Neil Booth
8 years ago
6 changed files with 209 additions and 34 deletions
@ -1 +1,2 @@ |
|||
Neil Booth: creator and maintainer |
|||
Johann Bauer: backend DB abstraction |
|||
@ -0,0 +1,152 @@ |
|||
import os |
|||
|
|||
|
|||
class Storage(object): |
|||
def __init__(self, name, create_if_missing=False, error_if_exists=False, compression=None): |
|||
if not create_if_missing and not os.path.exists(name): |
|||
raise NoDatabaseException |
|||
|
|||
def get(self, key): |
|||
raise NotImplementedError() |
|||
|
|||
def put(self, key, value): |
|||
raise NotImplementedError() |
|||
|
|||
def write_batch(self): |
|||
""" |
|||
Returns a context manager that provides `put` and `delete`. |
|||
Changes should only be committed when the context manager closes without an exception. |
|||
""" |
|||
raise NotImplementedError() |
|||
|
|||
def iterator(self, prefix=b""): |
|||
""" |
|||
Returns an iterator that yields (key, value) pairs from the database sorted by key. |
|||
If `prefix` is set, only keys starting with `prefix` will be included. |
|||
""" |
|||
raise NotImplementedError() |
|||
|
|||
|
|||
class NoDatabaseException(Exception): |
|||
pass |
|||
|
|||
|
|||
class LevelDB(Storage): |
|||
def __init__(self, name, create_if_missing=False, error_if_exists=False, compression=None): |
|||
super().__init__(name, create_if_missing, error_if_exists, compression) |
|||
import plyvel |
|||
self.db = plyvel.DB(name, create_if_missing=create_if_missing, |
|||
error_if_exists=error_if_exists, compression=compression) |
|||
|
|||
def get(self, key): |
|||
return self.db.get(key) |
|||
|
|||
def write_batch(self): |
|||
return self.db.write_batch(transaction=True) |
|||
|
|||
def iterator(self, prefix=b""): |
|||
return self.db.iterator(prefix=prefix) |
|||
|
|||
def put(self, key, value): |
|||
self.db.put(key, value) |
|||
|
|||
|
|||
class RocksDB(Storage): |
|||
rocksdb = None |
|||
|
|||
def __init__(self, name, create_if_missing=False, error_if_exists=False, compression=None): |
|||
super().__init__(name, create_if_missing, error_if_exists, compression) |
|||
import rocksdb |
|||
RocksDB.rocksdb = rocksdb |
|||
if not compression: |
|||
compression = "no" |
|||
compression = getattr(rocksdb.CompressionType, compression + "_compression") |
|||
self.db = rocksdb.DB(name, rocksdb.Options(create_if_missing=create_if_missing, |
|||
compression=compression, |
|||
target_file_size_base=33554432, |
|||
max_open_files=1024)) |
|||
|
|||
def get(self, key): |
|||
return self.db.get(key) |
|||
|
|||
class WriteBatch(object): |
|||
def __init__(self, db): |
|||
self.batch = RocksDB.rocksdb.WriteBatch() |
|||
self.db = db |
|||
|
|||
def __enter__(self): |
|||
return self.batch |
|||
|
|||
def __exit__(self, exc_type, exc_val, exc_tb): |
|||
if not exc_val: |
|||
self.db.write(self.batch) |
|||
|
|||
def write_batch(self): |
|||
return RocksDB.WriteBatch(self.db) |
|||
|
|||
class Iterator(object): |
|||
def __init__(self, db, prefix): |
|||
self.it = db.iteritems() |
|||
self.prefix = prefix |
|||
|
|||
def __iter__(self): |
|||
self.it.seek(self.prefix) |
|||
return self |
|||
|
|||
def __next__(self): |
|||
k, v = self.it.__next__() |
|||
if not k.startswith(self.prefix): |
|||
# We're already ahead of the prefix |
|||
raise StopIteration |
|||
return k, v |
|||
|
|||
def iterator(self, prefix=b""): |
|||
return RocksDB.Iterator(self.db, prefix) |
|||
|
|||
def put(self, key, value): |
|||
return self.db.put(key, value) |
|||
|
|||
|
|||
class LMDB(Storage): |
|||
lmdb = None |
|||
|
|||
def __init__(self, name, create_if_missing=False, error_if_exists=False, compression=None): |
|||
super().__init__(name, create_if_missing, error_if_exists, compression) |
|||
import lmdb |
|||
LMDB.lmdb = lmdb |
|||
self.env = lmdb.Environment(".", subdir=True, create=create_if_missing, max_dbs=32, map_size=5 * 10 ** 10) |
|||
self.db = self.env.open_db(create=create_if_missing) |
|||
|
|||
def get(self, key): |
|||
with self.env.begin(db=self.db) as tx: |
|||
return tx.get(key) |
|||
|
|||
def put(self, key, value): |
|||
with self.env.begin(db=self.db, write=True) as tx: |
|||
tx.put(key, value) |
|||
|
|||
def write_batch(self): |
|||
return self.env.begin(db=self.db, write=True) |
|||
|
|||
def iterator(self, prefix=b""): |
|||
return LMDB.lmdb.Iterator(self.db, self.env, prefix) |
|||
|
|||
class Iterator: |
|||
def __init__(self, db, env, prefix): |
|||
self.transaction = env.begin(db=db) |
|||
self.transaction.__enter__() |
|||
self.db = db |
|||
self.prefix = prefix |
|||
|
|||
def __iter__(self): |
|||
self.iterator = LMDB.lmdb.Cursor(self.db, self.transaction) |
|||
self.iterator.set_range(self.prefix) |
|||
return self |
|||
|
|||
def __next__(self): |
|||
k, v = self.iterator.item() |
|||
if not k.startswith(self.prefix) or not self.iterator.next(): |
|||
# We're already ahead of the prefix |
|||
self.transaction.__exit__() |
|||
raise StopIteration |
|||
return k, v |
|||
Loading…
Reference in new issue