Add Maxima lists to bandwidth state.

Right now, Tor routers don't save the maxima values from the
bw_history_t between sessions.  That's no good, since we use those
values to determine bandwidth.  This code adds a new BWHist.*Maximum
set of values to the state file.  If they're not present, we estimate
them by taking the observed total bandwidth and dividing it by the
period length, which provides a lower bound.

This should fix bug 1863.  I'm calling it a feature.

1 files changed, 7 insertions, 1 deletions

diff --git a/src/or/or.h b/src/or/or.h
index cb36126d99..e0f8babe70 100644
--- a/src/or/or.h
+++ b/src/or/or.h
@@ -2856,19 +2856,25 @@ typedef struct {
    * bandwidth usage. The "Interval" fields hold the granularity, in seconds,
    * of the entries of Values.  The "Values" lists hold decimal string
    * representations of the number of bytes read or written in each
-   * interval. */
+   * interval. The "Maxima" list holds decimal strings describing the highest
+   * rate achieved during the interval.
+   */
   time_t      BWHistoryReadEnds;
   int         BWHistoryReadInterval;
   smartlist_t *BWHistoryReadValues;
+  smartlist_t *BWHistoryReadMaxima;
   time_t      BWHistoryWriteEnds;
   int         BWHistoryWriteInterval;
   smartlist_t *BWHistoryWriteValues;
+  smartlist_t *BWHistoryWriteMaxima;
   time_t      BWHistoryDirReadEnds;
   int         BWHistoryDirReadInterval;
   smartlist_t *BWHistoryDirReadValues;
+  smartlist_t *BWHistoryDirReadMaxima;
   time_t      BWHistoryDirWriteEnds;
   int         BWHistoryDirWriteInterval;
   smartlist_t *BWHistoryDirWriteValues;
+  smartlist_t *BWHistoryDirWriteMaxima;
 
   /** Build time histogram */
   config_line_t * BuildtimeHistogram;