github.com/lianghucheng/zrddz@v0.0.0-20200923083010-c71f680932e2/src/golang.org/x/net/context/ctxhttp/ctxhttp_pre17.go (about)

     1  // Copyright 2015 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // +build !go1.7
     6  
     7  package ctxhttp // import "golang.org/x/net/context/ctxhttp"
     8  
     9  import (
    10  	"io"
    11  	"net/http"
    12  	"net/url"
    13  	"strings"
    14  
    15  	"golang.org/x/net/context"
    16  )
    17  
    18  func nop() {}
    19  
    20  var (
    21  	testHookContextDoneBeforeHeaders = nop
    22  	testHookDoReturned               = nop
    23  	testHookDidBodyClose             = nop
    24  )
    25  
    26  // Do sends an HTTP request with the provided http.Client and returns an HTTP response.
    27  // If the client is nil, http.DefaultClient is used.
    28  // If the context is canceled or times out, ctx.Err() will be returned.
    29  func Do(ctx context.Context, client *http.Client, req *http.Request) (*http.Response, error) {
    30  	if client == nil {
    31  		client = http.DefaultClient
    32  	}
    33  
    34  	// TODO(djd): Respect any existing value of req.Cancel.
    35  	cancel := make(chan struct{})
    36  	req.Cancel = cancel
    37  
    38  	type responseAndError struct {
    39  		resp *http.Response
    40  		err  error
    41  	}
    42  	result := make(chan responseAndError, 1)
    43  
    44  	// Make local copies of test hooks closed over by goroutines below.
    45  	// Prevents data races in tests.
    46  	testHookDoReturned := testHookDoReturned
    47  	testHookDidBodyClose := testHookDidBodyClose
    48  
    49  	go func() {
    50  		resp, err := client.Do(req)
    51  		testHookDoReturned()
    52  		result <- responseAndError{resp, err}
    53  	}()
    54  
    55  	var resp *http.Response
    56  
    57  	select {
    58  	case <-ctx.Done():
    59  		testHookContextDoneBeforeHeaders()
    60  		close(cancel)
    61  		// Clean up after the goroutine calling client.Do:
    62  		go func() {
    63  			if r := <-result; r.resp != nil {
    64  				testHookDidBodyClose()
    65  				r.resp.Body.Close()
    66  			}
    67  		}()
    68  		return nil, ctx.Err()
    69  	case r := <-result:
    70  		var err error
    71  		resp, err = r.resp, r.err
    72  		if err != nil {
    73  			return resp, err
    74  		}
    75  	}
    76  
    77  	c := make(chan struct{})
    78  	go func() {
    79  		select {
    80  		case <-ctx.Done():
    81  			close(cancel)
    82  		case <-c:
    83  			// The response's Body is closed.
    84  		}
    85  	}()
    86  	resp.Body = &notifyingReader{resp.Body, c}
    87  
    88  	return resp, nil
    89  }
    90  
    91  // Get issues a GET request via the Do function.
    92  func Get(ctx context.Context, client *http.Client, url string) (*http.Response, error) {
    93  	req, err := http.NewRequest("GET", url, nil)
    94  	if err != nil {
    95  		return nil, err
    96  	}
    97  	return Do(ctx, client, req)
    98  }
    99  
   100  // Head issues a HEAD request via the Do function.
   101  func Head(ctx context.Context, client *http.Client, url string) (*http.Response, error) {
   102  	req, err := http.NewRequest("HEAD", url, nil)
   103  	if err != nil {
   104  		return nil, err
   105  	}
   106  	return Do(ctx, client, req)
   107  }
   108  
   109  // Post issues a POST request via the Do function.
   110  func Post(ctx context.Context, client *http.Client, url string, bodyType string, body io.Reader) (*http.Response, error) {
   111  	req, err := http.NewRequest("POST", url, body)
   112  	if err != nil {
   113  		return nil, err
   114  	}
   115  	req.Header.Set("Content-Type", bodyType)
   116  	return Do(ctx, client, req)
   117  }
   118  
   119  // PostForm issues a POST request via the Do function.
   120  func PostForm(ctx context.Context, client *http.Client, url string, data url.Values) (*http.Response, error) {
   121  	return Post(ctx, client, url, "application/x-www-form-urlencoded", strings.NewReader(data.Encode()))
   122  }
   123  
   124  // notifyingReader is an io.ReadCloser that closes the notify channel after
   125  // Close is called or a Read fails on the underlying ReadCloser.
   126  type notifyingReader struct {
   127  	io.ReadCloser
   128  	notify chan<- struct{}
   129  }
   130  
   131  func (r *notifyingReader) Read(p []byte) (int, error) {
   132  	n, err := r.ReadCloser.Read(p)
   133  	if err != nil && r.notify != nil {
   134  		close(r.notify)
   135  		r.notify = nil
   136  	}
   137  	return n, err
   138  }
   139  
   140  func (r *notifyingReader) Close() error {
   141  	err := r.ReadCloser.Close()
   142  	if r.notify != nil {
   143  		close(r.notify)
   144  		r.notify = nil
   145  	}
   146  	return err
   147  }