forked from facebookarchive/dvara
/
rs_state.go
235 lines (207 loc) · 5.72 KB
/
rs_state.go
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package dvara
import (
"fmt"
"sort"
"time"
"github.com/davecgh/go-spew/spew"
"labix.org/v2/mgo"
"labix.org/v2/mgo/bson"
)
const errNotReplSet = "not running with --replSet"
// ReplicaSetState is a snapshot of the RS configuration at some point in time.
type ReplicaSetState struct {
lastRS *replSetGetStatusResponse
lastIM *isMasterResponse
singleAddr string // this is only set when we're not running against a RS
}
// NewReplicaSetState creates a new ReplicaSetState using the given address.
func NewReplicaSetState(addr string) (*ReplicaSetState, error) {
info := &mgo.DialInfo{
Addrs: []string{addr},
Direct: true,
Timeout: 5 * time.Second,
}
session, err := mgo.DialWithInfo(info)
if err != nil {
return nil, err
}
session.SetMode(mgo.Monotonic, true)
session.SetSyncTimeout(5 * time.Second)
session.SetSocketTimeout(5 * time.Second)
defer session.Close()
var r ReplicaSetState
if r.lastRS, err = replSetGetStatus(session); err != nil {
// This error indicates we're in Single Node Mode. That's okay.
if err.Error() != errNotReplSet {
return nil, err
}
r.singleAddr = addr
}
if r.lastIM, err = isMaster(session); err != nil {
return nil, err
}
if r.lastRS != nil && len(r.lastRS.Members) == 1 {
n := r.lastRS.Members[0]
if n.State != "PRIMARY" || n.State != "SECONDARY" {
return nil, fmt.Errorf("single node RS in bad state: %s", spew.Sdump(r))
}
}
return &r, nil
}
// AssertEqual checks if the given ReplicaSetState equals this one. It returns
// a rich error message including the entire state for easier debugging.
func (r *ReplicaSetState) AssertEqual(o *ReplicaSetState) error {
if r.Equal(o) {
return nil
}
return fmt.Errorf(
"conflicting ReplicaSetState:\n%s\nVS\n%s",
spew.Sdump(r),
spew.Sdump(o),
)
}
// Equal returns true if the given ReplicaSetState is the same as this one.
func (r *ReplicaSetState) Equal(o *ReplicaSetState) bool {
return r.SameIM(o.lastIM) && r.SameRS(o.lastRS)
}
// SameRS checks if the given replSetGetStatusResponse is the same as the one
// we have.
func (r *ReplicaSetState) SameRS(o *replSetGetStatusResponse) bool {
return sameRSMembers(r.lastRS, o)
}
// SameIM checks if the given isMasterResponse is the same as the one we have.
func (r *ReplicaSetState) SameIM(o *isMasterResponse) bool {
return sameIMMembers(r.lastIM, o)
}
// Addrs returns the addresses of all members.
func (r *ReplicaSetState) Addrs() []string {
if r.singleAddr != "" {
return []string{r.singleAddr}
}
members := make([]string, 0, len(r.lastRS.Members))
for _, m := range r.lastRS.Members {
members = append(members, m.Name)
}
return members
}
// ReplicaSetStateCreator allows for creating a ReplicaSetState from a given
// set of seed addresses.
type ReplicaSetStateCreator struct {
Log Logger `inject:""`
}
// FromAddrs creates a ReplicaSetState from the given set of see addresses. It
// requires the addresses to be part of the same Replica Set.
func (c *ReplicaSetStateCreator) FromAddrs(addrs []string) (*ReplicaSetState, error) {
var r *ReplicaSetState
for _, addr := range addrs {
ar, err := NewReplicaSetState(addr)
if err != nil {
c.Log.Errorf("ignoring failure against address %s: %s", addr, err)
continue
}
// First successful address.
if r == nil {
r = ar
continue
}
// Ensure same as already established ReplicaSetState.
if err := r.AssertEqual(ar); err != nil {
return nil, err
}
}
if r == nil {
return nil, fmt.Errorf("could not connect to any provided addresses: %v", addrs)
}
// Check if we're expecting an RS but got a single node.
if r.singleAddr != "" && len(addrs) != 1 {
return nil, fmt.Errorf(
"node %s is not in a replica set but was expecting it to be in a"+
" replica set with members %v",
r.singleAddr,
addrs,
)
}
return r, nil
}
var (
replSetGetStatusQuery = bson.D{
bson.DocElem{Name: "replSetGetStatus", Value: 1},
}
isMasterQuery = bson.D{
bson.DocElem{Name: "isMaster", Value: 1},
}
)
func replSetGetStatus(s *mgo.Session) (*replSetGetStatusResponse, error) {
var res replSetGetStatusResponse
if err := s.Run(replSetGetStatusQuery, &res); err != nil {
return nil, err
}
return &res, nil
}
func isMaster(s *mgo.Session) (*isMasterResponse, error) {
var res isMasterResponse
if err := s.Run(isMasterQuery, &res); err != nil {
return nil, fmt.Errorf("error in isMaster: %s", err)
}
return &res, nil
}
func sameRSMembers(a *replSetGetStatusResponse, b *replSetGetStatusResponse) bool {
if (a == nil || len(a.Members) == 0) && (b == nil || len(b.Members) == 0) {
return true
}
if a == nil || b == nil {
return false
}
l := len(a.Members)
if l != len(b.Members) {
return false
}
aMembers := make([]string, 0, l)
bMembers := make([]string, 0, l)
for i := 0; i < l; i++ {
aM := a.Members[i]
aMembers = append(aMembers, fmt.Sprintf("%s:%s", aM.Name, aM.State))
bM := b.Members[i]
bMembers = append(bMembers, fmt.Sprintf("%s:%s", bM.Name, bM.State))
}
sort.Strings(aMembers)
sort.Strings(bMembers)
for i := 0; i < l; i++ {
if aMembers[i] != bMembers[i] {
return false
}
}
return true
}
var emptyIsMasterResponse = isMasterResponse{}
func sameIMMembers(a *isMasterResponse, b *isMasterResponse) bool {
if a == nil && b == nil {
return true
}
if a == nil {
a = &emptyIsMasterResponse
}
if b == nil {
b = &emptyIsMasterResponse
}
l := len(a.Hosts)
if l != len(b.Hosts) {
return false
}
aHosts := make([]string, 0, l+1)
bHosts := make([]string, 0, l+1)
for i := 0; i < l; i++ {
aHosts = append(aHosts, a.Hosts[i])
bHosts = append(bHosts, b.Hosts[i])
}
sort.Strings(aHosts)
sort.Strings(bHosts)
aHosts = append(aHosts, a.Primary)
bHosts = append(bHosts, b.Primary)
for i := 0; i < l; i++ {
if aHosts[i] != bHosts[i] {
return false
}
}
return true
}