warren/cmd/warrend/conf/conf.go

package conf

import (
	"encoding/json"
	"errors"
	"fmt"
	"github.com/dballard/warren/lib/warren"
	"os"
)

type MsgType int
const (
    AddDeployment MsgType = iota
    RmDeploymen
)

type Msg struct {
    mType MsgType
    reply chan error
	Args map[string]string
}

func NewMsg(mType MsgType) *Msg {
    var m = &Msg{mType, make(chan error), make(map[string]string)}
    return m 
}  

func (m *Msg) Call() error {
    confChan <- *m
    err := <-m.reply
    return err
}

// Conf package - thread safe conf
// All write ops are public API functions ( Msg.Call() )
//   that internall use channels to thread safely queue writes
//   all write ops cause FS conf writes so that state is preserved
// Reads return copies of data

type Deployment struct {
	Path string
	Pool struct{Low int; High int}
}

type Conf struct {
	// name : path
	Deployments map[string]Deployment
}

var conf *Conf = nil
var Init = make(chan bool)

var confChan = make(chan Msg)


func loadConf() {
	file, err := os.Open(warren.WarrendConf)
	if err != nil {
		fmt.Println("Error loading ", warren.WarrendConf, ": ", err)
		return
	}
	defer file.Close()
	decoder := json.NewDecoder(file)
	conf = new(Conf)
	err = decoder.Decode(conf)
	if err != nil {
		conf = nil
		fmt.Println("Error parsing ", warren.WarrendConf, ": ", err)
	}
	if conf.Deployments == nil {
		conf.Deployments = make(map[string]Deployment)
	}
	// populate reverse map
	for nick, dep := range conf.Deployments {
		dirToNick[dep.Path] = nick
	}
}

func saveConf() error {
	file, err := os.Create(warren.WarrendConf)
	if err != nil {
		// TODO: Um, more than noting we might want to do something more drastic
		return errors.New("Error: could not open conf file for saving: " + err.Error())
	}
	defer file.Close()
	jdata, err := json.MarshalIndent(conf, "", "\t")
	if err != nil {
		return errors.New("Error: Could not enocde to json: " + err.Error())
	}

	if _, err := file.Write(jdata); err != nil {
		return errors.New("Error: Could not write to file: " + err.Error())
	}

	return nil
}

func GetConf() *Conf {
	var confCopy *Conf = new(Conf)
	confCopy.Deployments = make(map[string]Deployment)
	for key, deployment := range(conf.Deployments) {
		confCopy.Deployments[key] = deployment
	}
	return conf
}

func Run() {
	loadConf()
	if conf == nil {
		fmt.Println("failed to load conf")
		Init <- false
	}

	// set up comm chans

	Init <- true
	// loop for Writes
	for {
	    m := <- confChan
	    var err error = nil
		switch (m.mType) {
			case AddDeployment:
				err = addDeployment(&m)
				break
			case RmDeploymen:
				err = rmDeployment(&m)
				break;
			default:
				err = errors.New("Unknown command")
				break
		}
		m.reply <- err
	}

}