diff --git a/swh/storage/vault/cookers/revision_git.py b/swh/storage/vault/cookers/revision_git.py index f366ee1..6fbb935 100644 --- a/swh/storage/vault/cookers/revision_git.py +++ b/swh/storage/vault/cookers/revision_git.py @@ -1,171 +1,204 @@ # Copyright (C) 2017 The Software Heritage developers # See the AUTHORS file at the top-level directory of this distribution # License: GNU General Public License version 3, or any later version # See top-level LICENSE file for more information import collections import fastimport.commands import functools import logging import os from .base import BaseVaultCooker class RevisionGitCooker(BaseVaultCooker): """Cooker to create a git fast-import bundle """ CACHE_TYPE_KEY = 'revision_git' def prepare_bundle(self): commands = self.fastexport(self.storage.revision_log([self.obj_id])) bundle_content = b'\n'.join(bytes(command) for command in commands) return bundle_content def fastexport(self, log): """Generate all the git fast-import commands from a given log. """ self.rev_by_id = {r['id']: r for r in log} self.rev_sorted = list(self._toposort(self.rev_by_id)) - self.dir_by_id = {} self.obj_done = set() self.obj_to_mark = {} self.next_available_mark = 1 + # We want a single transaction for the whole export, so we store a + # cursor and use it during the process. with self.storage.db.transaction() as self.cursor: for i, rev in enumerate(self.rev_sorted, 1): logging.info('Computing revision %d/%d', i, len(self.rev_sorted)) yield from self._compute_commit_command(rev) def _toposort(self, rev_by_id): """Perform a topological sort on the revision graph. """ - children = collections.defaultdict(list) - in_degree = collections.defaultdict(int) - for rev_id, rev in rev_by_id.items(): - for parent in rev['parents']: - in_degree[rev_id] += 1 - children[parent].append(rev_id) + children = collections.defaultdict(list) # rev -> children + in_degree = {} # rev -> numbers of parents left to compute + # Compute the in_degrees and the parents of all the revisions. + # Add the roots to the processing queue. queue = collections.deque() - for rev_id in rev_by_id.keys(): - if in_degree[rev_id] == 0: + for rev_id, rev in rev_by_id.items(): + in_degree[rev_id] = len(rev['parents']) + if not rev['parents']: queue.append(rev_id) + for parent in rev['parents']: + children[parent].append(rev_id) + # Topological sort: yield the 'ready' nodes, decrease the in degree of + # their children and add the 'ready' ones to the queue. while queue: rev_id = queue.popleft() yield rev_by_id[rev_id] for child in children[rev_id]: in_degree[child] -= 1 if in_degree[child] == 0: queue.append(child) def mark(self, obj_id): """Get the mark ID as bytes of a git object. If the object has not yet been marked, assign a new ID and add it to the mark dictionary. """ if obj_id not in self.obj_to_mark: self.obj_to_mark[obj_id] = self.next_available_mark self.next_available_mark += 1 return str(self.obj_to_mark[obj_id]).encode() def _compute_blob_command_content(self, file_data): """Compute the blob command of a file entry if it has not been computed yet. """ obj_id = file_data['sha1'] if obj_id in self.obj_done: return content = list(self.storage.content_get([obj_id]))[0]['data'] yield fastimport.commands.BlobCommand( mark=self.mark(obj_id), data=content, ) self.obj_done.add(obj_id) def _compute_commit_command(self, rev): """Compute a commit command from a specific revision. """ if 'parents' in rev and rev['parents']: from_ = b':' + self.mark(rev['parents'][0]) merges = [b':' + self.mark(r) for r in rev['parents'][1:]] parent = self.rev_by_id[rev['parents'][0]] else: + # We issue a reset command before all the new roots so that they + # are not automatically added as children of the current branch. yield fastimport.commands.ResetCommand(b'refs/heads/master', None) from_ = None merges = None parent = None + + # Retrieve the file commands while yielding new blob commands if + # needed. files = yield from self._compute_file_commands(rev, parent) + + # Construct and yield the commit command author = (rev['author']['name'], rev['author']['email'], rev['date']['timestamp']['seconds'], rev['date']['offset'] * 60) committer = (rev['committer']['name'], rev['committer']['email'], rev['committer_date']['timestamp']['seconds'], rev['committer_date']['offset'] * 60) yield fastimport.commands.CommitCommand( ref=b'refs/heads/master', mark=self.mark(rev['id']), author=author, committer=committer, message=rev['message'], from_=from_, merges=merges, file_iter=files, ) @functools.lru_cache(maxsize=4096) def _get_dir_ents(self, dir_id=None): + """Get the entities of a directory as a dictionary (name -> entity). + + This function has a cache to avoid doing multiple requests to retrieve + the same entities, as doing a directory_ls() is expensive. + """ data = (self.storage.directory_ls(dir_id, cur=self.cursor) if dir_id is not None else []) return {f['name']: f for f in data} def _compute_file_commands(self, rev, parent=None): """Compute all the file commands of a revision. Generate a diff of the files between the revision and its main parent to find the necessary file commands to apply. """ commands = [] + # Initialize the stack with the root of the tree. cur_dir = rev['directory'] parent_dir = parent['directory'] if parent else None + stack = [(b'', cur_dir, parent_dir)] - queue = collections.deque() # base path, rev dir id, parent dir id - queue.append((b'', cur_dir, parent_dir)) - - while queue: - root, cur_dir_id, prev_dir_id = queue.pop() + while stack: + # Retrieve the current directory and the directory of the parent + # commit in order to compute the diff of the trees. + root, cur_dir_id, prev_dir_id = stack.pop() cur_dir = self._get_dir_ents(cur_dir_id) prev_dir = self._get_dir_ents(prev_dir_id) + # Find subtrees to delete: + # - Subtrees that are not in the new tree (file or directory + # deleted). + # - Subtrees that do not have the same type in the new tree + # (file -> directory or directory -> file) + # After this step, every node remaining in the previous directory + # has the same type than the one in the current directory. for fname, f in prev_dir.items(): if ((fname not in cur_dir or f['type'] != cur_dir[fname]['type'])): commands.append(fastimport.commands.FileDeleteCommand( path=os.path.join(root, fname) )) + # Find subtrees to modify: + # - Leaves (files) will be added or modified using `filemodify` + # - Other subtrees (directories) will be added to the stack and + # processed in the next iteration. for fname, f in cur_dir.items(): + # A file is added or modified if it was not in the tree, if its + # permissions changed or if its content changed. if (f['type'] == 'file' and (fname not in prev_dir or f['sha1'] != prev_dir[fname]['sha1'] or f['perms'] != prev_dir[fname]['perms'])): + # Issue a blob command for the new blobs if needed. yield from self._compute_blob_command_content(f) commands.append(fastimport.commands.FileModifyCommand( path=os.path.join(root, fname), mode=f['perms'], dataref=(b':' + self.mark(f['sha1'])), data=None, )) + # A directory is added or modified if it was not in the tree or + # if its target changed. elif f['type'] == 'dir': f_prev_target = None if fname in prev_dir and prev_dir[fname]['type'] == 'dir': f_prev_target = prev_dir[fname]['target'] - queue.append((os.path.join(root, fname), - f['target'], f_prev_target)) - + if f_prev_target is None or f['target'] != f_prev_target: + stack.append((os.path.join(root, fname), + f['target'], f_prev_target)) return commands