18c2ecf20Sopenharmony_ci#!/usr/bin/env python 28c2ecf20Sopenharmony_ci# SPDX-License-Identifier: GPL-2.0+ 38c2ecf20Sopenharmony_ci# 48c2ecf20Sopenharmony_ci# This determines how many parallel tasks "make" is expecting, as it is 58c2ecf20Sopenharmony_ci# not exposed via an special variables, reserves them all, runs a subprocess 68c2ecf20Sopenharmony_ci# with PARALLELISM environment variable set, and releases the jobs back again. 78c2ecf20Sopenharmony_ci# 88c2ecf20Sopenharmony_ci# https://www.gnu.org/software/make/manual/html_node/POSIX-Jobserver.html#POSIX-Jobserver 98c2ecf20Sopenharmony_cifrom __future__ import print_function 108c2ecf20Sopenharmony_ciimport os, sys, errno 118c2ecf20Sopenharmony_ciimport subprocess 128c2ecf20Sopenharmony_ci 138c2ecf20Sopenharmony_ci# Extract and prepare jobserver file descriptors from envirnoment. 148c2ecf20Sopenharmony_ciclaim = 0 158c2ecf20Sopenharmony_cijobs = b"" 168c2ecf20Sopenharmony_citry: 178c2ecf20Sopenharmony_ci # Fetch the make environment options. 188c2ecf20Sopenharmony_ci flags = os.environ['MAKEFLAGS'] 198c2ecf20Sopenharmony_ci 208c2ecf20Sopenharmony_ci # Look for "--jobserver=R,W" 218c2ecf20Sopenharmony_ci # Note that GNU Make has used --jobserver-fds and --jobserver-auth 228c2ecf20Sopenharmony_ci # so this handles all of them. 238c2ecf20Sopenharmony_ci opts = [x for x in flags.split(" ") if x.startswith("--jobserver")] 248c2ecf20Sopenharmony_ci 258c2ecf20Sopenharmony_ci # Parse out R,W file descriptor numbers and set them nonblocking. 268c2ecf20Sopenharmony_ci fds = opts[0].split("=", 1)[1] 278c2ecf20Sopenharmony_ci reader, writer = [int(x) for x in fds.split(",", 1)] 288c2ecf20Sopenharmony_ci # Open a private copy of reader to avoid setting nonblocking 298c2ecf20Sopenharmony_ci # on an unexpecting process with the same reader fd. 308c2ecf20Sopenharmony_ci reader = os.open("/proc/self/fd/%d" % (reader), 318c2ecf20Sopenharmony_ci os.O_RDONLY | os.O_NONBLOCK) 328c2ecf20Sopenharmony_ci 338c2ecf20Sopenharmony_ci # Read out as many jobserver slots as possible. 348c2ecf20Sopenharmony_ci while True: 358c2ecf20Sopenharmony_ci try: 368c2ecf20Sopenharmony_ci slot = os.read(reader, 8) 378c2ecf20Sopenharmony_ci jobs += slot 388c2ecf20Sopenharmony_ci except (OSError, IOError) as e: 398c2ecf20Sopenharmony_ci if e.errno == errno.EWOULDBLOCK: 408c2ecf20Sopenharmony_ci # Stop at the end of the jobserver queue. 418c2ecf20Sopenharmony_ci break 428c2ecf20Sopenharmony_ci # If something went wrong, give back the jobs. 438c2ecf20Sopenharmony_ci if len(jobs): 448c2ecf20Sopenharmony_ci os.write(writer, jobs) 458c2ecf20Sopenharmony_ci raise e 468c2ecf20Sopenharmony_ci # Add a bump for our caller's reserveration, since we're just going 478c2ecf20Sopenharmony_ci # to sit here blocked on our child. 488c2ecf20Sopenharmony_ci claim = len(jobs) + 1 498c2ecf20Sopenharmony_ciexcept (KeyError, IndexError, ValueError, OSError, IOError) as e: 508c2ecf20Sopenharmony_ci # Any missing environment strings or bad fds should result in just 518c2ecf20Sopenharmony_ci # not being parallel. 528c2ecf20Sopenharmony_ci pass 538c2ecf20Sopenharmony_ci 548c2ecf20Sopenharmony_ci# We can only claim parallelism if there was a jobserver (i.e. a top-level 558c2ecf20Sopenharmony_ci# "-jN" argument) and there were no other failures. Otherwise leave out the 568c2ecf20Sopenharmony_ci# environment variable and let the child figure out what is best. 578c2ecf20Sopenharmony_ciif claim > 0: 588c2ecf20Sopenharmony_ci os.environ['PARALLELISM'] = '%d' % (claim) 598c2ecf20Sopenharmony_ci 608c2ecf20Sopenharmony_circ = subprocess.call(sys.argv[1:]) 618c2ecf20Sopenharmony_ci 628c2ecf20Sopenharmony_ci# Return all the reserved slots. 638c2ecf20Sopenharmony_ciif len(jobs): 648c2ecf20Sopenharmony_ci os.write(writer, jobs) 658c2ecf20Sopenharmony_ci 668c2ecf20Sopenharmony_cisys.exit(rc) 67