Skip to content

Commit

Permalink
Refactor load balancer.
Browse files Browse the repository at this point in the history 
Flatten 3 parallel maps into a map to structs (balancerState).
  • Loading branch information
@thockin
thockin committed Feb 23, 2015
1 parent 8503c34 commit 5dc9896
Show file tree
Hide file tree
Showing 2 changed files with 114 additions and 81 deletions.
165 changes: 99 additions & 66 deletions pkg/proxy/roundrobin.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -18,6 +18,7 @@ package proxy

import (
"errors"
"fmt"
"net"
"reflect"
"strconv"
Expand Down Expand Up @@ -53,10 +54,14 @@ type balancerKey string

// LoadBalancerRR is a round-robin load balancer.
type LoadBalancerRR struct {
lock sync.RWMutex
endpointsMap map[balancerKey][]string
rrIndex map[balancerKey]int
serviceDtlMap map[balancerKey]affinityPolicy
lock sync.RWMutex
services map[balancerKey]*balancerState
}

type balancerState struct {
endpoints []string
index int
affinity affinityPolicy
}

func newAffinityPolicy(affinityType api.AffinityType, ttlMinutes int) *affinityPolicy {
Expand All @@ -70,9 +75,7 @@ func newAffinityPolicy(affinityType api.AffinityType, ttlMinutes int) *affinityP
// NewLoadBalancerRR returns a new LoadBalancerRR.
func NewLoadBalancerRR() *LoadBalancerRR {
return &LoadBalancerRR{
endpointsMap: make(map[balancerKey][]string),
rrIndex: make(map[balancerKey]int),
serviceDtlMap: make(map[balancerKey]affinityPolicy),
services: map[balancerKey]*balancerState{},
}
}

Expand All @@ -85,19 +88,22 @@ func (lb *LoadBalancerRR) NewService(service string, affinityType api.AffinityTy
}

// This assumes that lb.lock is already held.
func (lb *LoadBalancerRR) newServiceInternal(service string, affinityType api.AffinityType, ttlMinutes int) {
func (lb *LoadBalancerRR) newServiceInternal(service string, affinityType api.AffinityType, ttlMinutes int) *balancerState {
if ttlMinutes == 0 {
ttlMinutes = 180 //default to 3 hours if not specified. Should 0 be unlimeted instead????
}
if _, exists := lb.serviceDtlMap[balancerKey(service)]; !exists {
lb.serviceDtlMap[balancerKey(service)] = *newAffinityPolicy(affinityType, ttlMinutes)
glog.V(4).Infof("NewService. Service does not exist. So I created it: %+v", lb.serviceDtlMap[balancerKey(service)])

key := balancerKey(service)
if _, exists := lb.services[key]; !exists {
lb.services[key] = &balancerState{affinity: *newAffinityPolicy(affinityType, ttlMinutes)}
glog.V(4).Infof("LoadBalancerRR service %q did not exist, created", service)
}
return lb.services[key]
}

// return true if this service is using some form of session affinity.
func isSessionAffinity(affinity *affinityPolicy) bool {
//Should never be empty string, but chekcing for it to be safe.
// Should never be empty string, but checking for it to be safe.
if affinity.affinityType == "" || affinity.affinityType == api.AffinityTypeNone {
return false
}
Expand All @@ -107,54 +113,57 @@ func isSessionAffinity(affinity *affinityPolicy) bool {
// NextEndpoint returns a service endpoint.
// The service endpoint is chosen using the round-robin algorithm.
func (lb *LoadBalancerRR) NextEndpoint(service string, srcAddr net.Addr) (string, error) {
var ipaddr string
glog.V(4).Infof("NextEndpoint. service: %s. srcAddr: %+v. Endpoints: %+v", service, srcAddr, lb.endpointsMap)

lb.lock.RLock()
serviceDtls, exists := lb.serviceDtlMap[balancerKey(service)]
endpoints, _ := lb.endpointsMap[balancerKey(service)]
index := lb.rrIndex[balancerKey(service)]
sessionAffinityEnabled := isSessionAffinity(&serviceDtls)
// Coarse locking is simple. We can get more fine-grained if/when we
// can prove it matters.
lb.lock.Lock()
defer lb.lock.Unlock()

lb.lock.RUnlock()
if !exists {
key := balancerKey(service)
state, exists := lb.services[key]
if !exists || state == nil {
return "", ErrMissingServiceEntry
}
if len(endpoints) == 0 {
if len(state.endpoints) == 0 {
return "", ErrMissingEndpoints
}
glog.V(4).Infof("NextEndpoint for service %q, srcAddr=%v: endpoints: %+v", service, srcAddr, state.endpoints)

sessionAffinityEnabled := isSessionAffinity(&state.affinity)

var ipaddr string
if sessionAffinityEnabled {
if _, _, err := net.SplitHostPort(srcAddr.String()); err == nil {
ipaddr, _, _ = net.SplitHostPort(srcAddr.String())
// Caution: don't shadow ipaddr
var err error
ipaddr, _, err = net.SplitHostPort(srcAddr.String())
if err != nil {
return "", fmt.Errorf("malformed source address %q: %v", srcAddr.String(), err)
}
sessionAffinity, exists := serviceDtls.affinityMap[ipaddr]
glog.V(4).Infof("NextEndpoint. Key: %s. sessionAffinity: %+v", ipaddr, sessionAffinity)
if exists && int(time.Now().Sub(sessionAffinity.lastUsed).Minutes()) < serviceDtls.ttlMinutes {
sessionAffinity, exists := state.affinity.affinityMap[ipaddr]
if exists && int(time.Now().Sub(sessionAffinity.lastUsed).Minutes()) < state.affinity.ttlMinutes {
// Affinity wins.
endpoint := sessionAffinity.endpoint
sessionAffinity.lastUsed = time.Now()
glog.V(4).Infof("NextEndpoint. Key: %s. sessionAffinity: %+v", ipaddr, sessionAffinity)
glog.V(4).Infof("NextEndpoint for service %q from IP %s with sessionAffinity %+v: %s", service, ipaddr, sessionAffinity, endpoint)
return endpoint, nil
}
}
endpoint := endpoints[index]
lb.lock.Lock()
lb.rrIndex[balancerKey(service)] = (index + 1) % len(endpoints)
// Take the next endpoint.
endpoint := state.endpoints[state.index]
state.index = (state.index + 1) % len(state.endpoints)

if sessionAffinityEnabled {
var affinity *affinityState
affinity, _ = lb.serviceDtlMap[balancerKey(service)].affinityMap[ipaddr]
affinity = state.affinity.affinityMap[ipaddr]
if affinity == nil {
affinity = new(affinityState) //&affinityState{ipaddr, "TCP", "", endpoint, time.Now()}
lb.serviceDtlMap[balancerKey(service)].affinityMap[ipaddr] = affinity
state.affinity.affinityMap[ipaddr] = affinity
}
affinity.lastUsed = time.Now()
affinity.endpoint = endpoint
affinity.clientIP = ipaddr

glog.V(4).Infof("NextEndpoint. New Affinity key %s: %+v", ipaddr, lb.serviceDtlMap[balancerKey(service)].affinityMap[ipaddr])
glog.V(4).Infof("Updated affinity key %s: %+v", ipaddr, state.affinity.affinityMap[ipaddr])
}

lb.lock.Unlock()
return endpoint, nil
}

Expand All @@ -175,32 +184,35 @@ func filterValidEndpoints(endpoints []api.Endpoint) []string {
return result
}

//remove any session affinity records associated to a particular endpoint (for example when a pod goes down).
func removeSessionAffinityByEndpoint(lb *LoadBalancerRR, service balancerKey, endpoint string) {
for _, affinity := range lb.serviceDtlMap[service].affinityMap {
// Remove any session affinity records associated to a particular endpoint (for example when a pod goes down).
func removeSessionAffinityByEndpoint(state *balancerState, service balancerKey, endpoint string) {
for _, affinity := range state.affinity.affinityMap {
if affinity.endpoint == endpoint {
glog.V(4).Infof("Removing client: %s from affinityMap for service: %s", affinity.endpoint, service)
delete(lb.serviceDtlMap[service].affinityMap, affinity.clientIP)
glog.V(4).Infof("Removing client: %s from affinityMap for service %q", affinity.endpoint, service)
delete(state.affinity.affinityMap, affinity.clientIP)
}
}
}

// Loop through the valid endpoints and then the endpoints associated with the Load Balancer.
// Then remove any session affinity records that are not in both lists.
// This assumes the lb.lock is held.
func updateAffinityMap(lb *LoadBalancerRR, service balancerKey, newEndpoints []string) {
func (lb *LoadBalancerRR) updateAffinityMap(service balancerKey, newEndpoints []string) {
allEndpoints := map[string]int{}
for _, validEndpoint := range newEndpoints {
allEndpoints[validEndpoint] = 1
for _, newEndpoint := range newEndpoints {
allEndpoints[newEndpoint] = 1
}
state, exists := lb.services[service]
if !exists {
return
}
for _, existingEndpoint := range lb.endpointsMap[service] {
for _, existingEndpoint := range state.endpoints {
allEndpoints[existingEndpoint] = allEndpoints[existingEndpoint] + 1
}
for mKey, mVal := range allEndpoints {
if mVal == 1 {
glog.V(3).Infof("Delete endpoint %s for service: %s", mKey, service)
removeSessionAffinityByEndpoint(lb, service, mKey)
delete(lb.serviceDtlMap[service].affinityMap, mKey)
glog.V(3).Infof("Delete endpoint %s for service %q", mKey, service)
removeSessionAffinityByEndpoint(state, service, mKey)
}
}
}
Expand All @@ -212,43 +224,64 @@ func (lb *LoadBalancerRR) OnUpdate(allEndpoints []api.Endpoints) {
registeredEndpoints := make(map[balancerKey]bool)
lb.lock.Lock()
defer lb.lock.Unlock()

// Update endpoints for services.
for _, svcEndpoints := range allEndpoints {
curEndpoints, exists := lb.endpointsMap[balancerKey(svcEndpoints.Name)]
key := balancerKey(svcEndpoints.Name)
state, exists := lb.services[key]
curEndpoints := []string{}
if state != nil {
curEndpoints = state.endpoints
}
newEndpoints := filterValidEndpoints(svcEndpoints.Endpoints)
if !exists || !reflect.DeepEqual(slice.SortStrings(slice.CopyStrings(curEndpoints)), slice.SortStrings(newEndpoints)) {
if !exists || state == nil || len(curEndpoints) != len(newEndpoints) || !slicesEquiv(slice.CopyStrings(curEndpoints), newEndpoints) {
glog.V(3).Infof("LoadBalancerRR: Setting endpoints for %s to %+v", svcEndpoints.Name, svcEndpoints.Endpoints)
updateAffinityMap(lb, balancerKey(svcEndpoints.Name), newEndpoints)
lb.updateAffinityMap(key, newEndpoints)
// On update can be called without NewService being called externally.
// to be safe we will call it here. A new service will only be created
// To be safe we will call it here. A new service will only be created
// if one does not already exist.
lb.newServiceInternal(svcEndpoints.Name, api.AffinityTypeNone, 0)
lb.endpointsMap[balancerKey(svcEndpoints.Name)] = slice.ShuffleStrings(newEndpoints)
state = lb.newServiceInternal(svcEndpoints.Name, api.AffinityTypeNone, 0)
state.endpoints = slice.ShuffleStrings(newEndpoints)

// Reset the round-robin index.
lb.rrIndex[balancerKey(svcEndpoints.Name)] = 0
state.index = 0
}
registeredEndpoints[balancerKey(svcEndpoints.Name)] = true
registeredEndpoints[key] = true
}
// Remove endpoints missing from the update.
for k, v := range lb.endpointsMap {
for k := range lb.services {
if _, exists := registeredEndpoints[k]; !exists {
glog.V(3).Infof("LoadBalancerRR: Removing endpoints for %s -> %+v", k, v)
delete(lb.endpointsMap, k)
delete(lb.serviceDtlMap, k)
glog.V(3).Infof("LoadBalancerRR: Removing endpoints for %s", k)
delete(lb.services, k)
}
}
}

// Tests whether two slices are equivalent. This sorts both slices in-place.
func slicesEquiv(lhs, rhs []string) bool {
if len(lhs) != len(rhs) {
return false
}
if reflect.DeepEqual(slice.SortStrings(lhs), slice.SortStrings(rhs)) {
return true
}
return false
}

func (lb *LoadBalancerRR) CleanupStaleStickySessions(service string) {
lb.lock.Lock()
defer lb.lock.Unlock()

ttlMinutes := lb.serviceDtlMap[balancerKey(service)].ttlMinutes
for ip, affinity := range lb.serviceDtlMap[balancerKey(service)].affinityMap {
if int(time.Now().Sub(affinity.lastUsed).Minutes()) >= ttlMinutes {
glog.V(4).Infof("Removing client: %s from affinityMap for service: %s. Last used is greater than %d minutes....", affinity.clientIP, service, ttlMinutes)
delete(lb.serviceDtlMap[balancerKey(service)].affinityMap, ip)
key := balancerKey(service)
state, exists := lb.services[key]
if !exists {
glog.Warning("CleanupStaleStickySessions called for non-existent balancer key %q", service)
return
}
for ip, affinity := range state.affinity.affinityMap {
if int(time.Now().Sub(affinity.lastUsed).Minutes()) >= state.affinity.ttlMinutes {
glog.V(4).Infof("Removing client %s from affinityMap for service %q", affinity.clientIP, service)
delete(state.affinity.affinityMap, ip)
}
}
}
Loading

0 comments on commit 5dc9896

Please sign in to comment.