Google Cloud Pub/Sub C++ Client  2.5.0
A C++ Client Library for Google Cloud Pub/Sub
application_callback.h
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1 // Copyright 2020 Google LLC
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 // https://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
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12 // See the License for the specific language governing permissions and
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14 
15 #ifndef GOOGLE_CLOUD_CPP_GOOGLE_CLOUD_PUBSUB_APPLICATION_CALLBACK_H
16 #define GOOGLE_CLOUD_CPP_GOOGLE_CLOUD_PUBSUB_APPLICATION_CALLBACK_H
17 
18 #include "google/cloud/pubsub/version.h"
19 #include <functional>
20 
21 namespace google {
22 namespace cloud {
23 namespace pubsub {
25 class Message;
26 class AckHandler;
28 
29 /**
30  * Defines the interface for application-level callbacks.
31  *
32  * Applications provide a callable compatible with this type to receive
33  * messages. They acknowledge (or reject) messages using `AckHandler`. This is
34  * a move-only type to support asynchronously acknowledgments.
35  */
36 using ApplicationCallback = std::function<void(Message, AckHandler)>;
37 
38 /**
39  * Defines the interface for application-level callbacks with exactly-once
40  * delivery.
41  *
42  * Applications provide a callable compatible with this type to receive
43  * messages. They acknowledge (or reject) messages using
44  * `ExactlyOnceAckHandler`. This is a move-only type to support asynchronous
45  * acknowledgments.
46  */
47 using ExactlyOnceApplicationCallback =
48  std::function<void(pubsub::Message, ExactlyOnceAckHandler)>;
49 
51 } // namespace pubsub
52 } // namespace cloud
53 } // namespace google
54 
55 #endif // GOOGLE_CLOUD_CPP_GOOGLE_CLOUD_PUBSUB_APPLICATION_CALLBACK_H