// Copyright 2018 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
// Package shed provides a simple abstraction components to compose
// more complex operations on storage data organized in fields and indexes.
//
// Only type which holds logical information about swarm storage chunks data
// and metadata is Item. This part is not generalized mostly for
// performance reasons.
package shed
import (
"errors"
"fmt"
"strconv"
"strings"
"time"
"github.com/dexon-foundation/dexon/metrics"
"github.com/dexon-foundation/dexon/swarm/log"
"github.com/syndtr/goleveldb/leveldb"
"github.com/syndtr/goleveldb/leveldb/iterator"
"github.com/syndtr/goleveldb/leveldb/opt"
)
const (
openFileLimit = 128 // The limit for LevelDB OpenFilesCacheCapacity.
writePauseWarningThrottler = 1 * time.Minute
)
// DB provides abstractions over LevelDB in order to
// implement complex structures using fields and ordered indexes.
// It provides a schema functionality to store fields and indexes
// information about naming and types.
type DB struct {
ldb *leveldb.DB
compTimeMeter metrics.Meter // Meter for measuring the total time spent in database compaction
compReadMeter metrics.Meter // Meter for measuring the data read during compaction
compWriteMeter metrics.Meter // Meter for measuring the data written during compaction
writeDelayNMeter metrics.Meter // Meter for measuring the write delay number due to database compaction
writeDelayMeter metrics.Meter // Meter for measuring the write delay duration due to database compaction
diskReadMeter metrics.Meter // Meter for measuring the effective amount of data read
diskWriteMeter metrics.Meter // Meter for measuring the effective amount of data written
quitChan chan chan error // Quit channel to stop the metrics collection before closing the database
}
// NewDB constructs a new DB and validates the schema
// if it exists in database on the given path.
// metricsPrefix is used for metrics collection for the given DB.
func NewDB(path string, metricsPrefix string) (db *DB, err error) {
ldb, err := leveldb.OpenFile(path, &opt.Options{
OpenFilesCacheCapacity: openFileLimit,
})
if err != nil {
return nil, err
}
db = &DB{
ldb: ldb,
}
if _, err = db.getSchema(); err != nil {
if err == leveldb.ErrNotFound {
// save schema with initialized default fields
if err = db.putSchema(schema{
Fields: make(map[string]fieldSpec),
Indexes: make(map[byte]indexSpec),
}); err != nil {
return nil, err
}
} else {
return nil, err
}
}
// Configure meters for DB
db.configure(metricsPrefix)
// Create a quit channel for the periodic metrics collector and run it
db.quitChan = make(chan chan error)
go db.meter(10 * time.Second)
return db, nil
}
// Put wraps LevelDB Put method to increment metrics counter.
func (db *DB) Put(key []byte, value []byte) (err error) {
err = db.ldb.Put(key, value, nil)
if err != nil {
metrics.GetOrRegisterCounter("DB.putFail", nil).Inc(1)
return err
}
metrics.GetOrRegisterCounter("DB.put", nil).Inc(1)
return nil
}
// Get wraps LevelDB Get method to increment metrics counter.
func (db *DB) Get(key []byte) (value []byte, err error) {
value, err = db.ldb.Get(key, nil)
if err != nil {
if err == leveldb.ErrNotFound {
metrics.GetOrRegisterCounter("DB.getNotFound", nil).Inc(1)
} else {
metrics.GetOrRegisterCounter("DB.getFail", nil).Inc(1)
}
return nil, err
}
metrics.GetOrRegisterCounter("DB.get", nil).Inc(1)
return value, nil
}
// Delete wraps LevelDB Delete method to increment metrics counter.
func (db *DB) Delete(key []byte) (err error) {
err = db.ldb.Delete(key, nil)
if err != nil {
metrics.GetOrRegisterCounter("DB.deleteFail", nil).Inc(1)
return err
}
metrics.GetOrRegisterCounter("DB.delete", nil).Inc(1)
return nil
}
// NewIterator wraps LevelDB NewIterator method to increment metrics counter.
func (db *DB) NewIterator() iterator.Iterator {
metrics.GetOrRegisterCounter("DB.newiterator", nil).Inc(1)
return db.ldb.NewIterator(nil, nil)
}
// WriteBatch wraps LevelDB Write method to increment metrics counter.
func (db *DB) WriteBatch(batch *leveldb.Batch) (err error) {
err = db.ldb.Write(batch, nil)
if err != nil {
metrics.GetOrRegisterCounter("DB.writebatchFail", nil).Inc(1)
return err
}
metrics.GetOrRegisterCounter("DB.writebatch", nil).Inc(1)
return nil
}
// Close closes LevelDB database.
func (db *DB) Close() (err error) {
close(db.quitChan)
return db.ldb.Close()
}
// Configure configures the database metrics collectors
func (db *DB) configure(prefix string) {
// Initialize all the metrics collector at the requested prefix
db.compTimeMeter = metrics.NewRegisteredMeter(prefix+"compact/time", nil)
db.compReadMeter = metrics.NewRegisteredMeter(prefix+"compact/input", nil)
db.compWriteMeter = metrics.NewRegisteredMeter(prefix+"compact/output", nil)
db.diskReadMeter = metrics.NewRegisteredMeter(prefix+"disk/read", nil)
db.diskWriteMeter = metrics.NewRegisteredMeter(prefix+"disk/write", nil)
db.writeDelayMeter = metrics.NewRegisteredMeter(prefix+"compact/writedelay/duration", nil)
db.writeDelayNMeter = metrics.NewRegisteredMeter(prefix+"compact/writedelay/counter", nil)
}
func (db *DB) meter(refresh time.Duration) {
// Create the counters to store current and previous compaction values
compactions := make([][]float64, 2)
for i := 0; i < 2; i++ {
compactions[i] = make([]float64, 3)
}
// Create storage for iostats.
var iostats [2]float64
// Create storage and warning log tracer for write delay.
var (
delaystats [2]int64
lastWritePaused time.Time
)
var (
errc chan error
merr error
)
// Iterate ad infinitum and collect the stats
for i := 1; errc == nil && merr == nil; i++ {
// Retrieve the database stats
stats, err := db.ldb.GetProperty("leveldb.stats")
if err != nil {
log.Error("Failed to read database stats", "err", err)
merr = err
continue
}
// Find the compaction table, skip the header
lines := strings.Split(stats, "\n")
for len(lines) > 0 && strings.TrimSpace(lines[0]) != "Compactions" {
lines = lines[1:]
}
if len(lines) <= 3 {
log.Error("Compaction table not found")
merr = errors.New("compaction table not found")
continue
}
lines = lines[3:]
// Iterate over all the table rows, and accumulate the entries
for j := 0; j < len(compactions[i%2]); j++ {
compactions[i%2][j] = 0
}
for _, line := range lines {
parts := strings.Split(line, "|")
if len(parts) != 6 {
break
}
for idx, counter := range parts[3:] {
value, err := strconv.ParseFloat(strings.TrimSpace(counter), 64)
if err != nil {
log.Error("Compaction entry parsing failed", "err", err)
merr = err
continue
}
compactions[i%2][idx] += value
}
}
// Update all the requested meters
if db.compTimeMeter != nil {
db.compTimeMeter.Mark(int64((compactions[i%2][0] - compactions[(i-1)%2][0]) * 1000 * 1000 * 1000))
}
if db.compReadMeter != nil {
db.compReadMeter.Mark(int64((compactions[i%2][1] - compactions[(i-1)%2][1]) * 1024 * 1024))
}
if db.compWriteMeter != nil {
db.compWriteMeter.Mark(int64((compactions[i%2][2] - compactions[(i-1)%2][2]) * 1024 * 1024))
}
// Retrieve the write delay statistic
writedelay, err := db.ldb.GetProperty("leveldb.writedelay")
if err != nil {
log.Error("Failed to read database write delay statistic", "err", err)
merr = err
continue
}
var (
delayN int64
delayDuration string
duration time.Duration
paused bool
)
if n, err := fmt.Sscanf(writedelay, "DelayN:%d Delay:%s Paused:%t", &delayN, &delayDuration, &paused); n != 3 || err != nil {
log.Error("Write delay statistic not found")
merr = err
continue
}
duration, err = time.ParseDuration(delayDuration)
if err != nil {
log.Error("Failed to parse delay duration", "err", err)
merr = err
continue
}
if db.writeDelayNMeter != nil {
db.writeDelayNMeter.Mark(delayN - delaystats[0])
}
if db.writeDelayMeter != nil {
db.writeDelayMeter.Mark(duration.Nanoseconds() - delaystats[1])
}
// If a warning that db is performing compaction has been displayed, any subsequent
// warnings will be withheld for one minute not to overwhelm the user.
if paused && delayN-delaystats[0] == 0 && duration.Nanoseconds()-delaystats[1] == 0 &&
time.Now().After(lastWritePaused.Add(writePauseWarningThrottler)) {
log.Warn("Database compacting, degraded performance")
lastWritePaused = time.Now()
}
delaystats[0], delaystats[1] = delayN, duration.Nanoseconds()
// Retrieve the database iostats.
ioStats, err := db.ldb.GetProperty("leveldb.iostats")
if err != nil {
log.Error("Failed to read database iostats", "err", err)
merr = err
continue
}
var nRead, nWrite float64
parts := strings.Split(ioStats, " ")
if len(parts) < 2 {
log.Error("Bad syntax of ioStats", "ioStats", ioStats)
merr = fmt.Errorf("bad syntax of ioStats %s", ioStats)
continue
}
if n, err := fmt.Sscanf(parts[0], "Read(MB):%f", &nRead); n != 1 || err != nil {
log.Error("Bad syntax of read entry", "entry", parts[0])
merr = err
continue
}
if n, err := fmt.Sscanf(parts[1], "Write(MB):%f", &nWrite); n != 1 || err != nil {
log.Error("Bad syntax of write entry", "entry", parts[1])
merr = err
continue
}
if db.diskReadMeter != nil {
db.diskReadMeter.Mark(int64((nRead - iostats[0]) * 1024 * 1024))
}
if db.diskWriteMeter != nil {
db.diskWriteMeter.Mark(int64((nWrite - iostats[1]) * 1024 * 1024))
}
iostats[0], iostats[1] = nRead, nWrite
// Sleep a bit, then repeat the stats collection
select {
case errc = <-db.quitChan:
// Quit requesting, stop hammering the database
case <-time.After(refresh):
// Timeout, gather a new set of stats
}
}
if errc == nil {
errc = <-db.quitChan
}
errc <- merr
}
