122 lines
2.6 KiB
Go
122 lines
2.6 KiB
Go
package main
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import (
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"asink"
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"bytes"
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"encoding/json"
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"errors"
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"fmt"
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"io/ioutil"
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"net/http"
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"strconv"
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"time"
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)
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const MIN_ERROR_WAIT = 100 // 1/10 of a second
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const MAX_ERROR_WAIT = 10000 // 10 seconds
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func SendEvent(globals AsinkGlobals, event *asink.Event) error {
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url := "http://" + globals.server + ":" + strconv.Itoa(int(globals.port)) + "/events/"
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//construct json payload
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events := asink.EventList{
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Events: []*asink.Event{event},
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}
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b, err := json.Marshal(events)
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if err != nil {
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return err
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}
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//actually make the request
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resp, err := http.Post(url, "application/json", bytes.NewReader(b))
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if err != nil {
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return err
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}
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defer resp.Body.Close()
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//check to make sure request succeeded
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body, err := ioutil.ReadAll(resp.Body)
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if err != nil {
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return err
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}
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var apistatus asink.APIResponse
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err = json.Unmarshal(body, &apistatus)
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if err != nil {
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return err
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}
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if apistatus.Status != asink.SUCCESS {
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return errors.New("API response was not success: " + apistatus.Explanation)
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}
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return nil
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}
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func GetEvents(globals AsinkGlobals, events chan *asink.Event) {
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url := "http://" + globals.server + ":" + strconv.Itoa(int(globals.port)) + "/events/"
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var successiveErrors uint = 0
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errorWait := func(err error) {
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fmt.Println(err)
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var waitMilliseconds time.Duration = MIN_ERROR_WAIT << successiveErrors
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if waitMilliseconds > MAX_ERROR_WAIT {
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waitMilliseconds = MAX_ERROR_WAIT
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}
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time.Sleep(waitMilliseconds * time.Millisecond)
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successiveErrors++
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}
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//query DB for latest remote event version number that we've seen locally
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latestEvent, err := globals.db.DatabaseLatestRemoteEvent()
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if err != nil {
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panic(err)
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}
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for {
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//query for events after latest_event
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var fullUrl string
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if latestEvent != nil {
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fullUrl = url + strconv.FormatInt(latestEvent.Id+1, 10)
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} else {
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fullUrl = url + "0"
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}
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resp, err := http.Get(fullUrl)
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//if error, perform exponential backoff (with maximum timeout)
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if err != nil {
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if resp != nil {
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resp.Body.Close()
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}
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errorWait(err)
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continue
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}
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body, err := ioutil.ReadAll(resp.Body)
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resp.Body.Close() //must be done after the last time resp is used
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if err != nil {
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errorWait(err)
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continue
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}
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var apistatus asink.APIResponse
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err = json.Unmarshal(body, &apistatus)
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if err != nil {
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errorWait(err)
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continue
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}
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if apistatus.Status != asink.SUCCESS {
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errorWait(err)
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continue
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}
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for _, event := range apistatus.Events {
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if latestEvent != nil && event.Id != latestEvent.Id+1 {
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break
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}
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events <- event
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latestEvent = event
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}
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successiveErrors = 0
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}
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}
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