/
doppler_server.go
190 lines (160 loc) · 4.88 KB
/
doppler_server.go
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package v1
import (
"log"
"sync/atomic"
"time"
"code.cloudfoundry.org/go-batching"
gendiode "code.cloudfoundry.org/go-diodes"
"code.cloudfoundry.org/loggregator-release/src/diodes"
"code.cloudfoundry.org/loggregator-release/src/metricemitter"
"code.cloudfoundry.org/loggregator-release/src/plumbing"
"golang.org/x/net/context"
)
// Registrar registers stream and firehose DataSetters to accept reads.
type Registrar interface {
Register(req *plumbing.SubscriptionRequest, setter DataSetter) func()
}
// DataSetter accepts writes of marshalled data.
type DataSetter interface {
Set(data []byte)
}
// DopplerServer is the GRPC server component that accepts requests for firehose
// streams, application streams, and recent logs.
type DopplerServer struct {
plumbing.DopplerServer
registrar Registrar
egressMetric *metricemitter.Counter
egressDropped *metricemitter.Counter
subscriptionsMetric *metricemitter.Gauge
batchInterval time.Duration
batchSize uint
bufferSize int
}
type sender interface {
Send(*plumbing.Response) error
Context() context.Context
}
// 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
}
// NewDopplerServer creates a new DopplerServer.
func NewDopplerServer(
registrar Registrar,
metricClient MetricClient,
droppedMetric *metricemitter.Counter,
subscriptionsMetric *metricemitter.Gauge,
batchInterval time.Duration,
batchSize uint,
bufferSize int,
) *DopplerServer {
// metric-documentation-v2: (loggregator.doppler.egress) Number of
// envelopes read from a diode to be sent to subscriptions.
egressMetric := metricClient.NewCounter("egress",
metricemitter.WithVersion(2, 0),
)
m := &DopplerServer{
registrar: registrar,
egressMetric: egressMetric,
egressDropped: droppedMetric,
subscriptionsMetric: subscriptionsMetric,
batchInterval: batchInterval,
batchSize: batchSize,
bufferSize: bufferSize,
}
return m
}
// Subscribe is called by GRPC on stream requests.
func (m *DopplerServer) Subscribe(req *plumbing.SubscriptionRequest, sender plumbing.Doppler_SubscribeServer) error {
m.subscriptionsMetric.Increment(1.0)
defer m.subscriptionsMetric.Decrement(1.0)
return m.sendData(req, sender)
}
// BatchSubscribe is called by GRPC on stream batch requests.
func (m *DopplerServer) BatchSubscribe(req *plumbing.SubscriptionRequest, sender plumbing.Doppler_BatchSubscribeServer) error {
m.subscriptionsMetric.Increment(1.0)
defer m.subscriptionsMetric.Decrement(1.0)
return m.sendBatchData(req, sender)
}
func (m *DopplerServer) sendData(req *plumbing.SubscriptionRequest, sender sender) error {
d := diodes.NewOneToOne(m.bufferSize, gendiode.AlertFunc(func(missed int) {
log.Printf("Dropped %d envelopes (v1 buffer) ShardID: %s", missed, req.ShardID)
m.Alert(missed)
}))
cleanup := m.registrar.Register(req, d)
defer cleanup()
var done int64
go m.monitorContext(sender.Context(), &done)
for {
if atomic.LoadInt64(&done) > 0 {
break
}
data, ok := d.TryNext()
if !ok {
time.Sleep(10 * time.Millisecond)
continue
}
err := sender.Send(&plumbing.Response{Payload: data})
if err != nil {
return err
}
m.egressMetric.Increment(1)
}
return sender.Context().Err()
}
type batchWriter struct {
sender plumbing.Doppler_BatchSubscribeServer
errStream chan<- error
egressMetric *metricemitter.Counter
}
func (b *batchWriter) Write(batch [][]byte) {
err := b.sender.Send(&plumbing.BatchResponse{Payload: batch})
if err != nil {
b.errStream <- err
return
}
b.egressMetric.Increment(uint64(len(batch)))
}
func (m *DopplerServer) sendBatchData(req *plumbing.SubscriptionRequest, sender plumbing.Doppler_BatchSubscribeServer) error {
d := diodes.NewOneToOne(m.bufferSize, gendiode.AlertFunc(func(missed int) {
log.Printf("Dropped %d envelopes (v1 buffer) ShardID: %s", missed, req.ShardID)
m.Alert(missed)
}))
cleanup := m.registrar.Register(req, d)
defer cleanup()
errStream := make(chan error, 1)
batcher := batching.NewByteBatcher(
int(m.batchSize),
m.batchInterval,
&batchWriter{
sender: sender,
errStream: errStream,
egressMetric: m.egressMetric,
},
)
for {
select {
case <-sender.Context().Done():
return sender.Context().Err()
case err := <-errStream:
return err
default:
data, ok := d.TryNext()
if !ok {
batcher.Flush()
time.Sleep(10 * time.Millisecond)
continue
}
batcher.Write(data)
}
}
}
// Alert logs dropped message counts to stderr.
func (m *DopplerServer) Alert(missed int) {
m.egressDropped.Increment(uint64(missed))
}
func (m *DopplerServer) monitorContext(ctx context.Context, done *int64) {
<-ctx.Done()
atomic.StoreInt64(done, 1)
}