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moby--moby/pkg/httputils/resumablerequestreader.go

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package httputils
import (
"fmt"
"io"
"log"
"net/http"
"time"
)
type resumableRequestReader struct {
client *http.Client
request *http.Request
lastRange int64
totalSize int64
currentResponse *http.Response
failures uint32
maxFailures uint32
}
// ResumableRequestReader makes it possible to resume reading a request's body transparently
// maxfail is the number of times we retry to make requests again (not resumes)
// totalsize is the total length of the body; auto detect if not provided
func ResumableRequestReader(c *http.Client, r *http.Request, maxfail uint32, totalsize int64) io.ReadCloser {
return &resumableRequestReader{client: c, request: r, maxFailures: maxfail, totalSize: totalsize}
}
func ResumableRequestReaderWithInitialResponse(c *http.Client, r *http.Request, maxfail uint32, totalsize int64, initialResponse *http.Response) io.ReadCloser {
return &resumableRequestReader{client: c, request: r, maxFailures: maxfail, totalSize: totalsize, currentResponse: initialResponse}
}
func (r *resumableRequestReader) Read(p []byte) (n int, err error) {
if r.client == nil || r.request == nil {
return 0, fmt.Errorf("client and request can't be nil\n")
}
isFreshRequest := false
if r.lastRange != 0 && r.currentResponse == nil {
readRange := fmt.Sprintf("bytes=%d-%d", r.lastRange, r.totalSize)
r.request.Header.Set("Range", readRange)
time.Sleep(5 * time.Second)
}
if r.currentResponse == nil {
r.currentResponse, err = r.client.Do(r.request)
isFreshRequest = true
}
if err != nil && r.failures+1 != r.maxFailures {
r.cleanUpResponse()
r.failures += 1
time.Sleep(5 * time.Duration(r.failures) * time.Second)
return 0, nil
} else if err != nil {
r.cleanUpResponse()
return 0, err
}
if r.currentResponse.StatusCode == 416 && r.lastRange == r.totalSize && r.currentResponse.ContentLength == 0 {
r.cleanUpResponse()
return 0, io.EOF
} else if r.currentResponse.StatusCode != 206 && r.lastRange != 0 && isFreshRequest {
r.cleanUpResponse()
return 0, fmt.Errorf("the server doesn't support byte ranges")
}
if r.totalSize == 0 {
r.totalSize = r.currentResponse.ContentLength
} else if r.totalSize <= 0 {
r.cleanUpResponse()
return 0, fmt.Errorf("failed to auto detect content length")
}
n, err = r.currentResponse.Body.Read(p)
r.lastRange += int64(n)
if err != nil {
r.cleanUpResponse()
}
if err != nil && err != io.EOF {
log.Printf("encountered error during pull and clearing it before resume: %s", err)
err = nil
}
return n, err
}
func (r *resumableRequestReader) Close() error {
r.cleanUpResponse()
r.client = nil
r.request = nil
return nil
}
func (r *resumableRequestReader) cleanUpResponse() {
if r.currentResponse != nil {
r.currentResponse.Body.Close()
r.currentResponse = nil
}
}