Removed Common

Change-Id: I01ea8f07220375c2ad9bc0092281d4f27c642303
diff --git a/aos/util/log_interval.h b/aos/util/log_interval.h
new file mode 100644
index 0000000..5e76166
--- /dev/null
+++ b/aos/util/log_interval.h
@@ -0,0 +1,97 @@
+#ifndef AOS_UTIL_LOG_INTERVAL_H_
+#define AOS_UTIL_LOG_INTERVAL_H_
+
+#include "aos/time/time.h"
+#include "aos/logging/logging.h"
+
+#include <string>
+
+namespace aos {
+namespace util {
+
+// A class to help with logging things that happen a lot only occasionally.
+//
+// Intended use {
+//   static LogInterval interval(::std::chrono::millseconds(200));
+//
+//   if (WantToLog()) {
+//     interval.WantToLog();
+//   }
+//   if (interval.ShouldLog()) {
+//     LOG(DEBUG, "thingie happened! (%d times)\n", interval.Count());
+//   }
+// }
+class LogInterval {
+ public:
+  constexpr LogInterval(::std::chrono::nanoseconds interval)
+      : interval_(interval) {}
+
+  void WantToLog() {
+    if (count_ == 0) {
+      last_done_ = ::aos::monotonic_clock::now();
+    }
+    ++count_;
+  }
+  bool ShouldLog() {
+    const ::aos::monotonic_clock::time_point now =
+        ::aos::monotonic_clock::now();
+    const bool r = now >= interval_ + last_done_ && count_ > 0;
+    if (r) {
+      last_done_ = now;
+    }
+    return r;
+  }
+  int Count() {
+    const int r = count_;
+    count_ = 0;
+    return r;
+  }
+
+  ::std::chrono::nanoseconds interval() const { return interval_; }
+
+ private:
+  int count_ = 0;
+  const ::std::chrono::nanoseconds interval_;
+  ::aos::monotonic_clock::time_point last_done_ =
+      ::aos::monotonic_clock::min_time;
+};
+
+// This one is even easier to use. It always logs with a message "%s %d
+// times\n". Call LOG_INTERVAL wherever it should log and make sure Print gets
+// called often (ie not after a conditional return)
+class SimpleLogInterval {
+ public:
+  SimpleLogInterval(::std::chrono::nanoseconds interval, log_level level,
+                    const ::std::string &message)
+      : interval_(interval), level_(level), message_(message) {}
+
+#define LOG_INTERVAL(simple_log) \
+  simple_log.WantToLog(LOG_SOURCENAME ": " STRINGIFY(__LINE__))
+  void WantToLog(const char *context) {
+    context_ = context;
+    interval_.WantToLog();
+  }
+
+  void Print() {
+    if (interval_.ShouldLog()) {
+      CHECK_NOTNULL(context_);
+      log_do(level_, "%s: %.*s %d times over %f sec\n", context_,
+             static_cast<int>(message_.size()), message_.data(),
+             interval_.Count(),
+             ::std::chrono::duration_cast<::std::chrono::duration<double>>(
+                 interval_.interval()).count());
+      context_ = NULL;
+    }
+  }
+
+ private:
+  LogInterval interval_;
+  const log_level level_;
+  const ::std::string message_;
+  const char *context_ = NULL;
+};
+
+}  // namespace util
+}  // namespace aos
+
+#endif  // AOS_UTIL_LOG_INTERVAL_H_