Add connection pool implementation (part 2)

Signed-off-by: Pavel Korotkov <pavel@nspcc.ru>

.test.env

@@ -9,7 +9,7 @@ HTTP_GW_KEEPALIVE_TIMEOUT=300s
 HTTP_GW_KEEPALIVE_TIME=120s
 HTTP_GW_KEEPALIVE_PERMIT_WITHOUT_STREAM=True
 HTTP_GW_CONN_TTL=1h
-HTTP_GW_PEERS_0_WEIGHT=0.6
+HTTP_GW_PEERS_0_WEIGHT=0.4
 HTTP_GW_PEERS_0_ADDRESS=s01.neofs.devenv:8080
-HTTP_GW_PEERS_1_WEIGHT=0.4
+HTTP_GW_PEERS_1_WEIGHT=0.6
 HTTP_GW_PEERS_1_ADDRESS=s02.neofs.devenv:8080

connections/generator.go

@@ -3,7 +3,7 @@ package connections
 import "math/rand"
 
 // https://www.keithschwarz.com/darts-dice-coins/
-type Generator struct {
+type Sampler struct {
 	randomGenerator *rand.Rand
 	probabilities   []float64
 	alias           []int
@@ -22,8 +22,8 @@ func (wl *workList) pop() int {
 	return n
 }
 
-func NewGenerator(probabilities []float64, source rand.Source) *Generator {
-	generator := &Generator{}
+func NewSampler(probabilities []float64, source rand.Source) *Sampler {
+	generator := &Sampler{}
 	var (
 		small workList
 		large workList
@@ -66,7 +66,7 @@ func NewGenerator(probabilities []float64, source rand.Source) *Generator {
 	return generator
 }
 
-func (g *Generator) Next() int {
+func (g *Sampler) Next() int {
 	n := len(g.alias)
 	i := g.randomGenerator.Intn(n)
 	if g.randomGenerator.Float64() < g.probabilities[i] {

connections/pool.go

@@ -6,6 +6,7 @@ import (
 	"errors"
 	"math"
 	"math/rand"
+	"sync"
 	"time"
 
 	"github.com/nspcc-dev/neofs-api-go/pkg/client"
@@ -17,6 +18,8 @@ type PoolBuilderOptions struct {
 	NodeConnectionTimeout   time.Duration
 	NodeRequestTimeout      time.Duration
 	ClientRebalanceInterval time.Duration
+	weights                 []float64
+	connections             []*grpc.ClientConn
 }
 
 type PoolBuilder struct {
@@ -50,7 +53,9 @@ func (pb *PoolBuilder) Build(ctx context.Context, options *PoolBuilderOptions) (
 		}
 		cons[i] = con
 	}
-	return new(pb.weights, options.Key, cons)
+	options.weights = pb.weights
+	options.connections = cons
+	return new(ctx, options)
 }
 
 type Pool interface {
@@ -58,29 +63,70 @@ type Pool interface {
 }
 
 type pool struct {
-	generator *Generator
+	lock    sync.RWMutex
+	sampler *Sampler
 	clients []client.Client
+	healthy []bool
 }
 
-func new(weights []float64, key *ecdsa.PrivateKey, connections []*grpc.ClientConn) (Pool, error) {
-	clients := make([]client.Client, len(weights))
-	for i, con := range connections {
-		c, err := client.New(client.WithDefaultPrivateKey(key), client.WithGRPCConnection(con))
+func new(ctx context.Context, options *PoolBuilderOptions) (Pool, error) {
+	n := len(options.weights)
+	clients := make([]client.Client, n)
+	healthy := make([]bool, n)
+	for i, con := range options.connections {
+		c, err := client.New(client.WithDefaultPrivateKey(options.Key), client.WithGRPCConnection(con))
 		if err != nil {
 			return nil, err
 		}
 		clients[i] = c
+		healthy[i] = true
 	}
 	source := rand.NewSource(time.Now().UnixNano())
-	return &pool{
-		generator: NewGenerator(weights, source),
+	pool := &pool{
+		sampler: NewSampler(options.weights, source),
 		clients: clients,
-	}, nil
+		healthy: healthy,
+	}
+	go func() {
+		ticker := time.NewTimer(options.ClientRebalanceInterval)
+		for range ticker.C {
+			ok := true
+			for i, client := range pool.clients {
+				func() {
+					tctx, c := context.WithTimeout(ctx, options.NodeRequestTimeout)
+					defer c()
+					if _, err := client.EndpointInfo(tctx); err != nil {
+						ok = false
+					}
+					pool.lock.Lock()
+					pool.healthy[i] = ok
+					pool.lock.Unlock()
+				}()
+			}
+			ticker.Reset(options.ClientRebalanceInterval)
+		}
+	}()
+	return pool, nil
 }
 
 func (p *pool) Client() client.Client {
+	p.lock.RLock()
+	defer p.lock.RUnlock()
 	if len(p.clients) == 1 {
+		if p.healthy[0] {
 			return p.clients[0]
 		}
-	return p.clients[p.generator.Next()]
+		return nil
+	}
+	var i *int = nil
+	for k := 0; k < 10; k++ {
+		i_ := p.sampler.Next()
+		if p.healthy[i_] {
+			i = &i_
+		}
+	}
+	if i != nil {
+		return p.clients[*i]
+	}
+	return nil
 }

global/context.go

@@ -10,14 +10,11 @@ import (
 var (
 	globalContext     context.Context
 	globalContextOnce sync.Once
-	globalContextBarrier = make(chan struct{})
 )
 
 func Context() context.Context {
 	globalContextOnce.Do(func() {
 		globalContext, _ = signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM, syscall.SIGHUP)
-		close(globalContextBarrier)
 	})
-	<-globalContextBarrier
 	return globalContext
 }

health._go_

@@ -1,33 +0,0 @@
-package main
-
-import (
-	"github.com/fasthttp/router"
-	"github.com/valyala/fasthttp"
-)
-
-type stater func() error
-
-const (
-	healthyState       = "NeoFS HTTP Gateway is "
-	defaultContentType = "text/plain; charset=utf-8"
-)
-
-func attachHealthy(r *router.Router, e stater) {
-	r.GET("/-/ready/", func(ctx *fasthttp.RequestCtx) {
-		ctx.SetStatusCode(fasthttp.StatusOK)
-		ctx.SetBodyString(healthyState + "ready")
-	})
-	r.GET("/-/healthy/", func(c *fasthttp.RequestCtx) {
-		code := fasthttp.StatusOK
-		msg := "healthy"
-
-		if err := e(); err != nil {
-			msg = "unhealthy: " + err.Error()
-			code = fasthttp.StatusBadRequest
-		}
-		c.Response.Reset()
-		c.SetStatusCode(code)
-		c.SetContentType(defaultContentType)
-		c.SetBodyString(healthyState + msg)
-	})
-}

neofs/client-plant.go

@@ -80,6 +80,9 @@ type neofsClientPlant struct {
 
 func (cp *neofsClientPlant) GetReusableArtifacts(ctx context.Context) (client.Client, *token.SessionToken, error) {
 	c := cp.pool.Client()
+	if c == nil {
+		return nil, nil, errors.New("failed to peek a healthy node to connect to")
+	}
 	st, err := c.CreateSession(ctx, math.MaxUint64)
 	if err != nil {
 		return nil, nil, errors.Wrap(err, "failed to create reusable neofs session token")