package runner
import (
"bytes"
"fmt"
"html/template"
"log"
"sync"
"time"
"github.com/knadh/listmonk/messenger"
"github.com/knadh/listmonk/models"
)
const (
batchSize = 10000
// BaseTPL is the name of the base template.
BaseTPL = "base"
// ContentTpl is the name of the compiled message.
ContentTpl = "content"
)
// DataSource represents a data backend, such as a database,
// that provides subscriber and campaign records.
type DataSource interface {
NextCampaigns(excludeIDs []int64) ([]*models.Campaign, error)
NextSubscribers(campID, limit int) ([]*models.Subscriber, error)
GetCampaign(campID int) (*models.Campaign, error)
UpdateCampaignStatus(campID int, status string) error
CreateLink(url string) (string, error)
}
// Runner handles the scheduling, processing, and queuing of campaigns
// and message pushes.
type Runner struct {
cfg Config
src DataSource
messengers map[string]messenger.Messenger
logger *log.Logger
// Campaigns that are currently running.
camps map[int]*models.Campaign
// Links generated using Track() are cached here so as to not query
// the database for the link UUID for every message sent. This has to
// be locked as it may be used externally when previewing campaigns.
links map[string]string
linksMutex sync.RWMutex
subFetchQueue chan *models.Campaign
msgQueue chan *Message
msgErrorQueue chan msgError
msgErrorCounts map[int]int
}
// Message represents an active subscriber that's being processed.
type Message struct {
Campaign *models.Campaign
Subscriber *models.Subscriber
UnsubscribeURL string
Body []byte
from string
to string
}
// Config has parameters for configuring the runner.
type Config struct {
Concurrency int
MaxSendErrors int
RequeueOnError bool
LinkTrackURL string
UnsubscribeURL string
ViewTrackURL string
}
type msgError struct {
camp *models.Campaign
err error
}
// New returns a new instance of Mailer.
func New(cfg Config, src DataSource, l *log.Logger) *Runner {
r := Runner{
cfg: cfg,
src: src,
logger: l,
messengers: make(map[string]messenger.Messenger),
camps: make(map[int]*models.Campaign, 0),
links: make(map[string]string, 0),
subFetchQueue: make(chan *models.Campaign, cfg.Concurrency),
msgQueue: make(chan *Message, cfg.Concurrency),
msgErrorQueue: make(chan msgError, cfg.MaxSendErrors),
msgErrorCounts: make(map[int]int),
}
return &r
}
// NewMessage creates and returns a Message that is made available
// to message templates while they're compiled.
func (r *Runner) NewMessage(c *models.Campaign, s *models.Subscriber) *Message {
return &Message{
from: c.FromEmail,
to: s.Email,
Campaign: c,
Subscriber: s,
UnsubscribeURL: fmt.Sprintf(r.cfg.UnsubscribeURL, c.UUID, s.UUID),
}
}
// AddMessenger adds a Messenger messaging backend to the runner process.
func (r *Runner) AddMessenger(msg messenger.Messenger) error {
id := msg.Name()
if _, ok := r.messengers[id]; ok {
return fmt.Errorf("messenger '%s' is already loaded", id)
}
r.messengers[id] = msg
return nil
}
// GetMessengerNames returns the list of registered messengers.
func (r *Runner) GetMessengerNames() []string {
var names []string
for n := range r.messengers {
names = append(names, n)
}
return names
}
// HasMessenger checks if a given messenger is registered.
func (r *Runner) HasMessenger(id string) bool {
_, ok := r.messengers[id]
return ok
}
// Run is a blocking function (and hence should be invoked as a goroutine)
// that scans the source db at regular intervals for pending campaigns,
// and queues them for processing. The process queue fetches batches of
// subscribers and pushes messages to them for each queued campaign
// until all subscribers are exhausted, at which point, a campaign is marked
// as "finished".
func (r *Runner) Run(tick time.Duration) {
go func() {
t := time.NewTicker(tick)
for {
select {
// Periodically scan the data source for campaigns to process.
case <-t.C:
campaigns, err := r.src.NextCampaigns(r.getPendingCampaignIDs())
if err != nil {
r.logger.Printf("error fetching campaigns: %v", err)
continue
}
for _, c := range campaigns {
if err := r.addCampaign(c); err != nil {
r.logger.Printf("error processing campaign (%s): %v", c.Name, err)
continue
}
r.logger.Printf("start processing campaign (%s)", c.Name)
// If subscriber processing is busy, move on. Blocking and waiting
// can end up in a race condition where the waiting campaign's
// state in the data source has changed.
select {
case r.subFetchQueue <- c:
default:
}
}
// Aggregate errors from sending messages to check against the error threshold
// after which a campaign is paused.
case e := <-r.msgErrorQueue:
if r.cfg.MaxSendErrors < 1 {
continue
}
// If the error threshold is met, pause the campaign.
r.msgErrorCounts[e.camp.ID]++
if r.msgErrorCounts[e.camp.ID] >= r.cfg.MaxSendErrors {
r.logger.Printf("error counted exceeded %d. pausing campaign %s",
r.cfg.MaxSendErrors, e.camp.Name)
if r.isCampaignProcessing(e.camp.ID) {
r.exhaustCampaign(e.camp, models.CampaignStatusPaused)
}
delete(r.msgErrorCounts, e.camp.ID)
}
}
}
}()
// Fetch the next set of subscribers for a campaign and process them.
for c := range r.subFetchQueue {
has, err := r.nextSubscribers(c, batchSize)
if err != nil {
r.logger.Printf("error processing campaign batch (%s): %v", c.Name, err)
continue
}
if has {
// There are more subscribers to fetch.
r.subFetchQueue <- c
} else {
// There are no more subscribers. Either the campaign status
// has changed or all subscribers have been processed.
if err := r.exhaustCampaign(c, ""); err != nil {
r.logger.Printf("error exhausting campaign (%s): %v", c.Name, err)
}
}
}
}
// SpawnWorkers spawns workers goroutines that push out messages.
func (r *Runner) SpawnWorkers() {
for i := 0; i < r.cfg.Concurrency; i++ {
go func() {
for m := range r.msgQueue {
if !r.isCampaignProcessing(m.Campaign.ID) {
continue
}
err := r.messengers[m.Campaign.MessengerID].Push(
m.from,
m.to,
m.Campaign.Subject,
m.Body)
if err != nil {
r.logger.Printf("error sending message in campaign %s: %v",
m.Campaign.Name, err)
select {
case r.msgErrorQueue <- msgError{camp: m.Campaign, err: err}:
default:
}
}
}
}()
}
}
// addCampaign adds a campaign to the process queue.
func (r *Runner) addCampaign(c *models.Campaign) error {
// Validate messenger.
if _, ok := r.messengers[c.MessengerID]; !ok {
r.src.UpdateCampaignStatus(c.ID, models.CampaignStatusCancelled)
return fmt.Errorf("unknown messenger %s on campaign %s", c.MessengerID, c.Name)
}
// Load the template.
if err := c.CompileTemplate(r.TemplateFuncs(c)); err != nil {
return err
}
// Add the campaign to the active map.
r.camps[c.ID] = c
return nil
}
// getPendingCampaignIDs returns the IDs of campaigns currently being processed.
func (r *Runner) getPendingCampaignIDs() []int64 {
// Needs to return an empty slice in case there are no campaigns.
ids := make([]int64, 0)
for _, c := range r.camps {
ids = append(ids, int64(c.ID))
}
return ids
}
// nextSubscribers processes the next batch of subscribers in a given campaign.
// If returns a bool indicating whether there any subscribers were processed
// in the current batch or not. This can happen when all the subscribers
// have been processed, or if a campaign has been paused or cancelled abruptly.
func (r *Runner) nextSubscribers(c *models.Campaign, batchSize int) (bool, error) {
// Fetch a batch of subscribers.
subs, err := r.src.NextSubscribers(c.ID, batchSize)
if err != nil {
return false, fmt.Errorf("error fetching campaign subscribers (%s): %v", c.Name, err)
}
// There are no subscribers.
if len(subs) == 0 {
return false, nil
}
// Push messages.
for _, s := range subs {
m := r.NewMessage(c, s)
if err := m.Render(); err != nil {
r.logger.Printf("error rendering message (%s) (%s): %v", c.Name, s.Email, err)
continue
}
// Push the message to the queue while blocking and waiting until
// the queue is drained.
r.msgQueue <- m
}
return true, nil
}
// isCampaignProcessing checks if the campaign is bing processed.
func (r *Runner) isCampaignProcessing(id int) bool {
_, ok := r.camps[id]
return ok
}
func (r *Runner) exhaustCampaign(c *models.Campaign, status string) error {
delete(r.camps, c.ID)
// A status has been passed. Change the campaign's status
// without further checks.
if status != "" {
if err := r.src.UpdateCampaignStatus(c.ID, status); err != nil {
r.logger.Printf("error updating campaign (%s) status to %s: %v", c.Name, status, err)
} else {
r.logger.Printf("set campaign (%s) to %s", c.Name, status)
}
return nil
}
// Fetch the up-to-date campaign status from the source.
cm, err := r.src.GetCampaign(c.ID)
if err != nil {
return err
}
// If a running campaign has exhausted subscribers, it's finished.
if cm.Status == models.CampaignStatusRunning {
if err := r.src.UpdateCampaignStatus(c.ID, models.CampaignStatusFinished); err != nil {
r.logger.Printf("error finishing campaign (%s): %v", c.Name, err)
} else {
r.logger.Printf("campaign (%s) finished", c.Name)
}
} else {
r.logger.Printf("stop processing campaign (%s)", c.Name)
}
return nil
}
// Render takes a Message, executes its pre-compiled Campaign.Tpl
// and applies the resultant bytes to Message.body to be used in messages.
func (m *Message) Render() error {
out := bytes.Buffer{}
if err := m.Campaign.Tpl.ExecuteTemplate(&out, models.BaseTpl, m); err != nil {
return err
}
m.Body = out.Bytes()
return nil
}
// trackLink register a URL and return its UUID to be used in message templates
// for tracking links.
func (r *Runner) trackLink(url, campUUID, subUUID string) string {
r.linksMutex.RLock()
if uu, ok := r.links[url]; ok {
r.linksMutex.RUnlock()
return fmt.Sprintf(r.cfg.LinkTrackURL, uu, campUUID, subUUID)
}
r.linksMutex.RUnlock()
// Register link.
uu, err := r.src.CreateLink(url)
if err != nil {
r.logger.Printf("error registering tracking for link '%s': %v", url, err)
// If the registration fails, fail over to the original URL.
return url
}
r.linksMutex.Lock()
r.links[url] = uu
r.linksMutex.Unlock()
return fmt.Sprintf(r.cfg.LinkTrackURL, uu, campUUID, subUUID)
}
// TemplateFuncs returns the template functions to be applied into
// compiled campaign templates.
func (r *Runner) TemplateFuncs(c *models.Campaign) template.FuncMap {
return template.FuncMap{
"TrackLink": func(url, campUUID, subUUID string) string {
return r.trackLink(url, campUUID, subUUID)
},
"TrackView": func(campUUID, subUUID string) template.HTML {
return template.HTML(fmt.Sprintf(`
`,
fmt.Sprintf(r.cfg.ViewTrackURL, campUUID, subUUID)))
},
"Date": func(layout string) string {
if layout == "" {
layout = time.ANSIC
}
return time.Now().Format(layout)
},
}
}