1 | /* |
2 | * Copyright 2014-present Facebook, Inc. |
3 | * |
4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
5 | * you may not use this file except in compliance with the License. |
6 | * You may obtain a copy of the License at |
7 | * |
8 | * http://www.apache.org/licenses/LICENSE-2.0 |
9 | * |
10 | * Unless required by applicable law or agreed to in writing, software |
11 | * distributed under the License is distributed on an "AS IS" BASIS, |
12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
13 | * See the License for the specific language governing permissions and |
14 | * limitations under the License. |
15 | */ |
16 | |
17 | #pragma once |
18 | |
19 | #include <chrono> |
20 | #include <memory> |
21 | #include <stdexcept> |
22 | |
23 | #include <folly/Executor.h> |
24 | #include <folly/lang/Exception.h> |
25 | |
26 | namespace folly { |
27 | // An executor that supports timed scheduling. Like RxScheduler. |
28 | class ScheduledExecutor : public virtual Executor { |
29 | public: |
30 | // Reality is that better than millisecond resolution is very hard to |
31 | // achieve. However, we reserve the right to be incredible. |
32 | typedef std::chrono::microseconds Duration; |
33 | typedef std::chrono::steady_clock::time_point TimePoint; |
34 | |
35 | ~ScheduledExecutor() override = default; |
36 | |
37 | void add(Func) override = 0; |
38 | |
39 | /// Alias for add() (for Rx consistency) |
40 | void schedule(Func&& a) { |
41 | add(std::move(a)); |
42 | } |
43 | |
44 | /// Schedule a Func to be executed after dur time has elapsed |
45 | /// Expect millisecond resolution at best. |
46 | void schedule(Func&& a, Duration const& dur) { |
47 | scheduleAt(std::move(a), now() + dur); |
48 | } |
49 | |
50 | /// Schedule a Func to be executed at time t, or as soon afterward as |
51 | /// possible. Expect millisecond resolution at best. Must be threadsafe. |
52 | virtual void scheduleAt(Func&& /* a */, TimePoint const& /* t */) { |
53 | throw_exception<std::logic_error>("unimplemented" ); |
54 | } |
55 | |
56 | /// Get this executor's notion of time. Must be threadsafe. |
57 | virtual TimePoint now() { |
58 | return std::chrono::steady_clock::now(); |
59 | } |
60 | }; |
61 | } // namespace folly |
62 | |