package server import ( "sort" "sync" "time" ) type memCache struct { messages map[string][]*message scheduled map[string]*message // Message ID -> message nop bool mu sync.Mutex } var _ cache = (*memCache)(nil) // newMemCache creates an in-memory cache func newMemCache() *memCache { return &memCache{ messages: make(map[string][]*message), scheduled: make(map[string]*message), nop: false, } } // newNopCache creates an in-memory cache that discards all messages; // it is always empty and can be used if caching is entirely disabled func newNopCache() *memCache { return &memCache{ messages: make(map[string][]*message), scheduled: make(map[string]*message), nop: true, } } func (c *memCache) AddMessage(m *message) error { c.mu.Lock() defer c.mu.Unlock() if c.nop { return nil } if m.Event != messageEvent { return errUnexpectedMessageType } if _, ok := c.messages[m.Topic]; !ok { c.messages[m.Topic] = make([]*message, 0) } delayed := m.Time > time.Now().Unix() if delayed { c.scheduled[m.ID] = m } c.messages[m.Topic] = append(c.messages[m.Topic], m) return nil } func (c *memCache) Messages(topic string, since sinceTime, scheduled bool) ([]*message, error) { c.mu.Lock() defer c.mu.Unlock() if _, ok := c.messages[topic]; !ok || since.IsNone() { return make([]*message, 0), nil } messages := make([]*message, 0) for _, m := range c.messages[topic] { _, messageScheduled := c.scheduled[m.ID] include := m.Time >= since.Time().Unix() && (!messageScheduled || scheduled) if include { messages = append(messages, m) } } sort.Slice(messages, func(i, j int) bool { return messages[i].Time < messages[j].Time }) return messages, nil } func (c *memCache) MessagesDue() ([]*message, error) { c.mu.Lock() defer c.mu.Unlock() messages := make([]*message, 0) for _, m := range c.scheduled { due := time.Now().Unix() >= m.Time if due { messages = append(messages, m) } } sort.Slice(messages, func(i, j int) bool { return messages[i].Time < messages[j].Time }) return messages, nil } func (c *memCache) MarkPublished(m *message) error { c.mu.Lock() delete(c.scheduled, m.ID) c.mu.Unlock() return nil } func (c *memCache) MessageCount(topic string) (int, error) { c.mu.Lock() defer c.mu.Unlock() if _, ok := c.messages[topic]; !ok { return 0, nil } return len(c.messages[topic]), nil } func (c *memCache) Topics() (map[string]*topic, error) { c.mu.Lock() defer c.mu.Unlock() topics := make(map[string]*topic) for topic := range c.messages { topics[topic] = newTopic(topic) } return topics, nil } func (c *memCache) Prune(olderThan time.Time) error { c.mu.Lock() defer c.mu.Unlock() for topic := range c.messages { c.pruneTopic(topic, olderThan) } return nil } func (c *memCache) pruneTopic(topic string, olderThan time.Time) { messages := make([]*message, 0) for _, m := range c.messages[topic] { if m.Time >= olderThan.Unix() { messages = append(messages, m) } } c.messages[topic] = messages }