Use native Pub/Sub library primitives.

common/gcloud/pubsub/ackbuffer/ack.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 ackbuffer
-
-import (
-        "github.com/luci/luci-go/common/gcloud/pubsub"
-        "golang.org/x/net/context"
-)
-
-// Acknowledger sends ACKs to a Pub/Sub interface.
-type Acknowledger interface {
-        // Ack acknowledges one or more Pub/Sub message ACK IDs.
-        Ack(ctx context.Context, ackIDs ...string) error
-
-        // AckBatchSize returns the maximum number of ACKs that can be sent at a time.
-        AckBatchSize() int
-}
-
-type pubsubACK struct {
-        ps    pubsub.Connection
-        sub   pubsub.Subscription
-        batch int
-}
-
-// NewACK creates a Acknowledger instance from a pubsub.Connection
-// implementation.
-//
-// If batch is <= 0, the maximum ACK batch size will be used.
-func NewACK(ps pubsub.Connection, s pubsub.Subscription, batch int) Acknowledger {
-        if batch <= 0 {
-                batch = pubsub.MaxMessageAckPerRequest
-        }
-
-        return &pubsubACK{
-                ps:    ps,
-                sub:   s,
-                batch: batch,
-        }
-}
-
-func (a *pubsubACK) Ack(c context.Context, ackIDs ...string) error {
-        return a.ps.Ack(c, a.sub, ackIDs...)
-}
-
-func (a *pubsubACK) AckBatchSize() int {
-        return a.batch
-}