162306a36Sopenharmony_ci#!/usr/bin/env python3 262306a36Sopenharmony_ci# SPDX-License-Identifier: GPL-2.0+ 362306a36Sopenharmony_ci# 462306a36Sopenharmony_ci# This determines how many parallel tasks "make" is expecting, as it is 562306a36Sopenharmony_ci# not exposed via an special variables, reserves them all, runs a subprocess 662306a36Sopenharmony_ci# with PARALLELISM environment variable set, and releases the jobs back again. 762306a36Sopenharmony_ci# 862306a36Sopenharmony_ci# https://www.gnu.org/software/make/manual/html_node/POSIX-Jobserver.html#POSIX-Jobserver 962306a36Sopenharmony_cifrom __future__ import print_function 1062306a36Sopenharmony_ciimport os, sys, errno 1162306a36Sopenharmony_ciimport subprocess 1262306a36Sopenharmony_ci 1362306a36Sopenharmony_ci# Extract and prepare jobserver file descriptors from environment. 1462306a36Sopenharmony_ciclaim = 0 1562306a36Sopenharmony_cijobs = b"" 1662306a36Sopenharmony_citry: 1762306a36Sopenharmony_ci # Fetch the make environment options. 1862306a36Sopenharmony_ci flags = os.environ['MAKEFLAGS'] 1962306a36Sopenharmony_ci 2062306a36Sopenharmony_ci # Look for "--jobserver=R,W" 2162306a36Sopenharmony_ci # Note that GNU Make has used --jobserver-fds and --jobserver-auth 2262306a36Sopenharmony_ci # so this handles all of them. 2362306a36Sopenharmony_ci opts = [x for x in flags.split(" ") if x.startswith("--jobserver")] 2462306a36Sopenharmony_ci 2562306a36Sopenharmony_ci # Parse out R,W file descriptor numbers and set them nonblocking. 2662306a36Sopenharmony_ci # If the MAKEFLAGS variable contains multiple instances of the 2762306a36Sopenharmony_ci # --jobserver-auth= option, the last one is relevant. 2862306a36Sopenharmony_ci fds = opts[-1].split("=", 1)[1] 2962306a36Sopenharmony_ci 3062306a36Sopenharmony_ci # Starting with GNU Make 4.4, named pipes are used for reader and writer. 3162306a36Sopenharmony_ci # Example argument: --jobserver-auth=fifo:/tmp/GMfifo8134 3262306a36Sopenharmony_ci _, _, path = fds.partition('fifo:') 3362306a36Sopenharmony_ci 3462306a36Sopenharmony_ci if path: 3562306a36Sopenharmony_ci reader = os.open(path, os.O_RDONLY | os.O_NONBLOCK) 3662306a36Sopenharmony_ci writer = os.open(path, os.O_WRONLY) 3762306a36Sopenharmony_ci else: 3862306a36Sopenharmony_ci reader, writer = [int(x) for x in fds.split(",", 1)] 3962306a36Sopenharmony_ci # Open a private copy of reader to avoid setting nonblocking 4062306a36Sopenharmony_ci # on an unexpecting process with the same reader fd. 4162306a36Sopenharmony_ci reader = os.open("/proc/self/fd/%d" % (reader), 4262306a36Sopenharmony_ci os.O_RDONLY | os.O_NONBLOCK) 4362306a36Sopenharmony_ci 4462306a36Sopenharmony_ci # Read out as many jobserver slots as possible. 4562306a36Sopenharmony_ci while True: 4662306a36Sopenharmony_ci try: 4762306a36Sopenharmony_ci slot = os.read(reader, 8) 4862306a36Sopenharmony_ci jobs += slot 4962306a36Sopenharmony_ci except (OSError, IOError) as e: 5062306a36Sopenharmony_ci if e.errno == errno.EWOULDBLOCK: 5162306a36Sopenharmony_ci # Stop at the end of the jobserver queue. 5262306a36Sopenharmony_ci break 5362306a36Sopenharmony_ci # If something went wrong, give back the jobs. 5462306a36Sopenharmony_ci if len(jobs): 5562306a36Sopenharmony_ci os.write(writer, jobs) 5662306a36Sopenharmony_ci raise e 5762306a36Sopenharmony_ci # Add a bump for our caller's reserveration, since we're just going 5862306a36Sopenharmony_ci # to sit here blocked on our child. 5962306a36Sopenharmony_ci claim = len(jobs) + 1 6062306a36Sopenharmony_ciexcept (KeyError, IndexError, ValueError, OSError, IOError) as e: 6162306a36Sopenharmony_ci # Any missing environment strings or bad fds should result in just 6262306a36Sopenharmony_ci # not being parallel. 6362306a36Sopenharmony_ci pass 6462306a36Sopenharmony_ci 6562306a36Sopenharmony_ci# We can only claim parallelism if there was a jobserver (i.e. a top-level 6662306a36Sopenharmony_ci# "-jN" argument) and there were no other failures. Otherwise leave out the 6762306a36Sopenharmony_ci# environment variable and let the child figure out what is best. 6862306a36Sopenharmony_ciif claim > 0: 6962306a36Sopenharmony_ci os.environ['PARALLELISM'] = '%d' % (claim) 7062306a36Sopenharmony_ci 7162306a36Sopenharmony_circ = subprocess.call(sys.argv[1:]) 7262306a36Sopenharmony_ci 7362306a36Sopenharmony_ci# Return all the reserved slots. 7462306a36Sopenharmony_ciif len(jobs): 7562306a36Sopenharmony_ci os.write(writer, jobs) 7662306a36Sopenharmony_ci 7762306a36Sopenharmony_cisys.exit(rc) 78