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events: decouple events package from grpc

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By defining a concrete, non-protobuf type for the events interface, we
can completely decouple it from the grpc packages that are expensive at
runtime. This does requires some allocation cost for converting between
types, but the saving for the size of the shim are worth it.

Signed-off-by: Stephen J Day <stephen.day@docker.com>
This commit is contained in:
Stephen J Day 2017-11-16 17:52:17 -08:00
parent 5c6e789dde
commit 2d05c4aa1a
No known key found for this signature in database
GPG Key ID: 67B3DED84EDC823F
4 changed files with 45 additions and 21 deletions
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21
events/events.go
View File

@ -2,10 +2,19 @@ package events
import (
"context"
"time"
events "github.com/containerd/containerd/api/services/events/v1"
"github.com/gogo/protobuf/types"
)
// Envelope provides the packaging for an event.
type Envelope struct {
Timestamp time.Time
Namespace string
Topic string
Event *types.Any
}
// Event is a generic interface for any type of event
type Event interface{}
@ -16,16 +25,10 @@ type Publisher interface {
// Forwarder forwards an event to the underlying event bus
type Forwarder interface {
Forward(ctx context.Context, envelope *events.Envelope) error
}
type publisherFunc func(ctx context.Context, topic string, event Event) error
func (fn publisherFunc) Publish(ctx context.Context, topic string, event Event) error {
return fn(ctx, topic, event)
Forward(ctx context.Context, envelope *Envelope) error
}
// Subscriber allows callers to subscribe to events
type Subscriber interface {
Subscribe(ctx context.Context, filters ...string) (ch <-chan *events.Envelope, errs <-chan error)
Subscribe(ctx context.Context, filters ...string) (ch <-chan *Envelope, errs <-chan error)
}

17
events/exchange/exchange.go
View File

@ -5,7 +5,6 @@ import (
"strings"
"time"
v1 "github.com/containerd/containerd/api/services/events/v1"
"github.com/containerd/containerd/errdefs"
"github.com/containerd/containerd/events"
"github.com/containerd/containerd/filters"
@ -31,11 +30,15 @@ func NewExchange() *Exchange {
}
}
var _ events.Publisher = &Exchange{}
var _ events.Forwarder = &Exchange{}
var _ events.Subscriber = &Exchange{}
// Forward accepts an envelope to be direcly distributed on the exchange.
//
// This is useful when an event is forwaded on behalf of another namespace or
// when the event is propagated on behalf of another publisher.
func (e *Exchange) Forward(ctx context.Context, envelope *v1.Envelope) (err error) {
func (e *Exchange) Forward(ctx context.Context, envelope *events.Envelope) (err error) {
if err := validateEnvelope(envelope); err != nil {
return err
}
@ -64,7 +67,7 @@ func (e *Exchange) Publish(ctx context.Context, topic string, event events.Event
var (
namespace string
encoded *types.Any
envelope v1.Envelope
envelope events.Envelope
)
namespace, err = namespaces.NamespaceRequired(ctx)
@ -109,9 +112,9 @@ func (e *Exchange) Publish(ctx context.Context, topic string, event events.Event
// Zero or more filters may be provided as strings. Only events that match
// *any* of the provided filters will be sent on the channel. The filters use
// the standard containerd filters package syntax.
func (e *Exchange) Subscribe(ctx context.Context, fs ...string) (ch <-chan *v1.Envelope, errs <-chan error) {
func (e *Exchange) Subscribe(ctx context.Context, fs ...string) (ch <-chan *events.Envelope, errs <-chan error) {
var (
evch = make(chan *v1.Envelope)
evch = make(chan *events.Envelope)
errq = make(chan error, 1)
channel = goevents.NewChannel(0)
queue = goevents.NewQueue(channel)
@ -151,7 +154,7 @@ func (e *Exchange) Subscribe(ctx context.Context, fs ...string) (ch <-chan *v1.E
for {
select {
case ev := <-channel.C:
env, ok := ev.(*v1.Envelope)
env, ok := ev.(*events.Envelope)
if !ok {
// TODO(stevvooe): For the most part, we are well protected
// from this condition. Both Forward and Publish protect
@ -205,7 +208,7 @@ func validateTopic(topic string) error {
return nil
}
func validateEnvelope(envelope *v1.Envelope) error {
func validateEnvelope(envelope *events.Envelope) error {
if err := namespaces.Validate(envelope.Namespace); err != nil {
return errors.Wrapf(err, "event envelope has invalid namespace")
}

5
events/exchange/exchange_test.go
View File

@ -9,7 +9,6 @@ import (
"time"
eventstypes "github.com/containerd/containerd/api/events"
v1 "github.com/containerd/containerd/api/services/events/v1"
"github.com/containerd/containerd/errdefs"
"github.com/containerd/containerd/events"
"github.com/containerd/containerd/namespaces"
@ -57,7 +56,7 @@ func TestExchangeBasic(t *testing.T) {
wg.Wait()
for _, subscriber := range []struct {
eventq <-chan *v1.Envelope
eventq <-chan *events.Envelope
errq <-chan error
cancel func()
}{
@ -133,7 +132,7 @@ func TestExchangeValidateTopic(t *testing.T) {
t.Fatal(err)
}
envelope := v1.Envelope{
envelope := events.Envelope{
Timestamp: time.Now().UTC(),
Namespace: namespace,
Topic: testcase.input,

23
services/events/service.go
View File

@ -3,6 +3,7 @@ package events
import (
api "github.com/containerd/containerd/api/services/events/v1"
"github.com/containerd/containerd/errdefs"
"github.com/containerd/containerd/events"
"github.com/containerd/containerd/events/exchange"
"github.com/containerd/containerd/plugin"
ptypes "github.com/gogo/protobuf/types"
@ -44,7 +45,7 @@ func (s *service) Publish(ctx context.Context, r *api.PublishRequest) (*ptypes.E
}
func (s *service) Forward(ctx context.Context, r *api.ForwardRequest) (*ptypes.Empty, error) {
if err := s.events.Forward(ctx, r.Envelope); err != nil {
if err := s.events.Forward(ctx, fromProto(r.Envelope)); err != nil {
return nil, errdefs.ToGRPC(err)
}
@ -59,7 +60,7 @@ func (s *service) Subscribe(req *api.SubscribeRequest, srv api.Events_SubscribeS
for {
select {
case ev := <-eventq:
if err := srv.Send(ev); err != nil {
if err := srv.Send(toProto(ev)); err != nil {
return errors.Wrapf(err, "failed sending event to subscriber")
}
case err := <-errq:
@ -71,3 +72,21 @@ func (s *service) Subscribe(req *api.SubscribeRequest, srv api.Events_SubscribeS
}
}
}
func toProto(env *events.Envelope) *api.Envelope {
return &api.Envelope{
Timestamp: env.Timestamp,
Namespace: env.Namespace,
Topic: env.Topic,
Event: env.Event,
}
}
func fromProto(env *api.Envelope) *events.Envelope {
return &events.Envelope{
Timestamp: env.Timestamp,
Namespace: env.Namespace,
Topic: env.Topic,
Event: env.Event,
}
}