// Copyright 2014 The go-ethereum Authors
// This file is part of go-ethereum.
//
// go-ethereum 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.
//
// go-ethereum 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 go-ethereum. If not, see <http://www.gnu.org/licenses/>.
package ethdb
import (
"strconv"
"strings"
"sync"
"time"
"github.com/ethereum/go-ethereum/compression/rle"
"github.com/ethereum/go-ethereum/logger"
"github.com/ethereum/go-ethereum/logger/glog"
"github.com/ethereum/go-ethereum/metrics"
"github.com/syndtr/goleveldb/leveldb"
"github.com/syndtr/goleveldb/leveldb/errors"
"github.com/syndtr/goleveldb/leveldb/iterator"
"github.com/syndtr/goleveldb/leveldb/opt"
gometrics "github.com/rcrowley/go-metrics"
)
var OpenFileLimit = 64
type LDBDatabase struct {
fn string // filename for reporting
db *leveldb.DB // LevelDB instance
getTimer gometrics.Timer // Timer for measuring the database get request counts and latencies
putTimer gometrics.Timer // Timer for measuring the database put request counts and latencies
delTimer gometrics.Timer // Timer for measuring the database delete request counts and latencies
missMeter gometrics.Meter // Meter for measuring the missed database get requests
readMeter gometrics.Meter // Meter for measuring the database get request data usage
writeMeter gometrics.Meter // Meter for measuring the database put request data usage
compTimeMeter gometrics.Meter // Meter for measuring the total time spent in database compaction
compReadMeter gometrics.Meter // Meter for measuring the data read during compaction
compWriteMeter gometrics.Meter // Meter for measuring the data written during compaction
quitLock sync.Mutex // Mutex protecting the quit channel access
quitChan chan chan error // Quit channel to stop the metrics collection before closing the database
}
// NewLDBDatabase returns a LevelDB wrapped object. LDBDatabase does not persist data by
// it self but requires a background poller which syncs every X. `Flush` should be called
// when data needs to be stored and written to disk.
func NewLDBDatabase(file string) (*LDBDatabase, error) {
// Open the db
db, err := leveldb.OpenFile(file, &opt.Options{OpenFilesCacheCapacity: OpenFileLimit})
// check for corruption and attempt to recover
if _, iscorrupted := err.(*errors.ErrCorrupted); iscorrupted {
db, err = leveldb.RecoverFile(file, nil)
}
// (re) check for errors and abort if opening of the db failed
if err != nil {
return nil, err
}
return &LDBDatabase{
fn: file,
db: db,
}, nil
}
// Put puts the given key / value to the queue
func (self *LDBDatabase) Put(key []byte, value []byte) error {
// Measure the database put latency, if requested
if self.putTimer != nil {
defer self.putTimer.UpdateSince(time.Now())
}
// Generate the data to write to disk, update the meter and write
dat := rle.Compress(value)
if self.writeMeter != nil {
self.writeMeter.Mark(int64(len(dat)))
}
return self.db.Put(key, dat, nil)
}
// Get returns the given key if it's present.
func (self *LDBDatabase) Get(key []byte) ([]byte, error) {
// Measure the database get latency, if requested
if self.getTimer != nil {
defer self.getTimer.UpdateSince(time.Now())
}
// Retrieve the key and increment the miss counter if not found
dat, err := self.db.Get(key, nil)
if err != nil {
if self.missMeter != nil {
self.missMeter.Mark(1)
}
return nil, err
}
// Otherwise update the actually retrieved amount of data
if self.readMeter != nil {
self.readMeter.Mark(int64(len(dat)))
}
return rle.Decompress(dat)
}
// Delete deletes the key from the queue and database
func (self *LDBDatabase) Delete(key []byte) error {
// Measure the database delete latency, if requested
if self.delTimer != nil {
defer self.delTimer.UpdateSince(time.Now())
}
// Execute the actual operation
return self.db.Delete(key, nil)
}
func (self *LDBDatabase) NewIterator() iterator.Iterator {
return self.db.NewIterator(nil, nil)
}
// Flush flushes out the queue to leveldb
func (self *LDBDatabase) Flush() error {
return nil
}
func (self *LDBDatabase) Close() {
// Stop the metrics collection to avoid internal database races
self.quitLock.Lock()
defer self.quitLock.Unlock()
if self.quitChan != nil {
errc := make(chan error)
self.quitChan <- errc
if err := <-errc; err != nil {
glog.V(logger.Error).Infof("metrics failure in '%s': %v\n", self.fn, err)
}
}
// Flush and close the database
if err := self.Flush(); err != nil {
glog.V(logger.Error).Infof("flushing '%s' failed: %v\n", self.fn, err)
}
self.db.Close()
glog.V(logger.Error).Infoln("flushed and closed db:", self.fn)
}
func (self *LDBDatabase) LDB() *leveldb.DB {
return self.db
}
// Meter configures the database metrics collectors and
func (self *LDBDatabase) Meter(prefix string) {
// Initialize all the metrics collector at the requested prefix
self.getTimer = metrics.NewTimer(prefix + "user/gets")
self.putTimer = metrics.NewTimer(prefix + "user/puts")
self.delTimer = metrics.NewTimer(prefix + "user/dels")
self.missMeter = metrics.NewMeter(prefix + "user/misses")
self.readMeter = metrics.NewMeter(prefix + "user/reads")
self.writeMeter = metrics.NewMeter(prefix + "user/writes")
self.compTimeMeter = metrics.NewMeter(prefix + "compact/time")
self.compReadMeter = metrics.NewMeter(prefix + "compact/input")
self.compWriteMeter = metrics.NewMeter(prefix + "compact/output")
// Create a quit channel for the periodic collector and run it
self.quitLock.Lock()
self.quitChan = make(chan chan error)
self.quitLock.Unlock()
go self.meter(3 * time.Second)
}
// meter periodically retrieves internal leveldb counters and reports them to
// the metrics subsystem.
//
// This is how a stats table look like (currently):
// Compactions
// Level | Tables | Size(MB) | Time(sec) | Read(MB) | Write(MB)
// -------+------------+---------------+---------------+---------------+---------------
// 0 | 0 | 0.00000 | 1.27969 | 0.00000 | 12.31098
// 1 | 85 | 109.27913 | 28.09293 | 213.92493 | 214.26294
// 2 | 523 | 1000.37159 | 7.26059 | 66.86342 | 66.77884
// 3 | 570 | 1113.18458 | 0.00000 | 0.00000 | 0.00000
func (self *LDBDatabase) meter(refresh time.Duration) {
// Create the counters to store current and previous values
counters := make([][]float64, 2)
for i := 0; i < 2; i++ {
counters[i] = make([]float64, 3)
}
// Iterate ad infinitum and collect the stats
for i := 1; ; i++ {
// Retrieve the database stats
stats, err := self.db.GetProperty("leveldb.stats")
if err != nil {
glog.V(logger.Error).Infof("failed to read database stats: %v", err)
return
}
// 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 {
glog.V(logger.Error).Infof("compaction table not found")
return
}
lines = lines[3:]
// Iterate over all the table rows, and accumulate the entries
for j := 0; j < len(counters[i%2]); j++ {
counters[i%2][j] = 0
}
for _, line := range lines {
parts := strings.Split(line, "|")
if len(parts) != 6 {
break
}
for idx, counter := range parts[3:] {
if value, err := strconv.ParseFloat(strings.TrimSpace(counter), 64); err != nil {
glog.V(logger.Error).Infof("compaction entry parsing failed: %v", err)
return
} else {
counters[i%2][idx] += value
}
}
}
// Update all the requested meters
if self.compTimeMeter != nil {
self.compTimeMeter.Mark(int64((counters[i%2][0] - counters[(i-1)%2][0]) * 1000 * 1000 * 1000))
}
if self.compReadMeter != nil {
self.compReadMeter.Mark(int64((counters[i%2][1] - counters[(i-1)%2][1]) * 1024 * 1024))
}
if self.compWriteMeter != nil {
self.compWriteMeter.Mark(int64((counters[i%2][2] - counters[(i-1)%2][2]) * 1024 * 1024))
}
// Sleep a bit, then repeat the stats collection
select {
case errc := <-self.quitChan:
// Quit requesting, stop hammering the database
errc <- nil
return
case <-time.After(refresh):
// Timeout, gather a new set of stats
}
}
}
