cluster.go

// Copyright (c) 2012 The gocql Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package gocql

import (
	"context"
	"crypto/tls"
	"crypto/x509"
	"errors"
	"fmt"
	"io/ioutil"
	"net"
	"sync/atomic"
	"time"
)

const defaultDriverName = "ScyllaDB GoCQL Driver"

// PoolConfig configures the connection pool used by the driver, it defaults to
// using a round-robin host selection policy and a round-robin connection selection
// policy for each host.
type PoolConfig struct {
	// HostSelectionPolicy sets the policy for selecting which host to use for a
	// given query (default: RoundRobinHostPolicy())
	// It is not supported to use a single HostSelectionPolicy in multiple sessions
	// (even if you close the old session before using in a new session).
	HostSelectionPolicy HostSelectionPolicy
}

func (p PoolConfig) buildPool(session *Session) *policyConnPool {
	return newPolicyConnPool(session)
}

// ClusterConfig is a struct to configure the default cluster implementation
// of gocql. It has a variety of attributes that can be used to modify the
// behavior to fit the most common use cases. Applications that require a
// different setup must implement their own cluster.
type ClusterConfig struct {
	// addresses for the initial connections. It is recommended to use the value set in
	// the Cassandra config for broadcast_address or listen_address, an IP address not
	// a domain name. This is because events from Cassandra will use the configured IP
	// address, which is used to index connected hosts. If the domain name specified
	// resolves to more than 1 IP address then the driver may connect multiple times to
	// the same host, and will not mark the node being down or up from events.
	Hosts []string

	// CQL version (default: 3.0.0)
	CQLVersion string

	// ProtoVersion sets the version of the native protocol to use, this will
	// enable features in the driver for specific protocol versions, generally this
	// should be set to a known version (2,3,4) for the cluster being connected to.
	//
	// If it is 0 or unset (the default) then the driver will attempt to discover the
	// highest supported protocol for the cluster. In clusters with nodes of different
	// versions the protocol selected is not defined (ie, it can be any of the supported in the cluster)
	ProtoVersion int

	// Timeout limits the time spent on the client side while executing a query.
	// Specifically, query or batch execution will return an error if the client does not receive a response
	// from the server within the Timeout period.
	// Timeout is also used to configure the read timeout on the underlying network connection.
	// Client Timeout should always be higher than the request timeouts configured on the server,
	// so that retries don't overload the server.
	// Timeout has a default value of 11 seconds, which is higher than default server timeout for most query types.
	// Timeout is not applied to requests during initial connection setup, see ConnectTimeout.
	Timeout time.Duration

	// ConnectTimeout limits the time spent during connection setup.
	// During initial connection setup, internal queries, AUTH requests will return an error if the client
	// does not receive a response within the ConnectTimeout period.
	// ConnectTimeout is applied to the connection setup queries independently.
	// ConnectTimeout also limits the duration of dialing a new TCP connection
	// in case there is no Dialer nor HostDialer configured.
	// ConnectTimeout has a default value of 11 seconds.
	ConnectTimeout time.Duration

	// WriteTimeout limits the time the driver waits to write a request to a network connection.
	// WriteTimeout should be lower than or equal to Timeout.
	// WriteTimeout defaults to the value of Timeout.
	WriteTimeout time.Duration

	// Port used when dialing.
	// Default: 9042
	Port int

	// Initial keyspace. Optional.
	Keyspace string

	// Number of connections per host.
	// Default: 2
	NumConns int

	// Maximum number of inflight requests allowed per connection.
	// Default: 32768 for CQL v3 and newer
	// Default: 128 for older CQL versions
	MaxRequestsPerConn int

	// Default consistency level.
	// Default: Quorum
	Consistency Consistency

	// Compression algorithm.
	// Default: nil
	Compressor Compressor

	// Default: nil
	Authenticator Authenticator

	// An Authenticator factory. Can be used to create alternative authenticators.
	// Default: nil
	AuthProvider func(h *HostInfo) (Authenticator, error)

	// Default retry policy to use for queries.
	// Default: no retries.
	RetryPolicy RetryPolicy

	// ConvictionPolicy decides whether to mark host as down based on the error and host info.
	// Default: SimpleConvictionPolicy
	ConvictionPolicy ConvictionPolicy

	// Default reconnection policy to use for reconnecting before trying to mark host as down.
	ReconnectionPolicy ReconnectionPolicy

	// A reconnection policy to use for reconnecting when connecting to the cluster first time.
	InitialReconnectionPolicy ReconnectionPolicy

	// The keepalive period to use, enabled if > 0 (default: 15 seconds)
	// SocketKeepalive is used to set up the default dialer and is ignored if Dialer or HostDialer is provided.
	SocketKeepalive time.Duration

	// Maximum cache size for prepared statements globally for gocql.
	// Default: 1000
	MaxPreparedStmts int

	// Maximum cache size for query info about statements for each session.
	// Default: 1000
	MaxRoutingKeyInfo int

	// Default page size to use for created sessions.
	// Default: 5000
	PageSize int

	// Consistency for the serial part of queries, values can be either SERIAL or LOCAL_SERIAL.
	// Default: unset
	SerialConsistency SerialConsistency

	// SslOpts configures TLS use when HostDialer is not set.
	// SslOpts is ignored if HostDialer is set.
	SslOpts       *SslOptions
	actualSslOpts atomic.Value

	// Sends a client side timestamp for all requests which overrides the timestamp at which it arrives at the server.
	// Default: true, only enabled for protocol 3 and above.
	DefaultTimestamp bool

	// The name of the driver that is going to be reported to the server.
	// Default: "ScyllaDB GoLang Driver"
	DriverName string

	// The version of the driver that is going to be reported to the server.
	// Defaulted to current library version
	DriverVersion string

	// PoolConfig configures the underlying connection pool, allowing the
	// configuration of host selection and connection selection policies.
	PoolConfig PoolConfig

	// If not zero, gocql attempt to reconnect known DOWN nodes in every ReconnectInterval.
	ReconnectInterval time.Duration

	// The maximum amount of time to wait for schema agreement in a cluster after
	// receiving a schema change frame. (default: 60s)
	MaxWaitSchemaAgreement time.Duration

	// HostFilter will filter all incoming events for host, any which don't pass
	// the filter will be ignored. If set will take precedence over any options set
	// via Discovery
	HostFilter HostFilter

	// AddressTranslator will translate addresses found on peer discovery and/or
	// node change events.
	AddressTranslator AddressTranslator

	// If IgnorePeerAddr is true and the address in system.peers does not match
	// the supplied host by either initial hosts or discovered via events then the
	// host will be replaced with the supplied address.
	//
	// For example if an event comes in with host=10.0.0.1 but when looking up that
	// address in system.local or system.peers returns 127.0.0.1, the peer will be
	// set to 10.0.0.1 which is what will be used to connect to.
	IgnorePeerAddr bool

	// If DisableInitialHostLookup then the driver will not attempt to get host info
	// from the system.peers table, this will mean that the driver will connect to
	// hosts supplied and will not attempt to lookup the hosts information, this will
	// mean that data_centre, rack and token information will not be available and as
	// such host filtering and token aware query routing will not be available.
	DisableInitialHostLookup bool

	// Configure events the driver will register for
	Events struct {
		// disable registering for status events (node up/down)
		DisableNodeStatusEvents bool
		// disable registering for topology events (node added/removed/moved)
		DisableTopologyEvents bool
		// disable registering for schema events (keyspace/table/function removed/created/updated)
		DisableSchemaEvents bool
	}

	// DisableSkipMetadata will override the internal result metadata cache so that the driver does not
	// send skip_metadata for queries, this means that the result will always contain
	// the metadata to parse the rows and will not reuse the metadata from the prepared
	// statement.
	//
	// See https://issues.apache.org/jira/browse/CASSANDRA-10786
	// See https://github.com/scylladb/scylladb/issues/20860
	//
	// Default: true
	DisableSkipMetadata bool

	// QueryObserver will set the provided query observer on all queries created from this session.
	// Use it to collect metrics / stats from queries by providing an implementation of QueryObserver.
	QueryObserver QueryObserver

	// BatchObserver will set the provided batch observer on all queries created from this session.
	// Use it to collect metrics / stats from batch queries by providing an implementation of BatchObserver.
	BatchObserver BatchObserver

	// ConnectObserver will set the provided connect observer on all queries
	// created from this session.
	ConnectObserver ConnectObserver

	// FrameHeaderObserver will set the provided frame header observer on all frames' headers created from this session.
	// Use it to collect metrics / stats from frames by providing an implementation of FrameHeaderObserver.
	FrameHeaderObserver FrameHeaderObserver

	// StreamObserver will be notified of stream state changes.
	// This can be used to track in-flight protocol requests and responses.
	StreamObserver StreamObserver

	// Default idempotence for queries
	DefaultIdempotence bool

	// The time to wait for frames before flushing the frames connection to Cassandra.
	// Can help reduce syscall overhead by making less calls to write. Set to 0 to
	// disable.
	//
	// (default: 200 microseconds)
	WriteCoalesceWaitTime time.Duration

	// Dialer will be used to establish all connections created for this Cluster.
	// If not provided, a default dialer configured with ConnectTimeout will be used.
	// Dialer is ignored if HostDialer is provided.
	Dialer Dialer

	// HostDialer will be used to establish all connections for this Cluster.
	// Unlike Dialer, HostDialer is responsible for setting up the entire connection, including the TLS session.
	// To support shard-aware port, HostDialer should implement ShardDialer.
	// If not provided, Dialer will be used instead.
	HostDialer HostDialer

	// DisableShardAwarePort will prevent the driver from connecting to Scylla's shard-aware port,
	// even if there are nodes in the cluster that support it.
	//
	// It is generally recommended to leave this option turned off because gocql can use
	// the shard-aware port to make the process of establishing more robust.
	// However, if you have a cluster with nodes which expose shard-aware port
	// but the port is unreachable due to network configuration issues, you can use
	// this option to work around the issue. Set it to true only if you neither can fix
	// your network nor disable shard-aware port on your nodes.
	DisableShardAwarePort bool

	// Logger for this ClusterConfig.
	// If not specified, defaults to the global gocql.Logger.
	Logger StdLogger

	// The timeout for the requests to the schema tables. (default: 60s)
	MetadataSchemaRequestTimeout time.Duration

	// internal config for testing
	disableControlConn bool
	disableInit        bool
}

type Dialer interface {
	DialContext(ctx context.Context, network, addr string) (net.Conn, error)
}

// NewCluster generates a new config for the default cluster implementation.
//
// The supplied hosts are used to initially connect to the cluster then the rest of
// the ring will be automatically discovered. It is recommended to use the value set in
// the Cassandra config for broadcast_address or listen_address, an IP address not
// a domain name. This is because events from Cassandra will use the configured IP
// address, which is used to index connected hosts. If the domain name specified
// resolves to more than 1 IP address then the driver may connect multiple times to
// the same host, and will not mark the node being down or up from events.
func NewCluster(hosts ...string) *ClusterConfig {
	cfg := &ClusterConfig{
		Hosts:                        hosts,
		CQLVersion:                   "3.0.0",
		Timeout:                      11 * time.Second,
		ConnectTimeout:               11 * time.Second,
		Port:                         9042,
		NumConns:                     2,
		Consistency:                  Quorum,
		MaxPreparedStmts:             defaultMaxPreparedStmts,
		MaxRoutingKeyInfo:            1000,
		PageSize:                     5000,
		DefaultTimestamp:             true,
		DriverName:                   defaultDriverName,
		DriverVersion:                defaultDriverVersion,
		MaxWaitSchemaAgreement:       60 * time.Second,
		ReconnectInterval:            60 * time.Second,
		ConvictionPolicy:             &SimpleConvictionPolicy{},
		ReconnectionPolicy:           &ConstantReconnectionPolicy{MaxRetries: 3, Interval: 1 * time.Second},
		InitialReconnectionPolicy:    &NoReconnectionPolicy{},
		SocketKeepalive:              15 * time.Second,
		WriteCoalesceWaitTime:        200 * time.Microsecond,
		MetadataSchemaRequestTimeout: 60 * time.Second,
		DisableSkipMetadata:          true,
	}

	return cfg
}

func (cfg *ClusterConfig) logger() StdLogger {
	if cfg.Logger == nil {
		return Logger
	}
	return cfg.Logger
}

// CreateSession initializes the cluster based on this config and returns a
// session object that can be used to interact with the database.
func (cfg *ClusterConfig) CreateSession() (*Session, error) {
	return NewSession(*cfg)
}

// translateAddressPort is a helper method that will use the given AddressTranslator
// if defined, to translate the given address and port into a possibly new address
// and port, If no AddressTranslator or if an error occurs, the given address and
// port will be returned.
func (cfg *ClusterConfig) translateAddressPort(addr net.IP, port int) (net.IP, int) {
	if cfg.AddressTranslator == nil || len(addr) == 0 {
		return addr, port
	}
	newAddr, newPort := cfg.AddressTranslator.Translate(addr, port)
	if gocqlDebug {
		cfg.logger().Printf("gocql: translating address '%v:%d' to '%v:%d'", addr, port, newAddr, newPort)
	}
	return newAddr, newPort
}

func (cfg *ClusterConfig) filterHost(host *HostInfo) bool {
	return !(cfg.HostFilter == nil || cfg.HostFilter.Accept(host))
}

func (cfg *ClusterConfig) ValidateAndInitSSL() error {
	if cfg.SslOpts == nil {
		return nil
	}
	actualTLSConfig, err := setupTLSConfig(cfg.SslOpts)
	if err != nil {
		return fmt.Errorf("failed to initialize ssl configuration: %s", err.Error())
	}

	cfg.actualSslOpts.Store(actualTLSConfig)
	return nil
}

func (cfg *ClusterConfig) getActualTLSConfig() *tls.Config {
	val, ok := cfg.actualSslOpts.Load().(*tls.Config)
	if !ok {
		return nil
	}
	return val.Clone()
}

func (cfg *ClusterConfig) Validate() error {
	if len(cfg.Hosts) == 0 {
		return ErrNoHosts
	}

	if cfg.Authenticator != nil && cfg.AuthProvider != nil {
		return errors.New("Can't use both Authenticator and AuthProvider in cluster config.")
	}

	if cfg.InitialReconnectionPolicy == nil {
		return errors.New("InitialReconnectionPolicy is nil")
	}

	if cfg.InitialReconnectionPolicy.GetMaxRetries() <= 0 {
		return errors.New("InitialReconnectionPolicy.GetMaxRetries returns negative number")
	}

	if cfg.ReconnectionPolicy == nil {
		return errors.New("ReconnectionPolicy is nil")
	}

	if cfg.InitialReconnectionPolicy.GetMaxRetries() <= 0 {
		return errors.New("ReconnectionPolicy.GetMaxRetries returns negative number")
	}

	if cfg.PageSize < 0 {
		return errors.New("PageSize should be positive number or zero")
	}

	if cfg.MaxRoutingKeyInfo < 0 {
		return errors.New("MaxRoutingKeyInfo should be positive number or zero")
	}

	if cfg.MaxPreparedStmts < 0 {
		return errors.New("MaxPreparedStmts should be positive number or zero")
	}

	if cfg.SocketKeepalive < 0 {
		return errors.New("SocketKeepalive should be positive time.Duration or zero")
	}

	if cfg.MaxRequestsPerConn < 0 {
		return errors.New("MaxRequestsPerConn should be positive number or zero")
	}

	if cfg.NumConns < 0 {
		return errors.New("NumConns should be positive non-zero number or zero")
	}

	if cfg.Port <= 0 || cfg.Port > 65535 {
		return errors.New("Port should be a valid port number: a number between 1 and 65535")
	}

	if cfg.WriteTimeout < 0 {
		return errors.New("WriteTimeout should be positive time.Duration or zero")
	}

	if cfg.Timeout < 0 {
		return errors.New("Timeout should be positive time.Duration or zero")
	}

	if cfg.ConnectTimeout < 0 {
		return errors.New("ConnectTimeout should be positive time.Duration or zero")
	}

	if cfg.MetadataSchemaRequestTimeout < 0 {
		return errors.New("MetadataSchemaRequestTimeout should be positive time.Duration or zero")
	}

	if cfg.WriteCoalesceWaitTime < 0 {
		return errors.New("WriteCoalesceWaitTime should be positive time.Duration or zero")
	}

	if cfg.ReconnectInterval < 0 {
		return errors.New("ReconnectInterval should be positive time.Duration or zero")
	}

	if cfg.MaxWaitSchemaAgreement < 0 {
		return errors.New("MaxWaitSchemaAgreement should be positive time.Duration or zero")
	}

	if cfg.ProtoVersion < 0 {
		return errors.New("ProtoVersion should be positive number or zero")
	}

	if !cfg.DisableSkipMetadata {
		Logger.Println("warning: enabling skipping metadata can lead to unpredictible results when executing query and altering columns involved in the query.")
	}

	return cfg.ValidateAndInitSSL()
}

var (
	ErrNoHosts              = errors.New("no hosts provided")
	ErrNoConnectionsStarted = errors.New("no connections were made when creating the session")
	ErrHostQueryFailed      = errors.New("unable to populate Hosts")
)

func setupTLSConfig(sslOpts *SslOptions) (*tls.Config, error) {
	//  Config.InsecureSkipVerify | EnableHostVerification | Result
	//  Config is nil             | true                   | verify host
	//  Config is nil             | false                  | do not verify host
	//  false                     | false                  | verify host
	//  true                      | false                  | do not verify host
	//  false                     | true                   | verify host
	//  true                      | true                   | verify host
	var tlsConfig *tls.Config
	if sslOpts.Config == nil {
		tlsConfig = &tls.Config{
			InsecureSkipVerify: !sslOpts.EnableHostVerification,
		}
	} else {
		// use clone to avoid race.
		tlsConfig = sslOpts.Config.Clone()
	}

	if tlsConfig.InsecureSkipVerify && sslOpts.EnableHostVerification {
		tlsConfig.InsecureSkipVerify = false
	}

	// ca cert is optional
	if sslOpts.CaPath != "" {
		if tlsConfig.RootCAs == nil {
			tlsConfig.RootCAs = x509.NewCertPool()
		}

		pem, err := ioutil.ReadFile(sslOpts.CaPath)
		if err != nil {
			return nil, fmt.Errorf("unable to open CA certs: %v", err)
		}

		if !tlsConfig.RootCAs.AppendCertsFromPEM(pem) {
			return nil, errors.New("failed parsing or CA certs")
		}
	}

	if sslOpts.CertPath != "" || sslOpts.KeyPath != "" {
		mycert, err := tls.LoadX509KeyPair(sslOpts.CertPath, sslOpts.KeyPath)
		if err != nil {
			return nil, fmt.Errorf("unable to load X509 key pair: %v", err)
		}
		tlsConfig.Certificates = append(tlsConfig.Certificates, mycert)
	}

	return tlsConfig, nil
}