#ifndef FOLLY_LOGGING_H_
#define FOLLY_LOGGING_H_
+#include <atomic>
#include <chrono>
#include <glog/logging.h>
* " since you last saw this.";
*
* The implementation uses for statements to introduce variables in
- * a nice way that doesn't mess surrounding statements.
+ * a nice way that doesn't mess surrounding statements. It is thread
+ * safe. Non-positive intervals will always log.
*/
-#define FB_LOG_EVERY_MS(severity, milli_interval) \
- for (bool FB_LEM_once = true; FB_LEM_once; ) \
- for (const auto FB_LEM_now = ::std::chrono::system_clock::now(); \
- FB_LEM_once; ) \
- for (static ::std::chrono::system_clock::time_point FB_LEM_last; \
- FB_LEM_once; FB_LEM_once = false) \
- if (FB_LEM_now - FB_LEM_last < \
- ::std::chrono::milliseconds(milli_interval)) { \
- } else \
- (FB_LEM_last = FB_LEM_now, LOG(severity))
+#define FB_LOG_EVERY_MS(severity, milli_interval) \
+ 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 = \
+ FB_LEM_interval <= 0 ? 0 : \
+ ::std::chrono::duration_cast< ::std::chrono::milliseconds>( \
+ ::std::chrono::system_clock::now().time_since_epoch() \
+ ).count(); \
+ FB_LEM_once; ) \
+ for (static ::std::atomic< ::std::chrono::milliseconds::rep> \
+ FB_LEM_hist; FB_LEM_once; FB_LEM_once = 0) \
+ if (FB_LEM_interval > 0 && \
+ (FB_LEM_now - (FB_LEM_prev = \
+ FB_LEM_hist.load(std::memory_order_acquire)) < \
+ FB_LEM_interval || \
+ !FB_LEM_hist.compare_exchange_strong(FB_LEM_prev,FB_LEM_now))) {\
+ } else \
+ LOG(severity)
#endif