diff options
Diffstat (limited to 'Lib/dbm/dumb.py')
| -rw-r--r-- | Lib/dbm/dumb.py | 32 |
1 files changed, 29 insertions, 3 deletions
diff --git a/Lib/dbm/dumb.py b/Lib/dbm/dumb.py index def120ffc37..1bc239a84ff 100644 --- a/Lib/dbm/dumb.py +++ b/Lib/dbm/dumb.py @@ -9,7 +9,7 @@ XXX TO DO: - seems to contain a bug when updating... - reclaim free space (currently, space once occupied by deleted or expanded -items is never reused) +items is not reused exept if .reorganize() is called) - support concurrent access (currently, if two processes take turns making updates, they can mess up the index) @@ -17,8 +17,6 @@ updates, they can mess up the index) - support efficient access to large databases (currently, the whole index is read when the database is opened, and some updates rewrite the whole index) -- support opening for read-only (flag = 'm') - """ import ast as _ast @@ -289,6 +287,34 @@ class _Database(collections.abc.MutableMapping): def __exit__(self, *args): self.close() + def reorganize(self): + if self._readonly: + raise error('The database is opened for reading only') + self._verify_open() + # Ensure all changes are committed before reorganizing. + self._commit() + # Open file in r+ to allow changing in-place. + with _io.open(self._datfile, 'rb+') as f: + reorganize_pos = 0 + + # Iterate over existing keys, sorted by starting byte. + for key in sorted(self._index, key = lambda k: self._index[k][0]): + pos, siz = self._index[key] + f.seek(pos) + val = f.read(siz) + + f.seek(reorganize_pos) + f.write(val) + self._index[key] = (reorganize_pos, siz) + + blocks_occupied = (siz + _BLOCKSIZE - 1) // _BLOCKSIZE + reorganize_pos += blocks_occupied * _BLOCKSIZE + + f.truncate(reorganize_pos) + # Commit changes to index, which were not in-place. + self._commit() + + def open(file, flag='c', mode=0o666): """Open the database file, filename, and return corresponding object. |