/
transmitter.go
237 lines (196 loc) · 6.74 KB
/
transmitter.go
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package apmz
import (
"bytes"
"compress/gzip"
"encoding/json"
"io/ioutil"
"net/http"
"sort"
"time"
)
type transmitter interface {
Transmit(payload []byte, items telemetryBufferItems) (*transmissionResult, error)
}
type httpTransmitter struct {
endpoint string
}
type transmissionResult struct {
statusCode int
retryAfter *time.Time
response *backendResponse
}
// Structures returned by data collector
type backendResponse struct {
ItemsReceived int `json:"itemsReceived"`
ItemsAccepted int `json:"itemsAccepted"`
Errors itemTransmissionResults `json:"errors"`
}
// This needs to be its own type because it implements sort.Interface
type itemTransmissionResults []*itemTransmissionResult
type itemTransmissionResult struct {
Index int `json:"index"`
StatusCode int `json:"statusCode"`
Message string `json:"message"`
}
const (
successResponse = 200
partialSuccessResponse = 206
requestTimeoutResponse = 408
tooManyRequestsResponse = 429
tooManyRequestsOverExtendedTimeResponse = 439
errorResponse = 500
serviceUnavailableResponse = 503
)
func newTransmitter(endpointAddress string) transmitter {
return &httpTransmitter{endpointAddress}
}
func (transmitter *httpTransmitter) Transmit(payload []byte, items telemetryBufferItems) (*transmissionResult, error) {
diagnosticsWriter.Printf("--------- Transmitting %d items ---------", len(items))
startTime := time.Now()
// Compress the payload
var postBody bytes.Buffer
gzipWriter := gzip.NewWriter(&postBody)
if _, err := gzipWriter.Write(payload); err != nil {
diagnosticsWriter.Printf("Failed to compress the payload: %s", err.Error())
gzipWriter.Close()
return nil, err
}
gzipWriter.Close()
req, err := http.NewRequest("POST", transmitter.endpoint, &postBody)
if err != nil {
return nil, err
}
req.Header.Set("Content-Encoding", "gzip")
req.Header.Set("Content-Type", "application/x-json-stream")
req.Header.Set("Accept-Encoding", "gzip, deflate")
client := http.DefaultClient
resp, err := client.Do(req)
if err != nil {
diagnosticsWriter.Printf("Failed to transmit telemetry: %s", err.Error())
return nil, err
}
defer resp.Body.Close()
body, err := ioutil.ReadAll(resp.Body)
if err != nil {
diagnosticsWriter.Printf("Failed to read response from server: %s", err.Error())
return nil, err
}
duration := time.Since(startTime)
result := &transmissionResult{statusCode: resp.StatusCode}
// Grab Retry-After header
if retryAfterValue, ok := resp.Header[http.CanonicalHeaderKey("Retry-After")]; ok && len(retryAfterValue) == 1 {
if retryAfterTime, err := time.Parse(time.RFC1123, retryAfterValue[0]); err == nil {
result.retryAfter = &retryAfterTime
}
}
// Parse body, if possible
response := &backendResponse{}
if err := json.Unmarshal(body, &response); err == nil {
result.response = response
}
// Write diagnostics
if diagnosticsWriter.hasListeners() {
diagnosticsWriter.Printf("Telemetry transmitted in %s", duration)
diagnosticsWriter.Printf("Response: %d", result.statusCode)
if result.response != nil {
diagnosticsWriter.Printf("Items accepted/received: %d/%d", result.response.ItemsAccepted, result.response.ItemsReceived)
if len(result.response.Errors) > 0 {
diagnosticsWriter.Printf("Errors:")
for _, err := range result.response.Errors {
if err.Index < len(items) {
diagnosticsWriter.Printf("#%d - %d %s", err.Index, err.StatusCode, err.Message)
diagnosticsWriter.Printf("Telemetry item:\n\t%s", string(items[err.Index:err.Index+1].serialize()))
}
}
}
}
}
return result, nil
}
func (result *transmissionResult) IsSuccess() bool {
return result.statusCode == successResponse ||
// Partial response but all items accepted
(result.statusCode == partialSuccessResponse &&
result.response != nil &&
result.response.ItemsReceived == result.response.ItemsAccepted)
}
func (result *transmissionResult) IsFailure() bool {
return result.statusCode != successResponse && result.statusCode != partialSuccessResponse
}
func (result *transmissionResult) CanRetry() bool {
if result.IsSuccess() {
return false
}
return result.statusCode == partialSuccessResponse ||
result.retryAfter != nil ||
(result.statusCode == requestTimeoutResponse ||
result.statusCode == serviceUnavailableResponse ||
result.statusCode == errorResponse ||
result.statusCode == tooManyRequestsResponse ||
result.statusCode == tooManyRequestsOverExtendedTimeResponse)
}
func (result *transmissionResult) IsPartialSuccess() bool {
return result.statusCode == partialSuccessResponse &&
result.response != nil &&
result.response.ItemsReceived != result.response.ItemsAccepted
}
func (result *transmissionResult) IsThrottled() bool {
return result.statusCode == tooManyRequestsResponse ||
result.statusCode == tooManyRequestsOverExtendedTimeResponse ||
result.retryAfter != nil
}
func (result *itemTransmissionResult) CanRetry() bool {
return result.StatusCode == requestTimeoutResponse ||
result.StatusCode == serviceUnavailableResponse ||
result.StatusCode == errorResponse ||
result.StatusCode == tooManyRequestsResponse ||
result.StatusCode == tooManyRequestsOverExtendedTimeResponse
}
func (result *transmissionResult) GetRetryItems(payload []byte, items telemetryBufferItems) ([]byte, telemetryBufferItems) {
if result.statusCode == partialSuccessResponse && result.response != nil {
// Make sure errors are ordered by index
sort.Sort(result.response.Errors)
var resultPayload bytes.Buffer
resultItems := make(telemetryBufferItems, 0)
ptr := 0
idx := 0
// Find each retryable error
for _, responseResult := range result.response.Errors {
if responseResult.CanRetry() {
// Advance ptr to start of desired line
for ; idx < responseResult.Index && ptr < len(payload); ptr++ {
if payload[ptr] == '\n' {
idx++
}
}
startPtr := ptr
// Read to end of line
for ; idx == responseResult.Index && ptr < len(payload); ptr++ {
if payload[ptr] == '\n' {
idx++
}
}
// Copy item into output buffer
resultPayload.Write(payload[startPtr:ptr])
resultItems = append(resultItems, items[responseResult.Index])
}
}
return resultPayload.Bytes(), resultItems
} else if result.CanRetry() {
return payload, items
} else {
return payload[:0], items[:0]
}
}
// sort.Interface implementation for Errors[] list
func (results itemTransmissionResults) Len() int {
return len(results)
}
func (results itemTransmissionResults) Less(i, j int) bool {
return results[i].Index < results[j].Index
}
func (results itemTransmissionResults) Swap(i, j int) {
tmp := results[i]
results[i] = results[j]
results[j] = tmp
}