Commit f13e9e39 authored by Nathan Bronson's avatar Nathan Bronson Committed by Sara Golemon

always log from LOG_EVERY_MS if interval is <= 0

Summary:
This diff changes LOG_EVERY_MS so that if the specified
interval is zero or negative, no clock call is made and LOG(severity) is
always called.  milli_interval is copied into a temporary to avoid
double-evaluation.

Test Plan:
1. unit tests
2. new unit test

Reviewed By: lesha@fb.com

FB internal diff: D1469366

Tasks: 4813858
parent e3e6edad
...@@ -31,21 +31,25 @@ ...@@ -31,21 +31,25 @@
* *
* The implementation uses for statements to introduce variables in * The implementation uses for statements to introduce variables in
* a nice way that doesn't mess surrounding statements. It is thread * a nice way that doesn't mess surrounding statements. It is thread
* safe. * safe. Non-positive intervals will always log.
*/ */
#define FB_LOG_EVERY_MS(severity, milli_interval) \ #define FB_LOG_EVERY_MS(severity, milli_interval) \
for (bool FB_LEM_once = true; FB_LEM_once; ) \ for (decltype(milli_interval) FB_LEM_once = 1, \
FB_LEM_interval = (milli_interval); \
FB_LEM_once; ) \
for (::std::chrono::milliseconds::rep FB_LEM_prev, FB_LEM_now = \ for (::std::chrono::milliseconds::rep FB_LEM_prev, FB_LEM_now = \
FB_LEM_interval <= 0 ? 0 : \
::std::chrono::duration_cast< ::std::chrono::milliseconds>( \ ::std::chrono::duration_cast< ::std::chrono::milliseconds>( \
::std::chrono::system_clock::now().time_since_epoch() \ ::std::chrono::system_clock::now().time_since_epoch() \
).count(); \ ).count(); \
FB_LEM_once; ) \ FB_LEM_once; ) \
for (static ::std::atomic< ::std::chrono::milliseconds::rep> \ for (static ::std::atomic< ::std::chrono::milliseconds::rep> \
FB_LEM_hist; FB_LEM_once; FB_LEM_once = false) \ FB_LEM_hist; FB_LEM_once; FB_LEM_once = 0) \
if (FB_LEM_now - (FB_LEM_prev = \ if (FB_LEM_interval > 0 && \
FB_LEM_hist.load(std::memory_order_acquire)) < \ (FB_LEM_now - (FB_LEM_prev = \
milli_interval || \ FB_LEM_hist.load(std::memory_order_acquire)) < \
!FB_LEM_hist.compare_exchange_strong(FB_LEM_prev, FB_LEM_now)) { \ FB_LEM_interval || \
!FB_LEM_hist.compare_exchange_strong(FB_LEM_prev,FB_LEM_now))) {\
} else \ } else \
LOG(severity) LOG(severity)
......
...@@ -40,6 +40,17 @@ TEST(LogEveryMs, basic) { ...@@ -40,6 +40,17 @@ TEST(LogEveryMs, basic) {
EXPECT_TRUE(atLeastOneIsGood); EXPECT_TRUE(atLeastOneIsGood);
} }
TEST(LogEveryMs, zero) {
int count = 0;
for (int i = 0; i < 10; ++i) {
FB_LOG_EVERY_MS(INFO, 0)
<< "test msg " << ++count;
}
EXPECT_EQ(10, count);
}
BENCHMARK(skip_overhead, iter) { BENCHMARK(skip_overhead, iter) {
auto prev = FLAGS_minloglevel; auto prev = FLAGS_minloglevel;
FLAGS_minloglevel = 2; FLAGS_minloglevel = 2;
......
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