Refactor current GAE abstraction library to be free of the SDK*

go/src/infra/gae/libs/wrapper/globalinfo.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 wrapper
-
-import (
-        "time"
-
-        "appengine"
-
-        "golang.org/x/net/context"
-)
-
-// GlobalInfo is the interface for all of the package methods which normally
-// would be in the 'appengine' package.
-type GlobalInfo interface {
-        // methods usually requiring a Context
-
-        AccessToken(scopes ...string) (token string, expiry time.Time, err error)
-        AppID() string
-        DefaultVersionHostname() string
-        ModuleHostname(module, version, instance string) (string, error)
-        ModuleName() string
-        PublicCertificates() ([]appengine.Certificate, error)
-        RequestID() string
-        ServiceAccount() (string, error)
-        SignBytes(bytes []byte) (keyName string, signature []byte, err error)
-        VersionID() string
-
-        // our tweaked interface
-
-        // Namespace takes the new namespace as a string, and returns a context
-        // set to use that namespace, or an error.
-        // The appengine SDK doesn't document what errors you can see from this
-        // method, or under what circumstances they might occur.
-        Namespace(namespace string) (context.Context, error)
-
-        // Really global functions... these don't normally even require context, but
-        // for the purposes of testing+consistency, they're included here.
-
-        Datacenter() string
-        InstanceID() string
-        IsDevAppserver() bool
-        ServerSoftware() string
-
-        IsCapabilityDisabled(err error) bool
-        IsOverQuota(err error) bool
-        IsTimeoutError(err error) bool
-
-        // Backends are deprecated in favor of modules, so simplify this a bit by
-        // omitting them from the interface.
-        // BackendHostname(name string, index int) string
-        // BackendInstance() (name string, index int)
-}
-
-// GIFactory is the function signature for factory methods compatible with
-// SetGIFactory.
-type GIFactory func(context.Context) GlobalInfo
-
-// GetGI gets gets the GlobalInfo implementation from context.
-func GetGI(c context.Context) GlobalInfo {
-        if f, ok := c.Value(globalInfoKey).(GIFactory); ok && f != nil {
-                return f(c)
-        }
-        return nil
-}
-
-// SetGIFactory sets the function to produce GlobalInfo instances, as returned
-// by the GetGI method.
-func SetGIFactory(c context.Context, gif GIFactory) context.Context {
-        return context.WithValue(c, globalInfoKey, gif)
-}
-
-// SetGI sets the current GlobalInfo object in the context. Useful for testing
-// with a quick mock. This is just a shorthand SetGIFactory invocation to set
-// a factory which always returns the same object.
-func SetGI(c context.Context, gi GlobalInfo) context.Context {
-        return SetGIFactory(c, func(context.Context) GlobalInfo { return gi })
-}