1 // Copyright (C) 2019 The Android Open Source Project
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 //      http://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14 
15 #ifndef IORAP_SRC_COMMON_RX_ASYNC_H_
16 #define IORAP_SRC_COMMON_RX_ASYNC_H_
17 
18 #include "common/async_pool.h"
19 
20 #include <rxcpp/rx.hpp>
21 
22 namespace iorap::common {
23 
24 // Helper functions to operate with rx chains asynchronously.
25 class RxAsync {
26  public:
27   // Subscribe to the observable on a new thread asynchronously.
28   // If no observe_on/subscribe_on is used, the chain will execute
29   // on that new thread.
30   //
31   // Returns the composite_subscription which can be used to
32   // unsubscribe from if we want to abort the chain early.
33   template <typename T, typename U>
SubscribeAsync(AsyncPool & async_pool,T && observable,U && subscriber)34   static rxcpp::composite_subscription SubscribeAsync(
35       AsyncPool& async_pool,
36       T&& observable,
37       U&& subscriber) {
38     rxcpp::composite_subscription subscription;
39 
40     async_pool.LaunchAsync([subscription,  // safe copy: ref-counted
41                             observable=std::forward<T>(observable),
42                             subscriber=std::forward<U>(subscriber)]() mutable {
43       observable
44         .as_blocking()
45         .subscribe(subscription,
46                    std::forward<decltype(subscriber)>(subscriber));
47     });
48 
49     return subscription;
50   }
51 
52   template <typename T, typename U, typename E>
SubscribeAsync(AsyncPool & async_pool,T && observable,U && on_next,E && on_error)53   static rxcpp::composite_subscription SubscribeAsync(
54       AsyncPool& async_pool,
55       T&& observable,
56       U&& on_next,
57       E&& on_error) {
58     rxcpp::composite_subscription subscription;
59 
60     async_pool.LaunchAsync([subscription,  // safe copy: ref-counted
61                             observable=std::forward<T>(observable),
62                             on_next=std::forward<U>(on_next),
63                             on_error=std::forward<E>(on_error)]() mutable {
64       observable
65         .as_blocking()
66         .subscribe(subscription,
67                    std::forward<decltype(on_next)>(on_next),
68                    std::forward<decltype(on_error)>(on_error));
69     });
70 
71     return subscription;
72   }
73 };
74 
75 }   // namespace iorap::common
76 
77 #endif  // IORAP_SRC_COMMON_RX_ASYNC_H_
78