128 lines
3.6 KiB
Go
128 lines
3.6 KiB
Go
// Copyright 2014 Google Inc. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// Package internal provides support for the cloud packages.
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//
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// Users should not import this package directly.
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package internal
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import (
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"fmt"
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"net/http"
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"sync"
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"golang.org/x/net/context"
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)
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type contextKey struct{}
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func WithContext(parent context.Context, projID string, c *http.Client) context.Context {
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if c == nil {
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panic("nil *http.Client passed to WithContext")
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}
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if projID == "" {
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panic("empty project ID passed to WithContext")
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}
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return context.WithValue(parent, contextKey{}, &cloudContext{
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ProjectID: projID,
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HTTPClient: c,
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})
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}
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const userAgent = "gcloud-golang/0.1"
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type cloudContext struct {
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ProjectID string
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HTTPClient *http.Client
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mu sync.Mutex // guards svc
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svc map[string]interface{} // e.g. "storage" => *rawStorage.Service
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}
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// Service returns the result of the fill function if it's never been
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// called before for the given name (which is assumed to be an API
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// service name, like "datastore"). If it has already been cached, the fill
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// func is not run.
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// It's safe for concurrent use by multiple goroutines.
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func Service(ctx context.Context, name string, fill func(*http.Client) interface{}) interface{} {
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return cc(ctx).service(name, fill)
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}
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func (c *cloudContext) service(name string, fill func(*http.Client) interface{}) interface{} {
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c.mu.Lock()
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defer c.mu.Unlock()
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if c.svc == nil {
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c.svc = make(map[string]interface{})
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} else if v, ok := c.svc[name]; ok {
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return v
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}
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v := fill(c.HTTPClient)
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c.svc[name] = v
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return v
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}
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// Transport is an http.RoundTripper that appends
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// Google Cloud client's user-agent to the original
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// request's user-agent header.
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type Transport struct {
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// Base represents the actual http.RoundTripper
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// the requests will be delegated to.
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Base http.RoundTripper
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}
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// RoundTrip appends a user-agent to the existing user-agent
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// header and delegates the request to the base http.RoundTripper.
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func (t *Transport) RoundTrip(req *http.Request) (*http.Response, error) {
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req = cloneRequest(req)
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ua := req.Header.Get("User-Agent")
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if ua == "" {
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ua = userAgent
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} else {
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ua = fmt.Sprintf("%s %s", ua, userAgent)
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}
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req.Header.Set("User-Agent", ua)
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return t.Base.RoundTrip(req)
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}
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// cloneRequest returns a clone of the provided *http.Request.
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// The clone is a shallow copy of the struct and its Header map.
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func cloneRequest(r *http.Request) *http.Request {
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// shallow copy of the struct
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r2 := new(http.Request)
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*r2 = *r
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// deep copy of the Header
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r2.Header = make(http.Header)
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for k, s := range r.Header {
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r2.Header[k] = s
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}
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return r2
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}
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func ProjID(ctx context.Context) string {
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return cc(ctx).ProjectID
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}
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func HTTPClient(ctx context.Context) *http.Client {
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return cc(ctx).HTTPClient
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}
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// cc returns the internal *cloudContext (cc) state for a context.Context.
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// It panics if the user did it wrong.
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func cc(ctx context.Context) *cloudContext {
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if c, ok := ctx.Value(contextKey{}).(*cloudContext); ok {
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return c
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}
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panic("invalid context.Context type; it should be created with cloud.NewContext")
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}
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