Remove unused histograms for QUIC

net/quic/chromium/quic_connection_logger.cc

 // Copyright (c) 2013 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/chromium/quic_connection_logger.h"
 
 #include <algorithm>
 #include <limits>
 #include <memory>
 #include <utility>
@@ skipping 774 matching lines @@
       ReceivedPacketLossRate() * 1000));
 }
 
 void QuicConnectionLogger::RecordLossHistograms() const {
   if (largest_received_packet_number_ == 0)
     return;  // Connection was never used.
   RecordAggregatePacketLossRate();
 
   base::HistogramBase* is_not_ack_histogram =
       GetPacketNumberHistogram("IsNotAck_");
-  base::HistogramBase* is_an_ack_histogram =
-      GetPacketNumberHistogram("IsAnAck_");
   base::HistogramBase* packet_arrived_histogram =
       GetPacketNumberHistogram("Ack_");
   base::HistogramBase* packet_missing_histogram =
       GetPacketNumberHistogram("Nack_");
   base::HistogramBase* ongoing_cumulative_packet_histogram =
       Get21CumulativeHistogram("Some21s_");
   base::HistogramBase* first_cumulative_packet_histogram =
       Get21CumulativeHistogram("First21_");
   base::HistogramBase* six_packet_histogram = Get6PacketHistogram("Some6s_");

[Ryan Hamilton, 2016/08/17 23:55:15]

I think you can get rid of all the histograms on line 795-803, fwiw.

[Zhongyi Shi, 2016/08/18 03:56:04]

Do we also want to remove the last one? All the other histograms are okay to
move as we didn't look at them. Not sure whether someone else is looking at the
last ones.

[Ryan Hamilton, 2016/08/18 04:05:21]

You could ask on quic-dev, though I suspect it's really unused.

 
   DCHECK_EQ(received_packets_.size(), received_acks_.size());
   const QuicPacketNumber last_index = std::min<QuicPacketNumber>(
       received_packets_.size() - 1, largest_received_packet_number_);
   const QuicPacketNumber index_of_first_21_contribution =
       std::min<QuicPacketNumber>(21, last_index);
   // Bit pattern of consecutively received packets that is maintained as we scan
   // through the received_packets_ vector. Less significant bits correspond to
   // less recent packets, and only the low order 21 bits are ever defined.
   // Bit is 1 iff corresponding packet was received.
   int packet_pattern_21 = 0;
   // Zero is an invalid packet sequence number.
   DCHECK(!received_packets_[0]);
   for (size_t i = 1; i <= last_index; ++i) {
-    if (received_acks_[i])
-      is_an_ack_histogram->Add(i);
-    else
+    if (!received_acks_[i])
       is_not_ack_histogram->Add(i);
 
     packet_pattern_21 >>= 1;
     if (received_packets_[i]) {
       packet_arrived_histogram->Add(i);
       packet_pattern_21 |= (1 << 20);  // Turn on the 21st bit.
     } else {
       packet_missing_histogram->Add(i);
     }
 
@@ skipping 17 matching lines @@
       continue;
     }
     // Record some overlapping patterns, to get a better picture, since this is
     // not very expensive.
     if (i % 3 == 0)
       six_packet_histogram->Add(recent_6_mask);
   }
 }
 
 }  // namespace net