import re import subprocess import pygit2 from git_deps.utils import abort, standard_logger from git_deps.gitutils import GitUtils from git_deps.listener.base import DependencyListener from git_deps.errors import InvalidCommitish class DependencyDetector(object): """Class for automatically detecting dependencies between git commits. A dependency is inferred by diffing the commit with each of its parents, and for each resulting hunk, performing a blame to see which commit was responsible for introducing the lines to which the hunk was applied. Dependencies can be traversed recursively, building a dependency tree represented (conceptually) by a list of edges. """ def __init__(self, options, repo=None, logger=None): self.options = options if logger is None: self.logger = standard_logger(self.__class__.__name__, options.debug) if repo is None: self.repo = GitUtils.get_repo() else: self.repo = repo # Nested dict mapping dependents -> dependencies -> files # causing that dependency -> numbers of lines within that file # causing that dependency. The first two levels form edges in # the dependency graph, and the latter two tell us what caused # those edges. self.dependencies = {} # A TODO list (queue) and dict of dependencies which haven't # yet been recursively followed. Only useful when recursing. self.todo = [] self.todo_d = {} # An ordered list and dict of commits whose dependencies we # have already detected. self.done = [] self.done_d = {} # A cache mapping SHA1s to commit objects self.commits = {} # Memoization for branch_contains() self.branch_contains_cache = {} # Callbacks to be invoked when a new dependency has been # discovered. self.listeners = [] def add_listener(self, listener): if not isinstance(listener, DependencyListener): raise RuntimeError("Listener must be a DependencyListener") self.listeners.append(listener) listener.set_detector(self) def notify_listeners(self, event, *args): for listener in self.listeners: fn = getattr(listener, event) fn(*args) def seen_commit(self, rev): return rev in self.commits def get_commit(self, rev): if rev in self.commits: return self.commits[rev] self.commits[rev] = GitUtils.ref_commit(self.repo, rev) return self.commits[rev] def find_dependencies(self, dependent_rev, recurse=None): """Find all dependencies of the given revision, recursively traversing the dependency tree if requested. """ if recurse is None: recurse = self.options.recurse try: dependent = self.get_commit(dependent_rev) except InvalidCommitish as e: abort(e.message()) self.todo.append(dependent) self.todo_d[dependent.hex] = True first_time = True while self.todo: sha1s = [commit.hex[:8] for commit in self.todo] if first_time: self.logger.debug("Initial TODO list: %s" % " ".join(sha1s)) first_time = False else: self.logger.debug(" TODO list now: %s" % " ".join(sha1s)) dependent = self.todo.pop(0) dependent_sha1 = dependent.hex del self.todo_d[dependent_sha1] self.logger.debug(" Processing %s from TODO list" % dependent_sha1[:8]) if dependent_sha1 in self.done_d: self.logger.debug(" %s already done previously" % dependent_sha1) continue self.notify_listeners('new_commit', dependent) for parent in dependent.parents: self.find_dependencies_with_parent(dependent, parent) self.done.append(dependent_sha1) self.done_d[dependent_sha1] = True self.logger.debug(" Found all dependencies for %s" % dependent_sha1[:8]) # A commit won't have any dependencies if it only added new files dependencies = self.dependencies.get(dependent_sha1, {}) self.notify_listeners('dependent_done', dependent, dependencies) self.logger.debug("Finished processing TODO list") self.notify_listeners('all_done') def find_dependencies_with_parent(self, dependent, parent): """Find all dependencies of the given revision caused by the given parent commit. This will be called multiple times for merge commits which have multiple parents. """ self.logger.debug(" Finding dependencies of %s via parent %s" % (dependent.hex[:8], parent.hex[:8])) diff = self.repo.diff(parent, dependent, context_lines=self.options.context_lines) for patch in diff: path = patch.delta.old_file.path self.logger.debug(" Examining hunks in %s" % path) for hunk in patch.hunks: self.blame_hunk(dependent, parent, path, hunk) def blame_hunk(self, dependent, parent, path, hunk): """Run git blame on the parts of the hunk which exist in the older commit in the diff. The commits generated by git blame are the commits which the newer commit in the diff depends on, because without the lines from those commits, the hunk would not apply correctly. """ line_range_before = "-%d,%d" % (hunk.old_start, hunk.old_lines) line_range_after = "+%d,%d" % (hunk.new_start, hunk.new_lines) self.logger.debug(" Blaming hunk %s @ %s" % (line_range_before, parent.hex[:8])) if not self.tree_lookup(path, parent): # This is probably because dependent added a new directory # which was not previously in the parent. return cmd = [ 'git', 'blame', '--porcelain', '-L', "%d,+%d" % (hunk.old_start, hunk.old_lines), parent.hex, '--', path ] blame = subprocess.check_output(cmd, universal_newlines=True) dependent_sha1 = dependent.hex if dependent_sha1 not in self.dependencies: self.logger.debug(" New dependent: %s" % GitUtils.commit_summary(dependent)) self.dependencies[dependent_sha1] = {} self.notify_listeners("new_dependent", dependent) line_to_culprit = {} for line in blame.split('\n'): self.logger.debug(" !" + line.rstrip()) m = re.match('^([0-9a-f]{40}) (\d+) (\d+)( \d+)?$', line) if not m: continue dependency_sha1, orig_line_num, line_num = m.group(1, 2, 3) line_num = int(line_num) dependency = self.get_commit(dependency_sha1) line_to_culprit[line_num] = dependency.hex if self.is_excluded(dependency): self.logger.debug( " Excluding dependency %s from line %s (%s)" % (dependency_sha1[:8], line_num, GitUtils.oneline(dependency))) continue if dependency_sha1 not in self.dependencies[dependent_sha1]: if not self.seen_commit(dependency): self.notify_listeners("new_commit", dependency) self.dependencies[dependent_sha1][dependency_sha1] = {} self.notify_listeners("new_dependency", dependent, dependency, path, line_num) self.logger.debug( " New dependency %s -> %s via line %s (%s)" % (dependent_sha1[:8], dependency_sha1[:8], line_num, GitUtils.oneline(dependency))) if dependency_sha1 in self.todo_d: self.logger.debug( " Dependency on %s via line %s already in TODO" % (dependency_sha1[:8], line_num,)) continue if dependency_sha1 in self.done_d: self.logger.debug( " Dependency on %s via line %s already done" % (dependency_sha1[:8], line_num,)) continue if dependency_sha1 not in self.dependencies: if self.options.recurse: self.todo.append(dependency) self.todo_d[dependency.hex] = True self.logger.debug(" + Added %s to TODO" % dependency.hex[:8]) dep_sources = self.dependencies[dependent_sha1][dependency_sha1] if path not in dep_sources: dep_sources[path] = {} self.notify_listeners('new_path', dependent, dependency, path, line_num) if line_num in dep_sources[path]: abort("line %d already found when blaming %s:%s\n" "old:\n %s\n" "new:\n %s" % (line_num, parent.hex[:8], path, dep_sources[path][line_num], line)) dep_sources[path][line_num] = line self.logger.debug(" New line for %s -> %s: %s" % (dependent_sha1[:8], dependency_sha1[:8], line)) self.notify_listeners('new_line', dependent, dependency, path, line_num) diff_format = ' |%8.8s %5s %s%s' hunk_header = '@@ %s %s @@' % (line_range_before, line_range_after) self.logger.debug(diff_format % ('--------', '-----', '', hunk_header)) line_num = hunk.old_start for line in hunk.lines: if "\n\\ No newline at end of file" == line.content.rstrip(): break if line.origin == '+': rev = ln = '' else: rev = line_to_culprit[line_num] ln = line_num line_num += 1 self.logger.debug(diff_format % (rev, ln, line.origin, line.content.rstrip())) def is_excluded(self, commit): if self.options.exclude_commits is not None: for exclude in self.options.exclude_commits: if self.branch_contains(commit, exclude): return True return False def branch_contains(self, commit, branch): sha1 = commit.hex branch_commit = self.get_commit(branch) branch_sha1 = branch_commit.hex self.logger.debug(" Does %s (%s) contain %s?" % (branch, branch_sha1[:8], sha1[:8])) if sha1 not in self.branch_contains_cache: self.branch_contains_cache[sha1] = {} if branch_sha1 in self.branch_contains_cache[sha1]: memoized = self.branch_contains_cache[sha1][branch_sha1] self.logger.debug(" %s (memoized)" % memoized) return memoized cmd = ['git', 'merge-base', sha1, branch_sha1] # self.logger.debug(" ".join(cmd)) out = subprocess.check_output(cmd, universal_newlines=True).strip() self.logger.debug(" merge-base returned: %s" % out[:8]) result = out == sha1 self.logger.debug(" %s" % result) self.branch_contains_cache[sha1][branch_sha1] = result return result def tree_lookup(self, target_path, commit): """Navigate to the tree or blob object pointed to by the given target path for the given commit. This is necessary because each git tree only contains entries for the directory it refers to, not recursively for all subdirectories. """ segments = target_path.split("/") tree_or_blob = commit.tree path = '' while segments: dirent = segments.pop(0) if isinstance(tree_or_blob, pygit2.Tree): if dirent in tree_or_blob: tree_or_blob = self.repo[tree_or_blob[dirent].oid] # self.logger.debug(" %s in %s" % (dirent, path)) if path: path += '/' path += dirent else: # This is probably because we were called on a # commit whose parent added a new directory. self.logger.debug(" %s not in %s in %s" % (dirent, path, commit.hex[:8])) return None else: self.logger.debug(" %s not a tree in %s" % (tree_or_blob, commit.hex[:8])) return None return tree_or_blob def edges(self): return [ [(dependent, dependency) for dependency in self.dependencies[dependent]] for dependent in self.dependencies.keys() ]