branchcache: skip entries that are topological heads in the on disk file
In the majority of cases, topological heads are also branch heads. We have
efficient way to get the topological heads and efficient way to retrieve
their branch information. So there is little value in putting them in the branch
cache file explicitly. On the contrary, writing them explicitly tend to create
very large cache file that are inefficient to read and update.
So the branch cache v3 format is no longer including them. This changeset focus
on the format aspect and have no focus on the performance aspect. We will cover
that later.
#!/usr/bin/env python3
#
# Copyright 2018 Gregory Szorc <gregory.szorc@gmail.com>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
import argparse
import pathlib
import shutil
import subprocess
import sys
def get_docker() -> str:
docker = shutil.which('docker.io') or shutil.which('docker')
if not docker:
print('could not find docker executable')
return 1
try:
out = subprocess.check_output([docker, '-h'], stderr=subprocess.STDOUT)
if b'Jansens' in out:
print(
'%s is the Docking System Tray; try installing docker.io'
% docker
)
sys.exit(1)
except subprocess.CalledProcessError as e:
print('error calling `%s -h`: %s' % (docker, e.output))
sys.exit(1)
out = subprocess.check_output([docker, 'version'], stderr=subprocess.STDOUT)
lines = out.splitlines()
if not any(l.startswith((b'Client:', b'Client version:')) for l in lines):
print('`%s version` does not look like Docker' % docker)
sys.exit(1)
if not any(l.startswith((b'Server:', b'Server version:')) for l in lines):
print('`%s version` does not look like Docker' % docker)
sys.exit(1)
return docker
def get_dockerfile(path: pathlib.Path, args: list) -> bytes:
with path.open('rb') as fh:
df = fh.read()
for k, v in args:
df = df.replace(bytes('%%%s%%' % k.decode(), 'utf-8'), v)
return df
def build_docker_image(dockerfile: pathlib.Path, params: list, tag: str):
"""Build a Docker image from a templatized Dockerfile."""
docker = get_docker()
dockerfile_path = pathlib.Path(dockerfile)
dockerfile = get_dockerfile(dockerfile_path, params)
print('building Dockerfile:')
print(dockerfile.decode('utf-8', 'replace'))
args = [
docker,
'build',
'--build-arg',
'http_proxy',
'--build-arg',
'https_proxy',
'--tag',
tag,
'-',
]
print('executing: %r' % args)
p = subprocess.Popen(args, stdin=subprocess.PIPE)
p.communicate(input=dockerfile)
if p.returncode:
raise subprocess.CalledProcessException(
p.returncode,
'failed to build docker image: %s %s' % (p.stdout, p.stderr),
)
def command_build(args):
build_args = []
for arg in args.build_arg:
k, v = arg.split('=', 1)
build_args.append((k.encode('utf-8'), v.encode('utf-8')))
build_docker_image(pathlib.Path(args.dockerfile), build_args, args.tag)
def command_docker(args):
print(get_docker())
def main() -> int:
parser = argparse.ArgumentParser()
subparsers = parser.add_subparsers(title='subcommands')
build = subparsers.add_parser('build', help='Build a Docker image')
build.set_defaults(func=command_build)
build.add_argument(
'--build-arg',
action='append',
default=[],
help='Substitution to perform in Dockerfile; ' 'format: key=value',
)
build.add_argument('dockerfile', help='path to Dockerfile to use')
build.add_argument('tag', help='Tag to apply to created image')
docker = subparsers.add_parser('docker-path', help='Resolve path to Docker')
docker.set_defaults(func=command_docker)
args = parser.parse_args()
return args.func(args)
if __name__ == '__main__':
sys.exit(main())