Xray-core/app/router/balancing.go

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package router
import (
"context"
sync "sync"
"github.com/xtls/xray-core/app/observatory"
"github.com/xtls/xray-core/common"
"github.com/xtls/xray-core/common/errors"
"github.com/xtls/xray-core/core"
"github.com/xtls/xray-core/features/extension"
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"github.com/xtls/xray-core/features/outbound"
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)
type BalancingStrategy interface {
PickOutbound([]string) string
}
type BalancingPrincipleTarget interface {
GetPrincipleTarget([]string) []string
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}
type RoundRobinStrategy struct {
FallbackTag string
ctx context.Context
observatory extension.Observatory
mu sync.Mutex
index int
}
func (s *RoundRobinStrategy) InjectContext(ctx context.Context) {
s.ctx = ctx
}
func (s *RoundRobinStrategy) GetPrincipleTarget(strings []string) []string {
return strings
}
func (s *RoundRobinStrategy) PickOutbound(tags []string) string {
if len(s.FallbackTag) > 0 && s.observatory == nil {
common.Must(core.RequireFeatures(s.ctx, func(observatory extension.Observatory) error {
s.observatory = observatory
return nil
}))
}
if s.observatory != nil {
observeReport, err := s.observatory.GetObservation(s.ctx)
if err == nil {
aliveTags := make([]string, 0)
if result, ok := observeReport.(*observatory.ObservationResult); ok {
status := result.Status
statusMap := make(map[string]*observatory.OutboundStatus)
for _, outboundStatus := range status {
statusMap[outboundStatus.OutboundTag] = outboundStatus
}
for _, candidate := range tags {
if outboundStatus, found := statusMap[candidate]; found {
if outboundStatus.Alive {
aliveTags = append(aliveTags, candidate)
}
} else {
// unfound candidate is considered alive
aliveTags = append(aliveTags, candidate)
}
}
tags = aliveTags
}
}
}
n := len(tags)
if n == 0 {
// goes to fallbackTag
return ""
}
s.mu.Lock()
defer s.mu.Unlock()
tag := tags[s.index%n]
s.index = (s.index + 1) % n
return tag
}
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type Balancer struct {
selectors []string
strategy BalancingStrategy
ohm outbound.Manager
fallbackTag string
override override
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}
// PickOutbound picks the tag of a outbound
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func (b *Balancer) PickOutbound() (string, error) {
candidates, err := b.SelectOutbounds()
if err != nil {
if b.fallbackTag != "" {
errors.LogInfo(context.Background(), "fallback to [", b.fallbackTag, "], due to error: ", err)
return b.fallbackTag, nil
}
return "", err
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}
var tag string
if o := b.override.Get(); o != "" {
tag = o
} else {
tag = b.strategy.PickOutbound(candidates)
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}
if tag == "" {
if b.fallbackTag != "" {
errors.LogInfo(context.Background(), "fallback to [", b.fallbackTag, "], due to empty tag returned")
return b.fallbackTag, nil
}
// will use default handler
return "", errors.New("balancing strategy returns empty tag")
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}
return tag, nil
}
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func (b *Balancer) InjectContext(ctx context.Context) {
if contextReceiver, ok := b.strategy.(extension.ContextReceiver); ok {
contextReceiver.InjectContext(ctx)
}
}
// SelectOutbounds select outbounds with selectors of the Balancer
func (b *Balancer) SelectOutbounds() ([]string, error) {
hs, ok := b.ohm.(outbound.HandlerSelector)
if !ok {
return nil, errors.New("outbound.Manager is not a HandlerSelector")
}
tags := hs.Select(b.selectors)
return tags, nil
}
// GetPrincipleTarget implements routing.BalancerPrincipleTarget
func (r *Router) GetPrincipleTarget(tag string) ([]string, error) {
if b, ok := r.balancers[tag]; ok {
if s, ok := b.strategy.(BalancingPrincipleTarget); ok {
candidates, err := b.SelectOutbounds()
if err != nil {
return nil, errors.New("unable to select outbounds").Base(err)
}
return s.GetPrincipleTarget(candidates), nil
}
return nil, errors.New("unsupported GetPrincipleTarget")
}
return nil, errors.New("cannot find tag")
}
// SetOverrideTarget implements routing.BalancerOverrider
func (r *Router) SetOverrideTarget(tag, target string) error {
if b, ok := r.balancers[tag]; ok {
b.override.Put(target)
return nil
}
return errors.New("cannot find tag")
}
// GetOverrideTarget implements routing.BalancerOverrider
func (r *Router) GetOverrideTarget(tag string) (string, error) {
if b, ok := r.balancers[tag]; ok {
return b.override.Get(), nil
}
return "", errors.New("cannot find tag")
}