gosora/common/counters/topics_views.go

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package counters
import (
"database/sql"
"sync"
".."
"../../query_gen/lib"
)
var TopicViewCounter *DefaultTopicViewCounter
// TODO: Use two odd-even maps for now, and move to something more concurrent later, maybe a sharded map?
type DefaultTopicViewCounter struct {
oddTopics map[int]*RWMutexCounterBucket // map[tid]struct{counter,sync.RWMutex}
evenTopics map[int]*RWMutexCounterBucket
oddLock sync.RWMutex
evenLock sync.RWMutex
update *sql.Stmt
}
func NewDefaultTopicViewCounter() (*DefaultTopicViewCounter, error) {
acc := qgen.NewAcc()
counter := &DefaultTopicViewCounter{
oddTopics: make(map[int]*RWMutexCounterBucket),
evenTopics: make(map[int]*RWMutexCounterBucket),
update: acc.Update("topics").Set("views = views + ?").Where("tid = ?").Prepare(),
}
common.AddScheduledFifteenMinuteTask(counter.Tick) // Who knows how many topics we have queued up, we probably don't want this running too frequently
//common.AddScheduledSecondTask(counter.Tick)
common.AddShutdownTask(counter.Tick)
return counter, acc.FirstError()
}
func (counter *DefaultTopicViewCounter) Tick() error {
// TODO: Fold multiple 1 view topics into one query
counter.oddLock.RLock()
oddTopics := counter.oddTopics
counter.oddLock.RUnlock()
for topicID, topic := range oddTopics {
var count int
topic.RLock()
count = topic.counter
topic.RUnlock()
// TODO: Only delete the bucket when it's zero to avoid hitting popular topics?
counter.oddLock.Lock()
delete(counter.oddTopics, topicID)
counter.oddLock.Unlock()
err := counter.insertChunk(count, topicID)
if err != nil {
return err
}
}
counter.evenLock.RLock()
evenTopics := counter.evenTopics
counter.evenLock.RUnlock()
for topicID, topic := range evenTopics {
var count int
topic.RLock()
count = topic.counter
topic.RUnlock()
// TODO: Only delete the bucket when it's zero to avoid hitting popular topics?
counter.evenLock.Lock()
delete(counter.evenTopics, topicID)
counter.evenLock.Unlock()
err := counter.insertChunk(count, topicID)
if err != nil {
return err
}
}
return nil
}
// TODO: Optimise this further. E.g. Using IN() on every one view topic. Rinse and repeat for two views, three views, four views and five views.
func (counter *DefaultTopicViewCounter) insertChunk(count int, topicID int) error {
if count == 0 {
return nil
}
common.DebugLogf("Inserting %d views into topic %d", count, topicID)
_, err := counter.update.Exec(count, topicID)
return err
}
func (counter *DefaultTopicViewCounter) Bump(topicID int) {
// Is the ID even?
if topicID%2 == 0 {
counter.evenLock.RLock()
topic, ok := counter.evenTopics[topicID]
counter.evenLock.RUnlock()
if ok {
topic.Lock()
topic.counter++
topic.Unlock()
} else {
counter.evenLock.Lock()
counter.evenTopics[topicID] = &RWMutexCounterBucket{counter: 1}
counter.evenLock.Unlock()
}
return
}
counter.oddLock.RLock()
topic, ok := counter.oddTopics[topicID]
counter.oddLock.RUnlock()
if ok {
topic.Lock()
topic.counter++
topic.Unlock()
} else {
counter.oddLock.Lock()
counter.oddTopics[topicID] = &RWMutexCounterBucket{counter: 1}
counter.oddLock.Unlock()
}
}