func TriggerBatchProcessing(c appengine.Context, article ArticleId) error {
// Instead of submitting a task to match incoming bids, resulting in one task per bid,
// we collect bids for up to two seconds and batch-process them afterwards.
semaphoreKey := "semaphore-" + string(article)
if semaphore, err := memcache.Increment(c, semaphoreKey, 1, 0); err != nil {
return err
} else if semaphore >= 2 {
c.Infof("Batch processing already triggered for article %v", article)
memcache.IncrementExisting(c, semaphoreKey, -1)
return nil
} else {
time.Sleep(1 * time.Second)
c.Infof("Starting batch processing...")
memcache.IncrementExisting(c, semaphoreKey, -1)
time_before := time.Now()
matchingErr := MatchIncomingBids(c, article)
time_after := time.Now()
duration := time_after.Sub(time_before)
if duration > 1000*time.Millisecond {
c.Errorf("Batch processing finished after %v. Limit exceeded!", duration)
} else if duration > 500*time.Millisecond {
c.Warningf("Batch processing finished after %v. Limit in danger.", duration)
} else {
c.Infof("Batch processing finished after %v.", duration)
}
return matchingErr
}
}
func IncrExisting(c TransactionContext, key string, delta int64) (newValue uint64, err error) {
k, err := Keyify(key)
if err != nil {
return
}
if newValue, err = memcache.IncrementExisting(c, k, delta); err != nil {
err = errors.Errorf("Error doing IncrementExisting %#v: %v", k, err)
return
}
return
}