From 0254020f0e1911c0eaf99111b91828d2a74a4ee1 Mon Sep 17 00:00:00 2001 From: Christopher Larson Date: Sat, 13 May 2017 02:46:27 +0500 Subject: git-make-shallow: add script to make a git repo shallow This script will be used by the git fetcher to create shallow mirror tarballs. usage: git-make-shallow [-h] [--ref REF] [--shrink] REVISION [REVISION ...] Remove the history of the specified revisions, then optionally filter the available refs to those specified. positional arguments: REVISION a git revision/commit optional arguments: -h, --help show this help message and exit --ref REF, -r REF remove all but the specified refs (cumulative) --shrink, -s shrink the git repository by repacking and pruning While git does provide the ability to clone at a specific depth, and fetch all remote refs at a particular depth, the depth is across all branches/tags, and doesn't provide the flexibility we need, hence this script. Refs (branches+tags) can be filtered, as the process of history removal scales up rapidly with the number of refs. Even the existing `git fetch --depth=` is extremely slow on an upstream kernel repository with all the branches and tags kept. This uses the same underlying mechanism to implement the history removal which git itself uses (.git/shallow), and the results, when configured similarly, are in line with the results git itself produces with `fetch --depth`. Signed-off-by: Christopher Larson Signed-off-by: Richard Purdie --- bin/git-make-shallow | 165 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 165 insertions(+) create mode 100755 bin/git-make-shallow (limited to 'bin') diff --git a/bin/git-make-shallow b/bin/git-make-shallow new file mode 100755 index 000000000..296d3a3db --- /dev/null +++ b/bin/git-make-shallow @@ -0,0 +1,165 @@ +#!/usr/bin/env python3 +"""git-make-shallow: make the current git repository shallow + +Remove the history of the specified revisions, then optionally filter the +available refs to those specified. +""" + +import argparse +import collections +import errno +import itertools +import os +import subprocess +import sys + +version = 1.0 + + +def main(): + if sys.version_info < (3, 4, 0): + sys.exit('Python 3.4 or greater is required') + + git_dir = check_output(['git', 'rev-parse', '--git-dir']).rstrip() + shallow_file = os.path.join(git_dir, 'shallow') + if os.path.exists(shallow_file): + try: + check_output(['git', 'fetch', '--unshallow']) + except subprocess.CalledProcessError: + try: + os.unlink(shallow_file) + except OSError as exc: + if exc.errno != errno.ENOENT: + raise + + args = process_args() + revs = check_output(['git', 'rev-list'] + args.revisions).splitlines() + + make_shallow(shallow_file, args.revisions, args.refs) + + ref_revs = check_output(['git', 'rev-list'] + args.refs).splitlines() + remaining_history = set(revs) & set(ref_revs) + for rev in remaining_history: + if check_output(['git', 'rev-parse', '{}^@'.format(rev)]): + sys.exit('Error: %s was not made shallow' % rev) + + filter_refs(args.refs) + + if args.shrink: + shrink_repo(git_dir) + subprocess.check_call(['git', 'fsck', '--unreachable']) + + +def process_args(): + # TODO: add argument to automatically keep local-only refs, since they + # can't be easily restored with a git fetch. + parser = argparse.ArgumentParser(description='Remove the history of the specified revisions, then optionally filter the available refs to those specified.') + parser.add_argument('--ref', '-r', metavar='REF', action='append', dest='refs', help='remove all but the specified refs (cumulative)') + parser.add_argument('--shrink', '-s', action='store_true', help='shrink the git repository by repacking and pruning') + parser.add_argument('revisions', metavar='REVISION', nargs='+', help='a git revision/commit') + if len(sys.argv) < 2: + parser.print_help() + sys.exit(2) + + args = parser.parse_args() + + if args.refs: + args.refs = check_output(['git', 'rev-parse', '--symbolic-full-name'] + args.refs).splitlines() + else: + args.refs = get_all_refs(lambda r, t, tt: t == 'commit' or tt == 'commit') + + args.refs = list(filter(lambda r: not r.endswith('/HEAD'), args.refs)) + args.revisions = check_output(['git', 'rev-parse'] + ['%s^{}' % i for i in args.revisions]).splitlines() + return args + + +def check_output(cmd, input=None): + return subprocess.check_output(cmd, universal_newlines=True, input=input) + + +def make_shallow(shallow_file, revisions, refs): + """Remove the history of the specified revisions.""" + for rev in follow_history_intersections(revisions, refs): + print("Processing %s" % rev) + with open(shallow_file, 'a') as f: + f.write(rev + '\n') + + +def get_all_refs(ref_filter=None): + """Return all the existing refs in this repository, optionally filtering the refs.""" + ref_output = check_output(['git', 'for-each-ref', '--format=%(refname)\t%(objecttype)\t%(*objecttype)']) + ref_split = [tuple(iter_extend(l.rsplit('\t'), 3)) for l in ref_output.splitlines()] + if ref_filter: + ref_split = (e for e in ref_split if ref_filter(*e)) + refs = [r[0] for r in ref_split] + return refs + + +def iter_extend(iterable, length, obj=None): + """Ensure that iterable is the specified length by extending with obj.""" + return itertools.islice(itertools.chain(iterable, itertools.repeat(obj)), length) + + +def filter_refs(refs): + """Remove all but the specified refs from the git repository.""" + all_refs = get_all_refs() + to_remove = set(all_refs) - set(refs) + if to_remove: + check_output(['xargs', '-0', '-n', '1', 'git', 'update-ref', '-d', '--no-deref'], + input=''.join(l + '\0' for l in to_remove)) + + +def follow_history_intersections(revisions, refs): + """Determine all the points where the history of the specified revisions intersects the specified refs.""" + queue = collections.deque(revisions) + seen = set() + + for rev in iter_except(queue.popleft, IndexError): + if rev in seen: + continue + + parents = check_output(['git', 'rev-parse', '%s^@' % rev]).splitlines() + + yield rev + seen.add(rev) + + if not parents: + continue + + check_refs = check_output(['git', 'merge-base', '--independent'] + sorted(refs)).splitlines() + for parent in parents: + for ref in check_refs: + print("Checking %s vs %s" % (parent, ref)) + try: + merge_base = check_output(['git', 'merge-base', parent, ref]).rstrip() + except subprocess.CalledProcessError: + continue + else: + queue.append(merge_base) + + +def iter_except(func, exception, start=None): + """Yield a function repeatedly until it raises an exception.""" + try: + if start is not None: + yield start() + while True: + yield func() + except exception: + pass + + +def shrink_repo(git_dir): + """Shrink the newly shallow repository, removing the unreachable objects.""" + subprocess.check_call(['git', 'reflog', 'expire', '--expire-unreachable=now', '--all']) + subprocess.check_call(['git', 'repack', '-ad']) + try: + os.unlink(os.path.join(git_dir, 'objects', 'info', 'alternates')) + except OSError as exc: + if exc.errno != errno.ENOENT: + raise + subprocess.check_call(['git', 'prune', '--expire', 'now']) + + +if __name__ == '__main__': + main() -- cgit 1.2.3-korg