Updates from orm branch (#36)

* improve sessions

* improve tests

dictdatabase/models.py

@@ -1,7 +1,7 @@
 from __future__ import annotations
 from typing import TypeVar, Any, Callable
 from . import utils, io_safe, config
-from . session import DDBSession
+from . sessions import SessionFileFull, SessionFileKey, SessionFileWhere, SessionDirFull, SessionDirWhere
 
 T = TypeVar("T")
 
@@ -200,7 +200,7 @@ def type_cast(value):
 		return type_cast(data)
 
 
-	def session(self, as_type: T = None) -> DDBSession[T]:
+	def session(self, as_type: T = None) -> SessionFileFull[T] | SessionFileKey[T] | SessionFileWhere[T] | SessionDirFull[T] | SessionDirWhere[T]:
 		"""
 		Opens a session to the selected file(s) or folder, depending on previous
 		`.at(...)` selection. Inside the with block, you have exclusive access
@@ -215,4 +215,13 @@ def session(self, as_type: T = None) -> DDBSession[T]:
 		- `FileNotFoundError`: If the file does not exist.
 		- `KeyError`: If a key is specified and it does not exist.
 		"""
-		return DDBSession(self.path, self.op_type, self.key, self.where, as_type)
+		if self.op_type.file_normal:
+			return SessionFileFull(self.path, as_type)
+		if self.op_type.file_key:
+			return SessionFileKey(self.path, self.key, as_type)
+		if self.op_type.file_where:
+			return SessionFileWhere(self.path, self.where, as_type)
+		if self.op_type.dir_normal:
+			return SessionDirFull(self.path, as_type)
+		if self.op_type.dir_where:
+			return SessionDirWhere(self.path, self.where, as_type)

dictdatabase/sessions.py

@@ -0,0 +1,211 @@
+from __future__ import annotations
+from typing import Tuple, TypeVar, Generic, Any, Callable
+from . import utils, io_unsafe, locking
+
+from contextlib import contextmanager
+
+
+T = TypeVar("T")
+JSONSerializable = TypeVar("JSONSerializable", str, int, float, bool, None, list, dict)
+
+
+
+def type_cast(obj, as_type):
+	return obj if as_type is None else as_type(obj)
+
+
+
+class SessionBase:
+	in_session: bool
+	db_name: str
+	as_type: T
+
+	def __init__(self, db_name: str, as_type):
+		self.in_session = False
+		self.db_name = db_name
+		self.as_type = as_type
+
+	def __enter__(self):
+		self.in_session = True
+		self.data_handle = {}
+
+	def __exit__(self, type, value, tb):
+		write_lock = getattr(self, "write_lock", None)
+		if write_lock is not None:
+			if isinstance(write_lock, list):
+				for lock in write_lock:
+					lock._unlock()
+			else:
+				write_lock._unlock()
+		self.write_lock, self.in_session = None, False
+
+	def write(self):
+		if not self.in_session:
+			raise PermissionError("Only call write() inside a with statement.")
+
+
+
+@contextmanager
+def safe_context(super, self, *, db_names_to_lock=None):
+	"""
+		If an exception happens in the context, the __exit__ method of the passed super
+		class will be called.
+	"""
+	super.__enter__()
+	try:
+		if isinstance(db_names_to_lock, str):
+			self.write_lock = locking.WriteLock(self.db_name)
+			self.write_lock._lock()
+		elif isinstance(db_names_to_lock, list):
+			self.write_lock = [locking.WriteLock(x) for x in self.db_name]
+			for lock in self.write_lock:
+				lock._lock()
+		yield
+	except BaseException as e:
+		super.__exit__(type(e), e, e.__traceback__)
+		raise e
+
+
+
+########################################################################################
+#### File sessions
+########################################################################################
+
+
+
+class SessionFileFull(SessionBase, Generic[T]):
+	"""
+		Context manager for read-write access to a full file.
+
+		Efficiency:
+		Reads and writes the entire file.
+	"""
+
+	def __enter__(self) -> Tuple[SessionFileFull, JSONSerializable | T]:
+		with safe_context(super(), self, db_names_to_lock=self.db_name):
+			self.data_handle = io_unsafe.read(self.db_name)
+			return self, type_cast(self.data_handle, self.as_type)
+
+	def write(self):
+		super().write()
+		io_unsafe.write(self.db_name, self.data_handle)
+
+
+
+class SessionFileKey(SessionBase, Generic[T]):
+	"""
+		Context manager for read-write access to a single key-value item in a file.
+
+		Efficiency:
+		Uses partial reading, which allows only reading the bytes of the key-value item.
+		When writing, only the bytes of the key-value and the bytes of the file after
+		the key-value are written.
+	"""
+
+	def __init__(self, db_name: str, key: str, as_type: T):
+		super().__init__(db_name, as_type)
+		self.key = key
+
+	def __enter__(self) -> Tuple[SessionFileKey, JSONSerializable | T]:
+		with safe_context(super(), self, db_names_to_lock=self.db_name):
+			self.partial_handle = io_unsafe.get_partial_file_handle(self.db_name, self.key)
+			self.data_handle = self.partial_handle.partial_dict.value
+			return self, type_cast(self.data_handle, self.as_type)
+
+	def write(self):
+		super().write()
+		io_unsafe.partial_write(self.partial_handle)
+
+
+
+class SessionFileWhere(SessionBase, Generic[T]):
+	"""
+		Context manager for read-write access to selection of key-value items in a file.
+		The where callable is called with the key and value of each item in the file.
+
+		Efficiency:
+		Reads and writes the entire file, so it is not more efficient than
+		SessionFileFull.
+	"""
+	def __init__(self, db_name: str, where: Callable[[Any, Any], bool], as_type: T):
+		super().__init__(db_name, as_type)
+		self.where = where
+
+	def __enter__(self) -> Tuple[SessionFileWhere, JSONSerializable | T]:
+		with safe_context(super(), self, db_names_to_lock=self.db_name):
+			self.original_data = io_unsafe.read(self.db_name)
+			for k, v in self.original_data.items():
+				if self.where(k, v):
+					self.data_handle[k] = v
+			return self, type_cast(self.data_handle, self.as_type)
+
+	def write(self):
+		super().write()
+		self.original_data.update(self.data_handle)
+		io_unsafe.write(self.db_name, self.original_data)
+
+
+
+########################################################################################
+#### File sessions
+########################################################################################
+
+
+
+class SessionDirFull(SessionBase, Generic[T]):
+	"""
+		Context manager for read-write access to all files in a directory.
+		They are provided as a dict of {str(file_name): dict(file_content)}, where the
+		file name does not contain the directory name nor the file extension.
+
+		Efficiency:
+		Fully reads and writes all files.
+	"""
+	def __init__(self, db_name: str, as_type: T):
+		super().__init__(utils.find_all(db_name), as_type)
+
+	def __enter__(self) -> Tuple[SessionDirFull, JSONSerializable | T]:
+		with safe_context(super(), self, db_names_to_lock=self.db_name):
+			self.data_handle = {n.split("/")[-1]: io_unsafe.read(n) for n in self.db_name}
+			return self, type_cast(self.data_handle, self.as_type)
+
+	def write(self):
+		super().write()
+		for name in self.db_name:
+			io_unsafe.write(name, self.data_handle[name.split("/")[-1]])
+
+
+
+class SessionDirWhere(SessionBase, Generic[T]):
+	"""
+		Context manager for read-write access to selection of files in a directory.
+		The where callable is called with the file name and parsed content of each file.
+
+		Efficiency:
+		Fully reads all files, but only writes the selected files.
+	"""
+	def __init__(self, db_name: str, where: Callable[[Any, Any], bool], as_type: T):
+		super().__init__(utils.find_all(db_name), as_type)
+		self.where = where
+
+	def __enter__(self) -> Tuple[SessionDirWhere, JSONSerializable | T]:
+		with safe_context(super(), self):
+			selected_db_names, write_lock = [], []
+			for db_name in self.db_name:
+				lock = locking.WriteLock(db_name)
+				lock._lock()
+				k, v = db_name.split("/")[-1], io_unsafe.read(db_name)
+				if self.where(k, v):
+					self.data_handle[k] = v
+					write_lock.append(lock)
+					selected_db_names.append(db_name)
+				else:
+					lock._unlock()
+			self.write_lock = write_lock
+			self.db_name = selected_db_names
+			return self, type_cast(self.data_handle, self.as_type)
+
+	def write(self):
+		super().write()
+		for name in self.db_name:
+			io_unsafe.write(name, self.data_handle[name.split("/")[-1]])

tests/conftest.py

@@ -2,15 +2,23 @@
 from tests import TEST_DIR
 import pytest
 import shutil
+import os
 
 
 @pytest.fixture(scope="session")
 def use_test_dir(request):
 	DDB.config.storage_directory = TEST_DIR
+	os.makedirs(TEST_DIR, exist_ok=True)
 	request.addfinalizer(lambda: shutil.rmtree(TEST_DIR))
 
 
 
+@pytest.fixture(scope="function")
+def name_of_test(request):
+	return request.function.__name__
+
+
+
 @pytest.fixture(params=[True, False])
 def use_compression(request):
 	DDB.config.use_compression = request.param