runbot/runbot_merge/git.py

import dataclasses
import itertools
import logging
import os
import pathlib
import resource
import subprocess
from typing import Optional, TypeVar, Union, Sequence, Tuple, Dict

from odoo.tools.appdirs import user_cache_dir
from .github import MergeError, PrCommit

_logger = logging.getLogger(__name__)


def source_url(repository, prefix: str) -> str:
    return 'https://{}@github.com/{}'.format(
        repository.project_id[f'{prefix}_token'],
        repository.name,
    )

Authorship = Union[Tuple[str, str], Tuple[str, str, str]]

def get_local(repository, prefix: Optional[str]) -> 'Optional[Repo]':
    repos_dir = pathlib.Path(user_cache_dir('mergebot'))
    repos_dir.mkdir(parents=True, exist_ok=True)
    # NB: `repository.name` is `$org/$name` so this will be a subdirectory, probably
    repo_dir = repos_dir / repository.name

    if repo_dir.is_dir():
        return git(repo_dir)
    elif prefix:
        _logger.info("Cloning out %s to %s", repository.name, repo_dir)
        subprocess.run(['git', 'clone', '--bare', source_url(repository, prefix), str(repo_dir)], check=True)
        # bare repos don't have fetch specs by default, and fetching *into*
        # them is a pain in the ass, configure fetch specs so `git fetch`
        # works properly
        repo = git(repo_dir)
        repo.config('--add', 'remote.origin.fetch', '+refs/heads/*:refs/heads/*')
        # negative refspecs require git 2.29
        repo.config('--add', 'remote.origin.fetch', '^refs/heads/tmp.*')
        repo.config('--add', 'remote.origin.fetch', '^refs/heads/staging.*')
        return repo


ALWAYS = ('gc.auto=0', 'maintenance.auto=0')


def _bypass_limits():
    resource.setrlimit(resource.RLIMIT_AS, (resource.RLIM_INFINITY, resource.RLIM_INFINITY))


def git(directory: str) -> 'Repo':
    return Repo(directory, check=True)


Self = TypeVar("Self", bound="Repo")
class Repo:
    def __init__(self, directory, **config) -> None:
        self._directory = str(directory)
        config.setdefault('stderr', subprocess.PIPE)
        self._config = config
        self._params = ()

    def __getattr__(self, name: str) -> 'GitCommand':
        return GitCommand(self, name.replace('_', '-'))

    def _run(self, *args, **kwargs) -> subprocess.CompletedProcess:
        opts = {**self._config, **kwargs}
        args = ('git', '-C', self._directory)\
            + tuple(itertools.chain.from_iterable(('-c', p) for p in self._params + ALWAYS))\
            + args
        try:
            return subprocess.run(args, preexec_fn=_bypass_limits, **opts)
        except subprocess.CalledProcessError as e:
            stream = e.stderr or e.stdout
            if stream:
                _logger.error("git call error: %s", stream)
            raise

    def stdout(self, flag: bool = True) -> Self:
        if flag is True:
            return self.with_config(stdout=subprocess.PIPE)
        elif flag is False:
            return self.with_config(stdout=None)
        return self.with_config(stdout=flag)

    def check(self, flag: bool) -> Self:
        return self.with_config(check=flag)

    def with_config(self, **kw) -> Self:
        opts = {**self._config, **kw}
        r = Repo(self._directory, **opts)
        r._params = self._params
        return r

    def with_params(self, *args) -> Self:
        r = self.with_config()
        r._params = args
        return r

    def clone(self, to: str, branch: Optional[str] = None) -> Self:
        self._run(
            'clone',
            *([] if branch is None else ['-b', branch]),
            self._directory, to,
        )
        return Repo(to)

    def get_tree(self, commit_hash: str) -> str:
        r = self.with_config(check=True).rev_parse(f'{commit_hash}^{{tree}}')

        return r.stdout.strip()

    def rebase(self, dest: str, commits: Sequence[PrCommit]) -> Tuple[str, Dict[str, str]]:
        """Implements rebase by hand atop plumbing so:

        - we can work without a working copy
        - we can track individual commits (and store the mapping)

        It looks like `--merge-base` is not sufficient for `merge-tree` to
        correctly keep track of history, so it loses contents. Therefore
        implement in two passes as in the github version.
        """
        repo = self.stdout().with_config(text=True, check=False)

        logger = _logger.getChild('rebase')
        logger.debug("rebasing %s on %s (reset=%s, commits=%s)",
                     self._repo, dest, len(commits))
        if not commits:
            raise MergeError("PR has no commits")

        prev_tree = repo.get_tree(dest)
        prev_original_tree = repo.get_tree(commits[0]['parents'][0]["sha"])

        new_trees = []
        parent = dest
        for original in commits:
            if len(original['parents']) != 1:
                raise MergeError(
                    f"commits with multiple parents ({original['sha']}) can not be rebased, "
                    "either fix the branch to remove merges or merge without "
                    "rebasing")

            new_trees.append(check(repo.merge_tree(parent, original['sha'])).stdout.strip())
            # allow merging empty commits, but not empty*ing* commits while merging
            if prev_original_tree != original['commit']['tree']['sha']:
                if new_trees[-1] == prev_tree:
                    raise MergeError(
                        f"commit {original['sha']} results in an empty tree when "
                        f"merged, it is likely a duplicate of a merged commit, "
                        f"rebase and remove."
                    )

            parent = check(repo.commit_tree(
                tree=new_trees[-1],
                parents=[parent, original['sha']],
                message=f'temp rebase {original["sha"]}',
            )).stdout.strip()
            prev_tree = new_trees[-1]
            prev_original_tree = original['commit']['tree']['sha']

        mapping = {}
        for original, tree in zip(commits, new_trees):
            authorship = check(repo.show('--no-patch', '--pretty="%an%n%ae%n%ai%n%cn%n%ce"', original['sha']))
            author_name, author_email, author_date, committer_name, committer_email =\
                authorship.stdout.splitlines()

            c = check(repo.commit_tree(
                tree=tree,
                parents=[dest],
                message=original['commit']['message'],
                author=(author_name, author_email, author_date),
                committer=(committer_name, committer_email),
            )).stdout.strip()

            logger.debug('copied %s to %s (parent: %s)', original['sha'], c, dest)
            dest = mapping[original['sha']] = c

        return dest, mapping

    def merge(self, c1: str, c2: str, msg: str, *, author: Tuple[str, str]) -> str:
        repo = self.stdout().with_config(text=True, check=False)

        t = repo.merge_tree(c1, c2)
        if t.returncode:
            raise MergeError(t.stderr)

        c = self.commit_tree(
            tree=t.stdout.strip(),
            message=msg,
            parents=[c1, c2],
            author=author,
        )
        if c.returncode:
            raise MergeError(c.stderr)
        return c.stdout.strip()

    def commit_tree(
        self, *, tree: str, message: str,
        parents: Sequence[str] = (),
        author: Optional[Authorship] = None,
        committer: Optional[Authorship] = None,
    ) -> subprocess.CompletedProcess:
        authorship = {}
        if author:
            authorship['GIT_AUTHOR_NAME'] = author[0]
            authorship['GIT_AUTHOR_EMAIL'] = author[1]
            if len(author) > 2:
                authorship['GIT_AUTHOR_DATE'] = author[2]
        if committer:
            authorship['GIT_COMMITTER_NAME'] = committer[0]
            authorship['GIT_COMMITTER_EMAIL'] = committer[1]
            if len(committer) > 2:
                authorship['GIT_COMMITTER_DATE'] = committer[2]

        return self.with_config(
            stdout=subprocess.PIPE,
            text=True,
            env={
                **os.environ,
                **authorship,
                # we don't want git to use the timezone of the machine it's
                # running on: previously it used the timezone configured in
                # github (?), which I think / assume defaults to a generic UTC
                'TZ': 'UTC',
            }
        )._run(
            'commit-tree',
            tree,
            '-m', message,
            *itertools.chain.from_iterable(('-p', p) for p in parents),
        )

def check(p: subprocess.CompletedProcess) -> subprocess.CompletedProcess:
    if not p.returncode:
        return p

    _logger.info("rebase failed at %s\nstdout:\n%s\nstderr:\n%s", p.args, p.stdout, p.stderr)
    raise MergeError(p.stderr or 'merge conflict')


@dataclasses.dataclass
class GitCommand:
    repo: Repo
    name: str

    def __call__(self, *args, **kwargs) -> subprocess.CompletedProcess:
        return self.repo._run(self.name, *args, *self._to_options(kwargs))

    def _to_options(self, d):
        for k, v in d.items():
            if len(k) == 1:
                yield '-' + k
            else:
                yield '--' + k.replace('_', '-')
            if v not in (None, True):
                assert v is not False
                yield str(v)