Allow to set preferred node id to execute query

Author: dcherednik

CHANGELOG.md

@@ -1,3 +1,5 @@
+* Allow to set preferred node id to execute query
+
 ## v3.90.1
 * Small broken change: added method `ID()` into `spans.Span` interface (need to implement in adapter) 
 * Fixed traceparent header for tracing grpc requests

context.go

@@ -19,3 +19,8 @@ func WithOperationTimeout(ctx context.Context, operationTimeout time.Duration) c
 func WithOperationCancelAfter(ctx context.Context, operationCancelAfter time.Duration) context.Context {
 	return operation.WithCancelAfter(ctx, operationCancelAfter)
 }
+
+// WithPreferredNodeID allows to set preferred node to get session from
+func WithPreferredNodeID(ctx context.Context, nodeID uint32) context.Context {
+	return operation.WithPreferredNodeID(ctx, nodeID)
+}

internal/conn/middleware.go

@@ -4,6 +4,8 @@ import (
 	"context"
 
 	"google.golang.org/grpc"
+
+	balancerContext "github.com/ydb-platform/ydb-go-sdk/v3/internal/endpoint"
 )
 
 var _ grpc.ClientConnInterface = (*middleware)(nil)
@@ -30,6 +32,16 @@ func (m *middleware) NewStream(
 	return m.newStream(ctx, desc, method, opts...)
 }
 
+func ModifyConn(cc grpc.ClientConnInterface, nodeID uint32) grpc.ClientConnInterface {
+	if nodeID != 0 {
+		return WithContextModifier(cc, func(ctx context.Context) context.Context {
+			return balancerContext.WithNodeID(ctx, nodeID)
+		})
+	}
+
+	return cc
+}
+
 func WithContextModifier(
 	cc grpc.ClientConnInterface,
 	modifyCtx func(ctx context.Context) context.Context,

internal/operation/context.go

@@ -8,6 +8,7 @@ import (
 type (
 	ctxOperationTimeoutKey     struct{}
 	ctxOperationCancelAfterKey struct{}
+	ctxWithPreferredNodeIDKey  struct{}
 )
 
 // WithTimeout returns a copy of parent context in which YDB operation timeout
@@ -33,6 +34,10 @@ func WithCancelAfter(ctx context.Context, operationCancelAfter time.Duration) co
 	return context.WithValue(ctx, ctxOperationCancelAfterKey{}, operationCancelAfter)
 }
 
+func WithPreferredNodeID(ctx context.Context, nodeID uint32) context.Context {
+	return context.WithValue(ctx, ctxWithPreferredNodeIDKey{}, nodeID)
+}
+
 // ctxTimeout returns the timeout within given context after which
 // YDB should try to cancel operation and return result regardless of the cancelation.
 func ctxTimeout(ctx context.Context) (d time.Duration, ok bool) {
@@ -57,3 +62,16 @@ func ctxUntilDeadline(ctx context.Context) (time.Duration, bool) {
 
 	return 0, false
 }
+
+func CtxPreferredNodeID(ctx context.Context) uint32 {
+	x := ctx.Value(ctxWithPreferredNodeIDKey{})
+	if x == nil {
+		return 0
+	}
+	val, ok := x.(uint32)
+	if !ok {
+		return 0
+	}
+
+	return val
+}

internal/pool/pool.go

@@ -8,6 +8,7 @@ import (
 
 	"github.com/jonboulle/clockwork"
 
+	"github.com/ydb-platform/ydb-go-sdk/v3/internal/operation"
 	"github.com/ydb-platform/ydb-go-sdk/v3/internal/stack"
 	"github.com/ydb-platform/ydb-go-sdk/v3/internal/xcontext"
 	"github.com/ydb-platform/ydb-go-sdk/v3/internal/xerrors"
@@ -20,6 +21,7 @@ type (
 	Item interface {
 		IsAlive() bool
 		Close(ctx context.Context) error
+		NodeID() uint32
 	}
 	ItemConstraint[T any] interface {
 		*T
@@ -30,7 +32,7 @@ type (
 		clock          clockwork.Clock
 		limit          int
 		createTimeout  time.Duration
-		createItem     func(ctx context.Context) (PT, error)
+		createItem     func(ctx context.Context, preferredNodeID uint32) (PT, error)
 		closeTimeout   time.Duration
 		closeItem      func(ctx context.Context, item PT)
 		idleTimeToLive time.Duration
@@ -48,7 +50,7 @@ type (
 	Pool[PT ItemConstraint[T], T any] struct {
 		config Config[PT, T]
 
-		createItem func(ctx context.Context) (PT, error)
+		createItem func(ctx context.Context, preferredNodeID uint32) (PT, error)
 		closeItem  func(ctx context.Context, item PT)
 
 		mu               xsync.RWMutex
@@ -63,7 +65,7 @@ type (
 	Option[PT ItemConstraint[T], T any] func(c *Config[PT, T])
 )
 
-func WithCreateItemFunc[PT ItemConstraint[T], T any](f func(ctx context.Context) (PT, error)) Option[PT, T] {
+func WithCreateItemFunc[PT ItemConstraint[T], T any](f func(context.Context, uint32) (PT, error)) Option[PT, T] {
 	return func(c *Config[PT, T]) {
 		c.createItem = f
 	}
@@ -173,7 +175,7 @@ func New[PT ItemConstraint[T], T any](
 }
 
 // defaultCreateItem returns a new item
-func defaultCreateItem[T any, PT ItemConstraint[T]](context.Context) (PT, error) {
+func defaultCreateItem[T any, PT ItemConstraint[T]](context.Context, uint32) (PT, error) {
 	var item T
 
 	return &item, nil
@@ -182,8 +184,8 @@ func defaultCreateItem[T any, PT ItemConstraint[T]](context.Context) (PT, error)
 // makeAsyncCreateItemFunc wraps the createItem function with timeout handling
 func makeAsyncCreateItemFunc[PT ItemConstraint[T], T any]( //nolint:funlen
 	p *Pool[PT, T],
-) func(ctx context.Context) (PT, error) {
-	return func(ctx context.Context) (PT, error) {
+) func(ctx context.Context, preferredNodeID uint32) (PT, error) {
+	return func(ctx context.Context, preferredNodeID uint32) (PT, error) {
 		if !xsync.WithLock(&p.mu, func() bool {
 			if len(p.index)+p.createInProgress < p.config.limit {
 				p.createInProgress++
@@ -222,7 +224,7 @@ func makeAsyncCreateItemFunc[PT ItemConstraint[T], T any]( //nolint:funlen
 				defer cancelCreate()
 			}
 
-			newItem, err := p.config.createItem(createCtx)
+			newItem, err := p.config.createItem(createCtx, preferredNodeID)
 			if newItem != nil {
 				p.mu.WithLock(func() {
 					var useCounter uint64
@@ -314,7 +316,7 @@ func (p *Pool[PT, T]) changeState(changeState func() Stats) {
 	}
 }
 
-func (p *Pool[PT, T]) try(ctx context.Context, f func(ctx context.Context, item PT) error) (finalErr error) {
+func (p *Pool[PT, T]) try(ctx context.Context, f func(context.Context, PT) error) (finalErr error) {
 	if onTry := p.config.trace.OnTry; onTry != nil {
 		onDone := onTry(&ctx,
 			stack.FunctionID("github.com/ydb-platform/ydb-go-sdk/v3/internal/pool.(*Pool).try"),
@@ -460,8 +462,13 @@ func (p *Pool[PT, T]) putWaitCh(ch *chan PT) { //nolint:gocritic
 }
 
 // p.mu must be held.
-func (p *Pool[PT, T]) peekFirstIdle() (item PT, touched time.Time) {
+func (p *Pool[PT, T]) peekFirstIdle(preferredNodeID uint32) (item PT, touched time.Time) {
 	el := p.idle.Front()
+	if preferredNodeID != 0 {
+		for el != nil && el.Value.NodeID() != preferredNodeID {
+			el = el.Next()
+		}
+	}
 	if el == nil {
 		return
 	}
@@ -478,8 +485,8 @@ func (p *Pool[PT, T]) peekFirstIdle() (item PT, touched time.Time) {
 // to prevent session from dying in the internalPoolGC after it was returned
 // to be used only in outgoing functions that make session busy.
 // p.mu must be held.
-func (p *Pool[PT, T]) removeFirstIdle() PT {
-	idle, _ := p.peekFirstIdle()
+func (p *Pool[PT, T]) removeFirstIdle(preferredNodeID uint32) PT {
+	idle, _ := p.peekFirstIdle(preferredNodeID)
 	if idle != nil {
 		info := p.removeIdle(idle)
 		p.index[idle] = info
@@ -585,6 +592,8 @@ func (p *Pool[PT, T]) getItem(ctx context.Context) (item PT, finalErr error) { /
 		}
 	}
 
+	preferredNodeID := operation.CtxPreferredNodeID(ctx)
+
 	for ; attempt < maxAttempts; attempt++ {
 		select {
 		case <-p.done:
@@ -593,7 +602,7 @@ func (p *Pool[PT, T]) getItem(ctx context.Context) (item PT, finalErr error) { /
 		}
 
 		if item := xsync.WithLock(&p.mu, func() PT { //nolint:nestif
-			return p.removeFirstIdle()
+			return p.removeFirstIdle(preferredNodeID)
 		}); item != nil {
 			if item.IsAlive() {
 				info := xsync.WithLock(&p.mu, func() itemInfo[PT, T] {
@@ -625,7 +634,7 @@ func (p *Pool[PT, T]) getItem(ctx context.Context) (item PT, finalErr error) { /
 			}
 		}
 
-		item, err := p.createItem(ctx)
+		item, err := p.createItem(ctx, preferredNodeID)
 		if item != nil {
 			return item, nil
 		}