1 | /* |
2 | * Copyright 2012-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 <atomic> |
20 | #include <chrono> |
21 | |
22 | #include <glog/logging.h> |
23 | |
24 | #ifndef FB_LOG_EVERY_MS |
25 | /** |
26 | * Issues a LOG(severity) no more often than every |
27 | * milliseconds. Example: |
28 | * |
29 | * FB_LOG_EVERY_MS(INFO, 10000) << "At least ten seconds passed" |
30 | * " since you last saw this."; |
31 | * |
32 | * The implementation uses for statements to introduce variables in |
33 | * a nice way that doesn't mess surrounding statements. It is thread |
34 | * safe. Non-positive intervals will always log. |
35 | */ |
36 | #define FB_LOG_EVERY_MS(severity, milli_interval) \ |
37 | for (decltype(milli_interval) FB_LEM_once = 1, \ |
38 | FB_LEM_interval = (milli_interval); \ |
39 | FB_LEM_once;) \ |
40 | for (::std::chrono::milliseconds::rep FB_LEM_prev, \ |
41 | FB_LEM_now = FB_LEM_interval <= 0 \ |
42 | ? 0 \ |
43 | : ::std::chrono::duration_cast<::std::chrono::milliseconds>( \ |
44 | ::std::chrono::system_clock::now().time_since_epoch()) \ |
45 | .count(); \ |
46 | FB_LEM_once;) \ |
47 | for (static ::std::atomic<::std::chrono::milliseconds::rep> FB_LEM_hist; \ |
48 | FB_LEM_once; \ |
49 | FB_LEM_once = 0) \ |
50 | if (FB_LEM_interval > 0 && \ |
51 | (FB_LEM_now - \ |
52 | (FB_LEM_prev = \ |
53 | FB_LEM_hist.load(std::memory_order_acquire)) < \ |
54 | FB_LEM_interval || \ |
55 | !FB_LEM_hist.compare_exchange_strong(FB_LEM_prev, FB_LEM_now))) { \ |
56 | } else \ |
57 | LOG(severity) |
58 | |
59 | #endif |
60 | |