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package pipeline
import (
"io"
"net/http"
"net/url"
"strconv"
)
// Request is a thin wrapper over an http.Request. The wrapper provides several helper methods.
type Request struct {
*http.Request
}
// NewRequest initializes a new HTTP request object with any desired options.
func NewRequest(method string, url url.URL, body io.ReadSeeker) (request Request, err error) {
// Note: the url is passed by value so that any pipeline operations that modify it do so on a copy.
// This code to construct an http.Request is copied from http.NewRequest(); we intentionally omitted removeEmptyPort for now.
request.Request = &http.Request{
Method: method,
URL: &url,
Proto: "HTTP/1.1",
ProtoMajor: 1,
ProtoMinor: 1,
Header: make(http.Header),
Host: url.Host,
}
if body != nil {
err = request.SetBody(body)
}
return
}
// SetBody sets the body and content length, assumes body is not nil.
func (r Request) SetBody(body io.ReadSeeker) error {
size, err := body.Seek(0, io.SeekEnd)
if err != nil {
return err
}
body.Seek(0, io.SeekStart)
r.ContentLength = size
r.Header["Content-Length"] = []string{strconv.FormatInt(size, 10)}
if size != 0 {
r.Body = &retryableRequestBody{body: body}
r.GetBody = func() (io.ReadCloser, error) {
_, err := body.Seek(0, io.SeekStart)
if err != nil {
return nil, err
}
return r.Body, nil
}
} else {
// in case the body is an empty stream, we need to use http.NoBody to explicitly provide no content
r.Body = http.NoBody
r.GetBody = func() (io.ReadCloser, error) {
return http.NoBody, nil
}
// close the user-provided empty body
if c, ok := body.(io.Closer); ok {
c.Close()
}
}
return nil
}
// Copy makes a copy of an http.Request. Specifically, it makes a deep copy
// of its Method, URL, Host, Proto(Major/Minor), Header. ContentLength, Close,
// RemoteAddr, RequestURI. Copy makes a shallow copy of the Body, GetBody, TLS,
// Cancel, Response, and ctx fields. Copy panics if any of these fields are
// not nil: TransferEncoding, Form, PostForm, MultipartForm, or Trailer.
func (r Request) Copy() Request {
if r.TransferEncoding != nil || r.Form != nil || r.PostForm != nil || r.MultipartForm != nil || r.Trailer != nil {
panic("Can't make a deep copy of the http.Request because at least one of the following is not nil:" +
"TransferEncoding, Form, PostForm, MultipartForm, or Trailer.")
}
copy := *r.Request // Copy the request
urlCopy := *(r.Request.URL) // Copy the URL
copy.URL = &urlCopy
copy.Header = http.Header{} // Copy the header
for k, vs := range r.Header {
for _, value := range vs {
copy.Header.Add(k, value)
}
}
return Request{Request: ©} // Return the copy
}
func (r Request) close() error {
if r.Body != nil && r.Body != http.NoBody {
c, ok := r.Body.(*retryableRequestBody)
if !ok {
panic("unexpected request body type (should be *retryableReadSeekerCloser)")
}
return c.realClose()
}
return nil
}
// RewindBody seeks the request's Body stream back to the beginning so it can be resent when retrying an operation.
func (r Request) RewindBody() error {
if r.Body != nil && r.Body != http.NoBody {
s, ok := r.Body.(io.Seeker)
if !ok {
panic("unexpected request body type (should be io.Seeker)")
}
// Reset the stream back to the beginning
_, err := s.Seek(0, io.SeekStart)
return err
}
return nil
}
// ********** The following type/methods implement the retryableRequestBody (a ReadSeekCloser)
// This struct is used when sending a body to the network
type retryableRequestBody struct {
body io.ReadSeeker // Seeking is required to support retries
}
// Read reads a block of data from an inner stream and reports progress
func (b *retryableRequestBody) Read(p []byte) (n int, err error) {
return b.body.Read(p)
}
func (b *retryableRequestBody) Seek(offset int64, whence int) (offsetFromStart int64, err error) {
return b.body.Seek(offset, whence)
}
func (b *retryableRequestBody) Close() error {
// We don't want the underlying transport to close the request body on transient failures so this is a nop.
// The pipeline closes the request body upon success.
return nil
}
func (b *retryableRequestBody) realClose() error {
if c, ok := b.body.(io.Closer); ok {
return c.Close()
}
return nil
}
|
