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nats.go
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nats.go
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// Package nats provides a NATS transport
package nats
import (
"context"
"errors"
"io"
"strings"
"sync"
"time"
"github.com/micro/go-micro/cmd"
"github.com/micro/go-micro/server"
"github.com/micro/go-micro/transport"
"github.com/micro/go-micro/transport/codec/json"
"github.com/nats-io/nats"
)
type ntport struct {
addrs []string
opts transport.Options
nopts nats.Options
}
type ntportClient struct {
conn *nats.Conn
addr string
id string
sub *nats.Subscription
opts transport.Options
}
type ntportSocket struct {
conn *nats.Conn
m *nats.Msg
r chan *nats.Msg
close chan bool
sync.Mutex
bl []*nats.Msg
opts transport.Options
}
type ntportListener struct {
conn *nats.Conn
addr string
exit chan bool
sync.RWMutex
so map[string]*ntportSocket
opts transport.Options
}
var (
DefaultTimeout = time.Minute
)
func init() {
cmd.DefaultTransports["nats"] = NewTransport
}
func setAddrs(addrs []string) []string {
var cAddrs []string
for _, addr := range addrs {
if len(addr) == 0 {
continue
}
if !strings.HasPrefix(addr, "nats://") {
addr = "nats://" + addr
}
cAddrs = append(cAddrs, addr)
}
if len(cAddrs) == 0 {
cAddrs = []string{nats.DefaultURL}
}
return cAddrs
}
func (n *ntportClient) Send(m *transport.Message) error {
b, err := n.opts.Codec.Marshal(m)
if err != nil {
return err
}
// no deadline
if n.opts.Timeout == time.Duration(0) {
return n.conn.PublishRequest(n.addr, n.id, b)
}
// use the deadline
ch := make(chan error, 1)
go func() {
ch <- n.conn.PublishRequest(n.addr, n.id, b)
}()
select {
case err := <-ch:
return err
case <-time.After(n.opts.Timeout):
return errors.New("deadline exceeded")
}
}
func (n *ntportClient) Recv(m *transport.Message) error {
timeout := time.Second * 10
if n.opts.Timeout > time.Duration(0) {
timeout = n.opts.Timeout
}
rsp, err := n.sub.NextMsg(timeout)
if err != nil {
return err
}
var mr transport.Message
if err := n.opts.Codec.Unmarshal(rsp.Data, &mr); err != nil {
return err
}
*m = mr
return nil
}
func (n *ntportClient) Close() error {
n.sub.Unsubscribe()
n.conn.Close()
return nil
}
func (n *ntportSocket) Recv(m *transport.Message) error {
if m == nil {
return errors.New("message passed in is nil")
}
var r *nats.Msg
var ok bool
// if there's a deadline we use it
if n.opts.Timeout > time.Duration(0) {
select {
case r, ok = <-n.r:
case <-time.After(n.opts.Timeout):
return errors.New("deadline exceeded")
}
} else {
r, ok = <-n.r
}
if !ok {
return io.EOF
}
n.Lock()
if len(n.bl) > 0 {
select {
case n.r <- n.bl[0]:
n.bl = n.bl[1:]
default:
}
}
n.Unlock()
if err := n.opts.Codec.Unmarshal(r.Data, m); err != nil {
return err
}
return nil
}
func (n *ntportSocket) Send(m *transport.Message) error {
b, err := n.opts.Codec.Marshal(m)
if err != nil {
return err
}
// no deadline
if n.opts.Timeout == time.Duration(0) {
return n.conn.Publish(n.m.Reply, b)
}
// use the deadline
ch := make(chan error, 1)
go func() {
ch <- n.conn.Publish(n.m.Reply, b)
}()
select {
case err := <-ch:
return err
case <-time.After(n.opts.Timeout):
return errors.New("deadline exceeded")
}
}
func (n *ntportSocket) Close() error {
select {
case <-n.close:
return nil
default:
close(n.close)
}
return nil
}
func (n *ntportListener) Addr() string {
return n.addr
}
func (n *ntportListener) Close() error {
n.exit <- true
n.conn.Close()
return nil
}
func (n *ntportListener) Accept(fn func(transport.Socket)) error {
s, err := n.conn.SubscribeSync(n.addr)
if err != nil {
return err
}
var lerr error
go func() {
<-n.exit
lerr = s.Unsubscribe()
}()
for {
m, err := s.NextMsg(time.Minute)
if err != nil && err == nats.ErrTimeout {
continue
} else if err != nil {
return err
}
n.RLock()
sock, ok := n.so[m.Reply]
n.RUnlock()
if !ok {
sock = &ntportSocket{
conn: n.conn,
m: m,
r: make(chan *nats.Msg, 1),
close: make(chan bool),
opts: n.opts,
}
n.Lock()
n.so[m.Reply] = sock
n.Unlock()
go func() {
// TODO: think of a better error response strategy
defer func() {
if r := recover(); r != nil {
sock.Close()
}
}()
fn(sock)
}()
go func() {
<-sock.close
n.Lock()
delete(n.so, sock.m.Reply)
n.Unlock()
}()
}
select {
case <-sock.close:
continue
default:
}
sock.Lock()
sock.bl = append(sock.bl, m)
select {
case sock.r <- sock.bl[0]:
sock.bl = sock.bl[1:]
default:
}
sock.Unlock()
}
}
func (n *ntport) Dial(addr string, dialOpts ...transport.DialOption) (transport.Client, error) {
dopts := transport.DialOptions{
Timeout: transport.DefaultDialTimeout,
}
for _, o := range dialOpts {
o(&dopts)
}
opts := n.nopts
opts.Servers = n.addrs
opts.Secure = n.opts.Secure
opts.TLSConfig = n.opts.TLSConfig
opts.Timeout = dopts.Timeout
// secure might not be set
if n.opts.TLSConfig != nil {
opts.Secure = true
}
c, err := opts.Connect()
if err != nil {
return nil, err
}
id := nats.NewInbox()
sub, err := c.SubscribeSync(id)
if err != nil {
return nil, err
}
return &ntportClient{
conn: c,
addr: addr,
id: id,
sub: sub,
opts: n.opts,
}, nil
}
func (n *ntport) Listen(addr string, listenOpts ...transport.ListenOption) (transport.Listener, error) {
opts := n.nopts
opts.Servers = n.addrs
opts.Secure = n.opts.Secure
opts.TLSConfig = n.opts.TLSConfig
// secure might not be set
if n.opts.TLSConfig != nil {
opts.Secure = true
}
c, err := opts.Connect()
if err != nil {
return nil, err
}
// in case address has not been specifically set, create a new nats.Inbox()
if addr == server.DefaultAddress {
addr = nats.NewInbox()
}
// make sure addr subject is not empty
if len(addr) == 0 {
return nil, errors.New("addr (nats subject) must not be empty")
}
// since NATS implements a text based protocol, no space characters are
// admitted in the addr (subject name)
if strings.Contains(addr, " ") {
return nil, errors.New("addr (nats subject) must not contain space characters")
}
return &ntportListener{
addr: addr,
conn: c,
exit: make(chan bool, 1),
so: make(map[string]*ntportSocket),
opts: n.opts,
}, nil
}
func (n *ntport) String() string {
return "nats"
}
func NewTransport(opts ...transport.Option) transport.Transport {
options := transport.Options{
// Default codec
Codec: json.NewCodec(),
Timeout: DefaultTimeout,
Context: context.Background(),
}
for _, o := range opts {
o(&options)
}
natsOptions := nats.GetDefaultOptions()
if n, ok := options.Context.Value(optionsKey{}).(nats.Options); ok {
natsOptions = n
}
// transport.Options have higher priority than nats.Options
// only if Addrs, Secure or TLSConfig were not set through a transport.Option
// we read them from nats.Option
if len(options.Addrs) == 0 {
options.Addrs = natsOptions.Servers
}
if !options.Secure {
options.Secure = natsOptions.Secure
}
if options.TLSConfig == nil {
options.TLSConfig = natsOptions.TLSConfig
}
// check & add nats:// prefix (this makes also sure that the addresses
// stored in natsRegistry.addrs and options.Addrs are identical)
options.Addrs = setAddrs(options.Addrs)
return &ntport{
addrs: options.Addrs,
opts: options,
nopts: natsOptions,
}
}