github.com/demonoid81/moby@v0.0.0-20200517203328-62dd8e17c460/registry/resumable/resumablerequestreader.go (about) 1 package resumable // import "github.com/demonoid81/moby/registry/resumable" 2 3 import ( 4 "fmt" 5 "io" 6 "net/http" 7 "time" 8 9 "github.com/sirupsen/logrus" 10 ) 11 12 type requestReader struct { 13 client *http.Client 14 request *http.Request 15 lastRange int64 16 totalSize int64 17 currentResponse *http.Response 18 failures uint32 19 maxFailures uint32 20 waitDuration time.Duration 21 } 22 23 // NewRequestReader makes it possible to resume reading a request's body transparently 24 // maxfail is the number of times we retry to make requests again (not resumes) 25 // totalsize is the total length of the body; auto detect if not provided 26 func NewRequestReader(c *http.Client, r *http.Request, maxfail uint32, totalsize int64) io.ReadCloser { 27 return &requestReader{client: c, request: r, maxFailures: maxfail, totalSize: totalsize, waitDuration: 5 * time.Second} 28 } 29 30 // NewRequestReaderWithInitialResponse makes it possible to resume 31 // reading the body of an already initiated request. 32 func NewRequestReaderWithInitialResponse(c *http.Client, r *http.Request, maxfail uint32, totalsize int64, initialResponse *http.Response) io.ReadCloser { 33 return &requestReader{client: c, request: r, maxFailures: maxfail, totalSize: totalsize, currentResponse: initialResponse, waitDuration: 5 * time.Second} 34 } 35 36 func (r *requestReader) Read(p []byte) (n int, err error) { 37 if r.client == nil || r.request == nil { 38 return 0, fmt.Errorf("client and request can't be nil") 39 } 40 isFreshRequest := false 41 if r.lastRange != 0 && r.currentResponse == nil { 42 readRange := fmt.Sprintf("bytes=%d-%d", r.lastRange, r.totalSize) 43 r.request.Header.Set("Range", readRange) 44 time.Sleep(r.waitDuration) 45 } 46 if r.currentResponse == nil { 47 r.currentResponse, err = r.client.Do(r.request) 48 isFreshRequest = true 49 } 50 if err != nil && r.failures+1 != r.maxFailures { 51 r.cleanUpResponse() 52 r.failures++ 53 time.Sleep(time.Duration(r.failures) * r.waitDuration) 54 return 0, nil 55 } else if err != nil { 56 r.cleanUpResponse() 57 return 0, err 58 } 59 if r.currentResponse.StatusCode == http.StatusRequestedRangeNotSatisfiable && r.lastRange == r.totalSize && r.currentResponse.ContentLength == 0 { 60 r.cleanUpResponse() 61 return 0, io.EOF 62 } else if r.currentResponse.StatusCode != http.StatusPartialContent && r.lastRange != 0 && isFreshRequest { 63 r.cleanUpResponse() 64 return 0, fmt.Errorf("the server doesn't support byte ranges") 65 } 66 if r.totalSize == 0 { 67 r.totalSize = r.currentResponse.ContentLength 68 } else if r.totalSize <= 0 { 69 r.cleanUpResponse() 70 return 0, fmt.Errorf("failed to auto detect content length") 71 } 72 n, err = r.currentResponse.Body.Read(p) 73 r.lastRange += int64(n) 74 if err != nil { 75 r.cleanUpResponse() 76 } 77 if err != nil && err != io.EOF { 78 logrus.Infof("encountered error during pull and clearing it before resume: %s", err) 79 err = nil 80 } 81 return n, err 82 } 83 84 func (r *requestReader) Close() error { 85 r.cleanUpResponse() 86 r.client = nil 87 r.request = nil 88 return nil 89 } 90 91 func (r *requestReader) cleanUpResponse() { 92 if r.currentResponse != nil { 93 r.currentResponse.Body.Close() 94 r.currentResponse = nil 95 } 96 }