[#1183] node: Add NATS client

Signed-off-by: Pavel Karpy <carpawell@nspcc.ru>
This commit is contained in:
Pavel Karpy 2021-03-01 14:51:38 +03:00 committed by Alex Vanin
parent 51f12ea22b
commit 79c6f52a27
4 changed files with 170 additions and 1 deletions

4
go.mod
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@ -8,10 +8,12 @@ require (
github.com/google/go-github/v39 v39.2.0 github.com/google/go-github/v39 v39.2.0
github.com/google/uuid v1.2.0 github.com/google/uuid v1.2.0
github.com/hashicorp/golang-lru v0.5.4 github.com/hashicorp/golang-lru v0.5.4
github.com/klauspost/compress v1.13.1 github.com/klauspost/compress v1.13.4
github.com/mitchellh/go-homedir v1.1.0 github.com/mitchellh/go-homedir v1.1.0
github.com/mr-tron/base58 v1.2.0 github.com/mr-tron/base58 v1.2.0
github.com/multiformats/go-multiaddr v0.4.0 github.com/multiformats/go-multiaddr v0.4.0
github.com/nats-io/nats-server/v2 v2.7.2 // indirect
github.com/nats-io/nats.go v1.13.1-0.20220121202836-972a071d373d
github.com/nspcc-dev/hrw v1.0.9 github.com/nspcc-dev/hrw v1.0.9
github.com/nspcc-dev/neo-go v0.98.0 github.com/nspcc-dev/neo-go v0.98.0
github.com/nspcc-dev/neofs-api-go/v2 v2.12.0 github.com/nspcc-dev/neofs-api-go/v2 v2.12.0

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@ -0,0 +1,38 @@
package nats
import (
"time"
"github.com/nats-io/nats.go"
"go.uber.org/zap"
)
func WithClientCert(certPath, keyPath string) Option {
return func(o *opts) {
o.nOpts = append(o.nOpts, nats.ClientCert(certPath, keyPath))
}
}
func WithRootCA(paths ...string) Option {
return func(o *opts) {
o.nOpts = append(o.nOpts, nats.RootCAs(paths...))
}
}
func WithTimeout(timeout time.Duration) Option {
return func(o *opts) {
o.nOpts = append(o.nOpts, nats.Timeout(timeout))
}
}
func WithConnectionName(name string) Option {
return func(o *opts) {
o.nOpts = append(o.nOpts, nats.Name(name))
}
}
func WithLogger(logger *zap.Logger) Option {
return func(o *opts) {
o.logger = logger
}
}

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@ -0,0 +1,129 @@
package nats
import (
"context"
"errors"
"fmt"
"sync"
"github.com/nats-io/nats.go"
addressSDK "github.com/nspcc-dev/neofs-sdk-go/object/address"
"go.uber.org/zap"
)
// Writer is a NATS object notification writer.
// It handles NATS JetStream connections and allows
// sending string representation of the address to
// the NATS server.
//
// For correct operation must be created via New function.
// new(Writer) or Writer{} construction leads to undefined
// behaviour and is not safe.
type Writer struct {
log *zap.Logger
js nats.JetStreamContext
nc *nats.Conn
m *sync.RWMutex
createdStreams map[string]struct{}
}
type opts struct {
logger *zap.Logger
nOpts []nats.Option
}
type Option func(*opts)
var errConnIsClosed = errors.New("connection to the server is closed")
// Notify sends object address's string representation to the provided topic.
// Uses first 4 bytes of object ID as a message ID to support 'exactly once message'
// delivery.
//
// Returns error only if:
// 1. underlying connection was closed and has not established again;
// 2. NATS server could not respond that is has saved the message.
func (n *Writer) Notify(topic string, address *addressSDK.Address) error {
if !n.nc.IsConnected() {
return errConnIsClosed
}
// use first 4 byte of the encoded string as
// message ID for the exactly-once delivery
messageID := address.ObjectID().String()[:4]
// check if the stream was previously created
n.m.RLock()
_, created := n.createdStreams[topic]
n.m.RUnlock()
if !created {
_, err := n.js.AddStream(&nats.StreamConfig{
Name: topic,
})
if err != nil {
return fmt.Errorf("could not add stream: %w", err)
}
n.m.Lock()
n.createdStreams[topic] = struct{}{}
n.m.Unlock()
}
_, err := n.js.Publish(topic, []byte(address.String()), nats.MsgId(messageID))
if err != nil {
return err
}
return nil
}
// New creates and inits new Writer.
// Connection is closed when passed context is done.
//
// Returns error only if fails to open connection to a NATS server
// with provided configuration.
func New(ctx context.Context, endpoint string, oo ...Option) (*Writer, error) {
opts := &opts{
logger: zap.L(),
nOpts: make([]nats.Option, 0, len(oo)+3),
}
for _, o := range oo {
o(opts)
}
opts.nOpts = append(opts.nOpts,
nats.NoCallbacksAfterClientClose(), // do not call callbacks when it was planned writer stop
nats.DisconnectErrHandler(func(conn *nats.Conn, err error) {
opts.logger.Error("nats: connection was lost", zap.Error(err))
}),
nats.ReconnectHandler(func(conn *nats.Conn) {
opts.logger.Warn("nats: reconnected to the server")
}),
)
nc, err := nats.Connect(endpoint, opts.nOpts...)
if err != nil {
return nil, fmt.Errorf("could not connect to server: %w", err)
}
// usage w/o options is error-free
js, _ := nc.JetStream()
go func() {
<-ctx.Done()
opts.logger.Info("nats: closing connection as the context is done")
nc.Close()
}()
return &Writer{
js: js,
nc: nc,
log: opts.logger,
m: &sync.RWMutex{},
createdStreams: make(map[string]struct{}),
}, nil
}