Source code for astropy.utils.data

# Licensed under a 3-clause BSD style license - see LICENSE.rst

""" This module contains helper functions for accessing, downloading, and
caching data files.
"""

import atexit
import contextlib
import fnmatch
import hashlib
import os
import io
import pathlib
import shutil
import socket
import sys
import time
import urllib.request
import urllib.error
import urllib.parse
import shelve

from tempfile import NamedTemporaryFile, gettempdir
from warnings import warn

from astropy import config as _config
from astropy.utils.exceptions import AstropyWarning
from astropy.utils.introspection import find_current_module, resolve_name

__all__ = [
    'Conf', 'conf', 'get_readable_fileobj', 'get_file_contents',
    'get_pkg_data_fileobj', 'get_pkg_data_filename',
    'get_pkg_data_contents', 'get_pkg_data_fileobjs',
    'get_pkg_data_filenames', 'compute_hash', 'clear_download_cache',
    'CacheMissingWarning', 'get_free_space_in_dir',
    'check_free_space_in_dir', 'download_file',
    'download_files_in_parallel', 'is_url_in_cache', 'get_cached_urls']

_dataurls_to_alias = {}


[docs]class Conf(_config.ConfigNamespace): """ Configuration parameters for `astropy.utils.data`. """ dataurl = _config.ConfigItem( 'http://data.astropy.org/', 'Primary URL for astropy remote data site.') dataurl_mirror = _config.ConfigItem( 'http://www.astropy.org/astropy-data/', 'Mirror URL for astropy remote data site.') remote_timeout = _config.ConfigItem( 10., 'Time to wait for remote data queries (in seconds).', aliases=['astropy.coordinates.name_resolve.name_resolve_timeout']) compute_hash_block_size = _config.ConfigItem( 2 ** 16, # 64K 'Block size for computing MD5 file hashes.') download_block_size = _config.ConfigItem( 2 ** 16, # 64K 'Number of bytes of remote data to download per step.') download_cache_lock_attempts = _config.ConfigItem( 5, 'Number of times to try to get the lock ' + 'while accessing the data cache before giving up.') delete_temporary_downloads_at_exit = _config.ConfigItem( True, 'If True, temporary download files created when the cache is ' 'inaccessible will be deleted at the end of the python session.')
conf = Conf()
[docs]class CacheMissingWarning(AstropyWarning): """ This warning indicates the standard cache directory is not accessible, with the first argument providing the warning message. If args[1] is present, it is a filename indicating the path to a temporary file that was created to store a remote data download in the absence of the cache. """
def _is_url(string): """ Test whether a string is a valid URL Parameters ---------- string : str The string to test """ url = urllib.parse.urlparse(string) # we can't just check that url.scheme is not an empty string, because # file paths in windows would return a non-empty scheme (e.g. e:\\ # returns 'e'). return url.scheme.lower() in ['http', 'https', 'ftp', 'sftp', 'ssh', 'file'] def _is_inside(path, parent_path): # We have to try realpath too to avoid issues with symlinks, but we leave # abspath because some systems like debian have the absolute path (with no # symlinks followed) match, but the real directories in different # locations, so need to try both cases. return os.path.abspath(path).startswith(os.path.abspath(parent_path)) \ or os.path.realpath(path).startswith(os.path.realpath(parent_path))
[docs]@contextlib.contextmanager def get_readable_fileobj(name_or_obj, encoding=None, cache=False, show_progress=True, remote_timeout=None): """ Given a filename, pathlib.Path object or a readable file-like object, return a context manager that yields a readable file-like object. This supports passing filenames, URLs, and readable file-like objects, any of which can be compressed in gzip, bzip2 or lzma (xz) if the appropriate compression libraries are provided by the Python installation. Notes ----- This function is a context manager, and should be used for example as:: with get_readable_fileobj('file.dat') as f: contents = f.read() Parameters ---------- name_or_obj : str or file-like object The filename of the file to access (if given as a string), or the file-like object to access. If a file-like object, it must be opened in binary mode. encoding : str, optional When `None` (default), returns a file-like object with a ``read`` method that returns `str` (``unicode``) objects, using `locale.getpreferredencoding` as an encoding. This matches the default behavior of the built-in `open` when no ``mode`` argument is provided. When ``'binary'``, returns a file-like object where its ``read`` method returns `bytes` objects. When another string, it is the name of an encoding, and the file-like object's ``read`` method will return `str` (``unicode``) objects, decoded from binary using the given encoding. cache : bool, optional Whether to cache the contents of remote URLs. show_progress : bool, optional Whether to display a progress bar if the file is downloaded from a remote server. Default is `True`. remote_timeout : float Timeout for remote requests in seconds (default is the configurable `astropy.utils.data.Conf.remote_timeout`, which is 3s by default) Returns ------- file : readable file-like object """ # close_fds is a list of file handles created by this function # that need to be closed. We don't want to always just close the # returned file handle, because it may simply be the file handle # passed in. In that case it is not the responsibility of this # function to close it: doing so could result in a "double close" # and an "invalid file descriptor" exception. PATH_TYPES = (str, pathlib.Path) close_fds = [] delete_fds = [] if remote_timeout is None: # use configfile default remote_timeout = conf.remote_timeout # Get a file object to the content if isinstance(name_or_obj, PATH_TYPES): # name_or_obj could be a Path object if pathlib is available name_or_obj = str(name_or_obj) is_url = _is_url(name_or_obj) if is_url: name_or_obj = download_file( name_or_obj, cache=cache, show_progress=show_progress, timeout=remote_timeout) fileobj = io.FileIO(name_or_obj, 'r') if is_url and not cache: delete_fds.append(fileobj) close_fds.append(fileobj) else: fileobj = name_or_obj # Check if the file object supports random access, and if not, # then wrap it in a BytesIO buffer. It would be nicer to use a # BufferedReader to avoid reading loading the whole file first, # but that is not compatible with streams or urllib2.urlopen # objects on Python 2.x. if not hasattr(fileobj, 'seek'): fileobj = io.BytesIO(fileobj.read()) # Now read enough bytes to look at signature signature = fileobj.read(4) fileobj.seek(0) if signature[:3] == b'\x1f\x8b\x08': # gzip import struct try: import gzip fileobj_new = gzip.GzipFile(fileobj=fileobj, mode='rb') fileobj_new.read(1) # need to check that the file is really gzip except (OSError, EOFError, struct.error): # invalid gzip file fileobj.seek(0) fileobj_new.close() else: fileobj_new.seek(0) fileobj = fileobj_new elif signature[:3] == b'BZh': # bzip2 try: import bz2 except ImportError: for fd in close_fds: fd.close() raise ValueError( ".bz2 format files are not supported since the Python " "interpreter does not include the bz2 module") try: # bz2.BZ2File does not support file objects, only filenames, so we # need to write the data to a temporary file with NamedTemporaryFile("wb", delete=False) as tmp: tmp.write(fileobj.read()) tmp.close() fileobj_new = bz2.BZ2File(tmp.name, mode='rb') fileobj_new.read(1) # need to check that the file is really bzip2 except OSError: # invalid bzip2 file fileobj.seek(0) fileobj_new.close() # raise else: fileobj_new.seek(0) close_fds.append(fileobj_new) fileobj = fileobj_new elif signature[:3] == b'\xfd7z': # xz try: import lzma fileobj_new = lzma.LZMAFile(fileobj, mode='rb') fileobj_new.read(1) # need to check that the file is really xz except ImportError: for fd in close_fds: fd.close() raise ValueError( ".xz format files are not supported since the Python " "interpreter does not include the lzma module.") except (OSError, EOFError) as e: # invalid xz file fileobj.seek(0) fileobj_new.close() # should we propagate this to the caller to signal bad content? # raise ValueError(e) else: fileobj_new.seek(0) fileobj = fileobj_new # By this point, we have a file, io.FileIO, gzip.GzipFile, bz2.BZ2File # or lzma.LZMAFile instance opened in binary mode (that is, read # returns bytes). Now we need to, if requested, wrap it in a # io.TextIOWrapper so read will return unicode based on the # encoding parameter. needs_textio_wrapper = encoding != 'binary' if needs_textio_wrapper: # A bz2.BZ2File can not be wrapped by a TextIOWrapper, # so we decompress it to a temporary file and then # return a handle to that. try: import bz2 except ImportError: pass else: if isinstance(fileobj, bz2.BZ2File): tmp = NamedTemporaryFile("wb", delete=False) data = fileobj.read() tmp.write(data) tmp.close() delete_fds.append(tmp) fileobj = io.FileIO(tmp.name, 'r') close_fds.append(fileobj) fileobj = io.BufferedReader(fileobj) fileobj = io.TextIOWrapper(fileobj, encoding=encoding) # Ensure that file is at the start - io.FileIO will for # example not always be at the start: # >>> import io # >>> f = open('test.fits', 'rb') # >>> f.read(4) # 'SIMP' # >>> f.seek(0) # >>> fileobj = io.FileIO(f.fileno()) # >>> fileobj.tell() # 4096L fileobj.seek(0) try: yield fileobj finally: for fd in close_fds: fd.close() for fd in delete_fds: os.remove(fd.name)
[docs]def get_file_contents(*args, **kwargs): """ Retrieves the contents of a filename or file-like object. See the `get_readable_fileobj` docstring for details on parameters. Returns ------- content The content of the file (as requested by ``encoding``). """ with get_readable_fileobj(*args, **kwargs) as f: return f.read()
[docs]@contextlib.contextmanager def get_pkg_data_fileobj(data_name, package=None, encoding=None, cache=True): """ Retrieves a data file from the standard locations for the package and provides the file as a file-like object that reads bytes. Parameters ---------- data_name : str Name/location of the desired data file. One of the following: * The name of a data file included in the source distribution. The path is relative to the module calling this function. For example, if calling from ``astropy.pkname``, use ``'data/file.dat'`` to get the file in ``astropy/pkgname/data/file.dat``. Double-dots can be used to go up a level. In the same example, use ``'../data/file.dat'`` to get ``astropy/data/file.dat``. * If a matching local file does not exist, the Astropy data server will be queried for the file. * A hash like that produced by `compute_hash` can be requested, prefixed by 'hash/' e.g. 'hash/34c33b3eb0d56eb9462003af249eff28'. The hash will first be searched for locally, and if not found, the Astropy data server will be queried. package : str, optional If specified, look for a file relative to the given package, rather than the default of looking relative to the calling module's package. encoding : str, optional When `None` (default), returns a file-like object with a ``read`` method returns `str` (``unicode``) objects, using `locale.getpreferredencoding` as an encoding. This matches the default behavior of the built-in `open` when no ``mode`` argument is provided. When ``'binary'``, returns a file-like object where its ``read`` method returns `bytes` objects. When another string, it is the name of an encoding, and the file-like object's ``read`` method will return `str` (``unicode``) objects, decoded from binary using the given encoding. cache : bool If True, the file will be downloaded and saved locally or the already-cached local copy will be accessed. If False, the file-like object will directly access the resource (e.g. if a remote URL is accessed, an object like that from `urllib.request.urlopen` is returned). Returns ------- fileobj : file-like An object with the contents of the data file available via ``read`` function. Can be used as part of a ``with`` statement, automatically closing itself after the ``with`` block. Raises ------ urllib2.URLError, urllib.error.URLError If a remote file cannot be found. OSError If problems occur writing or reading a local file. Examples -------- This will retrieve a data file and its contents for the `astropy.wcs` tests:: >>> from astropy.utils.data import get_pkg_data_fileobj >>> with get_pkg_data_fileobj('data/3d_cd.hdr', ... package='astropy.wcs.tests') as fobj: ... fcontents = fobj.read() ... This next example would download a data file from the astropy data server because the ``allsky/allsky_rosat.fits`` file is not present in the source distribution. It will also save the file locally so the next time it is accessed it won't need to be downloaded.:: >>> from astropy.utils.data import get_pkg_data_fileobj >>> with get_pkg_data_fileobj('allsky/allsky_rosat.fits', ... encoding='binary') as fobj: # doctest: +REMOTE_DATA +IGNORE_OUTPUT ... fcontents = fobj.read() ... Downloading http://data.astropy.org/allsky/allsky_rosat.fits [Done] This does the same thing but does *not* cache it locally:: >>> with get_pkg_data_fileobj('allsky/allsky_rosat.fits', ... encoding='binary', cache=False) as fobj: # doctest: +REMOTE_DATA +IGNORE_OUTPUT ... fcontents = fobj.read() ... Downloading http://data.astropy.org/allsky/allsky_rosat.fits [Done] See Also -------- get_pkg_data_contents : returns the contents of a file or url as a bytes object get_pkg_data_filename : returns a local name for a file containing the data """ datafn = _find_pkg_data_path(data_name, package=package) if os.path.isdir(datafn): raise OSError("Tried to access a data file that's actually " "a package data directory") elif os.path.isfile(datafn): # local file with get_readable_fileobj(datafn, encoding=encoding) as fileobj: yield fileobj else: # remote file all_urls = (conf.dataurl, conf.dataurl_mirror) for url in all_urls: try: with get_readable_fileobj(url + data_name, encoding=encoding, cache=cache) as fileobj: # We read a byte to trigger any URLErrors fileobj.read(1) fileobj.seek(0) yield fileobj break except urllib.error.URLError: pass else: urls = '\n'.join(' - {0}'.format(url) for url in all_urls) raise urllib.error.URLError("Failed to download {0} from the following " "repositories:\n\n{1}".format(data_name, urls))
[docs]def get_pkg_data_filename(data_name, package=None, show_progress=True, remote_timeout=None): """ Retrieves a data file from the standard locations for the package and provides a local filename for the data. This function is similar to `get_pkg_data_fileobj` but returns the file *name* instead of a readable file-like object. This means that this function must always cache remote files locally, unlike `get_pkg_data_fileobj`. Parameters ---------- data_name : str Name/location of the desired data file. One of the following: * The name of a data file included in the source distribution. The path is relative to the module calling this function. For example, if calling from ``astropy.pkname``, use ``'data/file.dat'`` to get the file in ``astropy/pkgname/data/file.dat``. Double-dots can be used to go up a level. In the same example, use ``'../data/file.dat'`` to get ``astropy/data/file.dat``. * If a matching local file does not exist, the Astropy data server will be queried for the file. * A hash like that produced by `compute_hash` can be requested, prefixed by 'hash/' e.g. 'hash/34c33b3eb0d56eb9462003af249eff28'. The hash will first be searched for locally, and if not found, the Astropy data server will be queried. package : str, optional If specified, look for a file relative to the given package, rather than the default of looking relative to the calling module's package. show_progress : bool, optional Whether to display a progress bar if the file is downloaded from a remote server. Default is `True`. remote_timeout : float Timeout for the requests in seconds (default is the configurable `astropy.utils.data.Conf.remote_timeout`, which is 3s by default) Raises ------ urllib2.URLError, urllib.error.URLError If a remote file cannot be found. OSError If problems occur writing or reading a local file. Returns ------- filename : str A file path on the local file system corresponding to the data requested in ``data_name``. Examples -------- This will retrieve the contents of the data file for the `astropy.wcs` tests:: >>> from astropy.utils.data import get_pkg_data_filename >>> fn = get_pkg_data_filename('data/3d_cd.hdr', ... package='astropy.wcs.tests') >>> with open(fn) as f: ... fcontents = f.read() ... This retrieves a data file by hash either locally or from the astropy data server:: >>> from astropy.utils.data import get_pkg_data_filename >>> fn = get_pkg_data_filename('hash/34c33b3eb0d56eb9462003af249eff28') # doctest: +SKIP >>> with open(fn) as f: ... fcontents = f.read() ... See Also -------- get_pkg_data_contents : returns the contents of a file or url as a bytes object get_pkg_data_fileobj : returns a file-like object with the data """ if remote_timeout is None: # use configfile default remote_timeout = conf.remote_timeout if data_name.startswith('hash/'): # first try looking for a local version if a hash is specified hashfn = _find_hash_fn(data_name[5:]) if hashfn is None: all_urls = (conf.dataurl, conf.dataurl_mirror) for url in all_urls: try: return download_file(url + data_name, cache=True, show_progress=show_progress, timeout=remote_timeout) except urllib.error.URLError: pass urls = '\n'.join(' - {0}'.format(url) for url in all_urls) raise urllib.error.URLError("Failed to download {0} from the following " "repositories:\n\n{1}\n\n".format(data_name, urls)) else: return hashfn else: fs_path = os.path.normpath(data_name) datafn = _find_pkg_data_path(fs_path, package=package) if os.path.isdir(datafn): raise OSError("Tried to access a data file that's actually " "a package data directory") elif os.path.isfile(datafn): # local file return datafn else: # remote file all_urls = (conf.dataurl, conf.dataurl_mirror) for url in all_urls: try: return download_file(url + data_name, cache=True, show_progress=show_progress, timeout=remote_timeout) except urllib.error.URLError: pass urls = '\n'.join(' - {0}'.format(url) for url in all_urls) raise urllib.error.URLError("Failed to download {0} from the following " "repositories:\n\n{1}".format(data_name, urls))
[docs]def get_pkg_data_contents(data_name, package=None, encoding=None, cache=True): """ Retrieves a data file from the standard locations and returns its contents as a bytes object. Parameters ---------- data_name : str Name/location of the desired data file. One of the following: * The name of a data file included in the source distribution. The path is relative to the module calling this function. For example, if calling from ``astropy.pkname``, use ``'data/file.dat'`` to get the file in ``astropy/pkgname/data/file.dat``. Double-dots can be used to go up a level. In the same example, use ``'../data/file.dat'`` to get ``astropy/data/file.dat``. * If a matching local file does not exist, the Astropy data server will be queried for the file. * A hash like that produced by `compute_hash` can be requested, prefixed by 'hash/' e.g. 'hash/34c33b3eb0d56eb9462003af249eff28'. The hash will first be searched for locally, and if not found, the Astropy data server will be queried. * A URL to some other file. package : str, optional If specified, look for a file relative to the given package, rather than the default of looking relative to the calling module's package. encoding : str, optional When `None` (default), returns a file-like object with a ``read`` method that returns `str` (``unicode``) objects, using `locale.getpreferredencoding` as an encoding. This matches the default behavior of the built-in `open` when no ``mode`` argument is provided. When ``'binary'``, returns a file-like object where its ``read`` method returns `bytes` objects. When another string, it is the name of an encoding, and the file-like object's ``read`` method will return `str` (``unicode``) objects, decoded from binary using the given encoding. cache : bool If True, the file will be downloaded and saved locally or the already-cached local copy will be accessed. If False, the file-like object will directly access the resource (e.g. if a remote URL is accessed, an object like that from `urllib.request.urlopen` is returned). Returns ------- contents : bytes The complete contents of the file as a bytes object. Raises ------ urllib2.URLError, urllib.error.URLError If a remote file cannot be found. OSError If problems occur writing or reading a local file. See Also -------- get_pkg_data_fileobj : returns a file-like object with the data get_pkg_data_filename : returns a local name for a file containing the data """ with get_pkg_data_fileobj(data_name, package=package, encoding=encoding, cache=cache) as fd: contents = fd.read() return contents
[docs]def get_pkg_data_filenames(datadir, package=None, pattern='*'): """ Returns the path of all of the data files in a given directory that match a given glob pattern. Parameters ---------- datadir : str Name/location of the desired data files. One of the following: * The name of a directory included in the source distribution. The path is relative to the module calling this function. For example, if calling from ``astropy.pkname``, use ``'data'`` to get the files in ``astropy/pkgname/data``. * Remote URLs are not currently supported. package : str, optional If specified, look for a file relative to the given package, rather than the default of looking relative to the calling module's package. pattern : str, optional A UNIX-style filename glob pattern to match files. See the `glob` module in the standard library for more information. By default, matches all files. Returns ------- filenames : iterator of str Paths on the local filesystem in *datadir* matching *pattern*. Examples -------- This will retrieve the contents of the data file for the `astropy.wcs` tests:: >>> from astropy.utils.data import get_pkg_data_filenames >>> for fn in get_pkg_data_filenames('data/maps', 'astropy.wcs.tests', ... '*.hdr'): ... with open(fn) as f: ... fcontents = f.read() ... """ path = _find_pkg_data_path(datadir, package=package) if os.path.isfile(path): raise OSError( "Tried to access a data directory that's actually " "a package data file") elif os.path.isdir(path): for filename in os.listdir(path): if fnmatch.fnmatch(filename, pattern): yield os.path.join(path, filename) else: raise OSError("Path not found")
[docs]def get_pkg_data_fileobjs(datadir, package=None, pattern='*', encoding=None): """ Returns readable file objects for all of the data files in a given directory that match a given glob pattern. Parameters ---------- datadir : str Name/location of the desired data files. One of the following: * The name of a directory included in the source distribution. The path is relative to the module calling this function. For example, if calling from ``astropy.pkname``, use ``'data'`` to get the files in ``astropy/pkgname/data`` * Remote URLs are not currently supported package : str, optional If specified, look for a file relative to the given package, rather than the default of looking relative to the calling module's package. pattern : str, optional A UNIX-style filename glob pattern to match files. See the `glob` module in the standard library for more information. By default, matches all files. encoding : str, optional When `None` (default), returns a file-like object with a ``read`` method that returns `str` (``unicode``) objects, using `locale.getpreferredencoding` as an encoding. This matches the default behavior of the built-in `open` when no ``mode`` argument is provided. When ``'binary'``, returns a file-like object where its ``read`` method returns `bytes` objects. When another string, it is the name of an encoding, and the file-like object's ``read`` method will return `str` (``unicode``) objects, decoded from binary using the given encoding. Returns ------- fileobjs : iterator of file objects File objects for each of the files on the local filesystem in *datadir* matching *pattern*. Examples -------- This will retrieve the contents of the data file for the `astropy.wcs` tests:: >>> from astropy.utils.data import get_pkg_data_filenames >>> for fd in get_pkg_data_fileobjs('data/maps', 'astropy.wcs.tests', ... '*.hdr'): ... fcontents = fd.read() ... """ for fn in get_pkg_data_filenames(datadir, package=package, pattern=pattern): with get_readable_fileobj(fn, encoding=encoding) as fd: yield fd
[docs]def compute_hash(localfn): """ Computes the MD5 hash for a file. The hash for a data file is used for looking up data files in a unique fashion. This is of particular use for tests; a test may require a particular version of a particular file, in which case it can be accessed via hash to get the appropriate version. Typically, if you wish to write a test that requires a particular data file, you will want to submit that file to the astropy data servers, and use e.g. ``get_pkg_data_filename('hash/34c33b3eb0d56eb9462003af249eff28')``, but with the hash for your file in place of the hash in the example. Parameters ---------- localfn : str The path to the file for which the hash should be generated. Returns ------- md5hash : str The hex digest of the MD5 hash for the contents of the ``localfn`` file. """ with open(localfn, 'rb') as f: h = hashlib.md5() block = f.read(conf.compute_hash_block_size) while block: h.update(block) block = f.read(conf.compute_hash_block_size) return h.hexdigest()
def _find_pkg_data_path(data_name, package=None): """ Look for data in the source-included data directories and return the path. """ if package is None: module = find_current_module(1, finddiff=['astropy.utils.data', 'contextlib']) if module is None: # not called from inside an astropy package. So just pass name # through return data_name if not hasattr(module, '__package__') or not module.__package__: # The __package__ attribute may be missing or set to None; see # PEP-366, also astropy issue #1256 if '.' in module.__name__: package = module.__name__.rpartition('.')[0] else: package = module.__name__ else: package = module.__package__ else: module = resolve_name(package) rootpkgname = package.partition('.')[0] rootpkg = resolve_name(rootpkgname) module_path = os.path.dirname(module.__file__) path = os.path.join(module_path, data_name) root_dir = os.path.dirname(rootpkg.__file__) if not _is_inside(path, root_dir): raise RuntimeError("attempted to get a local data file outside " "of the {} tree.".format(rootpkgname)) return path def _find_hash_fn(hash): """ Looks for a local file by hash - returns file name if found and a valid file, otherwise returns None. """ try: dldir, urlmapfn = _get_download_cache_locs() except OSError as e: msg = 'Could not access cache directory to search for data file: ' warn(CacheMissingWarning(msg + str(e))) return None hashfn = os.path.join(dldir, hash) if os.path.isfile(hashfn): return hashfn else: return None
[docs]def get_free_space_in_dir(path): """ Given a path to a directory, returns the amount of free space (in bytes) on that filesystem. Parameters ---------- path : str The path to a directory Returns ------- bytes : int The amount of free space on the partition that the directory is on. """ if sys.platform.startswith('win'): import ctypes free_bytes = ctypes.c_ulonglong(0) retval = ctypes.windll.kernel32.GetDiskFreeSpaceExW( ctypes.c_wchar_p(path), None, None, ctypes.pointer(free_bytes)) if retval == 0: raise OSError('Checking free space on {!r} failed ' 'unexpectedly.'.format(path)) return free_bytes.value else: stat = os.statvfs(path) return stat.f_bavail * stat.f_frsize
[docs]def check_free_space_in_dir(path, size): """ Determines if a given directory has enough space to hold a file of a given size. Raises an OSError if the file would be too large. Parameters ---------- path : str The path to a directory size : int A proposed filesize (in bytes) Raises ------- OSError : There is not enough room on the filesystem """ from astropy.utils.console import human_file_size space = get_free_space_in_dir(path) if space < size: raise OSError( "Not enough free space in '{0}' " "to download a {1} file".format( path, human_file_size(size)))
[docs]def download_file(remote_url, cache=False, show_progress=True, timeout=None): """ Accepts a URL, downloads and optionally caches the result returning the filename, with a name determined by the file's MD5 hash. If ``cache=True`` and the file is present in the cache, just returns the filename. Parameters ---------- remote_url : str The URL of the file to download cache : bool, optional Whether to use the cache show_progress : bool, optional Whether to display a progress bar during the download (default is `True`). Regardless of this setting, the progress bar is only displayed when outputting to a terminal. timeout : float, optional The timeout, in seconds. Otherwise, use `astropy.utils.data.Conf.remote_timeout`. Returns ------- local_path : str Returns the local path that the file was download to. Raises ------ urllib2.URLError, urllib.error.URLError Whenever there's a problem getting the remote file. """ from astropy.utils.console import ProgressBarOrSpinner if timeout is None: timeout = conf.remote_timeout missing_cache = False if cache: try: dldir, urlmapfn = _get_download_cache_locs() except OSError as e: msg = 'Remote data cache could not be accessed due to ' estr = '' if len(e.args) < 1 else (': ' + str(e)) warn(CacheMissingWarning(msg + e.__class__.__name__ + estr)) cache = False missing_cache = True # indicates that the cache is missing to raise a warning later url_key = remote_url # Check if URL is Astropy data server, which has alias, and cache it. if (url_key.startswith(conf.dataurl) and conf.dataurl not in _dataurls_to_alias): try: with urllib.request.urlopen(conf.dataurl, timeout=timeout) as remote: _dataurls_to_alias[conf.dataurl] = [conf.dataurl, remote.geturl()] except urllib.error.URLError: # Host unreachable _dataurls_to_alias[conf.dataurl] = [conf.dataurl] try: if cache: # We don't need to acquire the lock here, since we are only reading with shelve.open(urlmapfn) as url2hash: if url_key in url2hash: return url2hash[url_key] # If there is a cached copy from mirror, use it. else: for cur_url in _dataurls_to_alias.get(conf.dataurl, []): if url_key.startswith(cur_url): url_mirror = url_key.replace(cur_url, conf.dataurl_mirror) if url_mirror in url2hash: return url2hash[url_mirror] with urllib.request.urlopen(remote_url, timeout=timeout) as remote: # keep a hash to rename the local file to the hashed name hash = hashlib.md5() info = remote.info() if 'Content-Length' in info: try: size = int(info['Content-Length']) except ValueError: size = None else: size = None if size is not None: check_free_space_in_dir(gettempdir(), size) if cache: check_free_space_in_dir(dldir, size) if show_progress and sys.stdout.isatty(): progress_stream = sys.stdout else: progress_stream = io.StringIO() dlmsg = "Downloading {0}".format(remote_url) with ProgressBarOrSpinner(size, dlmsg, file=progress_stream) as p: with NamedTemporaryFile(delete=False) as f: try: bytes_read = 0 block = remote.read(conf.download_block_size) while block: f.write(block) hash.update(block) bytes_read += len(block) p.update(bytes_read) block = remote.read(conf.download_block_size) except BaseException: if os.path.exists(f.name): os.remove(f.name) raise if cache: _acquire_download_cache_lock() try: with shelve.open(urlmapfn) as url2hash: # We check now to see if another process has # inadvertently written the file underneath us # already if url_key in url2hash: return url2hash[url_key] local_path = os.path.join(dldir, hash.hexdigest()) shutil.move(f.name, local_path) url2hash[url_key] = local_path finally: _release_download_cache_lock() else: local_path = f.name if missing_cache: msg = ('File downloaded to temporary location due to problem ' 'with cache directory and will not be cached.') warn(CacheMissingWarning(msg, local_path)) if conf.delete_temporary_downloads_at_exit: global _tempfilestodel _tempfilestodel.append(local_path) except urllib.error.URLError as e: if hasattr(e, 'reason') and hasattr(e.reason, 'errno') and e.reason.errno == 8: e.reason.strerror = e.reason.strerror + '. requested URL: ' + remote_url e.reason.args = (e.reason.errno, e.reason.strerror) raise e except socket.timeout as e: # this isn't supposed to happen, but occasionally a socket.timeout gets # through. It's supposed to be caught in `urrlib2` and raised in this # way, but for some reason in mysterious circumstances it doesn't. So # we'll just re-raise it here instead raise urllib.error.URLError(e) return local_path
[docs]def is_url_in_cache(url_key): """ Check if a download from ``url_key`` is in the cache. Parameters ---------- url_key : string The URL retrieved Returns ------- in_cache : bool `True` if a download from ``url_key`` is in the cache """ # The code below is modified from astropy.utils.data.download_file() try: dldir, urlmapfn = _get_download_cache_locs() except OSError as e: msg = 'Remote data cache could not be accessed due to ' estr = '' if len(e.args) < 1 else (': ' + str(e)) warn(CacheMissingWarning(msg + e.__class__.__name__ + estr)) return False with shelve.open(urlmapfn) as url2hash: if url_key in url2hash: return True return False
def _do_download_files_in_parallel(args): return download_file(*args)
[docs]def download_files_in_parallel(urls, cache=True, show_progress=True, timeout=None): """ Downloads multiple files in parallel from the given URLs. Blocks until all files have downloaded. The result is a list of local file paths corresponding to the given urls. Parameters ---------- urls : list of str The URLs to retrieve. cache : bool, optional Whether to use the cache (default is `True`). .. versionchanged:: 3.0 The default was changed to ``True`` and setting it to ``False`` will print a Warning and set it to ``True`` again, because the function will not work properly without cache. show_progress : bool, optional Whether to display a progress bar during the download (default is `True`) timeout : float, optional Timeout for each individual requests in seconds (default is the configurable `astropy.utils.data.Conf.remote_timeout`). Returns ------- paths : list of str The local file paths corresponding to the downloaded URLs. """ from .console import ProgressBar if timeout is None: timeout = conf.remote_timeout if not cache: # See issue #6662, on windows won't work because the files are removed # again before they can be used. On *NIX systems it will behave as if # cache was set to True because multiprocessing cannot insert the items # in the list of to-be-removed files. warn("Disabling the cache does not work because of multiprocessing, it " "will be set to ``True``. You may need to manually remove the " "cached files afterwards.", AstropyWarning) cache = True if show_progress: progress = sys.stdout else: progress = io.BytesIO() # Combine duplicate URLs combined_urls = list(set(urls)) combined_paths = ProgressBar.map( _do_download_files_in_parallel, [(x, cache, False, timeout) for x in combined_urls], file=progress, multiprocess=True) paths = [] for url in urls: paths.append(combined_paths[combined_urls.index(url)]) return paths
# This is used by download_file and _deltemps to determine the files to delete # when the interpreter exits _tempfilestodel = [] @atexit.register def _deltemps(): global _tempfilestodel if _tempfilestodel is not None: while len(_tempfilestodel) > 0: fn = _tempfilestodel.pop() if os.path.isfile(fn): os.remove(fn)
[docs]def clear_download_cache(hashorurl=None): """ Clears the data file cache by deleting the local file(s). Parameters ---------- hashorurl : str or None If None, the whole cache is cleared. Otherwise, either specifies a hash for the cached file that is supposed to be deleted, or a URL that should be removed from the cache if present. """ try: dldir, urlmapfn = _get_download_cache_locs() except OSError as e: msg = 'Not clearing data cache - cache inacessable due to ' estr = '' if len(e.args) < 1 else (': ' + str(e)) warn(CacheMissingWarning(msg + e.__class__.__name__ + estr)) return _acquire_download_cache_lock() try: if hashorurl is None: # dldir includes both the download files and the urlmapfn. This structure # is required since we cannot know a priori the actual file name corresponding # to the shelve map named urlmapfn. if os.path.exists(dldir): shutil.rmtree(dldir) else: with shelve.open(urlmapfn) as url2hash: filepath = os.path.join(dldir, hashorurl) if not _is_inside(filepath, dldir): raise RuntimeError("attempted to use clear_download_cache on" " a path outside the data cache directory") hash_key = hashorurl if os.path.exists(filepath): for k, v in url2hash.items(): if v == filepath: del url2hash[k] os.unlink(filepath) elif hash_key in url2hash: filepath = url2hash[hash_key] del url2hash[hash_key] if os.path.exists(filepath): # Make sure the filepath still actually exists (perhaps user removed it) os.unlink(filepath) # Otherwise could not find file or url, but no worries. # Clearing download cache just makes sure that the file or url # is no longer in the cache regardless of starting condition. finally: # the lock will be gone if rmtree was used above, but release otherwise if os.path.exists(os.path.join(dldir, 'lock')): _release_download_cache_lock()
def _get_download_cache_locs(): """ Finds the path to the data cache directory and makes them if they don't exist. Returns ------- datadir : str The path to the data cache directory. shelveloc : str The path to the shelve object that stores the cache info. """ from astropy.config.paths import get_cache_dir # datadir includes both the download files and the shelveloc. This structure # is required since we cannot know a priori the actual file name corresponding # to the shelve map named shelveloc. (The backend can vary and is allowed to # do whatever it wants with the filename. Filename munging can and does happen # in practice). py_version = 'py' + str(sys.version_info.major) datadir = os.path.join(get_cache_dir(), 'download', py_version) shelveloc = os.path.join(datadir, 'urlmap') if not os.path.exists(datadir): try: os.makedirs(datadir) except OSError as e: if not os.path.exists(datadir): raise elif not os.path.isdir(datadir): msg = 'Data cache directory {0} is not a directory' raise OSError(msg.format(datadir)) if os.path.isdir(shelveloc): msg = 'Data cache shelve object location {0} is a directory' raise OSError(msg.format(shelveloc)) return datadir, shelveloc # the cache directory must be locked before any writes are performed. Same for # the hash shelve, so this should be used for both. def _acquire_download_cache_lock(): """ Uses the lock directory method. This is good because `mkdir` is atomic at the system call level, so it's thread-safe. """ lockdir = os.path.join(_get_download_cache_locs()[0], 'lock') for i in range(conf.download_cache_lock_attempts): try: os.mkdir(lockdir) # write the pid of this process for informational purposes with open(os.path.join(lockdir, 'pid'), 'w') as f: f.write(str(os.getpid())) except OSError: time.sleep(1) else: return msg = ("Unable to acquire lock for cache directory ({0} exists). " "You may need to delete the lock if the python interpreter wasn't " "shut down properly.") raise RuntimeError(msg.format(lockdir)) def _release_download_cache_lock(): lockdir = os.path.join(_get_download_cache_locs()[0], 'lock') if os.path.isdir(lockdir): # if the pid file is present, be sure to remove it pidfn = os.path.join(lockdir, 'pid') if os.path.exists(pidfn): os.remove(pidfn) os.rmdir(lockdir) else: msg = 'Error releasing lock. "{0}" either does not exist or is not ' +\ 'a directory.' raise RuntimeError(msg.format(lockdir))
[docs]def get_cached_urls(): """ Get the list of URLs in the cache. Especially useful for looking up what files are stored in your cache when you don't have internet access. Returns ------- cached_urls : list List of cached URLs. """ # The code below is modified from astropy.utils.data.download_file() try: dldir, urlmapfn = _get_download_cache_locs() except OSError as e: msg = 'Remote data cache could not be accessed due to ' estr = '' if len(e.args) < 1 else (': ' + str(e)) warn(CacheMissingWarning(msg + e.__class__.__name__ + estr)) return False with shelve.open(urlmapfn) as url2hash: return list(url2hash.keys())