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|
package logic
import (
"errors"
"fmt"
"github.com/PuerkitoBio/goquery"
"github.com/microcosm-cc/bluemonday"
"github.com/mmcdole/gofeed"
"github.com/spaolacci/murmur3"
"html"
"math/rand"
"net/http"
"net/url"
"os"
"rss_parrot/dal"
"rss_parrot/shared"
"rss_parrot/texts"
"sort"
"strings"
"sync"
"time"
)
const feedCheckLoopIdleWakeSec = 60
const postCountUpdateSecs = 60
type FeedStatus int32
const (
FsNew = 0
FsAlreadyFollowed = 1
FsError = -1
FsMastodon = -2
FsBanned = -3
FsOptOut = -4
)
const (
feedOrSiteTimeoutSec = 10
allowedFuturePostDays = 2
)
type IFeedFollower interface {
GetAccountForFeed(urlStr string) (acct *dal.Account, status FeedStatus, err error)
PurgeOldPosts(acct *dal.Account, minCount, minAgeDays int) error
}
type SiteInfo struct {
Url string
ParrotHandle string
FeedUrl string
LastUpdated time.Time
Title string
Description string
}
type feedFollower struct {
cfg *shared.Config
logger shared.ILogger
userAgent shared.IUserAgent
repo dal.IRepo
blockedFeeds IBlockedFeeds
messenger IMessenger
txt texts.ITexts
keyStore IKeyStore
metrics IMetrics
lastCheckedPostCount time.Time
muPurgingOldPosts sync.Mutex
isPurgingOldPosts bool
muPurgingUnfollowed sync.Mutex
isPurgingUnfollowed bool
}
func NewFeedFollower(
cfg *shared.Config,
logger shared.ILogger,
userAgent shared.IUserAgent,
repo dal.IRepo,
blockedFeeds IBlockedFeeds,
messenger IMessenger,
txt texts.ITexts,
keyStore IKeyStore,
metrics IMetrics,
) IFeedFollower {
ff := feedFollower{
cfg: cfg,
logger: logger,
userAgent: userAgent,
repo: repo,
blockedFeeds: blockedFeeds,
messenger: messenger,
txt: txt,
keyStore: keyStore,
metrics: metrics,
isPurgingUnfollowed: false,
}
ff.updateDBSizeMetric()
ff.updateTotalPostsMetric()
go ff.feedCheckLoop()
return &ff
}
func (ff *feedFollower) getFeedUrl(siteUrl *url.URL, doc *goquery.Document) string {
var feedUrlStr string
isFeedRss := false
doc.Find("link[rel='alternate']").Each(func(_ int, s *goquery.Selection) {
var aType, aHref string
var ok bool
if aType, ok = s.Attr("type"); !ok {
return
}
if aHref, ok = s.Attr("href"); !ok {
return
}
if aType == "application/atom+xml" && !isFeedRss && feedUrlStr == "" {
feedUrlStr = aHref
}
if aType == "application/rss+xml" && (feedUrlStr == "" || !isFeedRss) {
feedUrlStr = aHref
isFeedRss = true
}
})
// Make it absolute
feedUrl, err := url.Parse(feedUrlStr)
if err != nil {
return ""
}
if !feedUrl.IsAbs() {
feedUrl = siteUrl.ResolveReference(feedUrl)
}
// Remove (most) query parameters
ff.trimQueryParams(feedUrl)
// It's a keeper
res := feedUrl.String()
res = strings.TrimRight(res, "/")
return res
}
func (ff *feedFollower) trimQueryParams(feedUrl *url.URL) {
// The few exceptions where we keep the query param
// #33: Youtube feeds look like this: https://www.youtube.com/feeds/videos.xml?channel_id=UCfZz8F37oSJ2rtcEJHM2kCg
// #69: Youtube playlists feeds: https://www.youtube.com/feeds/videos.xml?playlist_id=PL8_lN8JGpWGzorDyFQ5sW-FutcpCTIKHs
if strings.Contains(feedUrl.Host, "youtube.com") {
if strings.Contains(feedUrl.RawQuery, "channel_id") || strings.Contains(feedUrl.RawQuery, "playlist_id") {
return
}
}
// #37: Archive.org: https://archive.org/services/collection-rss.php?collection=misczinespunk
if strings.Contains(feedUrl.Host, "archive.org") {
return
}
// #63: Language Log
if strings.Contains(feedUrl.Host, "languagelog.ldc.upenn.edu") {
return
}
// Squarespace RSS feeds have `?format=rss` (https://support.squarespace.com/hc/en-us/articles/215761717-Using-RSS-feeds)
if strings.Contains(feedUrl.RawQuery, "format=rss") {
feedUrl.RawQuery = "format=rss"
return
}
// All otheres: remove query
feedUrl.RawQuery = ""
}
func (ff *feedFollower) trimQueryParamsStr(urlStr string) (string, error) {
if parsedUrl, err := url.Parse(urlStr); err != nil {
return "", err
} else {
ff.trimQueryParams(parsedUrl)
return parsedUrl.String(), nil
}
}
func (ff *feedFollower) getMetas(doc *goquery.Document, si *SiteInfo) {
s := doc.Find("title").First()
if s.Length() != 0 {
si.Title = s.Text()
}
s = doc.Find("meta[name='description']").First()
if s.Length() != 0 {
si.Description = s.AttrOr("content", "")
}
}
func getLastUpdated(feed *gofeed.Feed) time.Time {
var t time.Time
if feed.PublishedParsed != nil {
t = *feed.PublishedParsed
}
if feed.UpdatedParsed != nil && feed.UpdatedParsed.After(t) {
t = *feed.UpdatedParsed
}
for _, itm := range feed.Items {
if itm.PublishedParsed != nil && itm.PublishedParsed.After(t) {
t = *itm.PublishedParsed
}
if itm.UpdatedParsed != nil && itm.UpdatedParsed.After(t) {
t = *itm.UpdatedParsed
}
}
return t
}
func (ff *feedFollower) validateSiteInfo(si *SiteInfo) error {
if _, err := url.Parse(si.FeedUrl); err != nil {
return err
}
if err := shared.ValidateHandle(si.ParrotHandle); err != nil {
return err
}
return nil
}
func (ff *feedFollower) getSiteInfo(urlStr string) (*SiteInfo, *gofeed.Feed, error) {
urlStr = strings.TrimRight(urlStr, "/")
var res SiteInfo
var err error
// First, let's see if this is the feed itself
var feed *gofeed.Feed
var noQueryUrlStr string
if noQueryUrlStr, err = ff.trimQueryParamsStr(urlStr); err != nil {
return nil, nil, err
}
feed, err = ff.fetchParseFeed(noQueryUrlStr)
if err == nil {
res.FeedUrl = noQueryUrlStr
res.LastUpdated = getLastUpdated(feed)
res.Title = feed.Title
res.Description = feed.Description
res.Url = feed.Link
res.ParrotHandle = shared.GetHandleFromUrl(res.Url)
return &res, feed, nil
}
// Normalize URL
siteUrl, err := url.Parse(urlStr)
if err != nil {
return nil, nil, err
}
res.Url = urlStr
res.ParrotHandle = shared.GetHandleFromUrl(res.Url)
// Get the page
client := http.Client{}
client.Timeout = feedOrSiteTimeoutSec * time.Second
resp, err := client.Get(urlStr)
if err != nil {
ff.logger.Warnf("Failed to get %s: %v", siteUrl, err)
return nil, nil, err
}
defer resp.Body.Close()
if resp.StatusCode != 200 {
err = fmt.Errorf("request for %s failed with status %d", siteUrl, resp.StatusCode)
ff.logger.Warnf("Failed to get site: %v", err)
return nil, nil, err
}
// Load the HTML document
doc, err := goquery.NewDocumentFromReader(resp.Body)
if err != nil {
ff.logger.Warnf("Failed to parse HTML from %s: %v", siteUrl, err)
return nil, nil, err
}
// Pick out the data we're interested in
res.FeedUrl = ff.getFeedUrl(siteUrl, doc)
if res.FeedUrl == "" {
ff.logger.Warnf("No feed URL found: %s", siteUrl)
return nil, nil, fmt.Errorf("no feed URL found at %s", siteUrl)
}
ff.getMetas(doc, &res)
// Get the feed to make sure it's there, and know when it's last changed
feed, err = ff.fetchParseFeed(res.FeedUrl)
if err != nil {
ff.logger.Warnf("Failed to retrieve and parse feed: %s, %v", res.FeedUrl, err)
return nil, nil, err
}
res.LastUpdated = getLastUpdated(feed)
return &res, feed, nil
}
func getItemHash(itm *gofeed.Item) uint {
str := itm.GUID + "\t" + itm.Link
hasher := murmur3.New32()
_, _ = hasher.Write([]byte(str))
return uint(hasher.Sum32())
}
func (ff *feedFollower) updateAccountPosts(
accountId int,
accountHandle string,
feed *gofeed.Feed,
tootNew bool,
) (err error) {
err = nil
var lastKnownFeedUpdated time.Time
if lastKnownFeedUpdated, err = ff.repo.GetFeedLastUpdated(accountId); err != nil {
return
}
// Deal with feed items newer than our last seen
// This goes from older to newer
keepers, newLastUpdated := getSortedPosts(feed.Items, lastKnownFeedUpdated)
for _, k := range keepers {
fixPodcastLink(k.itm)
if err = ff.storePostIfNew(accountId, accountHandle, k.postTime, k.itm, tootNew); err != nil {
return
}
}
nextCheckDue := ff.getNextCheckTime(newLastUpdated)
if err = ff.repo.UpdateAccountFeedTimes(accountId, newLastUpdated, nextCheckDue); err != nil {
return
}
return
}
func fixPodcastLink(itm *gofeed.Item) {
if itm.Link != "" {
return
}
for _, enc := range itm.Enclosures {
if !strings.HasPrefix(enc.Type, "audio/") || enc.URL == "" {
continue
}
parsedUrl, err := url.Parse(enc.URL)
if err != nil {
continue
}
parsedUrl.RawQuery = ""
itm.Link = parsedUrl.String()
return
}
}
type sortedPost struct {
itm *gofeed.Item
postTime time.Time
}
func getSortedPosts(items []*gofeed.Item, lastKnownFeedUpdated time.Time) ([]sortedPost, time.Time) {
var keepers []sortedPost
newLastUpdated := lastKnownFeedUpdated
futureLimit := time.Now().Add(allowedFuturePostDays * time.Hour * 24)
for _, itm := range items {
keeper, postTime := checkItemTime(itm, lastKnownFeedUpdated, futureLimit)
if !keeper {
continue
}
if postTime.After(newLastUpdated) {
newLastUpdated = postTime
}
keepers = append(keepers, sortedPost{itm, postTime})
}
sort.Slice(keepers, func(i, j int) bool {
return keepers[i].postTime.Before(keepers[j].postTime)
})
return keepers, newLastUpdated
}
func checkItemTime(itm *gofeed.Item, latestKown, futureLimit time.Time) (keeper bool, postTime time.Time) {
keeper = false
postTime = time.Time{}
if itm.PublishedParsed != nil && itm.PublishedParsed.After(latestKown) {
keeper = true
postTime = *itm.PublishedParsed
}
if itm.UpdatedParsed != nil && itm.UpdatedParsed.After(latestKown) {
keeper = true
if itm.UpdatedParsed.After(postTime) {
postTime = *itm.UpdatedParsed
}
}
// Accept posts a little bit into the future, but not far ahead
// Future posts would prevent us from routinely purging old posts
if futureLimit.Sub(postTime) < 0 {
keeper = false
}
return
}
func (ff *feedFollower) getNextCheckTime(lastChanged time.Time) time.Time {
return time.Now().Add(ff.getCheckInterval(lastChanged))
}
// getCheckInterval is how long to wait between two checks of a feed that last
// changed at lastChanged, from the update_schedule config (in hours).
func (ff *feedFollower) getCheckInterval(lastChanged time.Time) time.Duration {
// Pick by how long the feed has been idle:
// changed in the last day: update_schedule.day
// in the last week: .week; in the last 4 weeks: .weeks4; else: .older
var hours = float64(ff.cfg.UpdateSchedule.Day)
idleFor := time.Now().Sub(lastChanged)
if idleFor.Hours() > 24 {
hours = float64(ff.cfg.UpdateSchedule.Week)
}
if idleFor.Hours() > 168 {
hours = float64(ff.cfg.UpdateSchedule.Weeks4)
}
if idleFor.Hours() > 168*4 {
hours = float64(ff.cfg.UpdateSchedule.Older)
}
hours = hours * (0.8 + 0.4*rand.Float64()) // 0.8 - 1.2 random band around targeted value
return time.Duration(float64(time.Hour) * hours)
}
func stripHtml(htm string) string {
p := bluemonday.StrictPolicy()
plain := p.Sanitize(htm)
plain = html.UnescapeString(plain)
plain = strings.TrimSpace(plain)
return plain
}
func (ff *feedFollower) storePostIfNew(
accountId int,
accountHandle string,
postTime time.Time,
itm *gofeed.Item,
tootNew bool,
) (err error) {
var isNew bool
plainTitle := stripHtml(itm.Title)
plainDescription := stripHtml(itm.Description)
isNew, err = ff.repo.AddFeedPostIfNew(accountId, &dal.FeedPost{
PostGuidHash: int64(getItemHash(itm)),
PostTime: postTime,
Link: itm.Link,
Title: plainTitle,
Description: plainDescription,
})
if err != nil {
return
}
if isNew {
ff.metrics.NewPostSaved()
if err = ff.createToot(accountId, accountHandle, itm, tootNew); err != nil {
return
}
}
return
}
func (ff *feedFollower) createToot(accountId int, accountHandle string, itm *gofeed.Item, sendToot bool) error {
prettyUrl := itm.Link
prettyUrl = strings.TrimPrefix(prettyUrl, "http://")
prettyUrl = strings.TrimPrefix(prettyUrl, "https://")
prettyUrl = strings.TrimRight(prettyUrl, "/")
plainTitle := stripHtml(itm.Title)
plainDescription := stripHtml(itm.Description)
plainDescription = shared.TruncateWithEllipsis(plainDescription, shared.MaxDescriptionLen)
content := ff.txt.WithVals("toot_new_post.html", map[string]string{
"title": plainTitle,
"url": itm.Link,
"prettyUrl": prettyUrl,
"description": plainDescription,
})
idb := shared.IdBuilder{Host: ff.cfg.Host}
id := ff.repo.GetNextId()
statusId := idb.UserStatus(accountHandle, id)
tootedAt := time.Now()
err := ff.repo.AddToot(accountId, &dal.Toot{
PostGuidHash: int64(getItemHash(itm)),
TootedAt: tootedAt,
StatusId: statusId,
Content: content,
})
if err != nil {
return err
}
if sendToot {
if err = ff.messenger.EnqueueBroadcast(accountHandle, statusId, tootedAt, content); err != nil {
return err
}
}
return nil
}
func (ff *feedFollower) filterFeed(feedUrl string, feed *gofeed.Feed) (FeedStatus, error) {
// We don't parrot Mastond RSS feeds
generator := strings.ToLower(feed.Generator)
if strings.Contains(generator, "mastodon") {
return FsMastodon, nil
}
// We don't parrot blocked feeds
var err error
var blocked bool
blocked, err = ff.blockedFeeds.IsBlocked(feedUrl)
if err != nil {
return FsError, err
}
if blocked {
return FsOptOut, nil
}
// FsError is the OK response
return FsError, nil
}
func (ff *feedFollower) GetAccountForFeed(urlStr string) (acct *dal.Account, status FeedStatus, err error) {
ff.logger.Infof("Retrieving site information: %s", urlStr)
feedLabel := "failed"
defer func() {
ff.metrics.FeedRequested(feedLabel)
}()
acct = nil
status = FsError
err = nil
si, feed, siErr := ff.getSiteInfo(urlStr)
if siErr == nil {
siErr = ff.validateSiteInfo(si)
}
if siErr != nil {
err = siErr
return
}
status, err = ff.filterFeed(si.FeedUrl, feed)
if err != nil {
status = FsError
return
}
if status != FsError {
return
}
idb := shared.IdBuilder{Host: ff.cfg.Host}
var pubKey string
var privKey string
pubKey, privKey, err = ff.keyStore.MakeKeyPair()
if err != nil {
ff.logger.Errorf("Failed to create key pair: %v", err)
return
}
var isNew bool
isNew, err = ff.repo.AddAccountIfNotExist(&dal.Account{
CreatedAt: time.Now(),
Handle: si.ParrotHandle,
UserUrl: idb.UserUrl(si.ParrotHandle),
FeedName: si.Title,
FeedSummary: si.Description,
SiteUrl: si.Url,
FeedUrl: si.FeedUrl,
PubKey: pubKey,
}, privKey)
if err != nil {
ff.logger.Errorf("Failed to create/get account for %s: %v", si.ParrotHandle, isNew)
return
}
ff.logger.Infof("Account is %s; newly created: %v", si.ParrotHandle, isNew)
acct, err = ff.repo.GetAccount(si.ParrotHandle)
if err != nil {
ff.logger.Errorf("Failed to load account for %s; was newly created: %v", si.ParrotHandle, isNew)
acct = nil
return
}
err = ff.updateAccountPosts(acct.Id, si.ParrotHandle, feed, !isNew)
if err != nil {
ff.logger.Errorf("Failed to update account's posts: %s: %v", acct.Handle, err)
acct = nil
return
}
if isNew {
status = FsNew
feedLabel = "new"
} else {
status = FsAlreadyFollowed
feedLabel = "existing"
}
return
}
func (ff *feedFollower) fetchParseFeed(feedUrl string) (feed *gofeed.Feed, err error) {
res, err := ff.fetchFeed(feedUrl, "", "")
if err != nil {
return nil, err
}
if res.notModified {
// We sent no validators, so the server has nothing to compare against.
return nil, fmt.Errorf("unexpected 304 Not Modified for unconditional request")
}
return res.feed, nil
}
// feedFetchResult is the outcome of a successful fetchFeed: either the
// feed is unchanged (notModified, feed is nil), or it is the parsed feed
// together with the validators to send next time.
type feedFetchResult struct {
feed *gofeed.Feed
notModified bool
etag string
lastModified string
}
// fetchFeed GETs a feed. If etag or lastModified are set (from the last 200
// response), the request is conditional and a 304 is reported as notModified.
// A non-2xx status is returned as a *feedFetchError, carrying Retry-After.
func (ff *feedFollower) fetchFeed(feedUrl, etag, lastModified string) (*feedFetchResult, error) {
req, err := http.NewRequest("GET", feedUrl, nil)
if err != nil {
return nil, err
}
ff.userAgent.AddUserAgent(req)
if etag != "" {
req.Header.Set("If-None-Match", etag)
}
if lastModified != "" {
req.Header.Set("If-Modified-Since", lastModified)
}
client := http.Client{}
client.Timeout = time.Second * feedOrSiteTimeoutSec
resp, err := client.Do(req)
if err != nil {
return nil, err
}
defer resp.Body.Close()
switch resp.StatusCode {
case http.StatusOK:
case http.StatusNotModified:
return &feedFetchResult{notModified: true, etag: etag, lastModified: lastModified}, nil
default:
return nil, &feedFetchError{
StatusCode: resp.StatusCode,
RetryAfter: parseRetryAfter(resp.Header.Get("Retry-After"), time.Now()),
}
}
fp := gofeed.NewParser()
feed, err := fp.Parse(resp.Body)
if err != nil {
return nil, err
}
return &feedFetchResult{
feed: feed,
etag: resp.Header.Get("ETag"),
lastModified: resp.Header.Get("Last-Modified"),
}, nil
}
func (ff *feedFollower) updateFeed(acct *dal.Account) error {
var err error
ff.logger.Infof("Updating account %s: %s", acct.Handle, acct.FeedUrl)
ff.metrics.FeedUpdated()
var res *feedFetchResult
if res, err = ff.fetchFeed(acct.FeedUrl, acct.FeedEtag, acct.FeedLastModified); err != nil {
return err
}
if res.notModified {
// Nothing new: schedule the next check as if no new post appeared,
// which is exactly what happened.
ff.logger.Debugf("Feed not modified: %s", acct.Handle)
nextCheckDue := ff.getNextCheckTime(acct.FeedLastUpdated)
if err = ff.repo.UpdateAccountFeedTimes(acct.Id, acct.FeedLastUpdated, nextCheckDue); err != nil {
return err
}
return ff.repo.SetFeedFetchState(acct.Id, res.etag, res.lastModified, 0)
}
if err = ff.updateAccountPosts(acct.Id, acct.Handle, res.feed, true); err != nil {
return err
}
if err = ff.repo.SetFeedFetchState(acct.Id, res.etag, res.lastModified, 0); err != nil {
return err
}
go func() {
if err = ff.PurgeOldPosts(acct, ff.cfg.PostsMinCountKept, ff.cfg.PostsMinDaysKept); err != nil {
// If purging errors out: swallow it (updateFeed still succeeds); just log
ff.logger.Errorf("Error purging old posts for account %s: %v", acct.Handle, err)
}
}()
return nil
}
func (ff *feedFollower) PurgeOldPosts(acct *dal.Account, minCount, minAgeDays int) error {
if minCount <= 0 || minAgeDays <= 0 {
return nil
}
// We're fired off as a goroutine each time a feed has been refreshed
// Only run one purge at a time
canProceed := false
ff.muPurgingOldPosts.Lock()
if !ff.isPurgingOldPosts {
canProceed = true
ff.isPurgingOldPosts = true
}
ff.muPurgingOldPosts.Unlock()
if !canProceed {
return nil
}
signalDone := func() {
ff.muPurgingOldPosts.Lock()
ff.isPurgingOldPosts = false
ff.muPurgingOldPosts.Unlock()
}
defer signalDone()
if ff.cfg.PurgeWaitSec > 0 {
time.Sleep(time.Duration(ff.cfg.PurgeWaitSec) * time.Second)
}
var err error
var toots []*dal.Toot
if toots, err = ff.repo.GetTootExtracts(acct.Id); err != nil {
return err
}
// Fewer than minimum count - nothing to do
if len(toots) <= minCount {
return nil
}
// Sort from newest to oldest
sort.Slice(toots, func(i, j int) bool {
return toots[i].TootedAt.After(toots[j].TootedAt)
})
// Check each item from start; if we're past minimum count, find time of latest toot to delete
var fromBefore *time.Time = nil
nToDel := 0
now := time.Now().UTC()
for i, toot := range toots {
if i < minCount {
continue
}
tootAgeDays := now.Sub(toot.TootedAt).Hours() / 24.0
if tootAgeDays < float64(minAgeDays) {
continue
}
fromBefore = &time.Time{}
*fromBefore = toot.TootedAt
nToDel = len(toots) - i
break
}
if fromBefore == nil {
return nil
}
// Purge 'em
ff.logger.Infof("Purging %d old toots+posts from account %s", nToDel, acct.Handle)
if err = ff.repo.PurgePostsAndToots(acct.Id, *fromBefore); err != nil {
return err
}
ff.metrics.PostsDeleted(nToDel)
return nil
}
func (ff *feedFollower) purgeUnfollowedAccount(acct *dal.Account) {
// We're fired off as a goroutine each time there's a deletable account
// Only run one account deleting at a time
canProceed := false
ff.muPurgingUnfollowed.Lock()
if !ff.isPurgingUnfollowed {
canProceed = true
ff.isPurgingUnfollowed = true
}
ff.muPurgingUnfollowed.Unlock()
if !canProceed {
return
}
signalDone := func() {
ff.muPurgingUnfollowed.Lock()
ff.isPurgingUnfollowed = false
ff.muPurgingUnfollowed.Unlock()
}
defer signalDone()
followerCount, err := ff.repo.GetFollowerCount(acct.Handle, false)
if err != nil {
ff.logger.Errorf("Error getting follower count of feed: %s: %v", acct.Handle, err)
return
}
if followerCount != 0 {
return
}
ff.logger.Infof("Deleting account with 0 followers: %s", acct.Handle)
if err = ff.repo.BruteDeleteAccount(acct.Id); err != nil {
ff.logger.Errorf("Failed to brute-delete account: %s: %v", acct.Handle, err)
return
}
if ff.cfg.PurgeWaitSec > 0 {
time.Sleep(time.Duration(ff.cfg.PurgeWaitSec) * time.Second)
}
}
func (ff *feedFollower) updateDBSizeMetric() {
// In case feed follower is running on a mock config in a unit test: don't bother
if ff.cfg.DbFile == "" {
return
}
var err error
var fi os.FileInfo
fi, err = os.Stat(ff.cfg.DbFile)
if err != nil {
ff.logger.Errorf("Error getting DB file size: %v", err)
return
}
ff.metrics.DbFileSize(fi.Size())
}
func (ff *feedFollower) updateTotalPostsMetric() {
now := time.Now()
if now.Sub(ff.lastCheckedPostCount).Seconds() < postCountUpdateSecs {
return
}
ff.lastCheckedPostCount = now
ff.logger.Info("Updating total post count metric")
if count, err := ff.repo.GetTotalPostCount(); err != nil {
ff.logger.Errorf("Error getting total post count: %v", err)
return
} else {
ff.metrics.TotalPosts(int(count))
}
}
func (ff *feedFollower) feedCheckLoop() {
for {
// This is why we're here
ff.feedCheckLoopInner()
// This is real doggone ugly here, but -
// Other option is to create a logic class just for this
// Rather a little ugliness here, then all that boilerplate
// And we're already also setting the "feed-followers" metrics in this module
ff.updateDBSizeMetric()
ff.updateTotalPostsMetric()
}
}
func (ff *feedFollower) feedCheckLoopInner() {
defer func() {
if r := recover(); r != nil {
const panicSleepSec = 10
ff.logger.Errorf("Feed check cycle panicked: %v", r)
ff.logger.Infof("Sleeping %d seconds after panic", panicSleepSec)
time.Sleep(time.Second * panicSleepSec)
}
}()
var err error
var acct *dal.Account
var total int
if acct, total, err = ff.repo.GetAccountToCheck(time.Now()); err != nil {
ff.logger.Errorf("Failed to get next feed due for checking: %v", err)
time.Sleep(feedCheckLoopIdleWakeSec * time.Second)
return
}
ff.metrics.CheckableFeedCount(total)
if acct == nil {
ff.logger.Debugf("No feeds to check; sleeping %d seconds", feedCheckLoopIdleWakeSec)
time.Sleep(feedCheckLoopIdleWakeSec * time.Second)
return
}
lastUpdated := acct.FeedLastUpdated
err = ff.updateFeed(acct)
if err != nil {
// Back off: every consecutive failure doubles the wait, and a server
// that says when to come back (Retry-After) is listened to.
failures := acct.FetchFailures + 1
var retryAfter time.Duration
var fetchErr *feedFetchError
if errors.As(err, &fetchErr) {
retryAfter = fetchErr.RetryAfter
}
delay := backoffDelay(ff.getCheckInterval(lastUpdated), failures, retryAfter,
maxRetryDelay(ff.cfg.MaxRetryDelayHours))
ff.logger.Errorf("Error updating feed: %s: %v (failure %d, next check in %s)",
acct.Handle, err, failures, delay.Round(time.Minute))
if err = ff.repo.UpdateAccountFeedTimes(acct.Id, lastUpdated, time.Now().Add(delay)); err != nil {
ff.logger.Errorf("Failed to reschedule for checking after error: %s: %v", acct.Handle, err)
}
if err = ff.repo.SetFeedFetchState(acct.Id, acct.FeedEtag, acct.FeedLastModified, failures); err != nil {
ff.logger.Errorf("Failed to record fetch failure: %s: %v", acct.Handle, err)
}
}
// If no error, updateFeed has set next due date for checking
// Delete account if no followers; purge old posts
go ff.purgeUnfollowedAccount(acct)
}
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