commit | 5e7176d742c8c4b3bec4f21dabf8477ca28d1726 | [log] [tgz] |
---|---|---|
author | danakj <danakj@chromium.org> | Thu Jul 11 23:25:47 2024 |
committer | Copybara-Service <copybara-worker@google.com> | Fri Jul 12 00:06:30 2024 |
tree | 624ae4f3569486ffddd8fb0817347f9db218ebe0 | |
parent | 20b8b0791d8f29ce03ec84864f38467f0f9059b8 [diff] |
Allow span::copy_from to handle overlaps, add copy_from_nonoverlapping Currently we have no bounds-checked range-based way to copy overlapping spans. span::copy_from() DCHECKs that the spans do not overlap. Rename copy_from to copy_from_nonoverlapping, and add a new copy_from that handles overlap. std::copy/copy_backward can be used, we just have to carefully check that we use the right one to avoid UB. When the type is trivially copyable, we can use memmove() directly in copy_from() to avoid doing comparisons and branches, which helps with letting copy_from be inlined in most cases. If the spans are exactly equal, neither copy nor copy_backward is usable, but then there's also nothing to do so we do nothing. R=lukasza@chromium.org Bug: 40285824 Change-Id: Ib3cc76b4a343ddcee065ee86609001a3f2cf4738 Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5698066 Commit-Queue: danakj <danakj@chromium.org> Reviewed-by: Łukasz Anforowicz <lukasza@chromium.org> Cr-Commit-Position: refs/heads/main@{#1326456} NOKEYCHECK=True GitOrigin-RevId: 6f29fa5f78d52d1c991979f8e5800f4b58f33024
Contains a written down set of principles and other information on //base. Please add to it!
Chromium is a very mature project. Most things that are generally useful are already here and things not here aren't generally useful.
The bar for adding stuff to base is that it must have demonstrated wide applicability. Prefer to add things closer to where they're used (i.e. “not base”), and pull into base only when needed. In a project our size, sometimes even duplication is OK and inevitable.
Adding a new logging macro DPVELOG_NE
is not more clear than just writing the stuff you want to log in a regular logging statement, even if it makes your calling code longer. Just add it to your own code.
If the code in question does not need to be used inside base, but will have multiple consumers across the codebase, consider placing it in a new directory under components/ instead.
base is written for the Chromium project and is not intended to be used outside it. Using base outside of src.git is explicitly not supported, and base makes no guarantees about API (or even ABI) stability (like all other code in Chromium). New code that depends on base/ must be in src.git. Code that's not in src.git but pulled in through DEPS (for example, v8) cannot use base.
Owners are added when a contributor has shown the above qualifications and when they express interest. There isn't an upper bound on the number of OWNERS.
Since the primitives provided by //base are used very widely, it is important to ensure they scale to the necessary workloads and perform well under all supported platforms. The base_perftests
target is a suite of synthetic microbenchmarks that measure performance in various scenarios:
thread_local
, the implementation in //base, the POSIX/WinAPI directly)Regressions in these benchmarks can generally by caused by 1) operating system changes, 2) compiler version or flag changes or 3) changes in //base code itself.