def _compute_project_hash()

in build/fbcode_builder/getdeps/load.py [0:0]

• 43 lines of code
• 10 McCabe index (conditional complexity)

    def _compute_project_hash(self, manifest) -> str:
        """This recursive function computes a hash for a given manifest.
        The hash takes into account some environmental factors on the
        host machine and includes the hashes of its dependencies.
        No caching of the computation is performed, which is theoretically
        wasteful but the computation is fast enough that it is not required
        to cache across multiple invocations."""
        ctx = self.ctx_gen.get_context(manifest.name)

        hasher = hashlib.sha256()
        # Some environmental and configuration things matter
        env = {}
        env["install_dir"] = self.build_opts.install_dir
        env["scratch_dir"] = self.build_opts.scratch_dir
        env["vcvars_path"] = self.build_opts.vcvars_path
        env["os"] = self.build_opts.host_type.ostype
        env["distro"] = self.build_opts.host_type.distro
        env["distro_vers"] = self.build_opts.host_type.distrovers
        env["shared_libs"] = str(self.build_opts.shared_libs)
        for name in [
            "CXXFLAGS",
            "CPPFLAGS",
            "LDFLAGS",
            "CXX",
            "CC",
            "GETDEPS_CMAKE_DEFINES",
        ]:
            env[name] = os.environ.get(name)
        for tool in ["cc", "c++", "gcc", "g++", "clang", "clang++"]:
            env["tool-%s" % tool] = path_search(os.environ, tool)
        for name in manifest.get_section_as_args("depends.environment", ctx):
            env[name] = os.environ.get(name)

        fetcher = self.create_fetcher(manifest)
        env["fetcher.hash"] = fetcher.hash()

        for name in sorted(env.keys()):
            hasher.update(name.encode("utf-8"))
            value = env.get(name)
            if value is not None:
                try:
                    hasher.update(value.encode("utf-8"))
                except AttributeError as exc:
                    raise AttributeError("name=%r, value=%r: %s" % (name, value, exc))

        manifest.update_hash(hasher, ctx)

        dep_list = manifest.get_dependencies(ctx)
        for dep in dep_list:
            dep_manifest = self.load_manifest(dep)
            dep_hash = self.get_project_hash(dep_manifest)
            hasher.update(dep_hash.encode("utf-8"))

        # Use base64 to represent the hash, rather than the simple hex digest,
        # so that the string is shorter.  Use the URL-safe encoding so that
        # the hash can also be safely used as a filename component.
        h = base64.urlsafe_b64encode(hasher.digest()).decode("ascii")
        # ... and because cmd.exe is troublesome with `=` signs, nerf those.
        # They tend to be padding characters at the end anyway, so we can
        # safely discard them.
        h = h.replace("=", "")

        return h