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

go/src/infra/gae/libs/wrapper/taskqueue.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 (
-        "golang.org/x/net/context"
-
-        "appengine/taskqueue"
-)
-
-// TQSingleReadWriter allows you to add or delete a single Task from a queue.
-// See appengine.taskqueue.
-type TQSingleReadWriter interface {
-        Add(task *taskqueue.Task, queueName string) (*taskqueue.Task, error)
-        Delete(task *taskqueue.Task, queueName string) error
-}
-
-// TQMultiReadWriter allows you to add or delete a batch of Tasks from a queue.
-// See appengine.taskqueue.
-type TQMultiReadWriter interface {
-        TQSingleReadWriter
-
-        AddMulti(tasks []*taskqueue.Task, queueName string) ([]*taskqueue.Task, error)
-        DeleteMulti(tasks []*taskqueue.Task, queueName string) error
-}
-
-// TQLeaser allows you to lease tasks from a Pull queue.
-// See appengine.taskqueue.
-type TQLeaser interface {
-        Lease(maxTasks int, queueName string, leaseTime int) ([]*taskqueue.Task, error)
-        LeaseByTag(maxTasks int, queueName string, leaseTime int, tag string) ([]*taskqueue.Task, error)
-        ModifyLease(task *taskqueue.Task, queueName string, leaseTime int) error
-}
-
-// TQPurger allows you to drain a queue without processing it. See
-// appengine.taskqueue.
-type TQPurger interface {
-        Purge(queueName string) error
-}
-
-// TQStatter allows you to obtain semi-realtime stats on the current state of
-// a queue. See appengine.taskqueue.
-type TQStatter interface {
-        QueueStats(queueNames []string, maxTasks int) ([]taskqueue.QueueStatistics, error)
-}
-
-// TaskQueue is the full interface to the Task Queue service.
-type TaskQueue interface {
-        TQMultiReadWriter
-        TQLeaser
-        TQPurger
-}
-
-// TQFactory is the function signature for factory methods compatible with
-// SetTQFactory.
-type TQFactory func(context.Context) TaskQueue
-
-// GetTQ gets the TaskQueue implementation from context.
-func GetTQ(c context.Context) TaskQueue {
-        if f, ok := c.Value(taskQueueKey).(TQFactory); ok && f != nil {
-                return f(c)
-        }
-        return nil
-}
-
-// SetTQFactory sets the function to produce TaskQueue instances, as returned by
-// the GetTQ method.
-func SetTQFactory(c context.Context, tqf TQFactory) context.Context {
-        return context.WithValue(c, taskQueueKey, tqf)
-}
-
-// SetTQ sets the current TaskQueue object in the context. Useful for testing
-// with a quick mock. This is just a shorthand SetTQFactory invocation to set
-// a factory which always returns the same object.
-func SetTQ(c context.Context, tq TaskQueue) context.Context {
-        return SetTQFactory(c, func(context.Context) TaskQueue { return tq })
-}