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server.go
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/
server.go
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package egress
import (
"fmt"
"io"
"log"
"sync/atomic"
"time"
"code.cloudfoundry.org/go-loggregator/rpc/loggregator_v2"
"code.cloudfoundry.org/loggregator/metricemitter"
"code.cloudfoundry.org/loggregator/plumbing/batching"
"google.golang.org/grpc/codes"
"google.golang.org/grpc/status"
"golang.org/x/net/context"
)
const (
envelopeBufferSize = 10000
)
// HealthRegistrar provides an interface to record various counters.
type HealthRegistrar interface {
Inc(name string)
Dec(name string)
}
// Receiver creates a function which will receive envelopes on a stream.
type Receiver interface {
Subscribe(ctx context.Context, req *loggregator_v2.EgressBatchRequest) (rx func() (*loggregator_v2.Envelope, error), err error)
}
// MetricClient creates new CounterMetrics to be emitted periodically.
type MetricClient interface {
NewCounter(name string, opts ...metricemitter.MetricOption) *metricemitter.Counter
NewGauge(name, unit string, opts ...metricemitter.MetricOption) *metricemitter.Gauge
}
// Server represents a bridge between inbound data from the Receiver and
// outbound data on a gRPC stream.
type Server struct {
receiver Receiver
egressMetric *metricemitter.Counter
droppedMetric *metricemitter.Counter
rejectedMetric *metricemitter.Counter
subscriptionsMetric *metricemitter.Gauge
health HealthRegistrar
ctx context.Context
batchSize int
batchInterval time.Duration
maxStreams int64
subscriptions int64
}
// NewServer is the preferred way to create a new Server.
func NewServer(
r Receiver,
m MetricClient,
h HealthRegistrar,
c context.Context,
batchSize int,
batchInterval time.Duration,
opts ...ServerOption,
) *Server {
egressMetric := m.NewCounter("egress",
metricemitter.WithVersion(2, 0),
)
droppedMetric := m.NewCounter("dropped",
metricemitter.WithVersion(2, 0),
metricemitter.WithTags(map[string]string{
"direction": "egress",
}),
)
rejectedMetric := m.NewCounter("rejected_streams",
metricemitter.WithVersion(2, 0),
)
subscriptionsMetric := m.NewGauge("subscriptions", "total",
metricemitter.WithVersion(2, 0),
)
s := &Server{
receiver: r,
egressMetric: egressMetric,
droppedMetric: droppedMetric,
rejectedMetric: rejectedMetric,
subscriptionsMetric: subscriptionsMetric,
health: h,
ctx: c,
batchSize: batchSize,
batchInterval: batchInterval,
maxStreams: 500,
}
for _, o := range opts {
o(s)
}
return s
}
// ServerOption represents a function that cancel configure an RLP egress server.
type ServerOption func(*Server)
// WithMaxStreams specifies the maximum streams allowed by the RLP egress
// server.
func WithMaxStreams(conn int64) ServerOption {
return func(s *Server) {
s.maxStreams = conn
}
}
// Receiver implements the loggregator-api V2 gRPC interface for receiving
// envelopes from upstream connections.
func (s *Server) Receiver(r *loggregator_v2.EgressRequest, srv loggregator_v2.Egress_ReceiverServer) error {
s.health.Inc("subscriptionCount")
defer s.health.Dec("subscriptionCount")
s.subscriptionsMetric.Increment(1)
defer s.subscriptionsMetric.Decrement(1)
subCount := atomic.AddInt64(&s.subscriptions, 1)
defer atomic.AddInt64(&s.subscriptions, -1)
if subCount > s.maxStreams {
s.rejectedMetric.Increment(1)
return status.Errorf(codes.ResourceExhausted, "unable to create stream, max egress streams reached: %d", s.maxStreams)
}
ctx, cancel := context.WithCancel(srv.Context())
defer cancel()
buffer := make(chan *loggregator_v2.Envelope, envelopeBufferSize)
r.Selectors = s.convergeSelectors(r.GetLegacySelector(), r.GetSelectors())
r.LegacySelector = nil
if len(r.Selectors) == 0 {
return status.Errorf(codes.InvalidArgument, "Selectors cannot be empty")
}
for _, s := range r.Selectors {
if s.Message == nil {
return status.Errorf(codes.InvalidArgument, "Selectors must have a Message")
}
}
go func() {
select {
case <-s.ctx.Done():
cancel()
case <-ctx.Done():
cancel()
}
}()
br := &loggregator_v2.EgressBatchRequest{
ShardId: r.GetShardId(),
Selectors: r.GetSelectors(),
UsePreferredTags: r.GetUsePreferredTags(),
}
rx, err := s.receiver.Subscribe(ctx, br)
if err != nil {
log.Printf("Unable to setup subscription: %s", err)
return fmt.Errorf("unable to setup subscription")
}
go s.consumeReceiver(r.UsePreferredTags, buffer, rx, cancel)
for data := range buffer {
if err := srv.Send(data); err != nil {
log.Printf("Send error: %s", err)
return io.ErrUnexpectedEOF
}
// metric-documentation-v2: (loggregator.rlp.egress) Number of v2
// envelopes sent to RLP consumers.
s.egressMetric.Increment(1)
}
return nil
}
// BatchedReceiver implements the loggregator-api V2 gRPC interface for
// receiving batches of envelopes. Envelopes will be written to the egress
// batched receiver server whenever the configured interval or configured
// batch size is exceeded.
func (s *Server) BatchedReceiver(r *loggregator_v2.EgressBatchRequest, srv loggregator_v2.Egress_BatchedReceiverServer) error {
s.health.Inc("subscriptionCount")
defer s.health.Dec("subscriptionCount")
s.subscriptionsMetric.Increment(1)
defer s.subscriptionsMetric.Decrement(1)
subCount := atomic.AddInt64(&s.subscriptions, 1)
defer func() { atomic.AddInt64(&s.subscriptions, -1) }()
if subCount > s.maxStreams {
s.rejectedMetric.Increment(1)
return status.Errorf(codes.ResourceExhausted, "unable to create stream, max egress streams reached: %d", s.maxStreams)
}
r.Selectors = s.convergeSelectors(r.GetLegacySelector(), r.GetSelectors())
r.LegacySelector = nil
if len(r.Selectors) == 0 {
return status.Errorf(codes.InvalidArgument, "Selectors cannot be empty")
}
for _, s := range r.Selectors {
if s.Message == nil {
return status.Errorf(codes.InvalidArgument, "Selectors must have a Message")
}
}
ctx, cancel := context.WithCancel(srv.Context())
defer cancel()
buffer := make(chan *loggregator_v2.Envelope, envelopeBufferSize)
go func() {
select {
case <-s.ctx.Done():
cancel()
case <-ctx.Done():
cancel()
}
}()
rx, err := s.receiver.Subscribe(ctx, r)
if err != nil {
log.Printf("Unable to setup subscription: %s", err)
return fmt.Errorf("unable to setup subscription")
}
receiveErrorStream := make(chan error, 1)
go s.consumeBatchReceiver(r.UsePreferredTags, buffer, receiveErrorStream, rx, cancel)
senderErrorStream := make(chan error, 1)
batcher := batching.NewV2EnvelopeBatcher(
s.batchSize,
s.batchInterval,
&batchWriter{
srv: srv,
errStream: senderErrorStream,
egressMetric: s.egressMetric,
},
)
resetDuration := 100 * time.Millisecond
timer := time.NewTimer(resetDuration)
for {
select {
case data, ok := <-buffer:
if !ok {
continue
}
batcher.Write(data)
if !timer.Stop() {
<-timer.C
}
timer.Reset(resetDuration)
case <-senderErrorStream:
return io.ErrUnexpectedEOF
case <-receiveErrorStream:
for d := range buffer {
batcher.Write(d)
}
batcher.ForcedFlush()
return nil
case <-timer.C:
batcher.Flush()
timer.Reset(resetDuration)
}
}
return nil
}
// convergeSelectors takes in any LegacySelector on the request as well as
// Selectors and converts LegacySelector into a Selector based on Selector
// hierarchy.
func (s *Server) convergeSelectors(
legacy *loggregator_v2.Selector,
selectors []*loggregator_v2.Selector,
) []*loggregator_v2.Selector {
if legacy != nil && len(selectors) > 0 {
// Both would be set by the consumer for upgrade path purposes.
// The contract should be to assume that the Selectors encompasses
// the LegacySelector. Therefore, just ignore the LegacySelector.
return selectors
}
if legacy != nil {
return []*loggregator_v2.Selector{legacy}
}
return selectors
}
type batchWriter struct {
srv loggregator_v2.Egress_BatchedReceiverServer
errStream chan<- error
egressMetric *metricemitter.Counter
}
func (b *batchWriter) Write(batch []*loggregator_v2.Envelope) {
err := b.srv.Send(&loggregator_v2.EnvelopeBatch{Batch: batch})
if err != nil {
select {
case b.errStream <- err:
default:
}
return
}
// metric-documentation-v2: (loggregator.rlp.egress) Number of v2
// envelopes sent to RLP consumers.
b.egressMetric.Increment(uint64(len(batch)))
}
func (s *Server) consumeBatchReceiver(
usePreferred bool,
buffer chan<- *loggregator_v2.Envelope,
errorStream chan<- error,
rx func() (*loggregator_v2.Envelope, error),
cancel func(),
) {
defer cancel()
defer close(buffer)
for {
e, err := rx()
if err == io.EOF {
errorStream <- err
break
}
if err != nil {
log.Printf("Subscribe error: %s", err)
errorStream <- err
break
}
s.convergeTags(usePreferred, e)
select {
case buffer <- e:
default:
// metric-documentation-v2: (loggregator.rlp.dropped) Number of v2
// envelopes dropped while egressing to a consumer.
s.droppedMetric.Increment(1)
}
}
}
func (s *Server) consumeReceiver(
usePreferred bool,
buffer chan<- *loggregator_v2.Envelope,
rx func() (*loggregator_v2.Envelope, error),
cancel func(),
) {
defer cancel()
defer close(buffer)
for {
e, err := rx()
if err == io.EOF {
break
}
if err != nil {
log.Printf("Subscribe error: %s", err)
break
}
s.convergeTags(usePreferred, e)
select {
case buffer <- e:
default:
// metric-documentation-v2: (loggregator.rlp.dropped) Number of v2
// envelopes dropped while egressing to a consumer.
s.droppedMetric.Increment(1)
}
}
}
func (s *Server) convergeTags(usePreferred bool, e *loggregator_v2.Envelope) {
if usePreferred {
if e.Tags == nil {
e.Tags = make(map[string]string)
}
for name, value := range e.GetDeprecatedTags() {
switch x := value.Data.(type) {
case *loggregator_v2.Value_Decimal:
e.GetTags()[name] = fmt.Sprint(x.Decimal)
case *loggregator_v2.Value_Integer:
e.GetTags()[name] = fmt.Sprint(x.Integer)
case *loggregator_v2.Value_Text:
e.GetTags()[name] = x.Text
}
}
e.DeprecatedTags = nil
return
}
if e.DeprecatedTags == nil {
e.DeprecatedTags = make(map[string]*loggregator_v2.Value)
}
for name, value := range e.GetTags() {
e.GetDeprecatedTags()[name] = &loggregator_v2.Value{
Data: &loggregator_v2.Value_Text{
Text: value,
},
}
}
e.Tags = nil
}