metrics_hashes.cc 1.4 KB

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  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. #include "base/metrics/metrics_hashes.h"
  5. #include <string.h>
  6. #include "base/check_op.h"
  7. #include "base/hash/md5.h"
  8. #include "base/sys_byteorder.h"
  9. namespace base {
  10. namespace {
  11. // Converts the 8-byte prefix of an MD5 hash into a uint64_t value.
  12. inline uint64_t DigestToUInt64(const base::MD5Digest& digest) {
  13. uint64_t value;
  14. DCHECK_GE(sizeof(digest.a), sizeof(value));
  15. memcpy(&value, digest.a, sizeof(value));
  16. return base::NetToHost64(value);
  17. }
  18. // Converts the 4-byte prefix of an MD5 hash into a uint32_t value.
  19. inline uint32_t DigestToUInt32(const base::MD5Digest& digest) {
  20. uint32_t value;
  21. DCHECK_GE(sizeof(digest.a), sizeof(value));
  22. memcpy(&value, digest.a, sizeof(value));
  23. return base::NetToHost32(value);
  24. }
  25. } // namespace
  26. uint64_t HashMetricName(base::StringPiece name) {
  27. // Corresponding Python code for quick look up:
  28. //
  29. // import struct
  30. // import hashlib
  31. // struct.unpack('>Q', hashlib.md5(name.encode('utf-8')).digest()[:8])[0]
  32. //
  33. base::MD5Digest digest;
  34. base::MD5Sum(name.data(), name.size(), &digest);
  35. return DigestToUInt64(digest);
  36. }
  37. uint32_t HashMetricNameAs32Bits(base::StringPiece name) {
  38. base::MD5Digest digest;
  39. base::MD5Sum(name.data(), name.size(), &digest);
  40. return DigestToUInt32(digest);
  41. }
  42. } // namespace base