etcd/name_url_map.go

/*
Copyright 2013 CoreOS Inc.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

     http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package main

import (
	"net/url"
	"path"
)

// we map node name to url
type nodeInfo struct {
	raftVersion string
	raftURL     string
	etcdURL     string
}

var namesMap = make(map[string]*nodeInfo)

// nameToEtcdURL maps node name to its etcd http address
func nameToEtcdURL(name string) (string, bool) {

	if info, ok := namesMap[name]; ok {
		// first try to read from the map
		return info.etcdURL, true
	}

	// if fails, try to recover from etcd storage
	return readURL(name, "etcd")

}

// nameToRaftURL maps node name to its raft http address
func nameToRaftURL(name string) (string, bool) {
	if info, ok := namesMap[name]; ok {
		// first try to read from the map
		return info.raftURL, true

	}

	// if fails, try to recover from etcd storage
	return readURL(name, "raft")
}

// addNameToURL add a name that maps to raftURL and etcdURL
func addNameToURL(name string, version string, raftURL string, etcdURL string) {
	namesMap[name] = &nodeInfo{
		raftVersion: raftVersion,
		raftURL:     raftURL,
		etcdURL:     etcdURL,
	}
}

func readURL(nodeName string, urlName string) (string, bool) {
	// if fails, try to recover from etcd storage
	key := path.Join("/_etcd/machines", nodeName)

	resps, err := etcdStore.RawGet(key)

	if err != nil {
		return "", false
	}

	m, err := url.ParseQuery(resps[0].Value)

	if err != nil {
		panic("Failed to parse machines entry")
	}

	url := m[urlName][0]

	return url, true
}