60 lines
2.8 KiB
C++
60 lines
2.8 KiB
C++
/*
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* Copyright 2012-present Facebook, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#pragma once
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#include <atomic>
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#include <chrono>
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#include <glog/logging.h>
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#ifndef FB_LOG_EVERY_MS
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/**
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* Issues a LOG(severity) no more often than every
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* milliseconds. Example:
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*
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* FB_LOG_EVERY_MS(INFO, 10000) << "At least ten seconds passed"
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* " since you last saw this.";
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*
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* The implementation uses for statements to introduce variables in
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* a nice way that doesn't mess surrounding statements. It is thread
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* safe. Non-positive intervals will always log.
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*/
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#define FB_LOG_EVERY_MS(severity, milli_interval) \
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for (decltype(milli_interval) FB_LEM_once = 1, \
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FB_LEM_interval = (milli_interval); \
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FB_LEM_once;) \
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for (::std::chrono::milliseconds::rep FB_LEM_prev, \
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FB_LEM_now = FB_LEM_interval <= 0 \
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? 0 \
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: ::std::chrono::duration_cast<::std::chrono::milliseconds>( \
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::std::chrono::system_clock::now().time_since_epoch()) \
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.count(); \
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FB_LEM_once;) \
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for (static ::std::atomic<::std::chrono::milliseconds::rep> FB_LEM_hist; \
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FB_LEM_once; \
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FB_LEM_once = 0) \
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if (FB_LEM_interval > 0 && \
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(FB_LEM_now - \
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(FB_LEM_prev = \
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FB_LEM_hist.load(std::memory_order_acquire)) < \
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FB_LEM_interval || \
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!FB_LEM_hist.compare_exchange_strong(FB_LEM_prev, FB_LEM_now))) { \
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} else \
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LOG(severity)
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#endif
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