Add a couple of time helper functions.

Also add rounding support to tv_mdiff().

src/common/util.c

@@ -1034,6 +1034,42 @@ wrap_string(smartlist_t *out, const char *string, size_t width,
  * Time
  * ===== */
 
+/**
+ * Converts struct timeval to a double value.
+ * Preserves microsecond precision, but just barely.
+ * Error is approx +/- 0.1 usec when dealing with epoch values.
+ */
+double
+tv_to_double(const struct timeval *tv)
+{
+  double conv = tv->tv_sec;
+  conv += tv->tv_usec/1000000.0;
+  return conv;
+}
+
+/**
+ * Converts timeval to milliseconds.
+ */
+int64_t
+tv_to_msec(const struct timeval *tv)
+{
+  int64_t conv = ((int64_t)tv->tv_sec)*1000L;
+  /* Round ghetto-style */
+  conv += (tv->tv_usec+500)/1000L;
+  return conv;
+}
+
+/**
+ * Converts timeval to microseconds.
+ */
+int64_t
+tv_to_usec(const struct timeval *tv)
+{
+  int64_t conv = ((int64_t)tv->tv_sec)*1000000L;
+  conv += tv->tv_usec;
+  return conv;
+}
+
 /** Return the number of microseconds elapsed between *start and *end.
  */
 long
@@ -1066,7 +1102,9 @@ tv_mdiff(const struct timeval *start, const struct timeval *end)
     return LONG_MAX;
   }
 
-  mdiff = secdiff*1000L + ((long)end->tv_usec - (long)start->tv_usec) / 1000L;
+  /* Subtract and round */
+  mdiff = secdiff*1000L +
+      ((long)end->tv_usec - (long)start->tv_usec + 500L) / 1000L;
   return mdiff;
 }
 

src/common/util.h

@@ -212,6 +212,9 @@ void base16_encode(char *dest, size_t destlen, const char *src, size_t srclen);
 int base16_decode(char *dest, size_t destlen, const char *src, size_t srclen);
 
 /* Time helpers */
+double tv_to_double(const struct timeval *tv);
+int64_t tv_to_msec(const struct timeval *tv);
+int64_t tv_to_usec(const struct timeval *tv);
 long tv_udiff(const struct timeval *start, const struct timeval *end);
 long tv_mdiff(const struct timeval *start, const struct timeval *end);
 time_t tor_timegm(struct tm *tm);