components/metrics/metrics_hashes.cc

   1 // Copyright 2014 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/metrics/metrics_hashes.h"
   6
   7 #include "base/logging.h"
   8 #include "base/md5.h"
   9 #include "base/sys_byteorder.h"
  10
  11 namespace metrics {
  12
  13 namespace {
  14
  15 // Converts the 8-byte prefix of an MD5 hash into a uint64 value.
  16 inline uint64 HashToUInt64(const std::string& hash) {
  17   uint64 value;
  18   DCHECK_GE(hash.size(), sizeof(value));
  19   memcpy(&value, hash.data(), sizeof(value));
  20   return base::HostToNet64(value);
  21 }
  22
  23 }  // namespace
  24
  25 uint64 HashMetricName(const std::string& name) {
  26   // Create an MD5 hash of the given |name|, represented as a byte buffer
  27   // encoded as an std::string.
  28   base::MD5Context context;
  29   base::MD5Init(&context);
  30   base::MD5Update(&context, name);
  31
  32   base::MD5Digest digest;
  33   base::MD5Final(&digest, &context);
  34
  35   std::string hash_str(reinterpret_cast<char*>(digest.a), arraysize(digest.a));
  36   return HashToUInt64(hash_str);
  37 }
  38
  39 }  // namespace metrics