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source.go
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source.go
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package replication
import (
"errors"
"fmt"
"io"
"net"
"net/http"
"os"
"path"
"path/filepath"
"time"
"gopkg.in/fsnotify.v1"
"github.com/omniscale/imposm3"
"github.com/omniscale/imposm3/logging"
)
var log = logging.NewLogger("replication")
var NotAvailable = errors.New("file not available")
type Sequence struct {
Filename string
StateFilename string
Time time.Time
Sequence int
}
type Source interface {
Sequences() <-chan Sequence
}
// N = AAA*1000000 + BBB*1000 + CCC
func seqPath(seq int) string {
c := seq % 1000
b := seq / 1000 % 1000
a := seq / 1000000
return fmt.Sprintf("%03d/%03d/%03d", a, b, c)
}
var _ Source = &downloader{}
type downloader struct {
baseUrl string
dest string
fileExt string
stateExt string
lastSequence int
stateTime func(string) (time.Time, error)
interval time.Duration
errWaittime time.Duration
naWaittime time.Duration
sequences chan Sequence
client *http.Client
}
func newDownloader(dest, url string, seq int, interval time.Duration) *downloader {
client := &http.Client{
Transport: &http.Transport{
Proxy: http.ProxyFromEnvironment,
Dial: (&net.Dialer{
Timeout: 30 * time.Second,
KeepAlive: 1 * time.Second, // do not keep alive till next interval
}).Dial,
TLSHandshakeTimeout: 10 * time.Second,
ResponseHeaderTimeout: 10 * time.Second,
ExpectContinueTimeout: 1 * time.Second,
},
}
dl := &downloader{
baseUrl: url,
dest: dest,
lastSequence: seq,
interval: interval,
errWaittime: 60 * time.Second,
naWaittime: 10 * time.Second,
sequences: make(chan Sequence, 1),
client: client,
}
return dl
}
func (d *downloader) Sequences() <-chan Sequence {
return d.sequences
}
func (d *downloader) download(seq int, ext string) error {
dest := path.Join(d.dest, seqPath(seq)+ext)
url := d.baseUrl + seqPath(seq) + ext
if _, err := os.Stat(dest); err == nil {
return nil
}
if err := os.MkdirAll(path.Dir(dest), 0755); err != nil {
return err
}
tmpDest := fmt.Sprintf("%s~%d", dest, os.Getpid())
out, err := os.Create(tmpDest)
if err != nil {
return err
}
defer out.Close()
req, err := http.NewRequest("GET", url, nil)
if err != nil {
return err
}
req.Header.Set("User-Agent", "Imposm3 "+imposm3.Version)
resp, err := d.client.Do(req)
if err != nil {
return err
}
defer resp.Body.Close()
if resp.StatusCode == 404 {
return NotAvailable
}
if resp.StatusCode != 200 {
return errors.New(fmt.Sprintf("invalid repsonse: %v", resp))
}
_, err = io.Copy(out, resp.Body)
if err != nil {
return err
}
out.Close()
err = os.Rename(tmpDest, dest)
if err != nil {
return err
}
return nil
}
func (d *downloader) downloadTillSuccess(seq int, ext string) {
for {
err := d.download(seq, ext)
if err == nil {
break
}
if err == NotAvailable {
time.Sleep(d.naWaittime)
} else {
log.Warn(err)
time.Sleep(d.errWaittime)
}
}
}
func (d *downloader) fetchNextLoop() {
stateFile := path.Join(d.dest, seqPath(d.lastSequence)+d.stateExt)
lastTime, err := d.stateTime(stateFile)
for {
if err == nil {
nextDiffTime := lastTime.Add(d.interval)
if nextDiffTime.After(time.Now()) {
// we catched up and the next diff file is in the future.
// wait till last diff time + interval, before fetching next
nextDiffTime = lastTime.Add(d.interval + 2*time.Second /* allow small time diff between server*/)
waitFor := nextDiffTime.Sub(time.Now())
time.Sleep(waitFor)
}
}
nextSeq := d.lastSequence + 1
// download will retry until they succeed
d.downloadTillSuccess(nextSeq, d.stateExt)
d.downloadTillSuccess(nextSeq, d.fileExt)
d.lastSequence = nextSeq
base := path.Join(d.dest, seqPath(d.lastSequence))
lastTime, _ = d.stateTime(base + d.stateExt)
d.sequences <- Sequence{
Sequence: d.lastSequence,
Filename: base + d.fileExt,
StateFilename: base + d.stateExt,
Time: lastTime,
}
}
}
var _ Source = &reader{}
type reader struct {
dest string
fileExt string
stateExt string
lastSequence int
stateTime func(string) (time.Time, error)
sequences chan Sequence
}
func newReader(dest string, seq int) *reader {
r := &reader{
dest: dest,
lastSequence: seq,
sequences: make(chan Sequence, 1),
}
return r
}
func (d *reader) Sequences() <-chan Sequence {
return d.sequences
}
func (d *reader) waitTillPresent(seq int, ext string) error {
filename := path.Join(d.dest, seqPath(seq)+ext)
return waitTillPresent(filename)
}
func (d *reader) fetchNextLoop() {
for {
nextSeq := d.lastSequence + 1
if err := d.waitTillPresent(nextSeq, d.stateExt); err != nil {
log.Error(err)
}
if err := d.waitTillPresent(nextSeq, d.fileExt); err != nil {
log.Error(err)
}
d.lastSequence = nextSeq
base := path.Join(d.dest, seqPath(d.lastSequence))
lastTime, _ := d.stateTime(base + d.stateExt)
d.sequences <- Sequence{
Sequence: d.lastSequence,
Filename: base + d.fileExt,
StateFilename: base + d.stateExt,
Time: lastTime,
}
}
}
// waitTillPresent blocks till file is present.
func waitTillPresent(filename string) error {
if _, err := os.Stat(filename); err == nil {
return nil
}
// fsnotify does not work recursive. wait for parent dirs first (e.g. 002/134)
parent := filepath.Dir(filename)
if err := waitTillPresent(parent); err != nil {
return err
}
w, err := fsnotify.NewWatcher()
if err != nil {
return err
}
defer w.Close()
// need to watch on parent if we want to get events for new file
w.Add(parent)
// check again, in case file was created before we added the file
if _, err := os.Stat(filename); err == nil {
return nil
}
for {
select {
case evt := <-w.Events:
if evt.Op&fsnotify.Create == fsnotify.Create && evt.Name == filename {
return nil
}
}
}
return nil
}