config.go

package paxi

import (
	"encoding/json"
	"flag"
	"os"

	"github.com/ailidani/paxi/log"
)

var configFile = flag.String("config", "config.json", "Configuration file for paxi replica. Defaults to config.json.")

// Config contains every system configuration
type Config struct {
	Addrs           map[ID]string `json:"address"`           // address for node communication
	HTTPAddrs       map[ID]string `json:"http_address"`      // address for client server communication
	Algorithm       string        `json:"algorithm"`         // replication algorithm name
	Quorum          string        `json:"quorum"`            // type of the quorums
	F               int           `json:"f"`                 // number of failure zones in general grid quorums
	Transport       string        `json:"transport"`         // not used
	ReplyWhenCommit bool          `json:"reply_when_commit"` // reply to client when request is committed, instead of executed
	Adaptive        bool          `json:"adaptive"`          // adaptive leader change, if true paxos forward request to current leader
	Policy          string        `json:"policy"`            // leader change policy {consecutive, majority}
	Threshold       float64       `json:"threshold"`         // threshold for policy in WPaxos {n consecutive or time interval in ms}
	BackOff         int           `json:"backoff"`           // random backoff interval
	Thrifty         bool          `json:"thrifty"`           // only send messages to a quorum
	BufferSize      int           `json:"buffer_size"`       // buffer size for maps
	ChanBufferSize  int           `json:"chan_buffer_size"`  // buffer size for channels
	MultiVersion    bool          `json:"multiversion"`      // create multi-version database
	Benchmark       Bconfig       `json:"benchmark"`         // benchmark configuration

	// for future implementation
	// Batching bool `json:"batching"`
	// Consistency string `json:"consistency"`
	// Codec string `json:"codec"` // codec for message serialization between nodes

	n   int         // total number of nodes
	z   int         // total number of zones
	npz map[int]int // nodes per zone
}

// Config is global configuration singleton generated by init() func below
var config Config

func init() {
	config = MakeDefaultConfig()
}

// GetConfig returns paxi package configuration
func GetConfig() Config {
	return config
}

func Simulation() {
	config.Transport = "chan"
}

// MakeDefaultConfig returns Config object with few default values
// only used by init() and master
func MakeDefaultConfig() Config {
	return Config{
		Transport:       "tcp",
		ReplyWhenCommit: false,
		Adaptive:        true,
		Policy:          "consecutive",
		Threshold:       3,
		BufferSize:      1024,
		ChanBufferSize:  1024,
		MultiVersion:    false,
		Benchmark:       DefaultBConfig(),
	}
}

// IDs returns all node ids
func (c Config) IDs() []ID {
	ids := make([]ID, 0)
	for id := range c.Addrs {
		ids = append(ids, id)
	}
	return ids
}

func (c Config) N() int {
	return c.n
}

func (c Config) Z() int {
	return c.z
}

// String is implemented to print the config
func (c Config) String() string {
	config, err := json.Marshal(c)
	if err != nil {
		log.Error(err)
		return ""
	}
	return string(config)
}

// Load loads configuration from config file in JSON format
func (c *Config) Load() {
	file, err := os.Open(*configFile)
	if err != nil {
		log.Fatal(err)
	}
	decoder := json.NewDecoder(file)
	err = decoder.Decode(c)
	if err != nil {
		log.Fatal(err)
	}

	c.npz = make(map[int]int)
	for id := range c.Addrs {
		c.n++
		c.npz[id.Zone()]++
	}
	c.z = len(c.npz)
}

// Save saves configuration to file in JSON format
func (c Config) Save() error {
	file, err := os.Create(*configFile)
	if err != nil {
		return err
	}
	encoder := json.NewEncoder(file)
	return encoder.Encode(c)
}