perfetto: allow overriding write_version_header SCM revision via env (#5717)
Add \`PERFETTO_VERSION_HEADER_OVERRIDE_SCM_REVISION\` as an env-var
override for the SHA1 baked into \`perfetto_version{.gen.h,.ts}\`.
Embedders and forks that build the UI as part of a larger product want
the version footer (and the C++ macro) to identify their own checkout's
commit instead of perfetto's HEAD; today the only options are
post-processing the generated file or maintaining a local patch on
\`tools/write_version_header.py\`. An env var keeps the override out of
the build graph and inert for anyone who doesn't set it.
The override applies for any commit-ish passed to \`get_git_sha1\`, but
in practice the function is only invoked with \`HEAD\`. When the env var
is unset, behavior is unchanged.Perfetto is an open-source suite of SDKs, daemons and tools which use tracing to help developers understand the behaviour of complex systems and root-cause functional and performance issues on client and embedded systems.
It is a production-grade tool that is the default tracing system for the Android operating system and the Chromium browser.
Perfetto is not a single tool, but a collection of components that work together:
Perfetto was designed to be a versatile and powerful tracing system for a wide range of use cases.
ftrace, allowing you to visualize scheduling, syscalls, interrupts, and custom kernel tracepoints on a timeline.chrome://tracing. Use it to debug and root-cause issues in the browser, V8, and Blink.We‘ve designed our documentation to guide you to the right information as quickly as possible, whether you’re a newcomer to performance analysis or an experienced developer.
New to tracing? If you're unfamiliar with concepts like tracing and profiling, start here:
Ready to dive in? Our “Getting Started” guide is the main entry point for all users. It will help you find the right tutorials and documentation for your specific needs:
Want the full overview? For a comprehensive look at what Perfetto is, why it's useful, and who uses it, see our main documentation page:
For users interested in the Debian distribution of Perfetto, the official source of truth and packaging efforts are maintained at Debian Perfetto Salsa Repository
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