Driver

	// RequestTimeout is the maximum amount of time a Call() will wait for an
	// operation to complete.
	// If RequestTimeout is zero then no timeout is used.
	RequestTimeout() time.Duration

	// StreamTimeout is the maximum amount of time a StreamRead() will wait for
	// an operation to complete.
	// If StreamTimeout is zero then no timeout is used.
	StreamTimeout() time.Duration

	// OperationTimeout is the maximum amount of time a YDB server will process
	// an operation. After timeout exceeds YDB will try to cancel operation and
	// regardless of the cancellation appropriate error will be returned to
	// the client.
	// If OperationTimeout is zero then no timeout is used.
	OperationTimeout() time.Duration

	// OperationCancelAfter is the maximum amount of time a YDB server will process an
	// operation. After timeout exceeds YDB will try to cancel operation and if
	// it succeeds appropriate error will be returned to the client; otherwise
	// processing will be continued.
	// If OperationCancelAfter is zero then no timeout is used.
	OperationCancelAfter() time.Duration

	// DiscoveryInterval is the frequency of background tasks of ydb endpoints
	// discovery.
	// If DiscoveryInterval is zero then the DefaultDiscoveryInterval is used.
	// If DiscoveryInterval is negative, then no background discovery prepared.
	DiscoveryInterval() time.Duration

	// GrpcConnectionPolicy define lifecycle behavior of grpc connection
	// By default GrpcConnectionPolicy is sets to DefaultGrpcConnectionPolicy
	GrpcConnectionPolicy() GrpcConnectionPolicy

	// BalancingConfig is an optional configuration related to selected
	// BalancingMethod. That is, some balancing methods allow to be configured.
	BalancingConfig() BalancerConfig

	// RequestsType set an additional types hint to all requests.
	// It is needed only for debug purposes and advanced cases.
	RequestsType() string

	// FastDial will make dialer return Driver as soon as 1st connection succeeds.
	// NB: it may be not the fastest node to serve requests.
	FastDial() bool

	// DialTimeout is the maximum amount of time a dial will wait for a connect to
	// complete.
	// If DialTimeout is zero then no timeout is used.
	DialTimeout() time.Duration

	// TLSConfig specifies the TLS configuration to use for tls client.
	// If TLSConfig is zero then connections are insecure.
	TLSConfig() *tls.Config

	// NetDial is an optional function that may replace default network dialing
	// function such as net.Dial("tcp").
	NetDial() func(context.Context, string) (net.Conn, error)
}

type GrpcConnectionPolicy struct {
	keepalive.ClientParameters

	// TTL is a duration for automatically close idle connections
	// Zero TTL will disable automatically closing of idle connections
	// By default TTL is sets to DefaultGrpcConnectionTTL
	TTL time.Duration
}

type Option func(c *config)