/
client.go
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/
client.go
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// Copyright (c) 2019 Uber Technologies, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package eventstream
import (
"context"
"time"
pbevent "github.com/uber/peloton/.gen/peloton/private/eventstream/v1alpha/event"
pbeventstreamsvc "github.com/uber/peloton/.gen/peloton/private/eventstream/v1alpha/eventstreamsvc"
"github.com/uber/peloton/pkg/common/lifecycle"
"github.com/uber/peloton/pkg/common/metrics"
log "github.com/sirupsen/logrus"
"github.com/uber-go/tally"
"go.uber.org/yarpc"
"go.uber.org/yarpc/yarpcerrors"
)
var (
// TODO: move these into config, if necessary
maxEventSize = 100
requestTimeout = 10 * time.Second
errorRetrySleep = 10 * time.Second
noEventSleep = 100 * time.Millisecond
)
// EventHandler is the interface for handling task update events
type EventHandler interface {
// The event notification callback
OnV1Event(event *pbevent.Event)
// The events notification callback
OnV1Events(events []*pbevent.Event)
// Returns the event progress the handler has processed. The value
// will be used by the client to determine the purgeOffset
GetEventProgress() uint64
}
// Client is the event stream client
type Client struct {
// The rpc client to pull events from event stream handler
rpcClient pbeventstreamsvc.EventStreamServiceYARPCClient
// the client name
clientName string
// the stream id of the event stream
streamID string
// previousSeverPurgeOffset is the purge offset
// stores on the handler for the client when client inits
previousSeverPurgeOffset uint64
// beginOffset of the next pull event request
beginOffset uint64
// event purge offset to be send to the event stream handler
purgeOffset uint64
// event handler interface to process the received events
eventHandler EventHandler
// log.Entry used by client to share common log fields
log *log.Entry
lifeCycle lifecycle.LifeCycle
metrics *ClientMetrics
}
// NewEventStreamClient creates a client that
// consumes from remote event stream handler
func NewEventStreamClient(
d *yarpc.Dispatcher,
clientName string,
server string,
taskUpdateHandler EventHandler,
parentScope tally.Scope,
) *Client {
client := &Client{
clientName: clientName,
rpcClient: pbeventstreamsvc.NewEventStreamServiceYARPCClient(d.ClientConfig(server)),
eventHandler: taskUpdateHandler,
lifeCycle: lifecycle.NewLifeCycle(),
metrics: NewClientMetrics(parentScope.SubScope(metrics.SafeScopeName(clientName))),
log: log.WithFields(log.Fields{
"client": clientName,
"server": server,
}),
}
return client
}
func (c *Client) sendInitStreamRequest(
clientName string,
) (*pbeventstreamsvc.InitStreamResponse, error) {
ctx, cancelFunc := context.WithTimeout(context.Background(), requestTimeout)
defer cancelFunc()
c.metrics.InitStreamAPI.Inc(1)
request := &pbeventstreamsvc.InitStreamRequest{
ClientName: clientName,
}
response, err := c.rpcClient.InitStream(ctx, request)
if err != nil {
c.log.WithError(err).Error("sendInitStreamRequest failed")
c.metrics.InitStreamFail.Inc(1)
return response, err
}
c.metrics.InitStreamSuccess.Inc(1)
c.metrics.StreamIDChange.Inc(1)
c.log.WithField("init_stream_response", response).Infoln()
return response, nil
}
func (c *Client) initStream(clientName string) {
for {
select {
case <-c.lifeCycle.StopCh():
c.log.Info("initStream returned due to shutdown")
return
default:
response, err := c.sendInitStreamRequest(clientName)
if err != nil {
c.log.WithError(err).Error("sendInitStreamRequest failed")
time.Sleep(errorRetrySleep)
continue
}
c.streamID = response.StreamId
c.beginOffset = response.PreviousPurgeOffset
c.previousSeverPurgeOffset = response.PreviousPurgeOffset
if response.PreviousPurgeOffset < response.MinOffset {
c.log.WithFields(log.Fields{
"previous_purge_offset": response.PreviousPurgeOffset,
"min_offset": response.MinOffset,
}).Error("Need to adjust beginOffset")
c.beginOffset = response.MinOffset
}
return
}
}
}
func (c *Client) sendWaitEventRequest(
beginOffset uint64,
purgeOffset uint64,
) (*pbeventstreamsvc.WaitForEventsResponse, error) {
ctx, cancelFunc := context.WithTimeout(context.Background(), requestTimeout)
defer cancelFunc()
// We need to make this adjust for the first event,
// where c.eventHandler.GetEventProgress() and BeginOffset are both 0
purgeOffset = c.eventHandler.GetEventProgress() + 1
if purgeOffset > beginOffset {
purgeOffset = beginOffset
}
// This could happen before client processes the first event
// where c.eventHandler.GetEventProgress() returns 0.
if c.previousSeverPurgeOffset > purgeOffset {
purgeOffset = c.previousSeverPurgeOffset
}
c.metrics.WaitForEventsAPI.Inc(1)
c.metrics.PurgeOffset.Update(float64(purgeOffset))
request := &pbeventstreamsvc.WaitForEventsRequest{
BeginOffset: beginOffset,
// purgeOffset are used to move the circular buffer tail, thus plus 1
PurgeOffset: purgeOffset,
StreamId: c.streamID,
ClientName: c.clientName,
Limit: int32(maxEventSize),
}
response, err := c.rpcClient.WaitForEvents(ctx, request)
if err != nil {
c.log.WithError(err).Error("sendWaitForEventsRequest failed")
c.metrics.WaitForEventsFailed.Inc(1)
return nil, err
}
c.metrics.WaitForEventsSuccess.Inc(1)
return response, nil
}
func (c *Client) waitEventsLoop() {
for {
select {
case <-c.lifeCycle.StopCh():
c.log.Info("waitEventsLoop returned due to shutdown")
return
default:
c.purgeOffset = c.beginOffset
response, err := c.sendWaitEventRequest(c.beginOffset, c.purgeOffset)
if err != nil {
// Retry in case there is RPC error.
c.log.WithError(err).Error("sendWaitEventRequest failed")
if yarpcerrors.IsInvalidArgument(err) || yarpcerrors.IsOutOfRange(err) {
// return and let the outside loop call InitStream again on
// errors like invalid streamID.
return
}
time.Sleep(errorRetrySleep)
continue
}
if len(response.GetEvents()) == 0 {
time.Sleep(noEventSleep)
continue
}
for _, event := range response.Events {
c.log.WithField("event_offset", event.GetOffset()).
Debug("Processing event")
c.eventHandler.OnV1Event(event)
c.beginOffset = event.GetOffset() + 1
}
c.eventHandler.OnV1Events(response.Events)
c.metrics.EventsConsumed.Inc(int64(len(response.Events)))
}
}
}
// Start starts the client.
func (c *Client) Start() {
if !c.lifeCycle.Start() {
return
}
c.log.Info("Event stream client start() called")
go func() {
for {
select {
case <-c.lifeCycle.StopCh():
c.log.Info("Event stream client exits wait events")
c.lifeCycle.StopComplete()
return
default:
c.initStream(c.clientName)
c.waitEventsLoop()
}
}
}()
c.log.Info("Event stream client started")
}
// Stop stops the client.
func (c *Client) Stop() {
if !c.lifeCycle.Stop() {
return
}
c.log.Info("Event stream client stop() called")
// Wait until the event consuming go routine returns.
c.lifeCycle.Wait()
c.log.Info("Event stream client stopped")
}