Source code for fsspec.utils

import logging
import math
import os
import pathlib
import re
import sys
from contextlib import contextmanager
from functools import partial
from hashlib import md5
from urllib.parse import urlsplit

DEFAULT_BLOCK_SIZE = 5 * 2**20


def infer_storage_options(urlpath, inherit_storage_options=None):
    """Infer storage options from URL path and merge it with existing storage
    options.

    Parameters
    ----------
    urlpath: str or unicode
        Either local absolute file path or URL (hdfs://namenode:8020/file.csv)
    inherit_storage_options: dict (optional)
        Its contents will get merged with the inferred information from the
        given path

    Returns
    -------
    Storage options dict.

    Examples
    --------
    >>> infer_storage_options('/mnt/datasets/test.csv')  # doctest: +SKIP
    {"protocol": "file", "path", "/mnt/datasets/test.csv"}
    >>> infer_storage_options(
    ...     'hdfs://username:pwd@node:123/mnt/datasets/test.csv?q=1',
    ...     inherit_storage_options={'extra': 'value'},
    ... )  # doctest: +SKIP
    {"protocol": "hdfs", "username": "username", "password": "pwd",
    "host": "node", "port": 123, "path": "/mnt/datasets/test.csv",
    "url_query": "q=1", "extra": "value"}
    """
    # Handle Windows paths including disk name in this special case
    if (
        re.match(r"^[a-zA-Z]:[\\/]", urlpath)
        or re.match(r"^[a-zA-Z0-9]+://", urlpath) is None
    ):
        return {"protocol": "file", "path": urlpath}

    parsed_path = urlsplit(urlpath)
    protocol = parsed_path.scheme or "file"
    if parsed_path.fragment:
        path = "#".join([parsed_path.path, parsed_path.fragment])
    else:
        path = parsed_path.path
    if protocol == "file":
        # Special case parsing file protocol URL on Windows according to:
        # https://msdn.microsoft.com/en-us/library/jj710207.aspx
        windows_path = re.match(r"^/([a-zA-Z])[:|]([\\/].*)$", path)
        if windows_path:
            path = "%s:%s" % windows_path.groups()

    if protocol in ["http", "https"]:
        # for HTTP, we don't want to parse, as requests will anyway
        return {"protocol": protocol, "path": urlpath}

    options = {"protocol": protocol, "path": path}

    if parsed_path.netloc:
        # Parse `hostname` from netloc manually because `parsed_path.hostname`
        # lowercases the hostname which is not always desirable (e.g. in S3):
        # https://github.com/dask/dask/issues/1417
        options["host"] = parsed_path.netloc.rsplit("@", 1)[-1].rsplit(":", 1)[0]

        if protocol in ("s3", "s3a", "gcs", "gs"):
            options["path"] = options["host"] + options["path"]
        else:
            options["host"] = options["host"]
        if parsed_path.port:
            options["port"] = parsed_path.port
        if parsed_path.username:
            options["username"] = parsed_path.username
        if parsed_path.password:
            options["password"] = parsed_path.password

    if parsed_path.query:
        options["url_query"] = parsed_path.query
    if parsed_path.fragment:
        options["url_fragment"] = parsed_path.fragment

    if inherit_storage_options:
        update_storage_options(options, inherit_storage_options)

    return options


def update_storage_options(options, inherited=None):
    if not inherited:
        inherited = {}
    collisions = set(options) & set(inherited)
    if collisions:
        for collision in collisions:
            if options.get(collision) != inherited.get(collision):
                raise KeyError(
                    "Collision between inferred and specified storage "
                    "option:\n%s" % collision
                )
    options.update(inherited)


# Compression extensions registered via fsspec.compression.register_compression
compressions = {}


def infer_compression(filename):
    """Infer compression, if available, from filename.

    Infer a named compression type, if registered and available, from filename
    extension. This includes builtin (gz, bz2, zip) compressions, as well as
    optional compressions. See fsspec.compression.register_compression.
    """
    extension = os.path.splitext(filename)[-1].strip(".").lower()
    if extension in compressions:
        return compressions[extension]


def build_name_function(max_int):
    """Returns a function that receives a single integer
    and returns it as a string padded by enough zero characters
    to align with maximum possible integer

    >>> name_f = build_name_function(57)

    >>> name_f(7)
    '07'
    >>> name_f(31)
    '31'
    >>> build_name_function(1000)(42)
    '0042'
    >>> build_name_function(999)(42)
    '042'
    >>> build_name_function(0)(0)
    '0'
    """
    # handle corner cases max_int is 0 or exact power of 10
    max_int += 1e-8

    pad_length = int(math.ceil(math.log10(max_int)))

    def name_function(i):
        return str(i).zfill(pad_length)

    return name_function


def seek_delimiter(file, delimiter, blocksize):
    r"""Seek current file to file start, file end, or byte after delimiter seq.

    Seeks file to next chunk delimiter, where chunks are defined on file start,
    a delimiting sequence, and file end. Use file.tell() to see location afterwards.
    Note that file start is a valid split, so must be at offset > 0 to seek for
    delimiter.

    Parameters
    ----------
    file: a file
    delimiter: bytes
        a delimiter like ``b'\n'`` or message sentinel, matching file .read() type
    blocksize: int
        Number of bytes to read from the file at once.


    Returns
    -------
    Returns True if a delimiter was found, False if at file start or end.

    """

    if file.tell() == 0:
        # beginning-of-file, return without seek
        return False

    # Interface is for binary IO, with delimiter as bytes, but initialize last
    # with result of file.read to preserve compatibility with text IO.
    last = None
    while True:
        current = file.read(blocksize)
        if not current:
            # end-of-file without delimiter
            return False
        full = last + current if last else current
        try:
            if delimiter in full:
                i = full.index(delimiter)
                file.seek(file.tell() - (len(full) - i) + len(delimiter))
                return True
            elif len(current) < blocksize:
                # end-of-file without delimiter
                return False
        except (OSError, ValueError):
            pass
        last = full[-len(delimiter) :]


[docs]def read_block(f, offset, length, delimiter=None, split_before=False): """Read a block of bytes from a file Parameters ---------- f: File Open file offset: int Byte offset to start read length: int Number of bytes to read, read through end of file if None delimiter: bytes (optional) Ensure reading starts and stops at delimiter bytestring split_before: bool (optional) Start/stop read *before* delimiter bytestring. If using the ``delimiter=`` keyword argument we ensure that the read starts and stops at delimiter boundaries that follow the locations ``offset`` and ``offset + length``. If ``offset`` is zero then we start at zero, regardless of delimiter. The bytestring returned WILL include the terminating delimiter string. Examples -------- >>> from io import BytesIO # doctest: +SKIP >>> f = BytesIO(b'Alice, 100\\nBob, 200\\nCharlie, 300') # doctest: +SKIP >>> read_block(f, 0, 13) # doctest: +SKIP b'Alice, 100\\nBo' >>> read_block(f, 0, 13, delimiter=b'\\n') # doctest: +SKIP b'Alice, 100\\nBob, 200\\n' >>> read_block(f, 10, 10, delimiter=b'\\n') # doctest: +SKIP b'Bob, 200\\nCharlie, 300' """ if delimiter: f.seek(offset) found_start_delim = seek_delimiter(f, delimiter, 2**16) if length is None: return f.read() start = f.tell() length -= start - offset f.seek(start + length) found_end_delim = seek_delimiter(f, delimiter, 2**16) end = f.tell() # Adjust split location to before delimiter iff seek found the # delimiter sequence, not start or end of file. if found_start_delim and split_before: start -= len(delimiter) if found_end_delim and split_before: end -= len(delimiter) offset = start length = end - start f.seek(offset) b = f.read(length) return b
def tokenize(*args, **kwargs): """Deterministic token (modified from dask.base) >>> tokenize([1, 2, '3']) '9d71491b50023b06fc76928e6eddb952' >>> tokenize('Hello') == tokenize('Hello') True """ if kwargs: args += (kwargs,) try: return md5(str(args).encode()).hexdigest() except ValueError: # FIPS systems: https://github.com/fsspec/filesystem_spec/issues/380 return md5(str(args).encode(), usedforsecurity=False).hexdigest() def stringify_path(filepath): """Attempt to convert a path-like object to a string. Parameters ---------- filepath: object to be converted Returns ------- filepath_str: maybe a string version of the object Notes ----- Objects supporting the fspath protocol are coerced according to its __fspath__ method. For backwards compatibility with older Python version, pathlib.Path objects are specially coerced. Any other object is passed through unchanged, which includes bytes, strings, buffers, or anything else that's not even path-like. """ if isinstance(filepath, str): return filepath elif hasattr(filepath, "__fspath__"): return filepath.__fspath__() elif isinstance(filepath, pathlib.Path): return str(filepath) elif hasattr(filepath, "path"): return filepath.path else: return filepath def make_instance(cls, args, kwargs): inst = cls(*args, **kwargs) inst._determine_worker() return inst def common_prefix(paths): """For a list of paths, find the shortest prefix common to all""" parts = [p.split("/") for p in paths] lmax = min(len(p) for p in parts) end = 0 for i in range(lmax): end = all(p[i] == parts[0][i] for p in parts) if not end: break i += end return "/".join(parts[0][:i]) def other_paths(paths, path2, is_dir=None, exists=False): """In bulk file operations, construct a new file tree from a list of files Parameters ---------- paths: list of str The input file tree path2: str or list of str Root to construct the new list in. If this is already a list of str, we just assert it has the right number of elements. is_dir: bool (optional) For the special case where the input in one element, whether to regard the value as the target path, or as a directory to put a file path within. If None, a directory is inferred if the path ends in '/' exists: bool (optional) For a str destination, it is already exists (and is a dir), files should end up inside. Returns ------- list of str """ if isinstance(path2, str): is_dir = is_dir or path2.endswith("/") path2 = path2.rstrip("/") if len(paths) > 1: cp = common_prefix(paths) if exists: cp = cp.rsplit("/", 1)[0] path2 = [p.replace(cp, path2, 1) for p in paths] else: if is_dir: path2 = [path2.rstrip("/") + "/" + paths[0].rsplit("/")[-1]] else: path2 = [path2] else: assert len(paths) == len(path2) return path2 def is_exception(obj): return isinstance(obj, BaseException) def isfilelike(f): for attr in ["read", "close", "tell"]: if not hasattr(f, attr): return False return True def get_protocol(url): parts = re.split(r"(\:\:|\://)", url, 1) if len(parts) > 1: return parts[0] return "file" def can_be_local(path): """Can the given URL be used with open_local?""" from fsspec import get_filesystem_class try: return getattr(get_filesystem_class(get_protocol(path)), "local_file", False) except (ValueError, ImportError): # not in registry or import failed return False def get_package_version_without_import(name): """For given package name, try to find the version without importing it Import and package.__version__ is still the backup here, so an import *might* happen. Returns either the version string, or None if the package or the version was not readily found. """ if name in sys.modules: mod = sys.modules[name] if hasattr(mod, "__version__"): return mod.__version__ if sys.version_info >= (3, 8): try: import importlib.metadata return importlib.metadata.distribution(name).version except: # noqa: E722 pass else: try: import importlib_metadata return importlib_metadata.distribution(name).version except: # noqa: E722 pass try: import importlib mod = importlib.import_module(name) return mod.__version__ except (ImportError, AttributeError): return None def setup_logging(logger=None, logger_name=None, level="DEBUG", clear=True): if logger is None and logger_name is None: raise ValueError("Provide either logger object or logger name") logger = logger or logging.getLogger(logger_name) handle = logging.StreamHandler() formatter = logging.Formatter( "%(asctime)s - %(name)s - %(levelname)s - %(funcName)s -- %(message)s" ) handle.setFormatter(formatter) if clear: logger.handlers.clear() logger.addHandler(handle) logger.setLevel(level) return logger def _unstrip_protocol(name, fs): return fs.unstrip_protocol(name) def mirror_from(origin_name, methods): """Mirror attributes and methods from the given origin_name attribute of the instance to the decorated class""" def origin_getter(method, self): origin = getattr(self, origin_name) return getattr(origin, method) def wrapper(cls): for method in methods: wrapped_method = partial(origin_getter, method) setattr(cls, method, property(wrapped_method)) return cls return wrapper @contextmanager def nullcontext(obj): yield obj def merge_offset_ranges(paths, starts, ends, max_gap=0, max_block=None, sort=True): """Merge adjacent byte-offset ranges when the inter-range gap is <= `max_gap`, and when the merged byte range does not exceed `max_block` (if specified). By default, this function will re-order the input paths and byte ranges to ensure sorted order. If the user can guarantee that the inputs are already sorted, passing `sort=False` will skip the re-ordering. """ # Check input if not isinstance(paths, list): raise TypeError if not isinstance(starts, list): starts = [starts] * len(paths) if not isinstance(ends, list): ends = [starts] * len(paths) if len(starts) != len(paths) or len(ends) != len(paths): raise ValueError # Early Return if len(starts) <= 1: return paths, starts, ends # Sort by paths and then ranges if `sort=True` if sort: paths, starts, ends = [list(v) for v in zip(*sorted(zip(paths, starts, ends)))] if paths: # Loop through the coupled `paths`, `starts`, and # `ends`, and merge adjacent blocks when appropriate new_paths = paths[:1] new_starts = starts[:1] new_ends = ends[:1] for i in range(1, len(paths)): if ( paths[i] != paths[i - 1] or ((starts[i] - new_ends[-1]) > max_gap) or ((max_block is not None and (ends[i] - new_starts[-1]) > max_block)) ): # Cannot merge with previous block. # Add new `paths`, `starts`, and `ends` elements new_paths.append(paths[i]) new_starts.append(starts[i]) new_ends.append(ends[i]) else: # Merge with previous block by updating the # last element of `ends` new_ends[-1] = ends[i] return new_paths, new_starts, new_ends # `paths` is empty. Just return input lists return paths, starts, ends def file_size(filelike): """Find length of any open read-mode file-like""" pos = filelike.tell() try: return filelike.seek(0, 2) finally: filelike.seek(pos)