Source code for

Defines a class storing data on the file system using the hierarchical data
format (hdf).

.. codeauthor:: David Zwicker <> 

from __future__ import annotations

import json
import logging
from pathlib import Path
from typing import Any, Optional, Tuple  # @UnusedImport

import numpy as np

from ..fields.base import FieldBase
from import ensure_directory_exists, hdf_write_attributes
from .base import InfoDict, StorageBase

[docs]class FileStorage(StorageBase): """store discretized fields in a hdf5 file""" def __init__( self, filename: str, info: InfoDict = None, write_mode: str = "truncate_once", max_length: Optional[int] = None, compression: bool = True, keep_opened: bool = True, ): """ Args: filename (str): The path to the hdf5-file where the data is stored info (dict): Supplies extra information that is stored in the storage write_mode (str): Determines how new data is added to already existing data. Possible values are: 'append' (data is always appended), 'truncate' (data is cleared every time this storage is used for writing), or 'truncate_once' (data is cleared for the first writing, but appended subsequently). Alternatively, specifying 'readonly' will disable writing completely. max_length (int, optional): Maximal number of entries that will be stored in the file. This can be used to preallocate data, which can lead to smaller files, but is also less flexible. Giving `max_length = None`, allows for arbitrarily large data, which might lead to larger files. compression (bool): Whether to store the data in compressed form. Automatically enabled chunked storage. keep_opened (bool): Flag indicating whether the file should be kept opened after each writing. If `False`, the file will be closed after writing a dataset. This keeps the file in a consistent state, but also requires more work before data can be written. """ super().__init__(info=info, write_mode=write_mode) self.filename = Path(filename) self.compression = compression self.keep_opened = keep_opened self._logger = logging.getLogger(self.__class__.__name__) self._file: Any = None self._is_writing = False self._data_length: int = None # type: ignore self._max_length: Optional[int] = max_length if self.filename.is_file() and self.filename.stat().st_size > 0: try: self._open("reading") except (OSError, KeyError): self.close() self._logger.warning( f"File `{filename}` could not be opened for reading" ) def __del__(self): self.close() # ensure open files are closed when the FileStorage is deleted @property def _file_state(self) -> str: """str: the state that the file is currently in""" if self._file is None: return "closed" elif self._file.mode == "r": return "reading" elif self._file.mode == "r+": return "writing" else: raise NotImplementedError(f"Do not understand mode `{self._file.mode}")
[docs] def close(self) -> None: """close the currently opened file""" if self._file is not None:"Close file `{self.filename}`") self._file.close() self._file = None self._data_length = None # type: ignore
def __enter__(self) -> FileStorage: return self def __exit__(self, type, value, traceback): self.close() def _create_hdf_dataset( self, name: str, shape: Tuple[int, ...] = tuple(), dtype=np.double ): """create a hdf5 dataset with the given name and data_shape Args: name (str): Identifier of the hdf5 dataset shape (tuple): Data shape of the dataset dtype: The data type of the dataset """ if self.compression: kwargs = {"chunks": (1,) + shape, "compression": "gzip"} else: kwargs = {} if self._max_length: shape = (self._max_length,) + shape return self._file.create_dataset(name, shape=shape, dtype=dtype, **kwargs) else: return self._file.create_dataset( name, shape=(0,) + shape, dtype=dtype, maxshape=(None,) + shape, **kwargs, ) def _open(self, mode: str = "reading", info: InfoDict = None) -> None: """open the hdf file in a particular mode Args: mode (str): Determines how the file is opened. Possible values are `reading`, `appending`, `writing`, and `closed`. info (dict): Supplies extra information that is stored in the storage """ import h5py # lazy loading so it's not a hard dependence state = self._file_state if mode == "reading": # open file for reading if state in ["reading", "appending", "writing"]: return # we can read data when file is open for writing # close file to open it again for reading or appending if self._file: self._file.close()"Open file `{self.filename}` for reading") self._file = h5py.File(self.filename, mode="r") self._times = self._file["times"] self._data = self._file["data"] for k, v in self._file.attrs.items():[k] = json.loads(v) if info: self._data_shape =[1:] self._dtype = self._data_length ="data_length") # type: ignore elif mode == "appending": # open file for writing without deleting data if state in ["appending", "writing"]: return # we are already in a mode where we can append data if self.keep_opened and self._is_writing: raise RuntimeError( "Currently writing data, so mode cannot be switched." ) self.close() # open file for reading or appending"Open file `{self.filename}` for appending") self._file = h5py.File(self.filename, mode="a") if "times" in self._file and "data" in self._file: # extract data from datasets in the existing file self._times = self._file["times"] self._data = self._file["data"] # extract information for k, v in self._file.attrs.items():[k] = json.loads(v) self._data_shape =[1:] self._dtype = self._data_length ="data_length",[0]) else: # create new datasets self._times = self._create_hdf_dataset("times") self._data = self._create_hdf_dataset( "data", self.data_shape, dtype=self._dtype ) self._data_length = 0 if info: elif mode == "writing": # open file for writing data; delete potentially present data if self._is_writing: raise RuntimeError("Currently writing data, so mode cannot be switched") if self._file: self.close() else: ensure_directory_exists(self.filename.parent)"Open file `{self.filename}` for writing") self._file = h5py.File(self.filename, "w") self._times = self._create_hdf_dataset("times") self._data = self._create_hdf_dataset( "data", self.data_shape, dtype=self._dtype ) if info: self._data_length = 0 # start writing from the beginning elif mode == "closed": self.close() else: raise RuntimeError(f"Mode `{mode}` not implemented") def __len__(self): """return the number of stored items, i.e., time steps""" # determine size of data in HDF5 file try: length = len(self.times) except OSError: length = 0 if self._data_length is None: return length else: # size of stored data is smaller since preallocation was used return min(length, self._data_length) @property def times(self): """:class:`~numpy.ndarray`: The times at which data is available""" self._open("reading") return self._times @property def data(self): """:class:`~numpy.ndarray`: The actual data for all time""" self._open("reading") return self._data
[docs] def clear(self, clear_data_shape: bool = False): """truncate the storage by removing all stored data. Args: clear_data_shape (bool): Flag determining whether the data shape is also deleted. """ if self._is_writing: # remove data from opened file"Truncate data in hdf5 file") if "times" in self._file: del self._file["times"] self._times = self._create_hdf_dataset("times") if "data" in self._file: del self._file["data"] self._data = self._create_hdf_dataset( "data", self.data_shape, dtype=self.dtype ) self._data_length = 0 # start writing from start elif self.filename.is_file(): # we do not currently write to the file => clear by removing file completely"Truncate data by removing hdf5 file") self._open("closed") # close file if it was opened self.filename.unlink() # remove file else: self._logger.debug("Truncate is no-op since file does not exist") super().clear(clear_data_shape=clear_data_shape)
[docs] def start_writing(self, field: FieldBase, info: InfoDict = None) -> None: """initialize the storage for writing data Args: field (:class:`~pde.fields.FieldBase`): An example of the data that will be written to extract the grid and the data_shape info (dict): Supplies extra information that is stored in the storage """ if self._is_writing: raise RuntimeError(f"{self.__class__.__name__} is already in writing mode") # delete data if truncation is requested. This is for instance necessary # to remove older data with incompatible data_shape if self.write_mode == "truncate" or self.write_mode == "truncate_once": self.clear(clear_data_shape=True) # initialize the writing, setting current data shape super().start_writing(field, info=info) # initialize the file for writing with the correct mode self._logger.debug(f"Start writing with mode `{self.write_mode}`") if self.write_mode == "truncate_once": self._open("writing", info) self.write_mode = "append" # do not truncate for next writing elif self.write_mode == "truncate": self._open("writing", info) elif self.write_mode == "append": self._open("appending", info) elif self.write_mode == "readonly": raise RuntimeError("Cannot write in read-only mode") else: raise ValueError( f"Unknown write mode `{self.write_mode}`. Possible values are " "`truncate_once`, `truncate`, and `append`" ) if not self.keep_opened: # store extra information as attributes hdf_write_attributes(self._file, self._is_writing = True
def _append_data(self, data: np.ndarray, time: float) -> None: """append a new data set Args: data (:class:`~numpy.ndarray`): The actual data time (float): The time point associated with the data """ if self.keep_opened: if not self._is_writing or self._data_length is None: raise RuntimeError( "Writing not initialized. Call " f"`{self.__class__.__name__}.start_writing`" ) else: # need to reopen the file self._open("appending") # write the new data if self._data_length >= len(self._data): self._data.resize((self._data_length + 1,) + self.data_shape) self._data[self._data_length] = data # write the new time if time is None: if len(self._times) == 0: time = 0 else: time = self._times[self._data_length - 1] + 1 if self._data_length >= len(self._times): self._times.resize((self._data_length + 1,)) self._times[self._data_length] = time self._data_length += 1["data_length"] = self._data_length if not self.keep_opened: self.close()
[docs] def end_writing(self) -> None: """finalize the storage after writing. This makes sure the data is actually written to a file when self.keep_opened == False """ if not self._is_writing: return # writing mode was already ended self._logger.debug("End writing") # store extra information as attributes hdf_write_attributes(self._file, self._file.flush() self.close() self._is_writing = False