Test divisor for zero before generating statistic

net/quic/quic_client_session.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/quic/quic_client_session.h"
 
 #include "base/callback_helpers.h"
 #include "base/message_loop/message_loop.h"
 #include "base/metrics/histogram.h"
 #include "base/metrics/sparse_histogram.h"
@@ skipping 226 matching lines @@
   } else {
     if (port_selected) {
       UMA_HISTOGRAM_CUSTOM_COUNTS("Net.QuicSession.ConnectSelectPortForHTTPS",
                                   round_trip_handshakes, 0, 3, 4);
     } else {
       UMA_HISTOGRAM_CUSTOM_COUNTS("Net.QuicSession.ConnectRandomPortForHTTPS",
                                   round_trip_handshakes, 0, 3, 4);
     }
   }
   const QuicConnectionStats stats = connection()->GetStats();
-  uint64 reordering =
-      GG_UINT64_C(100) * stats.max_time_reordering_us / stats.min_rtt_us;
-    UMA_HISTOGRAM_CUSTOM_COUNTS("Net.QuicSession.MaxReorderingTime",
+  uint64 reordering = (stats.min_rtt_us == 0) ? GG_UINT64_C(100)

[Ryan Hamilton, 2014/05/24 21:34:21]

nit: no need for GG_UINT64_C() around the 100 here. I needed it below to ensure
that the multiplication was 64 bit, so it didn't overflow.

+      : GG_UINT64_C(100) * stats.max_time_reordering_us / stats.min_rtt_us;
+  UMA_HISTOGRAM_CUSTOM_COUNTS("Net.QuicSession.MaxReorderingTime",
                                 reordering, 0, 100, 50);
   if (stats.min_rtt_us > 100) {
     UMA_HISTOGRAM_CUSTOM_COUNTS("Net.QuicSession.MaxReorderingTimeLongRtt",
                                 reordering, 0, 100, 50);
   }
   UMA_HISTOGRAM_COUNTS("Net.QuicSession.MaxReordering",
                        stats.max_sequence_reordering);
 }
 
 void QuicClientSession::OnStreamFrames(
@@ skipping 528 matching lines @@
     RecordUnexpectedNotGoingAway(NOTIFY_FACTORY_OF_SESSION_CLOSED);
 
   going_away_ = true;
   DCHECK_EQ(0u, GetNumOpenStreams());
   // Will delete |this|.
   if (stream_factory_)
     stream_factory_->OnSessionClosed(this);
 }
 
 }  // namespace net