Use atomic sequence for sample trace ids

I noticed the current approach yielded collisions in the generated
sample trace ids on events with close timestamps, likely due to a
loss of precision in the way the hash seeds are casted and combined

In any case, for the sake of simplicity and performance (given the cost
of obtaining a timestamp with base::TimeTicks::now()) this implements
a helper that computes a trace id based on an atomic sequential number.

Bug: 390155857
Change-Id: I87969a7be30f30001655c63c8d93b49ad8158a00
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/6227576
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Commit-Queue: Andres Olivares <andoli@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/main@{#98566}
4 files changed
tree: d099cb4c0c360c3d786f0dbc9df7b7af7177da1b
  1. .github/
  2. bazel/
  3. build_overrides/
  4. custom_deps/
  5. docs/
  6. gni/
  7. include/
  8. infra/
  9. samples/
  10. src/
  11. test/
  12. testing/
  13. third_party/
  14. tools/
  15. .bazelrc
  16. .clang-format
  17. .clang-tidy
  18. .editorconfig
  19. .flake8
  20. .git-blame-ignore-revs
  21. .gitattributes
  22. .gitignore
  23. .gn
  24. .mailmap
  25. .style.yapf
  26. .vpython3
  27. .ycm_extra_conf.py
  28. AUTHORS
  29. BUILD.bazel
  30. BUILD.gn
  31. CODE_OF_CONDUCT.md
  32. codereview.settings
  33. COMMON_OWNERS
  34. DEPS
  35. DIR_METADATA
  36. ENG_REVIEW_OWNERS
  37. INFRA_OWNERS
  38. INTL_OWNERS
  39. LICENSE
  40. LICENSE.fdlibm
  41. LICENSE.strongtalk
  42. LICENSE.v8
  43. LOONG_OWNERS
  44. MIPS_OWNERS
  45. MODULE.bazel
  46. OWNERS
  47. PPC_OWNERS
  48. PRESUBMIT.py
  49. pyrightconfig.json
  50. README.md
  51. RISCV_OWNERS
  52. S390_OWNERS
  53. WATCHLISTS
README.md

V8 JavaScript Engine

V8 is Google's open source JavaScript engine.

V8 implements ECMAScript as specified in ECMA-262.

V8 is written in C++ and is used in Google Chrome, the open source browser from Google.

V8 can run standalone, or can be embedded into any C++ application.

V8 Project page: https://v8.dev/docs

Getting the Code

Checkout depot tools, and run

    fetch v8

This will checkout V8 into the directory v8 and fetch all of its dependencies. To stay up to date, run

    git pull origin
    gclient sync

For fetching all branches, add the following into your remote configuration in .git/config:

    fetch = +refs/branch-heads/*:refs/remotes/branch-heads/*
    fetch = +refs/tags/*:refs/tags/*

Contributing

Please follow the instructions mentioned at v8.dev/docs/contribute.