GODRIVER-3874 PoC for afterClusterTime.

.gitmodules

@@ -1,3 +1,3 @@
-[submodule "specifications"]
+[submodule "testdata/specifications"]
 	path = testdata/specifications
-	url = https://github.com/mongodb/specifications
+	url = https://github.com/matthewdale/specifications.git

internal/integration/unified/unified_spec_test.go

@@ -39,6 +39,7 @@ var (
 		"mongodb-handshake/tests/unified",
 		"client-backpressure/tests",
 		"transactions/tests/unified",
+		"causal-consistency/tests",
 	}
 	failDirectories = []string{
 		"unified-test-format/tests/valid-fail",

x/mongo/driver/operation.go

@@ -1583,6 +1583,28 @@ func (op Operation) addReadConcern(dst []byte, desc description.SelectedServer)
 		rc = &readconcern.ReadConcern{}
 	}
 
+	// If this is a write operation, then we add an empty read concern so the
+	// following code can set "afterClusterTime". That avoids a data correctness
+	// problem that can happen when there is a network partition in a sharded
+	// cluster. See DRIVERS-3274 for more details.
+	isWrite := op.Name == driverutil.InsertOp ||
+		op.Name == driverutil.UpdateOp ||
+		op.Name == driverutil.FindAndModifyOp ||
+		op.Name == driverutil.DeleteOp ||
+		op.Name == driverutil.BulkWriteOp ||
+		op.Name == driverutil.CreateOp ||
+		op.Name == driverutil.CreateIndexesOp ||
+		op.Name == driverutil.DropOp ||
+		op.Name == driverutil.DropDatabaseOp ||
+		op.Name == driverutil.DropIndexesOp
+	isNotInTxn := client != nil && (client.TransactionState == session.None ||
+		client.TransactionState == session.Committed ||
+		client.TransactionState == session.Aborted ||
+		client.TransactionState == session.Starting)
+	if rc == nil && client != nil && client.Consistent && client.OperationTime != nil && isWrite && isNotInTxn {
+		rc = &readconcern.ReadConcern{}
+	}
+
 	if client != nil && client.Snapshot {
 		if desc.WireVersion.Max < readSnapshotMinWireVersion {
 			return dst, errors.New("snapshot reads require MongoDB 5.0 or later")

x/mongo/driver/operation/create.go

@@ -80,6 +80,7 @@ func (c *Create) Execute(ctx context.Context) error {
 		WriteConcern:      c.writeConcern,
 		ServerAPI:         c.serverAPI,
 		Authenticator:     c.authenticator,
+		Name:              driverutil.CreateOp,
 	}.Execute(ctx)
 }