connect

README

Functional requirements

Upon receipt of a Request, the connect Server chain element must send, as a client, a corresponding request to another Server. For clarity, we will refer to the incoming Request to the server as the 'server Request'.

If the server request.GetConnection.GetId() is not associated to an existing client Connection, a new Connection must be established by sending a Request to the Server indicated by the clienturl.ClientURL(ctx).

If the server request.GetConnection.GetId() is associated to an existing client Connection, that client Connection needs to be sent as part of the client request to the server the client connection was received from.

If the server is asked to Close an existing server connection, it should also Close the corresponding client Connection with the server that client Connection was received from. Even if the attempt to Close the client connection fails, it should continue to call down the next.Server(ctx) chain.

Implementation

connectServer

connectServer keeps connInfos connectionInfoMap mapping incoming server Connection.ID to the remote server URL and to the client chain assigned to this URL mapping remote server URL to a connectClient. Notably, on every Close it is deleted from the clients map, so eventually its context will be canceled and the corresponding grpc.ClientConn will be closed.

Care is taken to make sure that each client chain results in one increment of the refcount on its creation, and one decrement when it receives a Close. In this way, we can be sure that clienturl.NewClient(...) context is closed after the last client chain using it has received its Close.

The overall result is that usually, connectServer will have no more than one clienturl.NewClient(...) per clientURL. It may occasionally have more than one in a transient fashion for the lifetime of one or more Connections. In all events it will have zero clienturl.NewClient(...) for a clientURL if it has no server Connections for that clientURL.

connectClient

connectClient handles the instantiation and management of the client connection from the clienturl.ClientURL(ctx) of the server Request.

Monitoring

Both connectServer and connectClient by themselves doesn't monitor gRPC connection for liveness. Every error received from Request, Close is simply returned to the previous chain elements. But there are some cases when connection should be closed and reopened on some event happens. For this purpose connectServer injects into the client chain context a cancel function for this context (cancelctx). When this context becomes canceled, connectClient closes corresponding gRPC connection and connectServer force decreases its refcount to 0.

The most common way for the NSM chains is using heal client for monitoring and canceling the connection, but it also can be implemented in some other way (example using gRPC health check API) or not be implemented at all.

Documentation

Overview

Code generated by "-output client_info_map.gen.go -type clientInfoMap<string,*clientInfo> -output client_info_map.gen.go -type clientInfoMap<string,*clientInfo>"; DO NOT EDIT.

Code generated by "-output connection_info_map.gen.go -type connectionInfoMap<string,connectionInfo> -output connection_info_map.gen.go -type connectionInfoMap<string,connectionInfo>"; DO NOT EDIT.

Package connect is intended to allow passthrough style Endpoints to have a server that also connects to a client

Index

• func NewServer(ctx context.Context, clientFactory ClientFactory, options ...Option) networkservice.NetworkServiceServer
• type ClientFactory
• type Option
  • func WithDialOptions(opts ...grpc.DialOption) Option
  • func WithDialTimeout(dialTimeout time.Duration) Option

Functions

func NewServer

func NewServer(
	ctx context.Context,
	clientFactory ClientFactory,
	options ...Option,
) networkservice.NetworkServiceServer

NewServer - server chain element that creates client subchains and requests them selecting by

clienturlctx.ClientURL(ctx)

Types

type ClientFactory

type ClientFactory = func(ctx context.Context, cc grpc.ClientConnInterface) networkservice.NetworkServiceClient

ClientFactory is used to created new clients when new connection is created.

type Option

type Option func(s *connectServer)

Option is an option for the connect server

func WithDialOptions

func WithDialOptions(opts ...grpc.DialOption) Option

WithDialOptions sets connect server client dial options

func WithDialTimeout

func WithDialTimeout(dialTimeout time.Duration) Option

WithDialTimeout sets connect server client dial timeout