Add truncation framework

cmd/influxd/config.go

@@ -46,6 +46,9 @@ const (
 	// shard groups need to be created in advance for writing
 	DefaultRetentionCreatePeriod = 45 * time.Minute
 
+	// DefaultBrokerTruncationInterval is the default period between truncating topics.
+	DefaultBrokerTruncationInterval = 10 * time.Minute
+
 	// DefaultMaxTopicSize is the default maximum size in bytes a topic can consume on disk of a broker.
 	DefaultBrokerMaxTopicSize = 1024 * 1024 * 1024
 
@@ -99,11 +102,12 @@ var DefaultSnapshotURL = url.URL{
 
 // Broker represents the configuration for a broker node
 type Broker struct {
-	Dir            string   `toml:"dir"`
-	Enabled        bool     `toml:"enabled"`
-	Timeout        Duration `toml:"election-timeout"`
-	MaxTopicSize   int64    `toml:"max-topic-size"`
-	MaxSegmentSize int64    `toml:"max-segment-size"`
+	Dir                string   `toml:"dir"`
+	Enabled            bool     `toml:"enabled"`
+	Timeout            Duration `toml:"election-timeout"`
+	TruncationInterval Duration `toml:"truncation-interval"`
+	MaxTopicSize       int64    `toml:"max-topic-size"`
+	MaxSegmentSize     int64    `toml:"max-segment-size"`
 }
 
 // Snapshot represents the configuration for a snapshot service. Snapshot configuration
@@ -241,6 +245,7 @@ func NewConfig() *Config {
 	c.ContinuousQuery.ComputeRunsPerInterval = DefaultContinuousQueryComputeRunsPerInterval
 	c.ContinuousQuery.ComputeNoMoreThan = Duration(DefaultContinousQueryComputeNoMoreThan)
 
+	c.Broker.TruncationInterval = Duration(DefaultBrokerTruncationInterval)
 	c.Broker.MaxTopicSize = DefaultBrokerMaxTopicSize
 	c.Broker.MaxSegmentSize = DefaultBrokerMaxSegmentSize
 

cmd/influxd/run.go

@@ -476,6 +476,7 @@ func (cmd *RunCommand) openBroker(brokerURLs []url.URL) {
 
 	// Create broker
 	b := influxdb.NewBroker()
+	b.TruncationInterval = time.Duration(cmd.config.Broker.TruncationInterval)
 	b.MaxTopicSize = cmd.config.Broker.MaxTopicSize
 	b.MaxSegmentSize = cmd.config.Broker.MaxSegmentSize
 	cmd.node.Broker = b

messaging/broker.go

@@ -24,6 +24,8 @@ import (
 // only occurs when the reader is at the end of all the data.
 const DefaultPollInterval = 100 * time.Millisecond
 
+const DefaultTruncationInterval = 10 * time.Minute
+
 // DefaultMaxTopicSize is the largest a topic can get before truncation.
 const DefaultMaxTopicSize = 1024 * 1024 * 1024 // 10MB
 
@@ -40,8 +42,13 @@ type Broker struct {
 	meta   *bolt.DB          // metadata
 	topics map[uint64]*Topic // topics by id
 
-	MaxTopicSize   int64 // Maximum size of a topic in bytes
-	MaxSegmentSize int64 // Maximum size of a segment in bytes
+	TruncationInterval time.Duration
+	MaxTopicSize       int64 // Maximum size of a topic in bytes
+	MaxSegmentSize     int64 // Maximum size of a segment in bytes
+
+	// Goroutinte shutdown
+	done chan struct{}
+	wg   sync.WaitGroup
 
 	// Log is the distributed raft log that commands are applied to.
 	Log interface {
@@ -59,11 +66,13 @@ type Broker struct {
 // NewBroker returns a new instance of a Broker with default values.
 func NewBroker() *Broker {
 	b := &Broker{
-		topics: make(map[uint64]*Topic),
-		Logger: log.New(os.Stderr, "[broker] ", log.LstdFlags),
+		topics:             make(map[uint64]*Topic),
+		Logger:             log.New(os.Stderr, "[broker] ", log.LstdFlags),
+		TruncationInterval: DefaultTruncationInterval,
+		MaxTopicSize:       DefaultMaxTopicSize,
+		MaxSegmentSize:     DefaultMaxSegmentSize,
+		done:               make(chan struct{}),
 	}
-	b.MaxTopicSize = DefaultMaxTopicSize
-	b.MaxSegmentSize = DefaultMaxSegmentSize
 	return b
 }
 
@@ -176,6 +185,16 @@ func (b *Broker) Open(path string) error {
 			return fmt.Errorf("open topics: %s", err)
 		}
 
+		// Start topic truncation.
+		go func() {
+			b.wg.Add(1)
+			tick := time.NewTicker(b.TruncationInterval)
+			for {
+				<-tick.C
+				b.TruncateTopics()
+			}
+		}()
+
 		return nil
 	}(); err != nil {
 		_ = b.close()
@@ -236,6 +255,11 @@ func (b *Broker) close() error {
 	// Close all topics.
 	b.closeTopics()
 
+	// Shutdown all goroutines.
+	close(b.done)
+	b.wg.Wait()
+	b.done = nil
+
 	return nil
 }
 
@@ -247,6 +271,19 @@ func (b *Broker) closeTopics() {
 	b.topics = make(map[uint64]*Topic)
 }
 
+// truncateTopics forces topics to truncate such that they are equal to
+// or less than the requested size, if possible.
+func (b *Broker) TruncateTopics() error {
+	for _, t := range b.topics {
+		if n, err := t.Truncate(b.MaxTopicSize); err != nil {
+			b.Logger.Printf("error truncating topic %s: %s", t.Path(), err.Error())
+		} else if n > 0 {
+			b.Logger.Printf("topic %s, %d bytes deleted", t.Path(), n)
+		}
+	}
+	return nil
+}
+
 // SetMaxIndex sets the highest index applied by the broker.
 // This is only used for internal log messages. Topics may have a higher index.
 func (b *Broker) SetMaxIndex(index uint64) error {
@@ -829,6 +866,12 @@ func (t *Topic) WriteMessage(m *Message) error {
 	return nil
 }
 
+// Truncate attempts to delete topic segments such that the total size of the topic on-disk
+// is equal to or less-than maxSize. Returns the number of bytes deleted, and error if any.
+func (t *Topic) Truncate(maxSize int64) (int64, error) {
+	return 0, nil
+}
+
 // Topics represents a list of topics sorted by id.
 type Topics []*Topic