refactor: remove forward auth, move module net/http to net/gphttp

internal/net/gphttp/loadbalancer/loadbalancer.go

@@ -0,0 +1,314 @@
+package loadbalancer
+
+import (
+	"net/http"
+	"sync"
+	"time"
+
+	"github.com/rs/zerolog"
+	"github.com/yusing/go-proxy/internal/gperr"
+	"github.com/yusing/go-proxy/internal/logging"
+	"github.com/yusing/go-proxy/internal/net/gphttp/httpheaders"
+	"github.com/yusing/go-proxy/internal/net/gphttp/loadbalancer/types"
+	"github.com/yusing/go-proxy/internal/route/routes"
+	"github.com/yusing/go-proxy/internal/task"
+	"github.com/yusing/go-proxy/internal/watcher/health"
+	"github.com/yusing/go-proxy/internal/watcher/health/monitor"
+)
+
+// TODO: stats of each server.
+// TODO: support weighted mode.
+type (
+	impl interface {
+		ServeHTTP(srvs Servers, rw http.ResponseWriter, r *http.Request)
+		OnAddServer(srv Server)
+		OnRemoveServer(srv Server)
+	}
+
+	LoadBalancer struct {
+		impl
+		*Config
+
+		task *task.Task
+
+		pool   Pool
+		poolMu sync.Mutex
+
+		sumWeight Weight
+		startTime time.Time
+
+		l zerolog.Logger
+	}
+)
+
+const maxWeight Weight = 100
+
+func New(cfg *Config) *LoadBalancer {
+	lb := &LoadBalancer{
+		Config: new(Config),
+		pool:   types.NewServerPool(),
+		l:      logging.With().Str("name", cfg.Link).Logger(),
+	}
+	lb.UpdateConfigIfNeeded(cfg)
+	return lb
+}
+
+// Start implements task.TaskStarter.
+func (lb *LoadBalancer) Start(parent task.Parent) gperr.Error {
+	lb.startTime = time.Now()
+	lb.task = parent.Subtask("loadbalancer."+lb.Link, false)
+	parent.OnCancel("lb_remove_route", func() {
+		routes.DeleteHTTPRoute(lb.Link)
+	})
+	lb.task.OnFinished("cleanup", func() {
+		if lb.impl != nil {
+			lb.pool.RangeAll(func(k string, v Server) {
+				lb.impl.OnRemoveServer(v)
+			})
+		}
+	})
+	return nil
+}
+
+// Task implements task.TaskStarter.
+func (lb *LoadBalancer) Task() *task.Task {
+	return lb.task
+}
+
+// Finish implements task.TaskFinisher.
+func (lb *LoadBalancer) Finish(reason any) {
+	lb.task.Finish(reason)
+}
+
+func (lb *LoadBalancer) updateImpl() {
+	switch lb.Mode {
+	case types.ModeUnset, types.ModeRoundRobin:
+		lb.impl = lb.newRoundRobin()
+	case types.ModeLeastConn:
+		lb.impl = lb.newLeastConn()
+	case types.ModeIPHash:
+		lb.impl = lb.newIPHash()
+	default: // should happen in test only
+		lb.impl = lb.newRoundRobin()
+	}
+	lb.pool.RangeAll(func(_ string, srv Server) {
+		lb.impl.OnAddServer(srv)
+	})
+}
+
+func (lb *LoadBalancer) UpdateConfigIfNeeded(cfg *Config) {
+	if cfg != nil {
+		lb.poolMu.Lock()
+		defer lb.poolMu.Unlock()
+
+		lb.Link = cfg.Link
+
+		if lb.Mode == types.ModeUnset && cfg.Mode != types.ModeUnset {
+			lb.Mode = cfg.Mode
+			if !lb.Mode.ValidateUpdate() {
+				lb.l.Error().Msgf("invalid mode %q, fallback to %q", cfg.Mode, lb.Mode)
+			}
+			lb.updateImpl()
+		}
+
+		if len(lb.Options) == 0 && len(cfg.Options) > 0 {
+			lb.Options = cfg.Options
+		}
+	}
+
+	if lb.impl == nil {
+		lb.updateImpl()
+	}
+}
+
+func (lb *LoadBalancer) AddServer(srv Server) {
+	lb.poolMu.Lock()
+	defer lb.poolMu.Unlock()
+
+	if lb.pool.Has(srv.Key()) { // FIXME: this should be a warning
+		old, _ := lb.pool.Load(srv.Key())
+		lb.sumWeight -= old.Weight()
+		lb.impl.OnRemoveServer(old)
+	}
+	lb.pool.Store(srv.Key(), srv)
+	lb.sumWeight += srv.Weight()
+
+	lb.rebalance()
+	lb.impl.OnAddServer(srv)
+
+	lb.l.Debug().
+		Str("action", "add").
+		Str("server", srv.Name()).
+		Msgf("%d servers available", lb.pool.Size())
+}
+
+func (lb *LoadBalancer) RemoveServer(srv Server) {
+	lb.poolMu.Lock()
+	defer lb.poolMu.Unlock()
+
+	if !lb.pool.Has(srv.Key()) {
+		return
+	}
+
+	lb.pool.Delete(srv.Key())
+
+	lb.sumWeight -= srv.Weight()
+	lb.rebalance()
+	lb.impl.OnRemoveServer(srv)
+
+	lb.l.Debug().
+		Str("action", "remove").
+		Str("server", srv.Name()).
+		Msgf("%d servers left", lb.pool.Size())
+
+	if lb.pool.Size() == 0 {
+		lb.task.Finish("no server left")
+		return
+	}
+}
+
+func (lb *LoadBalancer) rebalance() {
+	if lb.sumWeight == maxWeight {
+		return
+	}
+
+	poolSize := lb.pool.Size()
+	if poolSize == 0 {
+		return
+	}
+	if lb.sumWeight == 0 { // distribute evenly
+		weightEach := maxWeight / Weight(poolSize)
+		remainder := maxWeight % Weight(poolSize)
+		lb.pool.RangeAll(func(_ string, s Server) {
+			w := weightEach
+			lb.sumWeight += weightEach
+			if remainder > 0 {
+				w++
+				remainder--
+			}
+			s.SetWeight(w)
+		})
+		return
+	}
+
+	// scale evenly
+	scaleFactor := float64(maxWeight) / float64(lb.sumWeight)
+	lb.sumWeight = 0
+
+	lb.pool.RangeAll(func(_ string, s Server) {
+		s.SetWeight(Weight(float64(s.Weight()) * scaleFactor))
+		lb.sumWeight += s.Weight()
+	})
+
+	delta := maxWeight - lb.sumWeight
+	if delta == 0 {
+		return
+	}
+	lb.pool.Range(func(_ string, s Server) bool {
+		if delta == 0 {
+			return false
+		}
+		if delta > 0 {
+			s.SetWeight(s.Weight() + 1)
+			lb.sumWeight++
+			delta--
+		} else {
+			s.SetWeight(s.Weight() - 1)
+			lb.sumWeight--
+			delta++
+		}
+		return true
+	})
+}
+
+func (lb *LoadBalancer) ServeHTTP(rw http.ResponseWriter, r *http.Request) {
+	srvs := lb.availServers()
+	if len(srvs) == 0 {
+		http.Error(rw, "Service unavailable", http.StatusServiceUnavailable)
+		return
+	}
+	if r.Header.Get(httpheaders.HeaderGoDoxyCheckRedirect) != "" {
+		// wake all servers
+		for _, srv := range srvs {
+			if err := srv.TryWake(); err != nil {
+				lb.l.Warn().Err(err).
+					Str("server", srv.Name()).
+					Msg("failed to wake server")
+			}
+		}
+	}
+	lb.impl.ServeHTTP(srvs, rw, r)
+}
+
+// MarshalJSON implements health.HealthMonitor.
+func (lb *LoadBalancer) MarshalJSON() ([]byte, error) {
+	extra := make(map[string]any)
+	lb.pool.RangeAll(func(k string, v Server) {
+		extra[v.Key()] = v
+	})
+
+	return (&monitor.JSONRepresentation{
+		Name:    lb.Name(),
+		Status:  lb.Status(),
+		Started: lb.startTime,
+		Uptime:  lb.Uptime(),
+		Extra: map[string]any{
+			"config": lb.Config,
+			"pool":   extra,
+		},
+	}).MarshalJSON()
+}
+
+// Name implements health.HealthMonitor.
+func (lb *LoadBalancer) Name() string {
+	return lb.Link
+}
+
+// Status implements health.HealthMonitor.
+func (lb *LoadBalancer) Status() health.Status {
+	if lb.pool.Size() == 0 {
+		return health.StatusUnknown
+	}
+
+	isHealthy := true
+	lb.pool.Range(func(_ string, srv Server) bool {
+		if srv.Status().Bad() {
+			isHealthy = false
+			return false
+		}
+		return true
+	})
+	if !isHealthy {
+		return health.StatusUnhealthy
+	}
+	return health.StatusHealthy
+}
+
+// Uptime implements health.HealthMonitor.
+func (lb *LoadBalancer) Uptime() time.Duration {
+	return time.Since(lb.startTime)
+}
+
+// Latency implements health.HealthMonitor.
+func (lb *LoadBalancer) Latency() time.Duration {
+	var sum time.Duration
+	lb.pool.RangeAll(func(_ string, srv Server) {
+		sum += srv.Latency()
+	})
+	return sum
+}
+
+// String implements health.HealthMonitor.
+func (lb *LoadBalancer) String() string {
+	return lb.Name()
+}
+
+func (lb *LoadBalancer) availServers() []Server {
+	avail := make([]Server, 0, lb.pool.Size())
+	lb.pool.RangeAll(func(_ string, srv Server) {
+		if srv.Status().Good() {
+			avail = append(avail, srv)
+		}
+	})
+	return avail
+}