preparing for first release

pytorch_pretrained_bert/file_utils.py

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+"""
+Utilities for working with the local dataset cache.
+This file is adapted from the AllenNLP library at https://github.com/allenai/allennlp
+Copyright by the AllenNLP authors.
+"""
+
+import os
+import logging
+import shutil
+import tempfile
+import json
+from urllib.parse import urlparse
+from pathlib import Path
+from typing import Optional, Tuple, Union, IO, Callable, Set
+from hashlib import sha256
+from functools import wraps
+
+from tqdm import tqdm
+
+import boto3
+from botocore.exceptions import ClientError
+import requests
+
+logger = logging.getLogger(__name__)  # pylint: disable=invalid-name
+
+PYTORCH_PRETRAINED_BERT_CACHE = Path(os.getenv('PYTORCH_PRETRAINED_BERT_CACHE',
+                                               Path.home() / '.pytorch_pretrained_bert'))
+
+
+def url_to_filename(url: str, etag: str = None) -> str:
+    """
+    Convert `url` into a hashed filename in a repeatable way.
+    If `etag` is specified, append its hash to the url's, delimited
+    by a period.
+    """
+    url_bytes = url.encode('utf-8')
+    url_hash = sha256(url_bytes)
+    filename = url_hash.hexdigest()
+
+    if etag:
+        etag_bytes = etag.encode('utf-8')
+        etag_hash = sha256(etag_bytes)
+        filename += '.' + etag_hash.hexdigest()
+
+    return filename
+
+
+def filename_to_url(filename: str, cache_dir: str = None) -> Tuple[str, str]:
+    """
+    Return the url and etag (which may be ``None``) stored for `filename`.
+    Raise ``FileNotFoundError`` if `filename` or its stored metadata do not exist.
+    """
+    if cache_dir is None:
+        cache_dir = PYTORCH_PRETRAINED_BERT_CACHE
+
+    cache_path = os.path.join(cache_dir, filename)
+    if not os.path.exists(cache_path):
+        raise FileNotFoundError("file {} not found".format(cache_path))
+
+    meta_path = cache_path + '.json'
+    if not os.path.exists(meta_path):
+        raise FileNotFoundError("file {} not found".format(meta_path))
+
+    with open(meta_path) as meta_file:
+        metadata = json.load(meta_file)
+    url = metadata['url']
+    etag = metadata['etag']
+
+    return url, etag
+
+
+def cached_path(url_or_filename: Union[str, Path], cache_dir: str = None) -> str:
+    """
+    Given something that might be a URL (or might be a local path),
+    determine which. If it's a URL, download the file and cache it, and
+    return the path to the cached file. If it's already a local path,
+    make sure the file exists and then return the path.
+    """
+    if cache_dir is None:
+        cache_dir = PYTORCH_PRETRAINED_BERT_CACHE
+    if isinstance(url_or_filename, Path):
+        url_or_filename = str(url_or_filename)
+
+    parsed = urlparse(url_or_filename)
+
+    if parsed.scheme in ('http', 'https', 's3'):
+        # URL, so get it from the cache (downloading if necessary)
+        return get_from_cache(url_or_filename, cache_dir)
+    elif os.path.exists(url_or_filename):
+        # File, and it exists.
+        return url_or_filename
+    elif parsed.scheme == '':
+        # File, but it doesn't exist.
+        raise FileNotFoundError("file {} not found".format(url_or_filename))
+    else:
+        # Something unknown
+        raise ValueError("unable to parse {} as a URL or as a local path".format(url_or_filename))
+
+
+def split_s3_path(url: str) -> Tuple[str, str]:
+    """Split a full s3 path into the bucket name and path."""
+    parsed = urlparse(url)
+    if not parsed.netloc or not parsed.path:
+        raise ValueError("bad s3 path {}".format(url))
+    bucket_name = parsed.netloc
+    s3_path = parsed.path
+    # Remove '/' at beginning of path.
+    if s3_path.startswith("/"):
+        s3_path = s3_path[1:]
+    return bucket_name, s3_path
+
+
+def s3_request(func: Callable):
+    """
+    Wrapper function for s3 requests in order to create more helpful error
+    messages.
+    """
+
+    @wraps(func)
+    def wrapper(url: str, *args, **kwargs):
+        try:
+            return func(url, *args, **kwargs)
+        except ClientError as exc:
+            if int(exc.response["Error"]["Code"]) == 404:
+                raise FileNotFoundError("file {} not found".format(url))
+            else:
+                raise
+
+    return wrapper
+
+
+@s3_request
+def s3_etag(url: str) -> Optional[str]:
+    """Check ETag on S3 object."""
+    s3_resource = boto3.resource("s3")
+    bucket_name, s3_path = split_s3_path(url)
+    s3_object = s3_resource.Object(bucket_name, s3_path)
+    return s3_object.e_tag
+
+
+@s3_request
+def s3_get(url: str, temp_file: IO) -> None:
+    """Pull a file directly from S3."""
+    s3_resource = boto3.resource("s3")
+    bucket_name, s3_path = split_s3_path(url)
+    s3_resource.Bucket(bucket_name).download_fileobj(s3_path, temp_file)
+
+
+def http_get(url: str, temp_file: IO) -> None:
+    req = requests.get(url, stream=True)
+    content_length = req.headers.get('Content-Length')
+    total = int(content_length) if content_length is not None else None
+    progress = tqdm(unit="B", total=total)
+    for chunk in req.iter_content(chunk_size=1024):
+        if chunk: # filter out keep-alive new chunks
+            progress.update(len(chunk))
+            temp_file.write(chunk)
+    progress.close()
+
+
+def get_from_cache(url: str, cache_dir: str = None) -> str:
+    """
+    Given a URL, look for the corresponding dataset in the local cache.
+    If it's not there, download it. Then return the path to the cached file.
+    """
+    if cache_dir is None:
+        cache_dir = PYTORCH_PRETRAINED_BERT_CACHE
+
+    os.makedirs(cache_dir, exist_ok=True)
+
+    # Get eTag to add to filename, if it exists.
+    if url.startswith("s3://"):
+        etag = s3_etag(url)
+    else:
+        response = requests.head(url, allow_redirects=True)
+        if response.status_code != 200:
+            raise IOError("HEAD request failed for url {} with status code {}"
+                          .format(url, response.status_code))
+        etag = response.headers.get("ETag")
+
+    filename = url_to_filename(url, etag)
+
+    # get cache path to put the file
+    cache_path = os.path.join(cache_dir, filename)
+
+    if not os.path.exists(cache_path):
+        # Download to temporary file, then copy to cache dir once finished.
+        # Otherwise you get corrupt cache entries if the download gets interrupted.
+        with tempfile.NamedTemporaryFile() as temp_file:
+            logger.info("%s not found in cache, downloading to %s", url, temp_file.name)
+
+            # GET file object
+            if url.startswith("s3://"):
+                s3_get(url, temp_file)
+            else:
+                http_get(url, temp_file)
+
+            # we are copying the file before closing it, so flush to avoid truncation
+            temp_file.flush()
+            # shutil.copyfileobj() starts at the current position, so go to the start
+            temp_file.seek(0)
+
+            logger.info("copying %s to cache at %s", temp_file.name, cache_path)
+            with open(cache_path, 'wb') as cache_file:
+                shutil.copyfileobj(temp_file, cache_file)
+
+            logger.info("creating metadata file for %s", cache_path)
+            meta = {'url': url, 'etag': etag}
+            meta_path = cache_path + '.json'
+            with open(meta_path, 'w') as meta_file:
+                json.dump(meta, meta_file)
+
+            logger.info("removing temp file %s", temp_file.name)
+
+    return cache_path
+
+
+def read_set_from_file(filename: str) -> Set[str]:
+    '''
+    Extract a de-duped collection (set) of text from a file.
+    Expected file format is one item per line.
+    '''
+    collection = set()
+    with open(filename, 'r') as file_:
+        for line in file_:
+            collection.add(line.rstrip())
+    return collection
+
+
+def get_file_extension(path: str, dot=True, lower: bool = True):
+    ext = os.path.splitext(path)[1]
+    ext = ext if dot else ext[1:]
+    return ext.lower() if lower else ext