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Added LevelDB-based attribute container store
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,272 @@ | ||
| # -*- coding: utf-8 -*- | ||
| """LevelDB-based attribute container store.""" | ||
|
|
||
| import ast | ||
| import json | ||
| import os | ||
|
|
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| import leveldb # pylint: disable=import-error | ||
|
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| from acstore import interface | ||
| from acstore.containers import interface as containers_interface | ||
| from acstore.helpers import json_serializer | ||
|
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|
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| class LevelDBAttributeContainerStore( | ||
| interface.AttributeContainerStoreWithReadCache): | ||
| """LevelDB-based attribute container store. | ||
| Attributes: | ||
| format_version (int): storage format version. | ||
| serialization_format (str): serialization format. | ||
| """ | ||
|
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||
| _FORMAT_VERSION = 20230312 | ||
|
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| def __init__(self): | ||
| """Initializes a LevelDB attribute container store.""" | ||
| super(LevelDBAttributeContainerStore, self).__init__() | ||
| self._is_open = False | ||
| self._json_serializer = json_serializer.AttributeContainerJSONSerializer | ||
| self._leveldb_database = None | ||
|
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| self.format_version = self._FORMAT_VERSION | ||
| self.serialization_format = 'json' | ||
|
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| def _GetNumberOfAttributeContainerKeys(self, container_type): | ||
| """Retrieves the number of attribute container keys. | ||
| Args: | ||
| container_type (str): attribute container type. | ||
| Returns: | ||
| int: the number of keys of a specified attribute container type. | ||
| """ | ||
| first_key = f'{container_type:s}.1'.encode('utf8') | ||
|
|
||
| try: | ||
| # Check if the first key exists otherwise RangeIter will return all keys. | ||
| self._leveldb_database.Get(first_key) | ||
| except KeyError: | ||
| return 0 | ||
|
|
||
| return sum(1 for _ in self._leveldb_database.RangeIter(key_from=first_key)) | ||
|
|
||
| def _RaiseIfNotReadable(self): | ||
| """Raises if the attribute container store is not readable. | ||
| Raises: | ||
| IOError: when the attribute container store is closed. | ||
| OSError: when the attribute container store is closed. | ||
| """ | ||
| if not self._is_open: | ||
| raise IOError('Unable to read from closed attribute container store.') | ||
|
|
||
| def _RaiseIfNotWritable(self): | ||
| """Raises if the attribute container store is not writable. | ||
| Raises: | ||
| IOError: when the attribute container store is closed or read-only. | ||
| OSError: when the attribute container store is closed or read-only. | ||
| """ | ||
| if not self._is_open: | ||
| raise IOError('Unable to write to closed attribute container store.') | ||
|
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||
| def _WriteExistingAttributeContainer(self, container): | ||
| """Writes an existing attribute container to the store. | ||
| Args: | ||
| container (AttributeContainer): attribute container. | ||
| """ | ||
| identifier = container.GetIdentifier() | ||
|
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| key = identifier.CopyToString().encode('utf8') | ||
|
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| self._leveldb_database.Delete(key) | ||
|
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| json_dict = self._json_serializer.ConvertAttributeContainerToJSON(container) | ||
| json_string = json.dumps(json_dict) | ||
| value = json_string.encode('utf8') | ||
|
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| self._leveldb_database.Put(key=key, value=value) | ||
|
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| def _WriteNewAttributeContainer(self, container): | ||
| """Writes a new attribute container to the store. | ||
| Args: | ||
| container (AttributeContainer): attribute container. | ||
| """ | ||
| next_sequence_number = self._GetAttributeContainerNextSequenceNumber( | ||
| container.CONTAINER_TYPE) | ||
|
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| identifier = containers_interface.AttributeContainerIdentifier( | ||
| name=container.CONTAINER_TYPE, sequence_number=next_sequence_number) | ||
| container.SetIdentifier(identifier) | ||
|
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| key = identifier.CopyToString().encode('utf8') | ||
|
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| json_dict = self._json_serializer.ConvertAttributeContainerToJSON(container) | ||
| json_string = json.dumps(json_dict) | ||
| value = json_string.encode('utf8') | ||
|
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| self._leveldb_database.Put(key=key, value=value) | ||
|
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| self._CacheAttributeContainerByIndex(container, next_sequence_number - 1) | ||
|
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| def Close(self): | ||
| """Closes the file. | ||
| Raises: | ||
| IOError: if the attribute container store is already closed. | ||
| OSError: if the attribute container store is already closed. | ||
| """ | ||
| if not self._is_open: | ||
| raise IOError('Attribute container store already closed.') | ||
|
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| self._leveldb_database = None | ||
|
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| self._is_open = False | ||
|
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| def GetAttributeContainerByIdentifier(self, container_type, identifier): | ||
| """Retrieves a specific type of container with a specific identifier. | ||
| Args: | ||
| container_type (str): container type. | ||
| identifier (AttributeContainerIdentifier): attribute container identifier. | ||
| Returns: | ||
| AttributeContainer: attribute container or None if not available. | ||
| """ | ||
| key = identifier.CopyToString().encode('utf8') | ||
|
|
||
| try: | ||
| value = self._leveldb_database.Get(key) | ||
| except KeyError: | ||
| return None | ||
|
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| json_string = value.decode('utf8') | ||
| json_dict = json.loads(json_string) | ||
|
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| container = self._json_serializer.ConvertJSONToAttributeContainer(json_dict) | ||
| container.SetIdentifier(identifier) | ||
| return container | ||
|
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| def GetAttributeContainerByIndex(self, container_type, index): | ||
| """Retrieves a specific attribute container. | ||
| Args: | ||
| container_type (str): attribute container type. | ||
| index (int): attribute container index. | ||
| Returns: | ||
| AttributeContainer: attribute container or None if not available. | ||
| """ | ||
| identifier = containers_interface.AttributeContainerIdentifier( | ||
| name=container_type, sequence_number=index + 1) | ||
|
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| key = identifier.CopyToString().encode('utf8') | ||
|
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| try: | ||
| value = self._leveldb_database.Get(key) | ||
| except KeyError: | ||
| return None | ||
|
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| json_string = value.decode('utf8') | ||
| json_dict = json.loads(json_string) | ||
|
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| container = self._json_serializer.ConvertJSONToAttributeContainer(json_dict) | ||
| container.SetIdentifier(identifier) | ||
| return container | ||
|
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| def GetAttributeContainers(self, container_type, filter_expression=None): | ||
| """Retrieves a specific type of attribute containers. | ||
| Args: | ||
| container_type (str): attribute container type. | ||
| filter_expression (Optional[str]): expression to filter the resulting | ||
| attribute containers by. | ||
| Yields: | ||
| AttributeContainer: attribute container. | ||
| """ | ||
| last_key_index = self._attribute_container_sequence_numbers[container_type] | ||
|
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| first_key = f'{container_type:s}.1'.encode('utf8') | ||
| last_key = f'{container_type:s}.{last_key_index:d}'.encode('utf8') | ||
|
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| if filter_expression: | ||
| expression_ast = ast.parse(filter_expression, mode='eval') | ||
| filter_expression = compile(expression_ast, '<string>', mode='eval') | ||
|
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| for key, value in self._leveldb_database.RangeIter( | ||
| key_from=first_key, key_to=last_key): | ||
| json_string = value.decode('utf8') | ||
| json_dict = json.loads(json_string) | ||
|
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||
| container = self._json_serializer.ConvertJSONToAttributeContainer( | ||
| json_dict) | ||
| if container.MatchesExpression(filter_expression): | ||
| key = key.decode('utf8') | ||
| identifier = containers_interface.AttributeContainerIdentifier() | ||
| identifier.CopyFromString(key) | ||
|
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| container.SetIdentifier(identifier) | ||
| yield container | ||
|
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||
| def GetNumberOfAttributeContainers(self, container_type): | ||
| """Retrieves the number of a specific type of attribute containers. | ||
| Args: | ||
| container_type (str): attribute container type. | ||
| Returns: | ||
| int: the number of containers of a specified type. | ||
| """ | ||
| return self._attribute_container_sequence_numbers[container_type] | ||
|
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||
| def HasAttributeContainers(self, container_type): | ||
| """Determines if a store contains a specific type of attribute container. | ||
| Args: | ||
| container_type (str): attribute container type. | ||
| Returns: | ||
| bool: True if the store contains the specified type of attribute | ||
| containers. | ||
| """ | ||
| return self._attribute_container_sequence_numbers[container_type] > 0 | ||
|
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||
| def Open(self, path=None, **unused_kwargs): # pylint: disable=arguments-differ | ||
| """Opens the store. | ||
| Args: | ||
| path (Optional[str]): path to the attribute container store. | ||
| Raises: | ||
| IOError: if the attribute container store is already opened or if | ||
| the database cannot be connected. | ||
| OSError: if the attribute container store is already opened or if | ||
| the database cannot be connected. | ||
| ValueError: if path is missing. | ||
| """ | ||
| if self._is_open: | ||
| raise IOError('Attribute container store already opened.') | ||
|
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| if not path: | ||
| raise ValueError('Missing path.') | ||
|
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| path = os.path.abspath(path) | ||
|
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| self._leveldb_database = leveldb.LevelDB(path) | ||
|
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| self._is_open = True | ||
|
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| # TODO: read metadata. | ||
|
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| # Initialize next_sequence_number based on the file contents so that | ||
| # AttributeContainerIdentifier points to the correct attribute container. | ||
| for container_type in self._containers_manager.GetContainerTypes(): | ||
| next_sequence_number = self._GetNumberOfAttributeContainerKeys( | ||
| container_type) | ||
| self._SetAttributeContainerNextSequenceNumber( | ||
| container_type, next_sequence_number) |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1 +1,2 @@ | ||
| PyYAML >= 3.10 | ||
| leveldb @ git+https://github.com/joachimmetz/py-leveldb.git@0.202 |
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