from configparser import RawConfigParser from binascii import hexlify from itertools import islice import errno import os import shutil import struct import sys from zlib import crc32 from .hashindex import NSIndex from .helpers import Error, IntegrityError, read_msgpack, write_msgpack, unhexlify, UpgradableLock from .lrucache import LRUCache MAX_OBJECT_SIZE = 20 * 1024 * 1024 MAGIC = b'BORG_SEG' TAG_PUT = 0 TAG_DELETE = 1 TAG_COMMIT = 2 class Repository: """Filesystem based transactional key value store On disk layout: dir/README dir/config dir/data// dir/index.X dir/hints.X """ DEFAULT_MAX_SEGMENT_SIZE = 5 * 1024 * 1024 DEFAULT_SEGMENTS_PER_DIR = 10000 class DoesNotExist(Error): """Repository {} does not exist.""" class AlreadyExists(Error): """Repository {} already exists.""" class InvalidRepository(Error): """{} is not a valid repository.""" class CheckNeeded(Error): """Inconsistency detected. Please run "borg check {}".""" class ObjectNotFound(Error): """Object with key {} not found in repository {}.""" def __init__(self, path, create=False, exclusive=False): self.path = path self.io = None self.lock = None self.index = None self._active_txn = False if create: self.create(path) self.open(path, exclusive) def __del__(self): self.close() def create(self, path): """Create a new empty repository at `path` """ if os.path.exists(path) and (not os.path.isdir(path) or os.listdir(path)): raise self.AlreadyExists(path) if not os.path.exists(path): os.mkdir(path) with open(os.path.join(path, 'README'), 'w') as fd: fd.write('This is a Borg repository\n') os.mkdir(os.path.join(path, 'data')) config = RawConfigParser() config.add_section('repository') config.set('repository', 'version', '1') config.set('repository', 'segments_per_dir', self.DEFAULT_SEGMENTS_PER_DIR) config.set('repository', 'max_segment_size', self.DEFAULT_MAX_SEGMENT_SIZE) config.set('repository', 'id', hexlify(os.urandom(32)).decode('ascii')) with open(os.path.join(path, 'config'), 'w') as fd: config.write(fd) def destroy(self): """Destroy the repository at `self.path` """ self.close() os.remove(os.path.join(self.path, 'config')) # kill config first shutil.rmtree(self.path) def get_index_transaction_id(self): indices = sorted((int(name[6:]) for name in os.listdir(self.path) if name.startswith('index.') and name[6:].isdigit())) if indices: return indices[-1] else: return None def get_transaction_id(self): index_transaction_id = self.get_index_transaction_id() segments_transaction_id = self.io.get_segments_transaction_id() if index_transaction_id is not None and segments_transaction_id is None: raise self.CheckNeeded(self.path) # Attempt to automatically rebuild index if we crashed between commit # tag write and index save if index_transaction_id != segments_transaction_id: if index_transaction_id is not None and index_transaction_id > segments_transaction_id: replay_from = None else: replay_from = index_transaction_id self.replay_segments(replay_from, segments_transaction_id) return self.get_index_transaction_id() def open(self, path, exclusive): self.path = path if not os.path.isdir(path): raise self.DoesNotExist(path) self.config = RawConfigParser() self.config.read(os.path.join(self.path, 'config')) if 'repository' not in self.config.sections() or self.config.getint('repository', 'version') != 1: raise self.InvalidRepository(path) self.lock = UpgradableLock(os.path.join(path, 'config'), exclusive) self.max_segment_size = self.config.getint('repository', 'max_segment_size') self.segments_per_dir = self.config.getint('repository', 'segments_per_dir') self.id = unhexlify(self.config.get('repository', 'id').strip()) self.io = LoggedIO(self.path, self.max_segment_size, self.segments_per_dir) def close(self): if self.lock: if self.io: self.io.close() self.io = None self.lock.release() self.lock = None def commit(self): """Commit transaction """ self.io.write_commit() self.compact_segments() self.write_index() self.rollback() def open_index(self, transaction_id): if transaction_id is None: return NSIndex() return NSIndex.read((os.path.join(self.path, 'index.%d') % transaction_id).encode('utf-8')) def prepare_txn(self, transaction_id, do_cleanup=True): self._active_txn = True self.lock.upgrade() if not self.index: self.index = self.open_index(transaction_id) if transaction_id is None: self.segments = {} self.compact = set() else: if do_cleanup: self.io.cleanup(transaction_id) hints = read_msgpack(os.path.join(self.path, 'hints.%d' % transaction_id)) if hints[b'version'] != 1: raise ValueError('Unknown hints file version: %d' % hints['version']) self.segments = hints[b'segments'] self.compact = set(hints[b'compact']) def write_index(self): hints = {b'version': 1, b'segments': self.segments, b'compact': list(self.compact)} transaction_id = self.io.get_segments_transaction_id() write_msgpack(os.path.join(self.path, 'hints.%d' % transaction_id), hints) self.index.write(os.path.join(self.path, 'index.tmp')) os.rename(os.path.join(self.path, 'index.tmp'), os.path.join(self.path, 'index.%d' % transaction_id)) # Remove old indices current = '.%d' % transaction_id for name in os.listdir(self.path): if not name.startswith('index.') and not name.startswith('hints.'): continue if name.endswith(current): continue os.unlink(os.path.join(self.path, name)) self.index = None def compact_segments(self): """Compact sparse segments by copying data into new segments """ if not self.compact: return index_transaction_id = self.get_index_transaction_id() segments = self.segments for segment in sorted(self.compact): if self.io.segment_exists(segment): for tag, key, offset, data in self.io.iter_objects(segment, include_data=True): if tag == TAG_PUT and self.index.get(key, (-1, -1)) == (segment, offset): new_segment, offset = self.io.write_put(key, data) self.index[key] = new_segment, offset segments.setdefault(new_segment, 0) segments[new_segment] += 1 segments[segment] -= 1 elif tag == TAG_DELETE: if index_transaction_id is None or segment > index_transaction_id: self.io.write_delete(key) assert segments[segment] == 0 self.io.write_commit() for segment in sorted(self.compact): assert self.segments.pop(segment) == 0 self.io.delete_segment(segment) self.compact = set() def replay_segments(self, index_transaction_id, segments_transaction_id): self.prepare_txn(index_transaction_id, do_cleanup=False) for segment, filename in self.io.segment_iterator(): if index_transaction_id is not None and segment <= index_transaction_id: continue if segment > segments_transaction_id: break self.segments[segment] = 0 for tag, key, offset in self.io.iter_objects(segment): if tag == TAG_PUT: try: s, _ = self.index[key] self.compact.add(s) self.segments[s] -= 1 except KeyError: pass self.index[key] = segment, offset self.segments[segment] += 1 elif tag == TAG_DELETE: try: s, _ = self.index.pop(key) self.segments[s] -= 1 self.compact.add(s) except KeyError: pass self.compact.add(segment) elif tag == TAG_COMMIT: continue else: raise self.CheckNeeded(self.path) if self.segments[segment] == 0: self.compact.add(segment) self.write_index() self.rollback() def check(self, repair=False): """Check repository consistency This method verifies all segment checksums and makes sure the index is consistent with the data stored in the segments. """ error_found = False def report_error(msg): nonlocal error_found error_found = True print(msg, file=sys.stderr) assert not self._active_txn try: transaction_id = self.get_transaction_id() current_index = self.open_index(transaction_id) except Exception: transaction_id = self.io.get_segments_transaction_id() current_index = None if transaction_id is None: transaction_id = self.get_index_transaction_id() if transaction_id is None: transaction_id = self.io.get_latest_segment() if repair: self.io.cleanup(transaction_id) segments_transaction_id = self.io.get_segments_transaction_id() self.prepare_txn(None) for segment, filename in self.io.segment_iterator(): if segment > transaction_id: continue try: objects = list(self.io.iter_objects(segment)) except (IntegrityError, struct.error): report_error('Error reading segment {}'.format(segment)) objects = [] if repair: self.io.recover_segment(segment, filename) objects = list(self.io.iter_objects(segment)) self.segments[segment] = 0 for tag, key, offset in objects: if tag == TAG_PUT: try: s, _ = self.index[key] self.compact.add(s) self.segments[s] -= 1 except KeyError: pass self.index[key] = segment, offset self.segments[segment] += 1 elif tag == TAG_DELETE: try: s, _ = self.index.pop(key) self.segments[s] -= 1 self.compact.add(s) except KeyError: pass self.compact.add(segment) elif tag == TAG_COMMIT: continue else: report_error('Unexpected tag {} in segment {}'.format(tag, segment)) # We might need to add a commit tag if no committed segment is found if repair and segments_transaction_id is None: report_error('Adding commit tag to segment {}'.format(transaction_id)) self.io.segment = transaction_id + 1 self.io.write_commit() self.io.close_segment() if current_index and not repair: if len(current_index) != len(self.index): report_error('Index object count mismatch. {} != {}'.format(len(current_index), len(self.index))) elif current_index: for key, value in self.index.iteritems(): if current_index.get(key, (-1, -1)) != value: report_error('Index mismatch for key {}. {} != {}'.format(key, value, current_index.get(key, (-1, -1)))) if repair: self.compact_segments() self.write_index() self.rollback() return not error_found or repair def rollback(self): """ """ self.index = None self._active_txn = False def __len__(self): if not self.index: self.index = self.open_index(self.get_transaction_id()) return len(self.index) def list(self, limit=None, marker=None): if not self.index: self.index = self.open_index(self.get_transaction_id()) return [id_ for id_, _ in islice(self.index.iteritems(marker=marker), limit)] def get(self, id_): if not self.index: self.index = self.open_index(self.get_transaction_id()) try: segment, offset = self.index[id_] return self.io.read(segment, offset, id_) except KeyError: raise self.ObjectNotFound(id_, self.path) def get_many(self, ids, is_preloaded=False): for id_ in ids: yield self.get(id_) def put(self, id, data, wait=True): if not self._active_txn: self.prepare_txn(self.get_transaction_id()) try: segment, _ = self.index[id] self.segments[segment] -= 1 self.compact.add(segment) segment = self.io.write_delete(id) self.segments.setdefault(segment, 0) self.compact.add(segment) except KeyError: pass segment, offset = self.io.write_put(id, data) self.segments.setdefault(segment, 0) self.segments[segment] += 1 self.index[id] = segment, offset def delete(self, id, wait=True): if not self._active_txn: self.prepare_txn(self.get_transaction_id()) try: segment, offset = self.index.pop(id) except KeyError: raise self.ObjectNotFound(id, self.path) self.segments[segment] -= 1 self.compact.add(segment) segment = self.io.write_delete(id) self.compact.add(segment) self.segments.setdefault(segment, 0) def preload(self, ids): """Preload objects (only applies to remote repositories """ class LoggedIO: header_fmt = struct.Struct(' transaction_id: os.unlink(filename) else: break def is_committed_segment(self, filename): """Check if segment ends with a COMMIT_TAG tag """ with open(filename, 'rb') as fd: try: fd.seek(-self.header_fmt.size, os.SEEK_END) except OSError as e: # return False if segment file is empty or too small if e.errno == errno.EINVAL: return False raise e return fd.read(self.header_fmt.size) == self.COMMIT def segment_filename(self, segment): return os.path.join(self.path, 'data', str(segment // self.segments_per_dir), str(segment)) def get_write_fd(self, no_new=False): if not no_new and self.offset and self.offset > self.limit: self.close_segment() if not self._write_fd: if self.segment % self.segments_per_dir == 0: dirname = os.path.join(self.path, 'data', str(self.segment // self.segments_per_dir)) if not os.path.exists(dirname): os.mkdir(dirname) self._write_fd = open(self.segment_filename(self.segment), 'ab') self._write_fd.write(MAGIC) self.offset = 8 return self._write_fd def get_fd(self, segment): try: return self.fds[segment] except KeyError: fd = open(self.segment_filename(segment), 'rb') self.fds[segment] = fd return fd def delete_segment(self, segment): try: os.unlink(self.segment_filename(segment)) except OSError: pass def segment_exists(self, segment): return os.path.exists(self.segment_filename(segment)) def iter_objects(self, segment, include_data=False): fd = self.get_fd(segment) fd.seek(0) if fd.read(8) != MAGIC: raise IntegrityError('Invalid segment header') offset = 8 header = fd.read(self.header_fmt.size) while header: crc, size, tag = self.header_fmt.unpack(header) if size > MAX_OBJECT_SIZE: raise IntegrityError('Invalid segment object size') rest = fd.read(size - self.header_fmt.size) if crc32(rest, crc32(memoryview(header)[4:])) & 0xffffffff != crc: raise IntegrityError('Segment checksum mismatch') if tag not in (TAG_PUT, TAG_DELETE, TAG_COMMIT): raise IntegrityError('Invalid segment entry header') key = None if tag in (TAG_PUT, TAG_DELETE): key = rest[:32] if include_data: yield tag, key, offset, rest[32:] else: yield tag, key, offset offset += size header = fd.read(self.header_fmt.size) def recover_segment(self, segment, filename): self.fds.pop(segment).close() # FIXME: save a copy of the original file with open(filename, 'rb') as fd: data = memoryview(fd.read()) os.rename(filename, filename + '.beforerecover') print('attempting to recover ' + filename, file=sys.stderr) with open(filename, 'wb') as fd: fd.write(MAGIC) while len(data) >= self.header_fmt.size: crc, size, tag = self.header_fmt.unpack(data[:self.header_fmt.size]) if size < self.header_fmt.size or size > len(data): data = data[1:] continue if crc32(data[4:size]) & 0xffffffff != crc: data = data[1:] continue fd.write(data[:size]) data = data[size:] def read(self, segment, offset, id): if segment == self.segment and self._write_fd: self._write_fd.flush() fd = self.get_fd(segment) fd.seek(offset) header = fd.read(self.put_header_fmt.size) crc, size, tag, key = self.put_header_fmt.unpack(header) if size > MAX_OBJECT_SIZE: raise IntegrityError('Invalid segment object size') data = fd.read(size - self.put_header_fmt.size) if crc32(data, crc32(memoryview(header)[4:])) & 0xffffffff != crc: raise IntegrityError('Segment checksum mismatch') if tag != TAG_PUT or id != key: raise IntegrityError('Invalid segment entry header') return data def write_put(self, id, data): size = len(data) + self.put_header_fmt.size fd = self.get_write_fd() offset = self.offset header = self.header_no_crc_fmt.pack(size, TAG_PUT) crc = self.crc_fmt.pack(crc32(data, crc32(id, crc32(header))) & 0xffffffff) fd.write(b''.join((crc, header, id, data))) self.offset += size return self.segment, offset def write_delete(self, id): fd = self.get_write_fd() header = self.header_no_crc_fmt.pack(self.put_header_fmt.size, TAG_DELETE) crc = self.crc_fmt.pack(crc32(id, crc32(header)) & 0xffffffff) fd.write(b''.join((crc, header, id))) self.offset += self.put_header_fmt.size return self.segment def write_commit(self): fd = self.get_write_fd(no_new=True) header = self.header_no_crc_fmt.pack(self.header_fmt.size, TAG_COMMIT) crc = self.crc_fmt.pack(crc32(header) & 0xffffffff) fd.write(b''.join((crc, header))) self.close_segment() def close_segment(self): if self._write_fd: self.segment += 1 self.offset = 0 self._write_fd.flush() os.fsync(self._write_fd.fileno()) if hasattr(os, 'posix_fadvise'): # python >= 3.3, only on UNIX # tell the OS that it does not need to cache what we just wrote, # avoids spoiling the cache for the OS and other processes. os.posix_fadvise(self._write_fd.fileno(), 0, 0, os.POSIX_FADV_DONTNEED) self._write_fd.close() self._write_fd = None