# (Be in -*- python -*- mode.) # # ==================================================================== # Copyright (c) 2006-2008 CollabNet. All rights reserved. # # This software is licensed as described in the file COPYING, which # you should have received as part of this distribution. The terms # are also available at http://subversion.tigris.org/license-1.html. # If newer versions of this license are posted there, you may use a # newer version instead, at your option. # # This software consists of voluntary contributions made by many # individuals. For exact contribution history, see the revision # history and logs, available at http://cvs2svn.tigris.org/. # ==================================================================== """The changeset dependency graph.""" import heapq from cvs2svn_lib.log import logger from cvs2svn_lib.changeset import RevisionChangeset from cvs2svn_lib.changeset import OrderedChangeset from cvs2svn_lib.changeset import BranchChangeset from cvs2svn_lib.changeset import TagChangeset class CycleInGraphException(Exception): def __init__(self, cycle): Exception.__init__( self, 'Cycle found in graph: %s' % ' -> '.join(map(str, cycle + [cycle[0]]))) class NoPredNodeInGraphException(Exception): def __init__(self, node): Exception.__init__(self, 'Node %s has no predecessors' % (node,)) class _NoPredNodes(object): """Manage changesets that are ready to be processed. Output the changesets in order by time and changeset type.""" def __init__(self, changeset_db, initial_nodes): """Initialize. INITIAL_NODES is an iterable over node to add to this object on initialization.""" self.changeset_db = changeset_db # A heapified list of (node.time_range, changeset, node) tuples # that have no predecessors. These tuples sort in the desired # commit order: self._nodes = [ (node.time_range, self.changeset_db[node.id], node) for node in initial_nodes ] heapq.heapify(self._nodes) def __len__(self): return len(self._nodes) def add(self, node): node = (node.time_range, self.changeset_db[node.id], node) heapq.heappush(self._nodes, node) def get(self): """Return (node, changeset,) of the next node to be committed. 'Smallest' is defined by the ordering of the tuples in self._nodes; namely, the changeset with the earliest time_range, with ties broken by comparing the changesets themselves.""" (time_range, changeset, node) = heapq.heappop(self._nodes) return (node, changeset) class ChangesetGraph(object): """A graph of changesets and their dependencies.""" def __init__(self, changeset_db, cvs_item_to_changeset_id): self._changeset_db = changeset_db self._cvs_item_to_changeset_id = cvs_item_to_changeset_id # A map { id : ChangesetGraphNode } self.nodes = {} def close(self): self._cvs_item_to_changeset_id.close() self._cvs_item_to_changeset_id = None self._changeset_db.close() self._changeset_db = None def add_changeset(self, changeset): """Add CHANGESET to this graph. Determine and record any dependencies to changesets that are already in the graph. This method does not affect the databases.""" node = changeset.create_graph_node(self._cvs_item_to_changeset_id) # Now tie the node into our graph. If a changeset referenced by # node is already in our graph, then add the backwards connection # from the other node to the new one. If not, then delete the # changeset from node. for pred_id in list(node.pred_ids): pred_node = self.nodes.get(pred_id) if pred_node is not None: pred_node.succ_ids.add(node.id) else: node.pred_ids.remove(pred_id) for succ_id in list(node.succ_ids): succ_node = self.nodes.get(succ_id) if succ_node is not None: succ_node.pred_ids.add(node.id) else: node.succ_ids.remove(succ_id) self.nodes[node.id] = node def store_changeset(self, changeset): for cvs_item_id in changeset.cvs_item_ids: self._cvs_item_to_changeset_id[cvs_item_id] = changeset.id self._changeset_db.store(changeset) def add_new_changeset(self, changeset): """Add the new CHANGESET to the graph and also to the databases.""" if logger.is_on(logger.DEBUG): logger.debug('Adding changeset %r' % (changeset,)) self.add_changeset(changeset) self.store_changeset(changeset) def delete_changeset(self, changeset): """Remove CHANGESET from the graph and also from the databases. In fact, we don't remove CHANGESET from self._cvs_item_to_changeset_id, because in practice the CVSItems in CHANGESET are always added again as part of a new CHANGESET, which will cause the old values to be overwritten.""" if logger.is_on(logger.DEBUG): logger.debug('Removing changeset %r' % (changeset,)) del self[changeset.id] del self._changeset_db[changeset.id] def __nonzero__(self): """Instances are considered True iff they contain any nodes.""" return bool(self.nodes) def __contains__(self, id): """Return True if the specified ID is contained in this graph.""" return id in self.nodes def __getitem__(self, id): return self.nodes[id] def get(self, id): return self.nodes.get(id) def __delitem__(self, id): """Remove the node corresponding to ID. Also remove references to it from other nodes. This method does not change pred_ids or succ_ids of the node being deleted, nor does it affect the databases.""" node = self[id] for succ_id in node.succ_ids: succ = self[succ_id] succ.pred_ids.remove(node.id) for pred_id in node.pred_ids: pred = self[pred_id] pred.succ_ids.remove(node.id) del self.nodes[node.id] def keys(self): return self.nodes.keys() def __iter__(self): return self.nodes.itervalues() def _get_path(self, reachable_changesets, starting_node_id, ending_node_id): """Return the shortest path from ENDING_NODE_ID to STARTING_NODE_ID. Find a path from ENDING_NODE_ID to STARTING_NODE_ID in REACHABLE_CHANGESETS, where STARTING_NODE_ID is the id of a changeset that depends on the changeset with ENDING_NODE_ID. (See the comment in search_for_path() for a description of the format of REACHABLE_CHANGESETS.) Return a list of changesets, where the 0th one has ENDING_NODE_ID and the last one has STARTING_NODE_ID. If there is no such path described in in REACHABLE_CHANGESETS, return None.""" if ending_node_id not in reachable_changesets: return None path = [self._changeset_db[ending_node_id]] id = reachable_changesets[ending_node_id][1] while id != starting_node_id: path.append(self._changeset_db[id]) id = reachable_changesets[id][1] path.append(self._changeset_db[starting_node_id]) return path def search_for_path(self, starting_node_id, stop_set): """Search for paths to prerequisites of STARTING_NODE_ID. Try to find the shortest dependency path that causes the changeset with STARTING_NODE_ID to depend (directly or indirectly) on one of the changesets whose ids are contained in STOP_SET. We consider direct and indirect dependencies in the sense that the changeset can be reached by following a chain of predecessor nodes. When one of the changeset_ids in STOP_SET is found, terminate the search and return the path from that changeset_id to STARTING_NODE_ID. If no path is found to a node in STOP_SET, return None.""" # A map {node_id : (steps, next_node_id)} where NODE_ID can be # reached from STARTING_NODE_ID in STEPS steps, and NEXT_NODE_ID # is the id of the previous node in the path. STARTING_NODE_ID is # only included as a key if there is a loop leading back to it. reachable_changesets = {} # A list of (node_id, steps) that still have to be investigated, # and STEPS is the number of steps to get to NODE_ID. open_nodes = [(starting_node_id, 0)] # A breadth-first search: while open_nodes: (id, steps) = open_nodes.pop(0) steps += 1 node = self[id] for pred_id in node.pred_ids: # Since the search is breadth-first, we only have to set steps # that don't already exist. if pred_id not in reachable_changesets: reachable_changesets[pred_id] = (steps, id) open_nodes.append((pred_id, steps)) # See if we can stop now: if pred_id in stop_set: return self._get_path( reachable_changesets, starting_node_id, pred_id ) return None def consume_nopred_nodes(self): """Remove and yield changesets in dependency order. Each iteration, this generator yields a (changeset, time_range) tuple for the oldest changeset in the graph that doesn't have any predecessor nodes (i.e., it is ready to be committed). This is continued until there are no more nodes without predecessors (either because the graph has been emptied, or because of cycles in the graph). Among the changesets that are ready to be processed, the earliest one (according to the sorting of the TimeRange class) is yielded each time. (This is the order in which the changesets should be committed.) The graph should not be otherwise altered while this generator is running.""" # Find a list of (node,changeset,) where the node has no # predecessors: nopred_nodes = _NoPredNodes( self._changeset_db, ( node for node in self.nodes.itervalues() if not node.pred_ids ), ) while nopred_nodes: (node, changeset,) = nopred_nodes.get() del self[node.id] # See if any successors are now ready for extraction: for succ_id in node.succ_ids: succ = self[succ_id] if not succ.pred_ids: nopred_nodes.add(succ) yield (changeset, node.time_range) def find_cycle(self, starting_node_id): """Find a cycle in the dependency graph and return it. Use STARTING_NODE_ID as the place to start looking. This routine must only be called after all nopred_nodes have been removed. Return the list of changesets that are involved in the cycle (ordered such that cycle[n-1] is a predecessor of cycle[n] and cycle[-1] is a predecessor of cycle[0]).""" # Since there are no nopred nodes in the graph, all nodes in the # graph must either be involved in a cycle or depend (directly or # indirectly) on nodes that are in a cycle. # Pick an arbitrary node: node = self[starting_node_id] seen_nodes = [node] # Follow it backwards until a node is seen a second time; then we # have our cycle. while True: # Pick an arbitrary predecessor of node. It must exist, because # there are no nopred nodes: try: node_id = node.pred_ids.__iter__().next() except StopIteration: raise NoPredNodeInGraphException(node) node = self[node_id] try: i = seen_nodes.index(node) except ValueError: seen_nodes.append(node) else: seen_nodes = seen_nodes[i:] seen_nodes.reverse() return [self._changeset_db[node.id] for node in seen_nodes] def consume_graph(self, cycle_breaker=None): """Remove and yield changesets from this graph in dependency order. Each iteration, this generator yields a (changeset, time_range) tuple for the oldest changeset in the graph that doesn't have any predecessor nodes. If CYCLE_BREAKER is specified, then call CYCLE_BREAKER(cycle) whenever a cycle is encountered, where cycle is the list of changesets that are involved in the cycle (ordered such that cycle[n-1] is a predecessor of cycle[n] and cycle[-1] is a predecessor of cycle[0]). CYCLE_BREAKER should break the cycle in place then return. If a cycle is found and CYCLE_BREAKER was not specified, raise CycleInGraphException.""" while True: for (changeset, time_range) in self.consume_nopred_nodes(): yield (changeset, time_range) # If there are any nodes left in the graph, then there must be # at least one cycle. Find a cycle and process it. # This might raise StopIteration, but that indicates that the # graph has been fully consumed, so we just let the exception # escape. start_node_id = self.nodes.iterkeys().next() cycle = self.find_cycle(start_node_id) if cycle_breaker is not None: cycle_breaker(cycle) else: raise CycleInGraphException(cycle) def __repr__(self): """For convenience only. The format is subject to change at any time.""" if self.nodes: return 'ChangesetGraph:\n%s' \ % ''.join([' %r\n' % node for node in self]) else: return 'ChangesetGraph:\n EMPTY\n' node_colors = { RevisionChangeset : 'lightgreen', OrderedChangeset : 'cyan', BranchChangeset : 'orange', TagChangeset : 'yellow', } def output_coarse_dot(self, f): """Output the graph in DOT format to file-like object f. Such a file can be rendered into a visual representation of the graph using tools like graphviz. Include only changesets in the graph, and the dependencies between changesets.""" f.write('digraph G {\n') for node in self: f.write( ' C%x [style=filled, fillcolor=%s];\n' % ( node.id, self.node_colors[self._changeset_db[node.id].__class__], ) ) f.write('\n') for node in self: for succ_id in node.succ_ids: f.write(' C%x -> C%x\n' % (node.id, succ_id,)) f.write('\n') f.write('}\n') def output_fine_dot(self, f): """Output the graph in DOT format to file-like object f. Such a file can be rendered into a visual representation of the graph using tools like graphviz. Include all CVSItems and the CVSItem-CVSItem dependencies in the graph. Group the CVSItems into clusters by changeset.""" f.write('digraph G {\n') for node in self: f.write(' subgraph cluster_%x {\n' % (node.id,)) f.write(' label = "C%x";\n' % (node.id,)) changeset = self._changeset_db[node.id] for item_id in changeset.cvs_item_ids: f.write(' I%x;\n' % (item_id,)) f.write(' style=filled;\n') f.write( ' fillcolor=%s;\n' % (self.node_colors[self._changeset_db[node.id].__class__],)) f.write(' }\n\n') for node in self: changeset = self._changeset_db[node.id] for cvs_item in changeset.iter_cvs_items(): for succ_id in cvs_item.get_succ_ids(): f.write(' I%x -> I%x;\n' % (cvs_item.id, succ_id,)) f.write('\n') f.write('}\n')