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event_publisher.go
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event_publisher.go
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package events
import (
"bytes"
"encoding/json"
"fmt"
"io/ioutil"
"net/http"
"strconv"
"strings"
"sync"
"time"
"gopkg.in/launchdarkly/go-server-sdk.v4/ldlog"
"gopkg.in/launchdarkly/ld-relay.v5/internal/version"
)
const (
numAttempts = 2
defaultFlushInterval = time.Minute
defaultCapacity = 1000
inputQueueSize = 100
defaultEventsEndpointURI = "https://events.launchdarkly.com/bulk"
defaultEventsURIPath = "/bulk"
)
var (
defaultUserAgent = "LDRelay/" + version.Version
)
type EventPublisher interface {
Publish(...interface{})
PublishRaw(...json.RawMessage)
Flush()
}
type HttpEventPublisher struct {
eventsURI string
loggers ldlog.Loggers
client *http.Client
authKey string
userAgent string
closer chan<- struct{}
closeOnce sync.Once
wg sync.WaitGroup
inputQueue chan interface{}
queue []interface{}
capacity int
}
type batch []interface{}
type rawBatch []json.RawMessage
type flush struct{}
func (b batch) append(q *[]interface{}, max int, loggers *ldlog.Loggers, reachedCapacity *bool) {
available := max - len(*q)
taken := len(b)
if available < len(b) {
if !*reachedCapacity {
loggers.Warnf("Exceeded event queue capacity of %d. Increase capacity to avoid dropping events.", max)
}
*reachedCapacity = true
taken = available
}
*q = append(*q, b[:taken]...)
}
func (b rawBatch) append(q *[]interface{}, max int, loggers *ldlog.Loggers, reachedCapacity *bool) {
available := max - len(*q)
taken := len(b)
if available < len(b) {
if !*reachedCapacity {
loggers.Warnf("Exceeded event queue capacity of %d. Increase capacity to avoid dropping events.", max)
}
*reachedCapacity = true
taken = available
}
for _, e := range b[:taken] {
*q = append(*q, e)
}
}
type OptionType interface {
apply(*HttpEventPublisher) error
}
type OptionUri string
func (o OptionUri) apply(p *HttpEventPublisher) error {
p.eventsURI = strings.TrimRight(string(o), "/") + defaultEventsURIPath
return nil
}
type OptionEndpointURI string
func (o OptionEndpointURI) apply(p *HttpEventPublisher) error {
p.eventsURI = string(o)
return nil
}
type OptionFlushInterval time.Duration
func (o OptionFlushInterval) apply(p *HttpEventPublisher) error {
return nil
}
type OptionClient struct {
Client *http.Client
}
func (o OptionClient) apply(p *HttpEventPublisher) error {
p.client = o.Client
return nil
}
type OptionUserAgent string
func (o OptionUserAgent) apply(p *HttpEventPublisher) error {
p.userAgent = string(o)
return nil
}
type OptionCapacity int
func (o OptionCapacity) apply(p *HttpEventPublisher) error {
p.capacity = int(o)
return nil
}
func NewHttpEventPublisher(authKey string, loggers ldlog.Loggers, options ...OptionType) (*HttpEventPublisher, error) {
closer := make(chan struct{})
inputQueue := make(chan interface{}, inputQueueSize)
p := &HttpEventPublisher{
client: http.DefaultClient,
userAgent: defaultUserAgent,
eventsURI: defaultEventsEndpointURI,
authKey: authKey,
closer: closer,
capacity: defaultCapacity,
inputQueue: inputQueue,
loggers: loggers,
}
p.loggers.SetPrefix("HttpEventPublisher:")
flushInterval := defaultFlushInterval
for _, o := range options {
err := o.apply(p)
if err != nil {
return nil, err
}
switch o := o.(type) {
case OptionFlushInterval:
if o > 0 {
flushInterval = time.Duration(o)
}
}
}
p.queue = make([]interface{}, 0, p.capacity)
p.wg.Add(1)
ticker := time.NewTicker(flushInterval)
go func() {
for {
if err := recover(); err != nil {
p.loggers.Errorf("Unexpected panic in event relay : %+v", err)
continue
}
reachedCapacity := false
EventLoop:
for {
select {
case e := <-inputQueue:
switch e := e.(type) {
case flush:
p.flush()
continue EventLoop
case rawBatch:
e.append(&p.queue, p.capacity, &p.loggers, &reachedCapacity)
case batch:
e.append(&p.queue, p.capacity, &p.loggers, &reachedCapacity)
}
case <-ticker.C:
p.flush()
case <-closer:
break EventLoop
}
}
ticker.Stop()
p.wg.Done()
break
}
}()
return p, nil
}
func (p *HttpEventPublisher) Publish(events ...interface{}) {
p.inputQueue <- batch(events)
}
func (p *HttpEventPublisher) PublishRaw(events ...json.RawMessage) {
p.inputQueue <- rawBatch(events)
}
func (p *HttpEventPublisher) Flush() {
p.inputQueue <- flush{}
}
func (p *HttpEventPublisher) flush() {
if len(p.queue) == 0 {
return
}
payload, err := json.Marshal(p.queue[0:len(p.queue)])
p.queue = make([]interface{}, 0, p.capacity)
if err != nil {
p.loggers.Errorf("Unexpected error marshalling event json: %+v", err)
return
}
p.wg.Add(1)
go func() {
err := p.postEvents(payload)
if err != nil {
p.loggers.Error(err.Error())
}
p.wg.Done()
}()
}
func (p *HttpEventPublisher) Close() {
p.closeOnce.Do(func() {
close(p.closer)
p.wg.Wait()
})
}
func (p *HttpEventPublisher) postEvents(jsonPayload []byte) error {
var resp *http.Response
var respErr error
PostAttempts:
for attempt := 0; attempt < numAttempts; attempt++ {
if attempt > 0 {
if respErr != nil {
p.loggers.Errorf("Unexpected error while sending events: %+v", respErr)
}
p.loggers.Warn("Will retry posting events after 1 second")
time.Sleep(1 * time.Second)
}
req, reqErr := http.NewRequest("POST", p.eventsURI, bytes.NewReader(jsonPayload))
if reqErr != nil {
return reqErr
}
if p.authKey != "" {
req.Header.Add("Authorization", p.authKey)
}
req.Header.Add("Content-Type", "application/json")
req.Header.Add("User-Agent", "LDRelay/"+version.Version)
req.Header.Add(EventSchemaHeader, strconv.Itoa(SummaryEventsSchemaVersion))
resp, respErr = p.client.Do(req)
if respErr != nil {
continue
}
if resp != nil && resp.Body != nil {
_, _ = ioutil.ReadAll(resp.Body)
_ = resp.Body.Close()
}
statusCode := resp.StatusCode
if statusCode/100 == 2 {
return nil
}
respErr = fmt.Errorf("unexpected response code: %d when accessing URL: %s", statusCode, p.eventsURI)
switch statusCode {
case http.StatusUnauthorized, http.StatusTooManyRequests, http.StatusNotFound:
break PostAttempts
}
}
return respErr
}