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session.go
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session.go
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package getparty
import (
"context"
"encoding/json"
"fmt"
"io"
"log"
"os"
"strings"
"sync/atomic"
"time"
"github.com/pkg/errors"
"github.com/vbauerster/mpb/v8"
"github.com/vbauerster/mpb/v8/decor"
)
// Session represents download session state
type Session struct {
location string
URL string
OutputFileName string
ContentMD5 string
AcceptRanges string
ContentType string
StatusCode int
ContentLength int64
Redirected bool
Elapsed time.Duration
HeaderMap map[string]string
Parts []*Part
}
func (s *Session) calcParts(parts uint) error {
if !s.isResumable() {
parts = 1
}
fragment := s.ContentLength / int64(parts)
if parts != 1 && fragment < 64 {
return errors.New("Too fragmented")
}
s.Parts = make([]*Part, parts)
s.Parts[0] = &Part{
FileName: s.OutputFileName,
}
var stop int64
start := s.ContentLength
for i := parts - 1; i > 0; i-- {
stop = start - 1
start = stop - fragment
s.Parts[i] = &Part{
FileName: fmt.Sprintf("%s.%02d", s.OutputFileName, i),
Start: start,
Stop: stop,
}
}
s.Parts[0].Stop = start - 1
return nil
}
func (s *Session) dropSkipped() {
var skipped int
for _, p := range s.Parts {
if p.Skip {
skipped++
}
}
if skipped == len(s.Parts)-1 && !s.Parts[0].Skip {
s.Parts = s.Parts[:1]
}
}
func (s *Session) loadState(name string) error {
f, err := os.Open(name)
if err != nil {
return err
}
return firstNonNil(json.NewDecoder(f).Decode(s), f.Close())
}
func (s *Session) dumpState(name string) error {
f, err := os.Create(name)
if err != nil {
return err
}
return firstNonNil(json.NewEncoder(f).Encode(s), f.Close())
}
func (s Session) isResumable() bool {
return strings.EqualFold(s.AcceptRanges, "bytes") && s.ContentLength > 0
}
func (s Session) totalWritten() int64 {
var total int64
for _, p := range s.Parts {
total += p.Written
}
return total
}
func (s Session) summary(logger *log.Logger) {
format := fmt.Sprintf("Length: %%s [%s]", s.ContentType)
if s.ContentLength <= 0 {
logger.Printf(format, "unknown")
} else {
summary := fmt.Sprintf("%d (%.1f)", s.ContentLength, decor.SizeB1024(s.ContentLength))
logger.Printf(format, summary)
if total := s.totalWritten(); total != 0 {
remaining := s.ContentLength - total
logger.Printf("Remaining: %d (%.1f)", remaining, decor.SizeB1024(remaining))
}
}
if len(s.Parts) != 0 {
logger.Printf("Saving to: %q", s.OutputFileName)
}
if !s.isResumable() {
prefix := logger.Prefix()
logger.SetPrefix("[WARN] ")
logger.Println("Session is not resumable")
logger.SetPrefix(prefix)
}
}
func (s Session) isOutputFileExist() (bool, error) {
stat, err := os.Stat(s.OutputFileName)
if err != nil {
if errors.Is(err, os.ErrNotExist) {
return false, nil
}
return false, err
}
if stat.IsDir() {
return true, errors.Wrapf(os.ErrInvalid, "%q is a directory", s.OutputFileName)
}
return true, nil
}
func (s Session) checkContentSums(other Session) error {
if s.ContentLength != other.ContentLength {
return fmt.Errorf(
"ContentLength mismatch: expected %d got %d",
s.ContentLength, other.ContentLength,
)
}
if s.ContentMD5 != other.ContentMD5 {
return fmt.Errorf(
"%s mismatch: expected %q got %q",
hContentMD5, s.ContentMD5, other.ContentMD5,
)
}
return nil
}
func (s Session) checkSizeOfEachPart() error {
for _, part := range s.Parts {
if part.Written == 0 {
continue
}
stat, err := os.Stat(part.FileName)
if err != nil {
return err
}
if fileSize := stat.Size(); part.Written != fileSize {
return fmt.Errorf(
"%q size mismatch: expected %d got %d",
part.FileName, part.Written, fileSize,
)
}
}
return nil
}
func (s Session) makeTotalBar(
ctx context.Context,
progress *mpb.Progress,
doneCount *uint32,
quiet bool,
) (func(int), func(bool), error) {
if len(s.Parts) <= 1 || quiet {
return func(int) {}, func(bool) {}, nil
}
bar, err := progress.Add(s.ContentLength,
distinctBarRefiller(baseBarStyle()).Build(),
mpb.BarFillerTrim(),
mpb.BarExtender(mpb.BarFillerFunc(
func(w io.Writer, _ decor.Statistics) error {
_, err := fmt.Fprintln(w)
return err
}), true),
mpb.PrependDecorators(
decor.Any(func(_ decor.Statistics) string {
return fmt.Sprintf("Total(%d/%d)", atomic.LoadUint32(doneCount), len(s.Parts))
}, decor.WCSyncWidthR),
decor.OnComplete(decor.NewPercentage("%.2f", decor.WCSyncSpace), "100%"),
),
mpb.AppendDecorators(
decor.OnCompleteOrOnAbort(decor.AverageETA(decor.ET_STYLE_MMSS, decor.WCSyncWidth), ":"),
decor.AverageSpeed(decor.SizeB1024(0), "%.1f", decor.WCSyncSpace),
decor.Name("", decor.WCSyncSpace),
decor.Name("", decor.WCSyncSpace),
),
)
if err != nil {
return nil, nil, err
}
if written := s.totalWritten(); written != 0 {
bar.SetCurrent(written)
bar.SetRefill(written)
bar.DecoratorAverageAdjust(time.Now().Add(-s.Elapsed))
}
ch := make(chan int, len(s.Parts)-int(atomic.LoadUint32(doneCount)))
ctx, cancel := context.WithCancel(ctx)
dropCtx, dropCancel := context.WithCancel(context.Background())
done := make(chan struct{})
go func() {
defer close(done)
for {
select {
case n := <-ch:
bar.IncrBy(n)
case <-dropCtx.Done():
cancel()
bar.Abort(true)
return
case <-ctx.Done():
dropCancel()
bar.Abort(false)
return
}
}
}()
return func(n int) {
select {
case ch <- n:
case <-done:
}
}, func(drop bool) {
if drop {
dropCancel()
} else {
cancel()
}
}, nil
}
func (s Session) concatenateParts(progress *mpb.Progress, logger *log.Logger) (err error) {
if len(s.Parts) <= 1 {
return nil
}
totalWritten := s.totalWritten()
if totalWritten != s.ContentLength {
return errors.Errorf("Size mismatch: expected %d got %d", s.ContentLength, totalWritten)
}
bar, err := progress.Add(int64(len(s.Parts)-1),
baseBarStyle().Build(),
mpb.BarFillerTrim(),
mpb.BarPriority(len(s.Parts)+1),
mpb.PrependDecorators(
decor.Name("Concatenating", decor.WCSyncWidthR),
decor.NewPercentage("%d", decor.WCSyncSpace),
),
mpb.AppendDecorators(
decor.OnComplete(decor.AverageETA(decor.ET_STYLE_MMSS, decor.WCSyncWidth), ":"),
decor.Name("", decor.WCSyncSpace),
decor.Name("", decor.WCSyncSpace),
decor.Name("", decor.WCSyncSpace),
),
)
if err != nil {
return err
}
fpart0, err := os.OpenFile(s.Parts[0].FileName, os.O_APPEND|os.O_WRONLY, 0644)
if err != nil {
return err
}
defer func() {
if e := fpart0.Close(); err == nil {
err = e
}
bar.Abort(false) // if bar is completed bar.Abort is nop
}()
for i := 1; i < len(s.Parts); i++ {
if !s.Parts[i].Skip {
fparti, err := os.Open(s.Parts[i].FileName)
if err != nil {
return err
}
logger.Printf("concatenating: %q into %q", fparti.Name(), fpart0.Name())
_, err = io.Copy(fpart0, fparti)
err = firstNonNil(err, fparti.Close())
if err != nil {
return err
}
err = os.Remove(fparti.Name())
if err != nil {
return err
}
}
bar.Increment()
}
stat, err := fpart0.Stat()
if err != nil {
return err
}
if totalWritten != stat.Size() {
panic("totalWritten != stat.Size()")
}
return nil
}