micro/network/node.go

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package network
import (
"runtime/debug"
"sync"
"time"
"github.com/google/uuid"
"github.com/micro/go-micro/codec/proto"
"github.com/micro/go-micro/registry"
"github.com/micro/go-micro/transport"
"github.com/micro/go-micro/util/log"
pb "github.com/micro/go-micro/network/proto"
)
type node struct {
*network
// closed channel
closed chan bool
mtx sync.RWMutex
// the node id
id string
// address of this node
address string
// the node registry
registry registry.Registry
// the base level transport
transport transport.Transport
// the listener
listener transport.Listener
// leases for connections to us
// link id:link
links map[string]*link
}
// network methods
func newNode(n *network) (*node, error) {
// create a new node
node := new(node)
// closed channel
node.closed = make(chan bool)
// set the nodes network
node.network = n
// initially we have no id
// create an id and address
// TODO: create a real unique id and address
// lease := n.lease()
// set the node id
// node.id = lease.Node.Id
// get the transport we're going to use for our tunnels
t, ok := n.Options.Values().Get("network.transport")
if ok {
node.transport = t.(transport.Transport)
} else {
// TODO: set to quic
node.transport = transport.DefaultTransport
}
// we listen on a random address, this is not advertised
// TODO: use util/addr to get something anyone in the same private network can talk to
l, err := node.transport.Listen(":0")
if err != nil {
return nil, err
}
// set the listener
node.listener = l
// TODO: this should be an overlay address
// ideally received via some dhcp style broadcast
node.address = l.Addr()
// TODO: start the router and broadcast advertisements
// receive updates and push them to the network in accept(l) below
// chan, err := n.router.Advertise()
// u <- chan
// socket.send("route", u)
// u := socket.recv() => r.router.Update(u)
// process any incoming messages on the listener
// this is our inbound network connection
node.accept(l)
// register the node with the registry for the network
// TODO: use a registrar or something else for local things
r, ok := n.Options.Values().Get("network.registry")
if ok {
node.registry = r.(registry.Registry)
} else {
node.registry = registry.DefaultRegistry
}
// lookup the network to see if there's any nodes
records := n.lookup(node.registry)
// should we actually do this?
if len(records) == 0 {
// set your own node id
lease := n.lease()
node.id = lease.Node.Id
}
// register self with the network registry
// this is a local registry of nodes separate to the resolver
// maybe consolidate registry/resolver
// TODO: find a way to do this via gossip or something else
if err := node.registry.Register(&registry.Service{
// register with the network id
Name: "network:" + n.Id(),
Nodes: []*registry.Node{
{Id: node.id, Address: node.address},
},
}); err != nil {
node.Close()
return nil, err
}
// create a channel to get links
linkChan := make(chan *link, 1)
// we're going to wait for the first connection
go node.connect(linkChan)
// wait forever to connect
// TODO: do something with the links we receive
<-linkChan
return node, nil
}
// node methods
// Accept processes the incoming messages on its listener.
// This listener was created with the first call to network.Connect.
// Any inbound new socket here is essentially something else attempting
// to connect to the network. So we turn it into a socket, then process it.
func (n *node) accept(l transport.Listener) error {
return l.Accept(func(sock transport.Socket) {
defer func() {
// close socket
sock.Close()
if r := recover(); r != nil {
log.Log("panic recovered: ", r)
log.Log(string(debug.Stack()))
}
}()
// create a new link
// generate a new link
link := &link{
node: n,
id: uuid.New().String(),
}
// create a new network socket
sk := new(socket)
sk.node = n
sk.codec = proto.Marshaler{}
sk.socket = sock
// set link socket
link.socket = sk
// accept messages on the socket
// blocks forever or until error
if err := link.up(); err != nil {
// TODO: delete link
}
})
}
// connect attempts to periodically connect to new nodes in the network.
// It will only do this if it has less than 3 connections. this method
// is called by network.Connect and fired in a go routine after establishing
// the first connection and creating a node. The node attempts to maintain
// its connection to the network via multiple links.
func (n *node) connect(linkChan chan *link) {
// TODO: adjustable ticker
t := time.NewTicker(time.Second)
var lease *pb.Lease
for {
select {
// on every tick check the number of links and then attempt
// to connect to new nodes if we don't have sufficient links
case <-t.C:
n.mtx.RLock()
// only start processing if we have less than 3 links
if len(n.links) > 2 {
n.mtx.RUnlock()
continue
}
// get a list of link addresses so we don't reconnect
// to the ones we're already connected to
nodes := map[string]bool{}
for _, l := range n.links {
nodes[l.lease.Node.Address] = true
}
n.mtx.RUnlock()
records := n.network.lookup(n.registry)
// for each record check we haven't already got a connection
// attempt to dial it, create a new socket and call
// connect with our existing network lease.
// if its the first call we don't actually have a lease
// TODO: determine how to prioritise local records
// while still connecting to the global network
for _, record := range records {
// skip existing connections
if nodes[record.Address] {
continue
}
// attempt to connect and create a link
// connect to the node
s, err := n.transport.Dial(record.Address)
if err != nil {
continue
}
// create a new socket
sk := &socket{
node: n,
codec: &proto.Marshaler{},
socket: s,
}
// broadcast a "connect" request and get back "lease"
// this is your tunnel to the outside world and to the network
// then push updates and messages over this link
// first connect will not have a lease so we get one with node id/address
l, err := sk.connect(lease)
if err != nil {
s.Close()
continue
}
// set lease for next time
lease = l
// create a new link with the lease and socket
link := &link{
id: uuid.New().String(),
lease: lease,
node: n,
queue: make(chan *Message, 128),
socket: sk,
}
// bring up the link
go link.up()
// save the new link
n.mtx.Lock()
n.links[link.id] = link
n.mtx.Unlock()
// drop this down the link channel to the network
// so it can manage the links
select {
case linkChan <- link:
// we don't wait for anyone
default:
}
}
case <-n.closed:
return
}
}
}
func (n *node) Address() string {
return n.address
}
// Close shutdowns all the links and closes the listener
func (n *node) Close() error {
select {
case <-n.closed:
return nil
default:
close(n.closed)
// shutdown all the links
n.mtx.Lock()
for id, link := range n.links {
link.down()
delete(n.links, id)
}
n.mtx.Unlock()
// deregister self
n.registry.Deregister(&registry.Service{
Name: "network:" + n.network.Id(),
Nodes: []*registry.Node{
{Id: n.id, Address: n.address},
},
})
return n.listener.Close()
}
return nil
}
func (n *node) Accept() (*Message, error) {
// process the inbound cruft
return nil, nil
}
func (n *node) Network() string {
return n.network.id
}
func (n *node) Send(m *Message) error {
n.mtx.RLock()
defer n.mtx.RUnlock()
var gerr error
// send to all links
// TODO: be smarter
for _, link := range n.links {
// TODO: process the error, do some link flap detection
// blackhole the connection, etc
if err := link.socket.send(m, nil); err != nil {
gerr = err
continue
}
}
return gerr
}