etcd/etcdserver/cluster.go

/*
   Copyright 2014 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 etcdserver

import (
	"crypto/sha1"
	"encoding/binary"
	"encoding/json"
	"fmt"
	"log"
	"net/url"
	"path"
	"reflect"
	"sort"
	"strings"

	etcdErr "github.com/coreos/etcd/error"
	"github.com/coreos/etcd/pkg/flags"
	"github.com/coreos/etcd/pkg/types"
	"github.com/coreos/etcd/store"
)

const (
	raftAttributesSuffix = "raftAttributes"
	attributesSuffix     = "attributes"
)

type ClusterInfo interface {
	ID() uint64
	ClientURLs() []string
	// Members returns a slice of members sorted by their ID
	Members() []*Member
	Member(id uint64) *Member
}

// Cluster is a list of Members that belong to the same raft cluster
type Cluster struct {
	id      uint64
	name    string
	members map[uint64]*Member
	// removed contains the ids of removed members in the cluster.
	// removed id cannot be reused.
	removed map[uint64]bool
	store   store.Store
}

// NewClusterFromString returns Cluster through given clusterName and parsing
// members from a sets of names to IPs discovery formatted like:
// mach0=http://1.1.1.1,mach0=http://2.2.2.2,mach1=http://3.3.3.3,mach2=http://4.4.4.4
func NewClusterFromString(name string, cluster string) (*Cluster, error) {
	c := newCluster(name)

	v, err := url.ParseQuery(strings.Replace(cluster, ",", "&", -1))
	if err != nil {
		return nil, err
	}
	for name, urls := range v {
		if len(urls) == 0 || urls[0] == "" {
			return nil, fmt.Errorf("Empty URL given for %q", name)
		}
		purls := &flags.URLsValue{}
		if err := purls.Set(strings.Join(urls, ",")); err != nil {
			return nil, err
		}
		m := NewMember(name, types.URLs(*purls), c.name, nil)
		if _, ok := c.members[m.ID]; ok {
			return nil, fmt.Errorf("Member exists with identical ID %v", m)
		}
		c.members[m.ID] = m
	}
	c.genID()
	return c, nil
}

func NewClusterFromStore(name string, st store.Store) *Cluster {
	c := newCluster(name)
	c.store = st

	e, err := c.store.Get(storeMembersPrefix, true, true)
	if err != nil {
		if isKeyNotFound(err) {
			return c
		}
		log.Panicf("get storeMembers should never fail: %v", err)
	}
	for _, n := range e.Node.Nodes {
		m, err := nodeToMember(n)
		if err != nil {
			log.Panicf("nodeToMember should never fail: %v", err)
		}
		c.members[m.ID] = m
	}

	e, err = c.store.Get(storeRemovedMembersPrefix, true, true)
	if err != nil {
		if isKeyNotFound(err) {
			return c
		}
		log.Panicf("get storeRemovedMembers should never fail: %v", err)
	}
	for _, n := range e.Node.Nodes {
		c.removed[parseMemberID(n.Key)] = true
	}

	return c
}

func NewClusterFromMembers(name string, id uint64, membs []*Member) *Cluster {
	c := newCluster(name)
	c.id = id
	for _, m := range membs {
		c.members[m.ID] = m
	}
	return c
}

func newCluster(name string) *Cluster {
	return &Cluster{
		name:    name,
		members: make(map[uint64]*Member),
		removed: make(map[uint64]bool),
	}
}

func (c Cluster) ID() uint64 { return c.id }

func (c Cluster) Members() []*Member {
	var sms SortableMemberSlice
	for _, m := range c.members {
		sms = append(sms, m)
	}
	sort.Sort(sms)
	return []*Member(sms)
}

type SortableMemberSlice []*Member

func (s SortableMemberSlice) Len() int           { return len(s) }
func (s SortableMemberSlice) Less(i, j int) bool { return s[i].ID < s[j].ID }
func (s SortableMemberSlice) Swap(i, j int)      { s[i], s[j] = s[j], s[i] }

func (c *Cluster) Member(id uint64) *Member {
	return c.members[id]
}

// MemberByName returns a Member with the given name if exists.
// If more than one member has the given name, it will panic.
func (c *Cluster) MemberByName(name string) *Member {
	var memb *Member
	for _, m := range c.members {
		if m.Name == name {
			if memb != nil {
				panic("two members with the given name exist in the cluster")
			}
			memb = m
		}
	}
	return memb
}

func (c Cluster) MemberIDs() []uint64 {
	var ids []uint64
	for _, m := range c.members {
		ids = append(ids, m.ID)
	}
	sort.Sort(types.Uint64Slice(ids))
	return ids
}

func (c *Cluster) IsIDRemoved(id uint64) bool {
	return c.removed[id]
}

// PeerURLs returns a list of all peer addresses. Each address is prefixed
// with the scheme (currently "http://"). The returned list is sorted in
// ascending lexicographical order.
func (c Cluster) PeerURLs() []string {
	endpoints := make([]string, 0)
	for _, p := range c.members {
		for _, addr := range p.PeerURLs {
			endpoints = append(endpoints, addr)
		}
	}
	sort.Strings(endpoints)
	return endpoints
}

// ClientURLs returns a list of all client addresses. Each address is prefixed
// with the scheme (currently "http://"). The returned list is sorted in
// ascending lexicographical order.
func (c Cluster) ClientURLs() []string {
	urls := make([]string, 0)
	for _, p := range c.members {
		for _, url := range p.ClientURLs {
			urls = append(urls, url)
		}
	}
	sort.Strings(urls)
	return urls
}

func (c Cluster) String() string {
	sl := []string{}
	for _, m := range c.members {
		for _, u := range m.PeerURLs {
			sl = append(sl, fmt.Sprintf("%s=%s", m.Name, u))
		}
	}
	sort.Strings(sl)
	return strings.Join(sl, ",")
}

// ValidateAndAssignIDs validates the given members by matching their PeerURLs
// with the existing members in the cluster. If the validation succeeds, it
// assigns the IDs from the given members to the existing members in the
// cluster. If the validation fails, an error will be returned.
func (c *Cluster) ValidateAndAssignIDs(membs []*Member) error {
	if len(c.members) != len(membs) {
		return fmt.Errorf("cannot update %v from %v because the member count is unequal", c.members, membs)
	}
	omembs := make([]*Member, 0)
	for _, m := range c.members {
		omembs = append(omembs, m)
	}
	sort.Sort(SortableMemberSliceByPeerURLs(omembs))
	sort.Sort(SortableMemberSliceByPeerURLs(membs))
	for i := range omembs {
		if !reflect.DeepEqual(omembs[i].PeerURLs, membs[i].PeerURLs) {
			return fmt.Errorf("unmatched member while checking PeerURLs")
		}
		omembs[i].ID = membs[i].ID
	}
	c.members = make(map[uint64]*Member)
	for _, m := range omembs {
		c.members[m.ID] = m
	}
	return nil
}

func (c *Cluster) genID() {
	mIDs := c.MemberIDs()
	b := make([]byte, 8*len(mIDs))
	for i, id := range mIDs {
		binary.BigEndian.PutUint64(b[8*i:], id)
	}
	hash := sha1.Sum(b)
	c.id = binary.BigEndian.Uint64(hash[:8])
}

func (c *Cluster) SetID(id uint64) { c.id = id }

func (c *Cluster) SetStore(st store.Store) { c.store = st }

// AddMember puts a new Member into the store.
// A Member with a matching id must not exist.
func (c *Cluster) AddMember(m *Member) {
	b, err := json.Marshal(m.RaftAttributes)
	if err != nil {
		log.Panicf("marshal error: %v", err)
	}
	p := path.Join(memberStoreKey(m.ID), raftAttributesSuffix)
	if _, err := c.store.Create(p, false, string(b), false, store.Permanent); err != nil {
		log.Panicf("add raftAttributes should never fail: %v", err)
	}
	b, err = json.Marshal(m.Attributes)
	if err != nil {
		log.Panicf("marshal error: %v", err)
	}
	p = path.Join(memberStoreKey(m.ID), attributesSuffix)
	if _, err := c.store.Create(p, false, string(b), false, store.Permanent); err != nil {
		log.Panicf("add attributes should never fail: %v", err)
	}
	c.members[m.ID] = m
}

// RemoveMember removes a member from the store.
// The given id MUST exist, or the function panics.
func (c *Cluster) RemoveMember(id uint64) {
	if _, err := c.store.Delete(memberStoreKey(id), true, true); err != nil {
		log.Panicf("delete peer should never fail: %v", err)
	}
	delete(c.members, id)
	if _, err := c.store.Create(removedMemberStoreKey(id), false, "", false, store.Permanent); err != nil {
		log.Panicf("creating RemovedMember should never fail: %v", err)
	}
	c.removed[id] = true
}

// nodeToMember builds member through a store node.
// the child nodes of the given node should be sorted by key.
func nodeToMember(n *store.NodeExtern) (*Member, error) {
	m := &Member{ID: parseMemberID(n.Key)}
	if len(n.Nodes) != 2 {
		return m, fmt.Errorf("len(nodes) = %d, want 2", len(n.Nodes))
	}
	if w := path.Join(n.Key, attributesSuffix); n.Nodes[0].Key != w {
		return m, fmt.Errorf("key = %v, want %v", n.Nodes[0].Key, w)
	}
	if err := json.Unmarshal([]byte(*n.Nodes[0].Value), &m.Attributes); err != nil {
		return m, fmt.Errorf("unmarshal attributes error: %v", err)
	}
	if w := path.Join(n.Key, raftAttributesSuffix); n.Nodes[1].Key != w {
		return m, fmt.Errorf("key = %v, want %v", n.Nodes[1].Key, w)
	}
	if err := json.Unmarshal([]byte(*n.Nodes[1].Value), &m.RaftAttributes); err != nil {
		return m, fmt.Errorf("unmarshal raftAttributes error: %v", err)
	}
	return m, nil
}

func isKeyNotFound(err error) bool {
	e, ok := err.(*etcdErr.Error)
	return ok && e.ErrorCode == etcdErr.EcodeKeyNotFound
}