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timeseries.go
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timeseries.go
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package http
import (
"context"
"encoding/json"
"fmt"
"io"
"math/rand"
"net/http"
"os"
"regexp"
"strconv"
"strings"
"time"
"github.com/go-chi/chi"
"github.com/sanggonlee/plum"
"github.com/gorilla/websocket"
"github.com/pkg/errors"
)
const (
wsReadBufSize = 2048
wsWriteBufSize = 2048
)
const (
multipartFormMemoryLimit = 512 << 20 // 512 MB
)
const (
defaultTimeseriesInterval = 1 * time.Second
)
var letterRunes = []rune("ABCDEFGHIJKLMNOPQRSTUVWXYZ")
// TimeseriesParams specifies the optional parameters for fetching timeseries data.
type TimeseriesParams struct {
Interval time.Duration
Relations []string
SaveAs string
}
// StartTimeseriesConnection establishes a websocket connection for sending realtime
// database states in timeseries data
func (h *Handler) StartTimeseriesConnection(w http.ResponseWriter, r *http.Request) {
params, err := h.parseTimeseriesParams(r)
if err != nil {
_ = sendErrorResponse(w, http.StatusBadRequest, err)
return
}
var extraWriters []io.Writer
var filename string
if params.SaveAs != "" {
filename = getTimeseriesDataFilePath(params.SaveAs)
f, err := os.Create(filename)
if err != nil {
err = errors.Wrap(err, "creating jsonl file")
h.Logger.Println("Error:", err)
return
}
extraWriters = append(extraWriters, f)
}
if h.LogTimeseriesData {
extraWriters = append(extraWriters, h.Logger.Writer())
}
if err = h.sendTimeseriesData(w, r, params.Interval, func(cw io.WriteCloser, t time.Time) (io.Writer, []byte, error) {
wr := io.MultiWriter(append(extraWriters, cw)...)
ctx := context.Background()
bucket, err := h.getPGTablesSnapshot(ctx, params.Relations, t, t.Add(params.Interval))
if err != nil {
return wr, nil, errors.Wrap(err, "getting pg tables snapshot")
}
bytes, err := json.Marshal(bucket)
if err != nil {
return wr, nil, errors.Wrap(err, "marshal bucket")
}
return wr, bytes, nil
}); err != nil {
h.Logger.Println("Error:", err)
return
}
}
func (h *Handler) parseTimeseriesParams(r *http.Request) (TimeseriesParams, error) {
params := TimeseriesParams{
Interval: defaultTimeseriesInterval,
}
if intervalParam := r.URL.Query().Get("interval"); intervalParam != "" {
intervalMilliseconds, err := strconv.Atoi(intervalParam)
if err != nil {
return params, errors.Wrapf(err, "cannot parse %s", intervalParam)
}
// Convert milliseconds to duration, which is in nanoseconds.
params.Interval = time.Duration(1_000_000 * intervalMilliseconds)
}
if relaionsParam := r.URL.Query().Get("relations"); relaionsParam != "" {
params.Relations = strings.Split(relaionsParam, ",")
}
if saveAsParam := r.URL.Query().Get("save_as"); saveAsParam != "" {
params.SaveAs = saveAsParam
}
return params, nil
}
// TimeseriesReplayParams specifies the optional parameters for setting up
// timeseries replay websocket connection.
type TimeseriesReplayParams struct {
Interval time.Duration
FileID string
}
// StartTimeseriesReplayConnection establishes a websocket connection for sending timeseries replay data
func (h *Handler) StartTimeseriesReplayConnection(w http.ResponseWriter, r *http.Request) {
params, err := h.parseTimeseriesReplayParams(r)
if err != nil {
_ = sendErrorResponse(w, http.StatusBadRequest, err)
return
}
filename := getTimeseriesDataFilePath(params.FileID)
file, err := os.Open(filename)
if err != nil {
err = errors.Wrapf(err, "opening file %s", filename)
h.Logger.Println("Error:", err)
return
}
defer func() {
if err := os.Remove(filename); err != nil {
err = errors.Wrapf(err, "deleting file %s", filename)
h.Logger.Println("Error:", err)
}
}()
dec := json.NewDecoder(file)
if err = h.sendTimeseriesData(w, r, params.Interval, func(cw io.WriteCloser, t time.Time) (io.Writer, []byte, error) {
if !dec.More() {
// Done reading
return cw, nil, nil
}
var m map[string]interface{}
if err = dec.Decode(&m); err != nil {
err = errors.Wrap(err, "reading json chunk")
return cw, nil, err
}
bytes, err := json.Marshal(m)
if err != nil {
err = errors.Wrap(err, "marshaling a json chunk")
return cw, bytes, err
}
return cw, bytes, nil
}); err != nil {
h.Logger.Println("Error:", err)
return
}
}
func (h *Handler) sendTimeseriesData(
w http.ResponseWriter,
r *http.Request,
interval time.Duration,
getData func(io.WriteCloser, time.Time) (io.Writer, []byte, error),
) error {
websocketUpgrader := h.getWebsocketUpgrader()
conn, err := websocketUpgrader.Upgrade(w, r, nil)
if err != nil {
return errors.Wrap(err, "instantiating ws connection")
}
defer conn.Close()
go func() {
// Close the connection when it starts failing to read from client
if _, _, err := conn.ReadMessage(); err != nil {
conn.Close()
return
}
}()
ticker := time.NewTicker(interval)
defer ticker.Stop()
for t := range ticker.C {
cw, err := conn.NextWriter(websocket.TextMessage)
if err != nil {
if err != websocket.ErrCloseSent {
return errors.Wrap(err, "getting next writer")
}
return nil
}
wr, bytes, err := getData(cw, t)
if err != nil {
return errors.Wrap(err, "getting data to write")
}
if bytes == nil {
// Done
return nil
}
if _, err := wr.Write(bytes); err != nil {
return errors.Wrap(err, "writing to writer")
}
if err := cw.Close(); err != nil {
return errors.Wrap(err, "closing websocket connection writer")
}
}
return nil
}
// DownloadTimeseriesDataFileResponse is the response format for DownloadTimeseriesDataFile
type DownloadTimeseriesDataFileResponse struct {
FileID string `json:"file_id"`
}
// DownloadTimeseriesDataFile responds with the timeseries data file, and deletes it after.
func (h *Handler) DownloadTimeseriesDataFile(w http.ResponseWriter, r *http.Request) {
fs := http.FileServer(http.Dir("tmp"))
handler := http.StripPrefix("/timeseries/download/", fs)
w.Header().Set("Content-Disposition", "attachment")
handler.ServeHTTP(w, r)
filename := chi.URLParam(r, urlParamFilename)
if err := os.Remove(fmt.Sprintf("tmp/%s", filename)); err != nil {
err = errors.Wrap(err, "deleting timeseries data file")
h.Logger.Println("Error:", err)
}
}
// UploadTimeseriesDataFile persists the temporary file.
func (h *Handler) UploadTimeseriesDataFile(w http.ResponseWriter, r *http.Request) {
if err := r.ParseMultipartForm(multipartFormMemoryLimit); err != nil {
err = errors.Wrap(err, "parsing multipart form")
h.Logger.Println("Error:", err)
_ = sendErrorResponse(w, http.StatusInternalServerError, err)
return
}
file, _, err := r.FormFile("file")
if err != nil {
err = errors.Wrap(err, "reading form file")
h.Logger.Println("Error:", err)
_ = sendErrorResponse(w, http.StatusInternalServerError, err)
return
}
defer file.Close()
fileID := randStringRunes(16)
filename := getTimeseriesDataFilePath(fileID)
f, err := os.Create(filename)
if err != nil {
err = errors.Wrap(err, "creating temp file")
h.Logger.Println("Error:", err)
return
}
if _, err = io.Copy(f, file); err != nil {
err = errors.Wrap(err, "writing to the temp file")
h.Logger.Println("Error:", err)
return
}
_ = sendResponse(w, http.StatusOK, DownloadTimeseriesDataFileResponse{FileID: fileID})
}
func (h *Handler) parseTimeseriesReplayParams(r *http.Request) (TimeseriesReplayParams, error) {
params := TimeseriesReplayParams{
Interval: defaultTimeseriesInterval,
}
if intervalParam := r.URL.Query().Get("interval"); intervalParam != "" {
intervalMilliseconds, err := strconv.Atoi(intervalParam)
if err != nil {
return params, errors.Wrapf(err, "cannot parse %s", intervalParam)
}
// Convert milliseconds to duration, which is in nanoseconds.
params.Interval = time.Duration(1_000_000 * intervalMilliseconds)
}
if fileIDParam := r.URL.Query().Get("file_id"); fileIDParam != "" {
params.FileID = fileIDParam
}
return params, nil
}
func (h *Handler) getWebsocketUpgrader() websocket.Upgrader {
return websocket.Upgrader{
ReadBufferSize: wsReadBufSize,
WriteBufferSize: wsWriteBufSize,
CheckOrigin: func(r *http.Request) bool {
matched, err := regexp.MatchString(h.AllowedOrigins, r.Header.Get("Origin"))
if err != nil {
h.Logger.Println("Error matching the request origin with allowed origins:", err)
return false
}
return matched
},
}
}
func (h *Handler) getPGTablesSnapshot(
ctx context.Context,
relations []string,
start,
end time.Time,
) (plum.Bucket, error) {
tableStates, err := h.Database.GetPGTables(ctx, relations)
if err != nil {
return plum.Bucket{}, errors.Wrap(err, "getting pg table states from db")
}
numLocks, err := h.Database.GetCurrentNumLocks(ctx)
if err != nil {
return plum.Bucket{}, errors.Wrap(err, "getting the current number of locks from db")
}
return plum.Bucket{
TStart: start,
TEnd: end,
TableStates: tableStates,
NumLocks: numLocks,
}, nil
}
func getTimeseriesDataFilePath(saveAs string) string {
return fmt.Sprintf("tmp/%s.jsonl", saveAs)
}
func randStringRunes(n int) string {
b := make([]rune, n)
for i := range b {
b[i] = letterRunes[rand.Intn(len(letterRunes))]
}
return string(b)
}