bleve/index/store/metrics/store.go

//  Copyright (c) 2015 Couchbase, Inc.
//  Licensed under the Apache License, Version 2.0 (the "License");
//  you may not use this file except in compliance with the
//  License. You may obtain a copy of the License at
//    http://www.apache.org/licenses/LICENSE-2.0
//  Unless required by applicable law or agreed to in writing,
//  software distributed under the License is distributed on an "AS
//  IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
//  express or implied. See the License for the specific language
//  governing permissions and limitations under the License.

// Package metrics provides a bleve.store.KVStore implementation that
// wraps another, real KVStore implementation, and uses go-metrics to
// track runtime performance metrics.
package metrics

import (
	"container/list"
	"encoding/json"
	"fmt"
	"io"
	"sync"
	"time"

	"github.com/blevesearch/bleve/index/store"
	"github.com/blevesearch/bleve/registry"
	"github.com/rcrowley/go-metrics"
)

const Name = "metrics"

type Store struct {
	o store.KVStore

	TimerReaderGet            metrics.Timer
	TimerReaderPrefixIterator metrics.Timer
	TimerReaderRangeIterator  metrics.Timer
	TimerWriterExecuteBatch   metrics.Timer
	TimerIteratorSeek         metrics.Timer
	TimerIteratorNext         metrics.Timer
	TimerBatchMerge           metrics.Timer

	m      sync.Mutex // Protects the fields that follow.
	errors *list.List // Capped list of StoreError's.
}

func New(mo store.MergeOperator, config map[string]interface{}) (store.KVStore, error) {

	name, ok := config["kvStoreName_actual"].(string)
	if !ok || name == "" {
		return nil, fmt.Errorf("metrics: missing kvStoreName_actual,"+
			" config: %#v", config)
	}

	if name == Name {
		return nil, fmt.Errorf("metrics: circular kvStoreName_actual")
	}

	ctr := registry.KVStoreConstructorByName(name)
	if ctr == nil {
		return nil, fmt.Errorf("metrics: no kv store constructor,"+
			" kvStoreName_actual: %s", name)
	}

	kvs, err := ctr(mo, config)
	if err != nil {
		return nil, err
	}

	return &Store{
		o: kvs,

		TimerReaderGet:            metrics.NewTimer(),
		TimerReaderPrefixIterator: metrics.NewTimer(),
		TimerReaderRangeIterator:  metrics.NewTimer(),
		TimerWriterExecuteBatch:   metrics.NewTimer(),
		TimerIteratorSeek:         metrics.NewTimer(),
		TimerIteratorNext:         metrics.NewTimer(),
		TimerBatchMerge:           metrics.NewTimer(),

		errors: list.New(),
	}, nil
}

func init() {
	registry.RegisterKVStore(Name, New)
}

func (s *Store) Close() error {
	return s.o.Close()
}

func (s *Store) Reader() (store.KVReader, error) {
	o, err := s.o.Reader()
	if err != nil {
		s.AddError("Reader", err, nil)
		return nil, err
	}
	return &Reader{s: s, o: o}, nil
}

func (s *Store) Writer() (store.KVWriter, error) {
	o, err := s.o.Writer()
	if err != nil {
		s.AddError("Writer", err, nil)
		return nil, err
	}
	return &Writer{s: s, o: o}, nil
}

// Metric specific code below:

const MaxErrors = 100

type StoreError struct {
	Time string
	Op   string
	Err  string
	Key  string
}

func (s *Store) AddError(op string, err error, key []byte) {
	e := &StoreError{
		Time: time.Now().Format(time.RFC3339Nano),
		Op:   op,
		Err:  fmt.Sprintf("%v", err),
		Key:  string(key),
	}

	s.m.Lock()
	for s.errors.Len() >= MaxErrors {
		s.errors.Remove(s.errors.Front())
	}
	s.errors.PushBack(e)
	s.m.Unlock()
}

func (s *Store) WriteJSON(w io.Writer) {
	w.Write([]byte(`{"TimerReaderGet":`))
	WriteTimerJSON(w, s.TimerReaderGet)
	w.Write([]byte(`,"TimerReaderPrefixIterator":`))
	WriteTimerJSON(w, s.TimerReaderPrefixIterator)
	w.Write([]byte(`,"TimerReaderRangeIterator":`))
	WriteTimerJSON(w, s.TimerReaderRangeIterator)
	w.Write([]byte(`,"TimerWriterExecuteBatch":`))
	WriteTimerJSON(w, s.TimerWriterExecuteBatch)
	w.Write([]byte(`,"TimerIteratorSeek":`))
	WriteTimerJSON(w, s.TimerIteratorSeek)
	w.Write([]byte(`,"TimerIteratorNext":`))
	WriteTimerJSON(w, s.TimerIteratorNext)
	w.Write([]byte(`,"TimerBatchMerge":`))
	WriteTimerJSON(w, s.TimerBatchMerge)

	w.Write([]byte(`,"Errors":[`))
	s.m.Lock()
	e := s.errors.Front()
	i := 0
	for e != nil {
		se, ok := e.Value.(*StoreError)
		if ok && se != nil {
			if i > 0 {
				w.Write([]byte(","))
			}
			buf, err := json.Marshal(se)
			if err == nil {
				w.Write(buf)
			}
		}
		e = e.Next()
		i = i + 1
	}
	s.m.Unlock()
	w.Write([]byte(`]`))

	w.Write([]byte(`}`))
}

func (s *Store) WriteCSVHeader(w io.Writer) {
	WriteTimerCSVHeader(w, "TimerReaderGet")
	WriteTimerCSVHeader(w, "TimerReaderPrefixIterator")
	WriteTimerCSVHeader(w, "TimerReaderRangeIterator")
	WriteTimerCSVHeader(w, "TimerWtierExecuteBatch")
	WriteTimerCSVHeader(w, "TimerIteratorSeek")
	WriteTimerCSVHeader(w, "TimerIteratorNext")
	WriteTimerCSVHeader(w, "TimerBatchMerge")
}

func (s *Store) WriteCSV(w io.Writer) {
	WriteTimerCSV(w, s.TimerReaderGet)
	WriteTimerCSV(w, s.TimerReaderPrefixIterator)
	WriteTimerCSV(w, s.TimerReaderRangeIterator)
	WriteTimerCSV(w, s.TimerWriterExecuteBatch)
	WriteTimerCSV(w, s.TimerIteratorSeek)
	WriteTimerCSV(w, s.TimerIteratorNext)
	WriteTimerCSV(w, s.TimerBatchMerge)
}