Add .LastWrite() method to IsMaster

internal/cluster/is_master.go

@@ -21,6 +21,7 @@ func NewIsMaster(session *mgo.Session) (*IsMaster, error) {
 	return &i, err
 }
 
+// IsMasterDoc returns the raw response from the MongoDB 'isMaster' server command.
 func (i *IsMaster) IsMasterDoc() *mdbstructs.IsMaster {
 	return i.isMaster
 }
@@ -74,3 +75,9 @@ func (i *IsMaster) IsShardedCluster() bool {
 	}
 	return false
 }
+
+// LastWrite returns the last write to the MongoDB database as a
+// bson.MongoTimestamp
+func (i *IsMaster) LastWrite() bson.MongoTimestamp {
+	return i.isMaster.LastWrite.OpTime.Ts
+}

internal/cluster/is_master_test.go

@@ -4,7 +4,9 @@ import (
 	"testing"
 
 	"github.com/globalsign/mgo"
+	"github.com/globalsign/mgo/bson"
 	"github.com/percona/mongodb-backup/internal/testutils"
+	"github.com/percona/mongodb-backup/mdbstructs"
 )
 
 func TestNewIsMaster(t *testing.T) {
@@ -151,3 +153,19 @@ func TestIsMasterIsShardServer(t *testing.T) {
 		t.Fatalf("Expected false from .IsShardServer()")
 	}
 }
+
+func TestIsMasterLastWrite(t *testing.T) {
+	ts, _ := bson.NewMongoTimestamp(bson.Now(), 0)
+	isMaster := &IsMaster{
+		isMaster: &mdbstructs.IsMaster{
+			LastWrite: mdbstructs.IsMasterLastWrite{
+				OpTime: &mdbstructs.OpTime{
+					Ts: ts,
+				},
+			},
+		},
+	}
+	if isMaster.LastWrite() != ts {
+		t.Fatalf("Got invalid timestamp from .LastWrite()! Expected %v, got %v", ts, isMaster.LastWrite())
+	}
+}

internal/oplog/oplog_tail.go

@@ -274,7 +274,7 @@ func (ot *OplogTail) tailQuery() bson.M {
 		return query
 	}
 
-	query["ts"] = bson.M{"$gt": isMaster.IsMasterDoc().LastWrite.OpTime.Ts}
+	query["ts"] = bson.M{"$gt": isMaster.LastWrite()}
 	return query
 }
 

mdbstructs/is_master.go

@@ -6,34 +6,37 @@ import (
 	"github.com/globalsign/mgo/bson"
 )
 
+// IsMasterLastWrite represents the last write to the MongoDB server
+type IsMasterLastWrite struct {
+	OpTime            *OpTime   `bson:"opTime"`
+	LastWriteDate     time.Time `bson:"lastWriteDate"`
+	MajorityOpTime    *OpTime   `bson:"majorityTime"`
+	MajorityWriteDate time.Time `bson:"majorityWriteDate"`
+}
+
 // IsMaster represents the document returned by db.runCommand( { isMaster: 1 } )
 type IsMaster struct {
-	Hosts                        []string  `bson:"hosts,omitempty"`
-	IsMaster                     bool      `bson:"ismaster"`
-	Msg                          string    `bson:"msg"`
-	MaxBsonObjectSise            int64     `bson:"maxBsonObjectSize"`
-	MaxMessageSizeBytes          int64     `bson:"maxMessageSizeBytes"`
-	MaxWriteBatchSize            int64     `bson:"maxWriteBatchSize"`
-	LocalTime                    time.Time `bson:"localTime"`
-	LogicalSessionTimeoutMinutes int64     `bson:"logicalSessionTimeoutMinutes"`
-	MaxWireVersion               int64     `bson:"maxWireVersion"`
-	MinWireVersion               int64     `bson:"minWireVersion"`
-	Ok                           int       `bson:"ok"`
-	SetName                      string    `bson:"setName,omitempty"`
-	SetVersion                   string    `bson:"setVersion,omitempty"`
-	Primary                      string    `bson:"primary,omitempty"`
-	Secondary                    bool      `bson:"secondary,omitempty"`
-	Hidden                       bool      `bson:"hidden,omitempty"`
-	ConfigSvr                    int       `bson:"configsvr,omitempty"`
-	Me                           string    `bson:"me"`
-	LastWrite                    struct {
-		OpTime            *OpTime   `bson:"opTime"`
-		LastWriteDate     time.Time `bson:"lastWriteDate"`
-		MajorityOpTime    *OpTime   `bson:"majorityTime"`
-		MajorityWriteDate time.Time `bson:"majorityWriteDate"`
-	} `bson:"lastWrite"`
-	ClusterTime       *ClusterTime         `bson:"$clusterTime,omitempty"`
-	ConfigServerState *ConfigServerState   `bson:"$configServerState,omitempty"`
-	GleStats          *GleStats            `bson:"$gleStats,omitempty"`
-	OperationTime     *bson.MongoTimestamp `bson:"operationTime,omitempty"`
+	Hosts                        []string             `bson:"hosts,omitempty"`
+	IsMaster                     bool                 `bson:"ismaster"`
+	Msg                          string               `bson:"msg"`
+	MaxBsonObjectSise            int64                `bson:"maxBsonObjectSize"`
+	MaxMessageSizeBytes          int64                `bson:"maxMessageSizeBytes"`
+	MaxWriteBatchSize            int64                `bson:"maxWriteBatchSize"`
+	LocalTime                    time.Time            `bson:"localTime"`
+	LogicalSessionTimeoutMinutes int64                `bson:"logicalSessionTimeoutMinutes"`
+	MaxWireVersion               int64                `bson:"maxWireVersion"`
+	MinWireVersion               int64                `bson:"minWireVersion"`
+	Ok                           int                  `bson:"ok"`
+	SetName                      string               `bson:"setName,omitempty"`
+	SetVersion                   string               `bson:"setVersion,omitempty"`
+	Primary                      string               `bson:"primary,omitempty"`
+	Secondary                    bool                 `bson:"secondary,omitempty"`
+	Hidden                       bool                 `bson:"hidden,omitempty"`
+	ConfigSvr                    int                  `bson:"configsvr,omitempty"`
+	Me                           string               `bson:"me"`
+	LastWrite                    IsMasterLastWrite    `bson:"lastWrite"`
+	ClusterTime                  *ClusterTime         `bson:"$clusterTime,omitempty"`
+	ConfigServerState            *ConfigServerState   `bson:"$configServerState,omitempty"`
+	GleStats                     *GleStats            `bson:"$gleStats,omitempty"`
+	OperationTime                *bson.MongoTimestamp `bson:"operationTime,omitempty"`
 }