diff options
Diffstat (limited to 'tools/github-sync/converter.py')
| -rwxr-xr-x | tools/github-sync/converter.py | 481 |
1 files changed, 481 insertions, 0 deletions
diff --git a/tools/github-sync/converter.py b/tools/github-sync/converter.py new file mode 100755 index 0000000000..57db9286c1 --- /dev/null +++ b/tools/github-sync/converter.py @@ -0,0 +1,481 @@ +#!/usr/bin/env python3 + +# This Source Code Form is subject to the terms of the Mozilla Public +# License, v. 2.0. If a copy of the MPL was not distributed with this +# file, You can obtain one at http://mozilla.org/MPL/2.0/. + +import os +import re +import subprocess +import sys + +import hglib +import pygit2 + +DEBUG = False + + +def eprint(*args, **kwargs): + print(*args, file=sys.stderr, **kwargs) + + +def debugprint(*args, **kwargs): + if DEBUG: + eprint(*args, **kwargs) + + +class HgCommit: + def __init__(self, parent1, parent2): + self.parents = [] + if parent1 == NULL_PARENT_REV: + raise Exception( + "Encountered a hg changeset with no parents! We don't handle this...." + ) + self.parents.append(parent1) + if parent2 != NULL_PARENT_REV: + self.parents.append(parent2) + self.touches_sync_code = False + self.children = [] + + def add_child(self, rev): + self.children.append(rev) + + +class GitCommit: + def __init__(self, hg_rev, commit_obj): + self.hg_rev = hg_rev + self.commit_obj = commit_obj + + +def load_git_repository(): + commit_map = dict() + # First, scan the tags for "mozilla-xxx" that keep track of manually synchronized changes + sync_tags = filter( + lambda ref: ref.startswith("refs/tags/mozilla-"), + list(downstream_git_repo.references), + ) + for desc in sync_tags: + commit = downstream_git_repo.lookup_reference(desc).peel() + # cut out the revision hash from the output + hg_rev = desc[18:] + commit_map[hg_rev] = GitCommit(hg_rev, commit) + debugprint("Loaded pre-existing tag hg %s -> git %s" % (hg_rev, commit.oid)) + + # Next, scan the commits for a specific message format + re_commitmsg = re.compile( + r"^\[(ghsync|wrupdater)\] From https://hg.mozilla.org/mozilla-central/rev/([0-9a-fA-F]+)$", + re.MULTILINE, + ) + for commit in downstream_git_repo.walk(downstream_git_repo.head.target): + m = re_commitmsg.search(commit.message) + if not m: + continue + hg_rev = m.group(2) + commit_map[hg_rev] = GitCommit(hg_rev, commit) + debugprint("Loaded pre-existing commit hg %s -> git %s" % (hg_rev, commit.oid)) + return commit_map + + +def timeof(git_commit): + return git_commit.commit_obj.commit_time + git_commit.commit_obj.commit_time_offset + + +def find_newest_commit(commit_map): + newest_hg_rev = None + newest_commit_time = None + + for hg_rev, git_commit in commit_map.items(): + if newest_hg_rev is None or timeof(git_commit) > newest_commit_time: + newest_hg_rev = hg_rev + newest_commit_time = timeof(git_commit) + + return newest_hg_rev + + +def get_single_rev(revset): + output = subprocess.check_output( + ["hg", "log", "-r", revset, "--template", "{node}"] + ) + output = str(output, "ascii") + return output + + +def get_multiple_revs(revset, template): + output = subprocess.check_output( + ["hg", "log", "-r", revset, "--template", template + "\\n"] + ) + for line in output.splitlines(): + yield str(line, "ascii") + + +def get_base_hg_rev(commit_map): + base_hg_rev = find_newest_commit(commit_map) + eprint("Using %s as base hg revision" % base_hg_rev) + return base_hg_rev + + +def load_hg_commits(commits, query): + for cset in get_multiple_revs(query, "{node} {p1node} {p2node}"): + tokens = cset.split() + commits[tokens[0]] = HgCommit(tokens[1], tokens[2]) + return commits + + +def get_real_base_hg_rev(hg_data, commit_map): + # Some of the HG commits we want to port to github may have landed on codelines + # that branched off central prior to base_hg_rev. So when we create the git + # equivalents, they will have parents that are not the HEAD of the git repo, + # but instead will be descendants of older commits in the git repo. In order + # to do this correctly, we need to find the hg-equivalents of all of those + # possible git parents. So first we identify all the "tail" hg revisions in + # our hg_data set (think "tail" as in opposite of "head" which is the tipmost + # commit). The "tail" hg revisions are the ones for which we don't have their + # ancestors in hg_data. + tails = [] + for (rev, cset) in hg_data.items(): + for parent in cset.parents: + if parent not in hg_data: + tails.append(rev) + eprint("Found hg tail revisions %s" % tails) + # Then we find their common ancestor, which will be some ancestor of base_hg_rev + # from which those codelines. + if len(tails) == 0: + common_ancestor = get_single_rev(".") + else: + common_ancestor = get_single_rev("ancestor(" + ",".join(tails) + ")") + eprint("Found common ancestor of tail revisions: %s" % common_ancestor) + + # And then we find the newest git commit whose hg-equivalent is an ancestor of + # that common ancestor, to make sure we are starting from a known hg/git + # commit pair. + for git_commit in sorted(commit_map.values(), key=timeof, reverse=True): + new_base = get_single_rev( + "ancestor(" + common_ancestor + "," + git_commit.hg_rev + ")" + ) + if new_base == common_ancestor: + eprint( + "Pre-existing git commit %s from hg rev %s is descendant of common ancestor; %s" + % ( + git_commit.commit_obj.id, + git_commit.hg_rev, + "walking back further...", + ) + ) + continue + if new_base != git_commit.hg_rev: + eprint( + "Pre-existing git commit %s from hg rev %s is on sibling branch" + " of common ancestor; %s" + % ( + git_commit.commit_obj.id, + git_commit.hg_rev, + "walking back further...", + ) + ) + continue + eprint( + "Pre-existing git commit %s from hg rev %s is sufficiently old; stopping walk" + % (git_commit.commit_obj.id, git_commit.hg_rev) + ) + common_ancestor = new_base + break + + return common_ancestor + + +# Now we prune out all the uninteresting changesets from hg_commits. The +# uninteresting ones are ones that don't touch the target code, are not merges, +# and are not referenced by mozilla tags in the git repo. +# We do this by rewriting the parents to the "interesting" ancestor. +def prune_boring(rev): + while rev in hg_commits: + parent_pruned = False + for i in range(len(hg_commits[rev].parents)): + parent_rev = hg_commits[rev].parents[i] + if parent_rev not in hg_commits: + continue + if hg_commits[parent_rev].touches_sync_code: + continue + if len(hg_commits[parent_rev].parents) > 1: + continue + if parent_rev in hg_to_git_commit_map: + continue + + # If we get here, then `parent_rev` is a boring revision and we can + # prune it. Connect `rev` to its grandparent, and prune the parent + grandparent_rev = hg_commits[parent_rev].parents[0] + hg_commits[rev].parents[i] = grandparent_rev + # eprint("Pruned %s as boring parent of %s, using %s now" % + # (parent_rev, rev, grandparent_rev)) + parent_pruned = True + + if parent_pruned: + # If we pruned a parent, process `rev` again as we might want to + # prune more parents + continue + + # Collapse identical parents, because if the parents are identical + # we don't need to keep multiple copies of them. + hg_commits[rev].parents = list(dict.fromkeys(hg_commits[rev].parents)) + + # If we get here, all of `rev`s parents are interesting, so we can't + # prune them. Move up to the parent rev and start processing that, or + # if we have multiple parents then recurse on those nodes. + if len(hg_commits[rev].parents) == 1: + rev = hg_commits[rev].parents[0] + continue + + for parent_rev in hg_commits[rev].parents: + prune_boring(parent_rev) + return + + +class FakeCommit: + def __init__(self, oid): + self.oid = oid + + +def fake_commit(hg_rev, parent1, parent2): + if parent1 is None: + eprint("ERROR: Trying to build on None") + exit(1) + oid = "githash_%s" % hash(parent1) + eprint("Fake-built %s" % oid) + return FakeCommit(oid) + + +def build_tree(builder, treedata): + for (name, value) in treedata.items(): + if isinstance(value, dict): + subbuilder = downstream_git_repo.TreeBuilder() + build_tree(subbuilder, value) + builder.insert(name, subbuilder.write(), pygit2.GIT_FILEMODE_TREE) + else: + (filemode, contents) = value + blob_oid = downstream_git_repo.create_blob(contents) + builder.insert(name, blob_oid, filemode) + + +def author_to_signature(author): + pieces = author.strip().split("<") + if len(pieces) != 2 or pieces[1][-1] != ">": + # We could probably handle this better + return pygit2.Signature(author, "") + name = pieces[0].strip() + email = pieces[1][:-1].strip() + return pygit2.Signature(name, email) + + +def real_commit(hg_rev, parent1, parent2): + filetree = dict() + manifest = mozilla_hg_repo.manifest(rev=hg_rev) + for (nodeid, permission, executable, symlink, filename) in manifest: + if not filename.startswith(relative_path.encode("utf-8")): + continue + if symlink: + filemode = pygit2.GIT_FILEMODE_LINK + elif executable: + filemode = pygit2.GIT_FILEMODE_BLOB_EXECUTABLE + else: + filemode = pygit2.GIT_FILEMODE_BLOB + filecontent = mozilla_hg_repo.cat([filename], rev=hg_rev) + subtree = filetree + for component in filename.split(b"/")[2:-1]: + subtree = subtree.setdefault(component.decode("latin-1"), dict()) + filename = filename.split(b"/")[-1] + subtree[filename.decode("latin-1")] = (filemode, filecontent) + + builder = downstream_git_repo.TreeBuilder() + build_tree(builder, filetree) + tree_oid = builder.write() + + parent1_obj = downstream_git_repo.get(parent1) + if parent1_obj.tree_id == tree_oid: + eprint("Early-exit; tree matched that of parent git commit %s" % parent1) + return parent1_obj + + if parent2 is not None: + parent2_obj = downstream_git_repo.get(parent2) + if parent2_obj.tree_id == tree_oid: + eprint("Early-exit; tree matched that of parent git commit %s" % parent2) + return parent2_obj + + hg_rev_obj = mozilla_hg_repo.log(revrange=hg_rev, limit=1)[0] + commit_author = hg_rev_obj[4].decode("latin-1") + commit_message = hg_rev_obj[5].decode("latin-1") + commit_message += ( + "\n\n[ghsync] From https://hg.mozilla.org/mozilla-central/rev/%s" % hg_rev + + "\n" + ) + + parents = [parent1] + if parent2 is not None: + parents.append(parent2) + commit_oid = downstream_git_repo.create_commit( + None, + author_to_signature(commit_author), + author_to_signature(commit_author), + commit_message, + tree_oid, + parents, + ) + eprint("Built git commit %s" % commit_oid) + return downstream_git_repo.get(commit_oid) + + +def try_commit(hg_rev, parent1, parent2=None): + if False: + return fake_commit(hg_rev, parent1, parent2) + else: + return real_commit(hg_rev, parent1, parent2) + + +def build_git_commits(rev): + debugprint("build_git_commit(%s)..." % rev) + if rev in hg_to_git_commit_map: + debugprint(" maps to %s" % hg_to_git_commit_map[rev].commit_obj.oid) + return hg_to_git_commit_map[rev].commit_obj.oid + + if rev not in hg_commits: + debugprint(" not in hg_commits") + return None + + if len(hg_commits[rev].parents) == 1: + git_parent = build_git_commits(hg_commits[rev].parents[0]) + if not hg_commits[rev].touches_sync_code: + eprint( + "WARNING: Found rev %s that is non-merge and not related to the target" + % rev + ) + return git_parent + eprint("Building git equivalent for %s on top of %s" % (rev, git_parent)) + commit_obj = try_commit(rev, git_parent) + hg_to_git_commit_map[rev] = GitCommit(rev, commit_obj) + debugprint(" built %s as %s" % (rev, commit_obj.oid)) + return commit_obj.oid + + git_parent_1 = build_git_commits(hg_commits[rev].parents[0]) + git_parent_2 = build_git_commits(hg_commits[rev].parents[1]) + if git_parent_1 is None or git_parent_2 is None or git_parent_1 == git_parent_2: + git_parent = git_parent_1 if git_parent_2 is None else git_parent_2 + if not hg_commits[rev].touches_sync_code: + debugprint( + " %s is merge with no parents or doesn't touch WR, returning %s" + % (rev, git_parent) + ) + return git_parent + + eprint( + "WARNING: Found merge rev %s whose parents have identical target code" + ", but modifies the target" % rev + ) + eprint("Building git equivalent for %s on top of %s" % (rev, git_parent)) + commit_obj = try_commit(rev, git_parent) + hg_to_git_commit_map[rev] = GitCommit(rev, commit_obj) + debugprint(" built %s as %s" % (rev, commit_obj.oid)) + return commit_obj.oid + + # An actual merge + eprint( + "Building git equivalent for %s on top of %s, %s" + % (rev, git_parent_1, git_parent_2) + ) + commit_obj = try_commit(rev, git_parent_1, git_parent_2) + hg_to_git_commit_map[rev] = GitCommit(rev, commit_obj) + debugprint(" built %s as %s" % (rev, commit_obj.oid)) + return commit_obj.oid + + +def pretty_print(rev, cset): + desc = " %s" % rev + desc += " parents: %s" % cset.parents + if rev in hg_to_git_commit_map: + desc += " git: %s" % hg_to_git_commit_map[rev].commit_obj.oid + if rev == hg_tip: + desc += " (tip)" + return desc + + +if len(sys.argv) < 3: + eprint("Usage: %s <local-checkout-path> <repo-relative-path>" % sys.argv[0]) + eprint("Current dir must be the mozilla hg repo") + exit(1) + +local_checkout_path = sys.argv[1] +relative_path = sys.argv[2] +mozilla_hg_path = os.getcwd() +NULL_PARENT_REV = "0000000000000000000000000000000000000000" + +downstream_git_repo = pygit2.Repository(pygit2.discover_repository(local_checkout_path)) +mozilla_hg_repo = hglib.open(mozilla_hg_path) +hg_to_git_commit_map = load_git_repository() +base_hg_rev = get_base_hg_rev(hg_to_git_commit_map) +if base_hg_rev is None: + eprint("Found no sync commits or 'mozilla-xxx' tags") + exit(1) + +hg_commits = load_hg_commits(dict(), "only(.," + base_hg_rev + ")") +eprint("Initial set has %s changesets" % len(hg_commits)) +base_hg_rev = get_real_base_hg_rev(hg_commits, hg_to_git_commit_map) +eprint("Using hg rev %s as common ancestor of all interesting changesets" % base_hg_rev) + +# Refresh hg_commits with our wider dataset +hg_tip = get_single_rev(".") +wider_range = "%s::%s" % (base_hg_rev, hg_tip) +hg_commits = load_hg_commits(hg_commits, wider_range) +eprint("Updated set has %s changesets" % len(hg_commits)) + +if DEBUG: + eprint("Graph of descendants of %s" % base_hg_rev) + output = subprocess.check_output( + [ + "hg", + "log", + "--graph", + "-r", + "descendants(" + base_hg_rev + ")", + "--template", + "{node} {desc|firstline}\\n", + ] + ) + for line in output.splitlines(): + eprint(line.decode("utf-8", "ignore")) + +# Also flag any changes that touch the project +query = "(" + wider_range + ') & file("glob:' + relative_path + '/**")' +for cset in get_multiple_revs(query, "{node}"): + debugprint("Changeset %s modifies %s" % (cset, relative_path)) + hg_commits[cset].touches_sync_code = True +eprint( + "Identified %s changesets that touch the target code" + % sum([1 if v.touches_sync_code else 0 for (k, v) in hg_commits.items()]) +) + +prune_boring(hg_tip) + +# hg_tip itself might be boring +if not hg_commits[hg_tip].touches_sync_code and len(hg_commits[hg_tip].parents) == 1: + new_tip = hg_commits[hg_tip].parents[0] + eprint("Pruned tip %s as boring, using %s now" % (hg_tip, new_tip)) + hg_tip = new_tip + +eprint("--- Interesting changesets ---") +for (rev, cset) in hg_commits.items(): + if cset.touches_sync_code or len(cset.parents) > 1 or rev in hg_to_git_commit_map: + eprint(pretty_print(rev, cset)) +if DEBUG: + eprint("--- Other changesets (not really interesting) ---") + for (rev, cset) in hg_commits.items(): + if not ( + cset.touches_sync_code + or len(cset.parents) > 1 + or rev in hg_to_git_commit_map + ): + eprint(pretty_print(rev, cset)) + +git_tip = build_git_commits(hg_tip) +if git_tip is None: + eprint("No new changesets generated, exiting.") +else: + downstream_git_repo.create_reference("refs/heads/github-sync", git_tip, force=True) + eprint("Updated github-sync branch to %s, done!" % git_tip) |