components/proximity_auth/metrics.cc

   1 // Copyright 2015 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "components/proximity_auth/metrics.h"
   6
   7 #include "base/md5.h"
   8 #include "base/metrics/histogram_macros.h"
   9 #include "base/metrics/sparse_histogram.h"
  10 #include "base/sys_byteorder.h"
  11
  12 namespace proximity_auth {
  13 namespace metrics {
  14
  15 namespace {
  16
  17 // Converts the 4-byte prefix of an MD5 hash into a int32 value.
  18 int32 DigestToInt32(const base::MD5Digest& digest) {
  19   // First, copy to a uint32, since byte swapping and endianness conversions
  20   // expect unsigned integers.
  21   uint32 unsigned_value;
  22   DCHECK_GE(arraysize(digest.a), sizeof(unsigned_value));
  23   memcpy(&unsigned_value, digest.a, sizeof(unsigned_value));
  24   unsigned_value = base::ByteSwap(base::HostToNet32(unsigned_value));
  25
  26   // Then copy the resulting bit pattern to an int32 to match the datatype that
  27   // histograms expect.
  28   int32 value;
  29   memcpy(&value, &unsigned_value, sizeof(value));
  30   return value;
  31 }
  32
  33 // Returns a hash of the given |name|, encoded as a 32-bit signed integer.
  34 int32 HashDeviceModelName(const std::string& name) {
  35   base::MD5Digest digest;
  36   base::MD5Sum(name.c_str(), name.size(), &digest);
  37   return DigestToInt32(digest);
  38 }
  39
  40 }  // namespace
  41
  42 const char kUnknownDeviceModel[] = "Unknown";
  43 const int kUnknownProximityValue = 127;
  44
  45 void RecordAuthProximityRollingRssi(int rolling_rssi) {
  46   if (rolling_rssi != kUnknownProximityValue)
  47     rolling_rssi = std::min(50, std::max(-100, rolling_rssi));
  48
  49   UMA_HISTOGRAM_SPARSE_SLOWLY("EasyUnlock.AuthProximity.RollingRssi",
  50                               rolling_rssi);
  51 }
  52
  53 void RecordAuthProximityTransmitPowerDelta(int transmit_power_delta) {
  54   if (transmit_power_delta != kUnknownProximityValue)
  55     transmit_power_delta = std::min(50, std::max(-100, transmit_power_delta));
  56
  57   UMA_HISTOGRAM_SPARSE_SLOWLY("EasyUnlock.AuthProximity.TransmitPowerDelta",
  58                               transmit_power_delta);
  59 }
  60
  61 void RecordAuthProximityTimeSinceLastZeroRssi(
  62     base::TimeDelta time_since_last_zero_rssi) {
  63   UMA_HISTOGRAM_TIMES("EasyUnlock.AuthProximity.TimeSinceLastZeroRssi",
  64                       time_since_last_zero_rssi);
  65 }
  66
  67 void RecordAuthProximityRemoteDeviceModelHash(const std::string& device_model) {
  68   UMA_HISTOGRAM_SPARSE_SLOWLY("EasyUnlock.AuthProximity.RemoteDeviceModelHash",
  69                               HashDeviceModelName(device_model));
  70 }
  71
  72 }  // namespace metrics
  73 }  // namespace proximity_auth