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

go/src/infra/gae/libs/gae/prod/taskqueue.go

Index: go/src/infra/gae/libs/gae/prod/taskqueue.go
diff --git a/go/src/infra/gae/libs/gae/prod/taskqueue.go b/go/src/infra/gae/libs/gae/prod/taskqueue.go
new file mode 100644
index 0000000000000000000000000000000000000000..7d31ebf1a64a9551eebb913b43d7f3f016e1cb2b
--- /dev/null
+++ b/go/src/infra/gae/libs/gae/prod/taskqueue.go
@@ -0,0 +1,144 @@
+// 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 prod
+
+import (
+	"fmt"
+	"golang.org/x/net/context"

[Vadim Sh., 2015/07/14 00:12:37]

nit: move below

+	"reflect"
+
+	"infra/gae/libs/gae"
+
+	"google.golang.org/appengine/taskqueue"
+)
+
+// useTQ adds a gae.TaskQueue implementation to context, accessible
+// by gae.GetTQ(c)
+func useTQ(c context.Context) context.Context {
+	return gae.SetTQFactory(c, func(ci context.Context) gae.TaskQueue {
+		return tqImpl{ci}
+	})
+}
+
+type tqImpl struct {
+	context.Context
+}
+
+func init() {
+	const TASK_EXPECTED_FIELDS = 9
+	// Runtime-assert that the number of fields in the Task structs is 9, to
+	// avoid missing additional fields if they're added later.
+	// all other type assertions are statically enforced by o2n() and n2o()
+
+	oldType := reflect.TypeOf((*taskqueue.Task)(nil))
+	newType := reflect.TypeOf((*gae.TQTask)(nil))
+
+	if oldType.NumField() != newType.NumField() ||
+		oldType.NumField() != TASK_EXPECTED_FIELDS {
+		panic(fmt.Errorf(
+			"prod/taskqueue:init() field count differs: %v, %v",
+			oldType, newType))
+	}
+}
+
+func o2ne(o *taskqueue.Task, err error) (*gae.TQTask, error) {
+	if err != nil {
+		return nil, err
+	}
+	n := gae.TQTask{}
+	n.Path = o.Path
+	n.Payload = o.Payload
+	n.Header = o.Header
+	n.Method = o.Method
+	n.Name = o.Name
+	n.Delay = o.Delay
+	n.ETA = o.ETA
+	n.RetryCount = o.RetryCount
+	n.RetryOptions = (*gae.TQRetryOptions)(o.RetryOptions)
+	return &n, nil
+}
+
+func n2o(n *gae.TQTask) *taskqueue.Task {
+	o := taskqueue.Task{}
+	o.Path = n.Path
+	o.Payload = n.Payload
+	o.Header = n.Header
+	o.Method = n.Method
+	o.Name = n.Name
+	o.Delay = n.Delay
+	o.ETA = n.ETA
+	o.RetryCount = n.RetryCount
+	o.RetryOptions = (*taskqueue.RetryOptions)(n.RetryOptions)
+	return &o
+}
+
+func mo2ne(os []*taskqueue.Task, err error) ([]*gae.TQTask, error) {

[Vadim Sh., 2015/07/14 00:12:37]

cryptic names again.. :(

Write at least one comment explaining what various letters stand for.

[iannucci, 2015/07/14 01:07:46]

Done.

+	if err != nil {
+		return nil, gae.FixError(err)
+	}
+	ret := make([]*gae.TQTask, len(os))
+	for i, t := range os {
+		ret[i], _ = o2ne(t, nil)
+	}
+	return ret, nil
+}
+
+func mn2o(ns []*gae.TQTask) []*taskqueue.Task {
+	ret := make([]*taskqueue.Task, len(ns))
+	for i, t := range ns {
+		ret[i] = n2o(t)
+	}
+	return ret
+}
+
+//////// TQSingleReadWriter
+
+func (t tqImpl) Add(task *gae.TQTask, queueName string) (*gae.TQTask, error) {
+	return o2ne(taskqueue.Add(t.Context, n2o(task), queueName))
+}
+func (t tqImpl) Delete(task *gae.TQTask, queueName string) error {
+	return taskqueue.Delete(t.Context, n2o(task), queueName)
+}
+
+//////// TQMultiReadWriter
+
+func (t tqImpl) AddMulti(tasks []*gae.TQTask, queueName string) ([]*gae.TQTask, error) {
+	return mo2ne(taskqueue.AddMulti(t.Context, mn2o(tasks), queueName))
+}
+func (t tqImpl) DeleteMulti(tasks []*gae.TQTask, queueName string) error {
+	return gae.FixError(taskqueue.DeleteMulti(t.Context, mn2o(tasks), queueName))
+}
+
+//////// TQLeaser
+
+func (t tqImpl) Lease(maxTasks int, queueName string, leaseTime int) ([]*gae.TQTask, error) {
+	return mo2ne(taskqueue.Lease(t.Context, maxTasks, queueName, leaseTime))
+}
+func (t tqImpl) LeaseByTag(maxTasks int, queueName string, leaseTime int, tag string) ([]*gae.TQTask, error) {
+	return mo2ne(taskqueue.LeaseByTag(t.Context, maxTasks, queueName, leaseTime, tag))
+}
+func (t tqImpl) ModifyLease(task *gae.TQTask, queueName string, leaseTime int) error {
+	return taskqueue.ModifyLease(t.Context, n2o(task), queueName, leaseTime)
+}
+
+//////// TQPurger
+
+func (t tqImpl) Purge(queueName string) error {
+	return taskqueue.Purge(t.Context, queueName)
+}
+
+//////// TQStatter
+
+func (t tqImpl) QueueStats(queueNames []string) ([]gae.TQStatistics, error) {
+	stats, err := taskqueue.QueueStats(t.Context, queueNames)
+	if err != nil {
+		return nil, err
+	}
+	ret := make([]gae.TQStatistics, len(stats))
+	for i, s := range stats {
+		ret[i] = gae.TQStatistics(s)
+	}
+	return ret, nil
+}