Move retry and lhttp packages from client/internal to common/.

client/internal/lhttp/client.go

-// Copyright 2015 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-package lhttp
-
-import (
-        "bytes"
-        "encoding/json"
-        "errors"
-        "fmt"
-        "io"
-        "io/ioutil"
-        "net/http"
-        "net/url"
-        "os"
-        "strings"
-
-        "github.com/luci/luci-go/client/internal/retry"
-)
-
-// Handler is called once or multiple times for each HTTP request that is tried.
-type Handler func(*http.Response) error
-
-// Retriable is a retry.Retriable that exposes the resulting HTTP status
-// code.
-type Retriable interface {
-        retry.Retriable
-        // Returns the HTTP status code of the last request, if set.
-        Status() int
-}
-
-// NewRequest returns a retriable request.
-//
-// To enable automatic retry support, the Request.Body, if present, must
-// implement io.Seeker.
-//
-// handler should return retry.Error in case of retriable error, for example if
-// a TCP connection is teared off while receiving the content.
-func NewRequest(c *http.Client, req *http.Request, handler Handler) (Retriable, error) {
-        // Handle req.Body if specified. It has to implement io.Seeker.
-        if req.URL.Scheme != "http" && req.URL.Scheme != "https" {
-                return nil, fmt.Errorf("unsupported protocol scheme \"%s\"", req.URL.Scheme)
-        }
-        newReq := *req
-        out := &retriable{
-                handler:   handler,
-                c:         c,
-                req:       &newReq,
-                closeBody: req.Body,
-        }
-        if req.Body != nil {
-                ok := false
-                if out.seekBody, ok = req.Body.(io.Seeker); !ok {
-                        return nil, errors.New("req.Body must implement io.Seeker")
-                }
-                // Make sure the body is not closed when calling http.Client.Do().
-                out.req.Body = ioutil.NopCloser(req.Body)
-        }
-        return out, nil
-}
-
-// NewRequestJSON returns a retriable request calling a JSON endpoint.
-func NewRequestJSON(c *http.Client, url, method string, in, out interface{}) (Retriable, error) {
-        var body io.Reader
-        if in != nil {
-                encoded, err := json.Marshal(in)
-                if err != nil {
-                        return nil, err
-                }
-                body = newReader(encoded)
-        }
-        req, err := http.NewRequest(method, url, body)
-        if err != nil {
-                return nil, err
-        }
-        if in != nil {
-                req.Header.Set("Content-Type", jsonContentType)
-        }
-        return NewRequest(c, req, func(resp *http.Response) error {
-                defer resp.Body.Close()
-                if ct := strings.ToLower(resp.Header.Get("Content-Type")); ct != jsonContentType {
-                        // Non-retriable.
-                        return fmt.Errorf("unexpected Content-Type, expected \"%s\", got \"%s\"", jsonContentType, ct)
-                }
-                if out == nil {
-                        // The client doesn't care about the response. Still ensure the response
-                        // is valid json.
-                        out = &map[string]interface{}{}
-                }
-                if err := json.NewDecoder(resp.Body).Decode(out); err != nil {
-                        // Retriable.
-                        return retry.Error{fmt.Errorf("bad response %s: %s", url, err)}
-                }
-                return nil
-        })
-}
-
-// GetJSON is a shorthand. It returns the HTTP status code and error if any.
-func GetJSON(config *retry.Config, c *http.Client, url string, out interface{}) (int, error) {
-        req, err := NewRequestJSON(c, url, "GET", nil, out)
-        if err != nil {
-                return 0, err
-        }
-        err = config.Do(req)
-        return req.Status(), err
-}
-
-// PostJSON is a shorthand. It returns the HTTP status code and error if any.
-func PostJSON(config *retry.Config, c *http.Client, url string, in, out interface{}) (int, error) {
-        req, err := NewRequestJSON(c, url, "POST", in, out)
-        if err != nil {
-                return 0, err
-        }
-        err = config.Do(req)
-        return req.Status(), err
-}
-
-// Private details.
-
-const jsonContentType = "application/json; charset=utf-8"
-
-// newReader returns a io.ReadCloser compatible read-only buffer that also
-// exposes io.Seeker. This should be used instead of bytes.NewReader(), which
-// doesn't implement Close().
-func newReader(p []byte) io.ReadCloser {
-        return &reader{bytes.NewReader(p)}
-}
-
-type reader struct {
-        *bytes.Reader
-}
-
-func (r *reader) Close() error {
-        return nil
-}
-
-type retriable struct {
-        handler   Handler
-        c         *http.Client
-        req       *http.Request
-        closeBody io.Closer
-        seekBody  io.Seeker
-        status    int
-}
-
-func (r *retriable) Close() error {
-        if r.closeBody != nil {
-                return r.closeBody.Close()
-        }
-        return nil
-}
-
-// Warning: it returns an error on HTTP >=400. This is different than
-// http.Client.Do() but hell it makes coding simpler.
-func (r *retriable) Do() error {
-        if r.seekBody != nil {
-                if _, err := r.seekBody.Seek(0, os.SEEK_SET); err != nil {
-                        // Can't be retried.
-                        return err
-                }
-        }
-        resp, err := r.c.Do(r.req)
-        if resp != nil {
-                r.status = resp.StatusCode
-        } else {
-                r.status = 0
-        }
-        if err != nil {
-                // Any TCP level failure can be retried but malformed URL should nt.
-                if err2, ok := err.(*url.Error); ok {
-                        return err2
-                }
-                return retry.Error{err}
-        }
-        // If the HTTP status code means the request should be retried.
-        if resp.StatusCode == 408 || resp.StatusCode == 429 || resp.StatusCode >= 500 {
-                return retry.Error{fmt.Errorf("http request failed: %s (HTTP %d)", http.StatusText(resp.StatusCode), resp.StatusCode)}
-        }
-        // Any other failure code is a hard failure.
-        if resp.StatusCode >= 400 {
-                return fmt.Errorf("http request failed: %s (HTTP %d)", http.StatusText(resp.StatusCode), resp.StatusCode)
-        }
-        // The handler may still return a retry.Error to indicate that the request
-        // should be retried even on successful status code.
-        return r.handler(resp)
-}
-
-func (r *retriable) Status() int {
-        return r.status
-}