Refactor distributor API so that methods always get the Quest_Desc too.

dm/appengine/distributor/task_description.go

-// Copyright 2016 The LUCI Authors. All rights reserved.
-// Use of this source code is governed under the Apache License, Version 2.0
-// that can be found in the LICENSE file.
-
-package distributor
-
-import (
-        "fmt"
-
-        "github.com/golang/protobuf/proto"
-        "github.com/luci/gae/service/info"
-        "github.com/luci/luci-go/common/gcloud/pubsub"
-        dm "github.com/luci/luci-go/dm/api/service/v1"
-        "golang.org/x/net/context"
-)
-
-// NewTaskDescription builds a new *TaskDescription.
-//
-// It's intended for use by the DM core logic, and not for use by distributor
-// implementations.
-func NewTaskDescription(c context.Context, payload *dm.Quest_Desc, exAuth *dm.Execution_Auth,
-        previousResult *dm.JsonResult) *TaskDescription {
-        return &TaskDescription{
-                c:              c,
-                payload:        payload,
-                executionAuth:  exAuth,
-                previousResult: previousResult,
-        }
-}
-
-// TaskDescription is the parameters for PrepareTask.
-type TaskDescription struct {
-        c              context.Context
-        payload        *dm.Quest_Desc
-        executionAuth  *dm.Execution_Auth
-        previousResult *dm.JsonResult
-}
-
-// PrepareTopic returns the pubsub topic that notifications should be sent to.
-//
-// It returns the full name of the topic and a token that will be used to route
-// PubSub messages back to the Distributor. The publisher to the topic must be
-// instructed to put the token into the 'auth_token' attribute of PubSub
-// messages. DM will know how to route such messages to D.HandleNotification.
-func (t *TaskDescription) PrepareTopic() (topic pubsub.Topic, token string, err error) {
-        topic = pubsub.NewTopic(info.Get(t.c).TrimmedAppID(), notifyTopicSuffix)
-        if err := topic.Validate(); err != nil {
-                panic(fmt.Errorf("failed to validate Topic %q: %s", topic, err))
-        }
-        token, err = encodeAuthToken(t.c, t.executionAuth.Id,
-                t.payload.DistributorConfigName)
-        return
-}
-
-// PreviousResult is the Result of the last successful Execution for the
-// Attempt. This will be nil for the first Execution.
-func (t *TaskDescription) PreviousResult() *dm.JsonResult {
-        if t.previousResult == nil {
-                return nil
-        }
-        return proto.Clone(t.previousResult).(*dm.JsonResult)
-}
-
-// Payload is description of the job to run.
-func (t *TaskDescription) Payload() *dm.Quest_Desc {
-        return proto.Clone(t.payload).(*dm.Quest_Desc)
-}
-
-// ExecutionAuth is the combined execution_id+activation token that the
-// execution must use to call ActivateExecution before making further API calls
-// into DM.
-func (t *TaskDescription) ExecutionAuth() *dm.Execution_Auth {
-        ret := *t.executionAuth
-        return &ret
-}