Add cloud datastore implementation.

impl/cloud/info.go

+// Copyright 2016 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 cloud
+
+import (
+        "errors"
+        "time"
+
+        infoS "github.com/luci/gae/service/info"
+
+        "golang.org/x/net/context"
+)
+
+var errNotImplemented = errors.New("not implemented")
+
+// cloudInfo is a reconstruction of the info service for the cloud API.
+//
+// It will return information sufficent for datastore operation.
+type infoState struct {
+        // namespace is the current namesapce, or the empty string for no namespace.
+        namespace string
+}
+
+var infoStateKey = "*cloud.infoState"
+
+func getInfoState(c context.Context) *infoState {
+        if is, ok := c.Value(&infoStateKey).(*infoState); ok {
+                return is
+        }
+        panic("no info state in Context")
+}
+
+func (ci *infoState) use(c context.Context) context.Context {
+        return context.WithValue(c, &infoStateKey, ci)
+}
+
+func (ci *infoState) derive(mutate func(*infoState)) *infoState {
+        dci := *ci
+        mutate(&dci)
+        return &dci
+}
+
+type infoService struct {
+        *infoState
+
+        ic context.Context
+}
+
+func useInfo(c context.Context) context.Context {
+        var baseInfoState infoState
+        c = baseInfoState.use(c)
+
+        return infoS.SetFactory(c, func(ic context.Context) infoS.Interface {
+                return &infoService{
+                        infoState: getInfoState(ic),
+                        ic:        ic,
+                }
+        })
+}
+
+func (i *infoService) AppID() string                { return "" }
+func (i *infoService) FullyQualifiedAppID() string  { return "" }
+func (i *infoService) GetNamespace() (string, bool) { return i.namespace, (i.namespace != "") }
+
+func (i *infoService) Datacenter() string             { return "" }
+func (i *infoService) DefaultVersionHostname() string { return "" }
+func (i *infoService) InstanceID() string             { return "" }
+func (i *infoService) IsDevAppServer() bool           { return false }
+func (i *infoService) IsOverQuota(err error) bool     { return false }
+func (i *infoService) IsTimeoutError(err error) bool  { return false }
+func (i *infoService) ModuleHostname(module, version, instance string) (string, error) {
+        return "", errNotImplemented
+}
+func (i *infoService) ModuleName() string              { return "" }
+func (i *infoService) RequestID() string               { return "" }
+func (i *infoService) ServerSoftware() string          { return "" }
+func (i *infoService) ServiceAccount() (string, error) { return "", errNotImplemented }
+func (i *infoService) VersionID() string               { return "" }

[iannucci, 2016/05/23 21:53:06]

let's return dummy values and/or panic; I'd rather know early that we're using
an unimplemented/meaningless interface rather than have things silently 'work'
with empty strings.

[dnj (Google), 2016/07/01 02:25:56]

Done I left FullyQualifiedAppID implemented and blank b/c datastore service
layer requires it. Empty string is fine I think, since it's not forwarded to
cloud SDK layer anyway.

+
+func (i *infoService) Namespace(namespace string) (context.Context, error) {
+        return i.MustNamespace(namespace), nil
+}
+
+func (i *infoService) MustNamespace(namespace string) context.Context {
+        return i.derive(func(ci *infoState) {
+                ci.namespace = namespace
+        }).use(i.ic)
+}
+
+func (i *infoService) AccessToken(scopes ...string) (token string, expiry time.Time, err error) {
+        return "", time.Time{}, errNotImplemented
+}
+
+func (i *infoService) PublicCertificates() ([]infoS.Certificate, error) {
+        return nil, errNotImplemented
+}
+
+func (i *infoService) SignBytes(bytes []byte) (keyName string, signature []byte, err error) {
+        return "", nil, errNotImplemented
+}
+
+func (i *infoService) Testable() infoS.Testable { return nil }