Return std::string from base::debug::ReadElfBuildId() Simplify ReadElfBuildId() to return std::string directly instead of writing to a fixed-size out-parameter (ElfBuildIdBuffer) and returning the byte length, and remove ElfBuildIdBuffer. Historically, ReadElfBuildId() returned base::Optional<std::string> until https://crrev.com/c/1474251 (2019), which switched to a fixed-size buffer with comments stating that elf_reader.cc may be used in crash-handling / signal-handler code and must avoid dynamic memory allocation. However, none of the functions in elf_reader.cc (ReadElfBuildId(), ReadElfLibraryName(), GetElfProgramHeaders(), GetRelocationOffset()) are used in crash handling or signal handlers: - stack_trace_posix.cc (which implements the in-process crash signal handler) does not use elf_reader.cc at all. - stack_trace_fuchsia.cc delegates crash stack dumping to the system crashlogger (Fuchsia does not use POSIX signal handlers), and StackTrace::OutputToStreamWithPrefixImpl() writes to std::ostream and LOG(WARNING). - stack_trace_android.cc only uses ReadElfBuildId() inside StackTrace::OutputToStreamWithPrefixImpl(), which already allocates std::string and std::vector on the heap. - All other callers (module_cache_posix.cc, anr_build_id_provider.cc, os_metrics_linux.cc, tracing_sampler_profiler.cc) immediately convert the buffer into a heap-allocated std::string. Returning std::string directly via HexEncode() / HexEncodeLower() simplifies all callers and removes manual buffer sizing. Bug: 559576258 Change-Id: I8c70698e98a3fe9e3046cb8f59588f3f87383f9d Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/8537546 Commit-Queue: Arthur Sonzogni <arthursonzogni@chromium.org> Reviewed-by: Daniel Cheng <dcheng@chromium.org> Reviewed-by: Tibor Goldschwendt <tiborg@chromium.org> Cr-Commit-Position: refs/heads/main@{#1716998} NOKEYCHECK=True GitOrigin-RevId: b7319baa74e502abd5a6bd022691472faa2a2666
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.
Rust code in base should be organized into very small crates, split up by function. Merging crates is sometimes unavoidable (due to dependency cycles or the orphaning rule).
Rust files should live near the equivalent C++ files (if any), and use the same naming scheme (for example, run_loop.rs, not run_loop_rust.rs).
When adding FFI shims, prefer separate _shim.h files rather than adding code to existing C++ files. This helps avoid circular dependencies with the //base target. It also avoids adding code to commonly-used headers, which can increase compile size by a lot.
Crates which you expect to be widely used should be added to the public_deps of the //base:base_rust target, so that developers can simply depend on //base:base_rust the same way they do with //base.