Basic instrumentation for shards

CHANGELOG.md

@@ -22,6 +22,7 @@ With this release InfluxDB is moving to Go 1.5.
 - [#4003](https://github.com/influxdb/influxdb/pull/4033): Add logrotate configuration.
 - [#4043](https://github.com/influxdb/influxdb/pull/4043): Add stats and batching to openTSDB input
 - [#4042](https://github.com/influxdb/influxdb/pull/4042): Add pending batches control to batcher
+- [#4006](https://github.com/influxdb/influxdb/pull/4006): Add basic statistics for shards
 
 ### Bugfixes
 - [#4042](https://github.com/influxdb/influxdb/pull/4042): Set UDP input batching defaults as needed.

tsdb/shard.go

@@ -4,19 +4,30 @@ import (
 	"encoding/binary"
 	"encoding/json"
 	"errors"
+	"expvar"
 	"fmt"
 	"io"
 	"math"
 	"os"
 	"sync"
 
+	"github.com/influxdb/influxdb"
 	"github.com/influxdb/influxdb/influxql"
 	"github.com/influxdb/influxdb/tsdb/internal"
 
 	"github.com/boltdb/bolt"
 	"github.com/gogo/protobuf/proto"
 )
 
+const (
+	statWriteReq        = "write_req"
+	statSeriesCreate    = "series_create"
+	statFieldsCreate    = "fields_create"
+	statWritePointsFail = "write_points_fail"
+	statWritePointsOK   = "write_points_ok"
+	statWriteBytes      = "write_bytes"
+)
+
 var (
 	// ErrFieldOverflow is returned when too many fields are created on a measurement.
 	ErrFieldOverflow = errors.New("field overflow")
@@ -49,12 +60,20 @@ type Shard struct {
 	mu                sync.RWMutex
 	measurementFields map[string]*MeasurementFields // measurement name to their fields
 
+	// expvar-based stats.
+	statMap *expvar.Map
+
 	// The writer used by the logger.
 	LogOutput io.Writer
 }
 
 // NewShard returns a new initialized Shard. walPath doesn't apply to the b1 type index
 func NewShard(id uint64, index *DatabaseIndex, path string, walPath string, options EngineOptions) *Shard {
+	// Configure statistics collection.
+	key := fmt.Sprintf("shard:%s:%d", path, id)
+	tags := map[string]string{"path": path, "id": fmt.Sprintf("%d", id), "engine": options.EngineVersion}
+	statMap := influxdb.NewStatistics(key, "shard", tags)
+
 	return &Shard{
 		index:             index,
 		path:              path,
@@ -63,6 +82,7 @@ func NewShard(id uint64, index *DatabaseIndex, path string, walPath string, opti
 		options:           options,
 		measurementFields: make(map[string]*MeasurementFields),
 
+		statMap:   statMap,
 		LogOutput: os.Stderr,
 	}
 }
@@ -172,10 +192,14 @@ type SeriesCreate struct {
 
 // WritePoints will write the raw data points and any new metadata to the index in the shard
 func (s *Shard) WritePoints(points []Point) error {
+	s.statMap.Add(statWriteReq, 1)
+
 	seriesToCreate, fieldsToCreate, seriesToAddShardTo, err := s.validateSeriesAndFields(points)
 	if err != nil {
 		return err
 	}
+	s.statMap.Add(statSeriesCreate, int64(len(seriesToCreate)))
+	s.statMap.Add(statFieldsCreate, int64(len(fieldsToCreate)))
 
 	// add any new series to the in-memory index
 	if len(seriesToCreate) > 0 {
@@ -229,8 +253,10 @@ func (s *Shard) WritePoints(points []Point) error {
 
 	// Write to the engine.
 	if err := s.engine.WritePoints(points, measurementFieldsToSave, seriesToCreate); err != nil {
+		s.statMap.Add(statWritePointsFail, 1)
 		return fmt.Errorf("engine: %s", err)
 	}
+	s.statMap.Add(statWritePointsOK, int64(len(points)))
 
 	return nil
 }
@@ -402,7 +428,11 @@ func (s *Shard) validateSeriesAndFields(points []Point) ([]*SeriesCreate, []*Fie
 func (s *Shard) SeriesCount() (int, error) { return s.engine.SeriesCount() }
 
 // WriteTo writes the shard's data to w.
-func (s *Shard) WriteTo(w io.Writer) (int64, error) { return s.engine.WriteTo(w) }
+func (s *Shard) WriteTo(w io.Writer) (int64, error) {
+	n, err := s.engine.WriteTo(w)
+	s.statMap.Add(statWriteBytes, int64(n))
+	return n, err
+}
 
 type MeasurementFields struct {
 	Fields map[string]*Field `json:"fields"`