GODRIVER-2742 Do not perform server selection to determine sessions s…

…upport (mongodb#1295)

Co-authored-by: Matt Dale <9760375+matthewdale@users.noreply.github.com>
Co-authored-by: Kevin Albertson <kevin.albertson@10gen.com>

internal/assert/assertions.go

@@ -899,6 +899,29 @@ func EqualError(t TestingT, theError error, errString string, msgAndArgs ...inte
 	return true
 }
 
+// ErrorIs asserts that at least one of the errors in err's chain matches target.
+// This is a wrapper for errors.Is.
+func ErrorIs(t TestingT, err, target error, msgAndArgs ...interface{}) bool {
+	if h, ok := t.(tHelper); ok {
+		h.Helper()
+	}
+	if errors.Is(err, target) {
+		return true
+	}
+
+	var expectedText string
+	if target != nil {
+		expectedText = target.Error()
+	}
+
+	chain := buildErrorChainString(err)
+
+	return Fail(t, fmt.Sprintf("Target error should be in err chain:\n"+
+		"expected: %q\n"+
+		"in chain: %s", expectedText, chain,
+	), msgAndArgs...)
+}
+
 // ErrorContains asserts that a function returned an error (i.e. not `nil`)
 // and that the error contains the specified substring.
 //
@@ -1036,3 +1059,17 @@ func Eventually(t TestingT, condition func() bool, waitFor time.Duration, tick t
 		}
 	}
 }
+
+func buildErrorChainString(err error) string {
+	if err == nil {
+		return ""
+	}
+
+	e := errors.Unwrap(err)
+	chain := fmt.Sprintf("%q", err.Error())
+	for e != nil {
+		chain += fmt.Sprintf("\n\t%q", e.Error())
+		e = errors.Unwrap(e)
+	}
+	return chain
+}

internal/ptrutil/int64.go

@@ -0,0 +1,39 @@
+// Copyright (C) MongoDB, Inc. 2023-present.
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License. You may obtain
+// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+
+package ptrutil
+
+// CompareInt64 is a piecewise function with the following return conditions:
+//
+// (1)  2, ptr1 != nil AND ptr2 == nil
+// (2)  1, *ptr1 > *ptr2
+// (3)  0, ptr1 == ptr2 or *ptr1 == *ptr2
+// (4) -1, *ptr1 < *ptr2
+// (5) -2, ptr1 == nil AND ptr2 != nil
+func CompareInt64(ptr1, ptr2 *int64) int {
+	if ptr1 == ptr2 {
+		// This will catch the double nil or same-pointer cases.
+		return 0
+	}
+
+	if ptr1 == nil && ptr2 != nil {
+		return -2
+	}
+
+	if ptr1 != nil && ptr2 == nil {
+		return 2
+	}
+
+	if *ptr1 > *ptr2 {
+		return 1
+	}
+
+	if *ptr1 < *ptr2 {
+		return -1
+	}
+
+	return 0
+}

internal/ptrutil/int64_test.go

@@ -0,0 +1,76 @@
+// Copyright (C) MongoDB, Inc. 2023-present.
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License. You may obtain
+// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+
+package ptrutil
+
+import (
+	"testing"
+
+	"go.mongodb.org/mongo-driver/internal/assert"
+)
+
+func TestCompareInt64(t *testing.T) {
+	t.Parallel()
+
+	int64ToPtr := func(i64 int64) *int64 { return &i64 }
+	int64Ptr := int64ToPtr(1)
+
+	tests := []struct {
+		name       string
+		ptr1, ptr2 *int64
+		want       int
+	}{
+		{
+			name: "empty",
+			want: 0,
+		},
+		{
+			name: "ptr1 nil",
+			ptr2: int64ToPtr(1),
+			want: -2,
+		},
+		{
+			name: "ptr2 nil",
+			ptr1: int64ToPtr(1),
+			want: 2,
+		},
+		{
+			name: "ptr1 and ptr2 have same value, different address",
+			ptr1: int64ToPtr(1),
+			ptr2: int64ToPtr(1),
+			want: 0,
+		},
+		{
+			name: "ptr1 and ptr2 have the same address",
+			ptr1: int64Ptr,
+			ptr2: int64Ptr,
+			want: 0,
+		},
+		{
+			name: "ptr1 GT ptr2",
+			ptr1: int64ToPtr(1),
+			ptr2: int64ToPtr(0),
+			want: 1,
+		},
+		{
+			name: "ptr1 LT ptr2",
+			ptr1: int64ToPtr(0),
+			ptr2: int64ToPtr(1),
+			want: -1,
+		},
+	}
+
+	for _, test := range tests {
+		test := test // capture the range variable
+
+		t.Run(test.name, func(t *testing.T) {
+			t.Parallel()
+
+			got := CompareInt64(test.ptr1, test.ptr2)
+			assert.Equal(t, test.want, got, "compareInt64() = %v, wanted %v", got, test.want)
+		})
+	}
+}

mongo/description/server.go

@@ -14,6 +14,7 @@ import (
 	"go.mongodb.org/mongo-driver/bson"
 	"go.mongodb.org/mongo-driver/bson/primitive"
 	"go.mongodb.org/mongo-driver/internal"
+	"go.mongodb.org/mongo-driver/internal/ptrutil"
 	"go.mongodb.org/mongo-driver/mongo/address"
 	"go.mongodb.org/mongo-driver/tag"
 )
@@ -31,35 +32,37 @@ type SelectedServer struct {
 type Server struct {
 	Addr address.Address
 
-	Arbiters              []string
-	AverageRTT            time.Duration
-	AverageRTTSet         bool
-	Compression           []string // compression methods returned by server
-	CanonicalAddr         address.Address
-	ElectionID            primitive.ObjectID
-	HeartbeatInterval     time.Duration
-	HelloOK               bool
-	Hosts                 []string
-	IsCryptd              bool
-	LastError             error
-	LastUpdateTime        time.Time
-	LastWriteTime         time.Time
-	MaxBatchCount         uint32
-	MaxDocumentSize       uint32
-	MaxMessageSize        uint32
-	Members               []address.Address
-	Passives              []string
-	Passive               bool
-	Primary               address.Address
-	ReadOnly              bool
-	ServiceID             *primitive.ObjectID // Only set for servers that are deployed behind a load balancer.
-	SessionTimeoutMinutes uint32
-	SetName               string
-	SetVersion            uint32
-	Tags                  tag.Set
-	TopologyVersion       *TopologyVersion
-	Kind                  ServerKind
-	WireVersion           *VersionRange
+	Arbiters          []string
+	AverageRTT        time.Duration
+	AverageRTTSet     bool
+	Compression       []string // compression methods returned by server
+	CanonicalAddr     address.Address
+	ElectionID        primitive.ObjectID
+	HeartbeatInterval time.Duration
+	HelloOK           bool
+	Hosts             []string
+	IsCryptd          bool
+	LastError         error
+	LastUpdateTime    time.Time
+	LastWriteTime     time.Time
+	MaxBatchCount     uint32
+	MaxDocumentSize   uint32
+	MaxMessageSize    uint32
+	Members           []address.Address
+	Passives          []string
+	Passive           bool
+	Primary           address.Address
+	ReadOnly          bool
+	ServiceID         *primitive.ObjectID // Only set for servers that are deployed behind a load balancer.
+	// Deprecated: Use SessionTimeoutMinutesPtr instead.
+	SessionTimeoutMinutes    uint32
+	SessionTimeoutMinutesPtr *int64
+	SetName                  string
+	SetVersion               uint32
+	Tags                     tag.Set
+	TopologyVersion          *TopologyVersion
+	Kind                     ServerKind
+	WireVersion              *VersionRange
 }
 
 // NewServer creates a new server description from the given hello command response.
@@ -166,7 +169,9 @@ func NewServer(addr address.Address, response bson.Raw) Server {
 				desc.LastError = fmt.Errorf("expected 'logicalSessionTimeoutMinutes' to be an integer but it's a BSON %s", element.Value().Type)
 				return desc
 			}
+
 			desc.SessionTimeoutMinutes = uint32(i64)
+			desc.SessionTimeoutMinutesPtr = &i64
 		case "maxBsonObjectSize":
 			i64, ok := element.Value().AsInt64OK()
 			if !ok {
@@ -462,7 +467,7 @@ func (s Server) Equal(other Server) bool {
 		return false
 	}
 
-	if s.SessionTimeoutMinutes != other.SessionTimeoutMinutes {
+	if ptrutil.CompareInt64(s.SessionTimeoutMinutesPtr, other.SessionTimeoutMinutesPtr) != 0 {
 		return false
 	}
 

mongo/description/server_test.go

@@ -18,6 +18,8 @@ import (
 )
 
 func TestServer(t *testing.T) {
+	int64ToPtr := func(i64 int64) *int64 { return &i64 }
+
 	t.Run("equals", func(t *testing.T) {
 		defaultServer := Server{}
 		// Only some of the Server fields affect equality
@@ -46,7 +48,14 @@ func TestServer(t *testing.T) {
 			{"passive", Server{Passive: true}, true},
 			{"primary", Server{Primary: address.Address("foo")}, false},
 			{"readOnly", Server{ReadOnly: true}, true},
-			{"sessionTimeoutMinutes", Server{SessionTimeoutMinutes: 1}, false},
+			{
+				"sessionTimeoutMinutes",
+				Server{
+					SessionTimeoutMinutesPtr: int64ToPtr(1),
+					SessionTimeoutMinutes:    1,
+				},
+				false,
+			},
 			{"setName", Server{SetName: "foo"}, false},
 			{"setVersion", Server{SetVersion: 1}, false},
 			{"tags", Server{Tags: tag.Set{tag.Tag{"foo", "bar"}}}, false},

mongo/description/topology.go

@@ -14,11 +14,13 @@ import (
 
 // Topology contains information about a MongoDB cluster.
 type Topology struct {
-	Servers               []Server
-	SetName               string
-	Kind                  TopologyKind
-	SessionTimeoutMinutes uint32
-	CompatibilityErr      error
+	Servers []Server
+	SetName string
+	Kind    TopologyKind
+	// Deprecated: Use SessionTimeoutMinutesPtr instead.
+	SessionTimeoutMinutes    uint32
+	SessionTimeoutMinutesPtr *int64
+	CompatibilityErr         error
 }
 
 // String implements the Stringer interface.

mongo/integration/mtest/opmsg_deployment.go

@@ -21,23 +21,28 @@ import (
 )
 
 const (
-	serverAddress                = address.Address("localhost:27017")
-	maxDocumentSize       uint32 = 16777216
-	maxMessageSize        uint32 = 48000000
-	maxBatchCount         uint32 = 100000
-	sessionTimeoutMinutes uint32 = 30
+	serverAddress          = address.Address("localhost:27017")
+	maxDocumentSize uint32 = 16777216
+	maxMessageSize  uint32 = 48000000
+	maxBatchCount   uint32 = 100000
 )
 
 var (
+	sessionTimeoutMinutes      uint32 = 30
+	sessionTimeoutMinutesInt64        = int64(sessionTimeoutMinutes)
+
 	// MockDescription is the server description used for the mock deployment. Each mocked connection returns this
 	// value from its Description method.
 	MockDescription = description.Server{
-		CanonicalAddr:         serverAddress,
-		MaxDocumentSize:       maxDocumentSize,
-		MaxMessageSize:        maxMessageSize,
-		MaxBatchCount:         maxBatchCount,
-		SessionTimeoutMinutes: sessionTimeoutMinutes,
-		Kind:                  description.RSPrimary,
+		CanonicalAddr:   serverAddress,
+		MaxDocumentSize: maxDocumentSize,
+		MaxMessageSize:  maxMessageSize,
+		MaxBatchCount:   maxBatchCount,
+		// TODO(GODRIVER-2885): This can be removed once legacy
+		// SessionTimeoutMinutes is removed.
+		SessionTimeoutMinutes:    sessionTimeoutMinutes,
+		SessionTimeoutMinutesPtr: &sessionTimeoutMinutesInt64,
+		Kind:                     description.RSPrimary,
 		WireVersion: &description.VersionRange{
 			Max: topology.SupportedWireVersions.Max,
 		},
@@ -162,7 +167,12 @@ func (md *mockDeployment) Disconnect(context.Context) error {
 func (md *mockDeployment) Subscribe() (*driver.Subscription, error) {
 	if md.updates == nil {
 		md.updates = make(chan description.Topology, 1)
+
 		md.updates <- description.Topology{
+			SessionTimeoutMinutesPtr: &sessionTimeoutMinutesInt64,
+
+			// TODO(GODRIVER-2885): This can be removed once legacy
+			// SessionTimeoutMinutes is removed.
 			SessionTimeoutMinutes: sessionTimeoutMinutes,
 		}
 	}