def cache_url(url, model_dir=None, progress=True):
r"""Loads the Torch serialized object at the given URL.
If the object is already present in `model_dir`, it's deserialized and
returned. The filename part of the URL should follow the naming convention
``filename-<sha256>.ext`` where ``<sha256>`` is the first eight or more
digits of the SHA256 hash of the contents of the file. The hash is used to
ensure unique names and to verify the contents of the file.
The default value of `model_dir` is ``$TORCH_HOME/models`` where
``$TORCH_HOME`` defaults to ``~/.torch``. The default directory can be
overridden with the ``$TORCH_MODEL_ZOO`` environment variable.
Args:
url (string): URL of the object to download
model_dir (string, optional): directory in which to save the object
progress (bool, optional): whether or not to display a progress bar to stderr
Example:
>>> cached_file = maskrcnn_benchmark.utils.model_zoo.cache_url('https://s3.amazonaws.com/pytorch/models/resnet18-5c106cde.pth')
"""
if model_dir is None:
torch_home = os.path.expanduser(os.getenv('TORCH_HOME', '~/.torch'))
model_dir = os.getenv('TORCH_MODEL_ZOO',
os.path.join(torch_home, 'models'))
if not os.path.exists(model_dir):
os.makedirs(model_dir)
parts = urlparse(url)
filename = os.path.basename(parts.path)
if filename == "model_final.pkl":
# workaround as pre-trained Caffe2 models from Detectron have all the same filename
# so make the full path the filename by replacing / with _
filename = parts.path.replace("/", "_")
cached_file = os.path.join(model_dir, filename)
if not os.path.exists(cached_file) and is_main_process():
sys.stderr.write('Downloading: "{}" to {}\n'.format(url, cached_file))
hash_prefix = HASH_REGEX.search(filename)
if hash_prefix is not None:
hash_prefix = hash_prefix.group(1)
# workaround: Caffe2 models don't have a hash, but follow the R-50 convention,
# which matches the hash PyTorch uses. So we skip the hash matching
# if the hash_prefix is less than 6 characters
if len(hash_prefix) < 6:
hash_prefix = None
_download_url_to_file(url, cached_file, hash_prefix, progress=progress)
synchronize()
return cached_file
def download_from_url(url):
torch_home = os.path.expanduser(os.getenv("TORCH_HOME", "~/.cache"))
model_dir = os.getenv("TORCH_MODEL_ZOO",
os.path.join(torch_home, "torch", "checkpoints"))
if not os.path.exists(model_dir):
os.makedirs(model_dir)
parts = urlparse(url)
filename = os.path.basename(parts.path)
cached_file = os.path.join(model_dir, filename)
if not os.path.exists(cached_file) and is_main_process():
sys.stderr.write('Downloading: "{}" to {}\n'.format(url, cached_file))
hash_prefix = HASH_REGEX.search(filename)
if hash_prefix is not None:
hash_prefix = hash_prefix.group(1)
if len(hash_prefix) < 6:
hash_prefix = None
download_url_to_file(url, cached_file, hash_prefix, progress=True)
synchronize()
return cached_file
def load_custom_pretrained(model,
cfg=None,
load_fn=None,
progress=False,
check_hash=False):
r"""Loads a custom (read non .pth) weight file
Downloads checkpoint file into cache-dir like torch.hub based loaders, but calls
a passed in custom load fun, or the `load_pretrained` model member fn.
If the object is already present in `model_dir`, it's deserialized and returned.
The default value of `model_dir` is ``<hub_dir>/checkpoints`` where
`hub_dir` is the directory returned by :func:`~torch.hub.get_dir`.
Args:
model: The instantiated model to load weights into
cfg (dict): Default pretrained model cfg
load_fn: An external stand alone fn that loads weights into provided model, otherwise a fn named
'laod_pretrained' on the model will be called if it exists
progress (bool, optional): whether or not to display a progress bar to stderr. Default: False
check_hash(bool, optional): If True, the filename part of the URL should follow the naming convention
``filename-<sha256>.ext`` where ``<sha256>`` is the first eight or more
digits of the SHA256 hash of the contents of the file. The hash is used to
ensure unique names and to verify the contents of the file. Default: False
"""
cfg = cfg or getattr(model, 'default_cfg')
if cfg is None or not cfg.get('url', None):
_logger.warning(
"No pretrained weights exist for this model. Using random initialization."
)
return
url = cfg['url']
# Issue warning to move data if old env is set
if os.getenv('TORCH_MODEL_ZOO'):
_logger.warning(
'TORCH_MODEL_ZOO is deprecated, please use env TORCH_HOME instead')
hub_dir = get_dir()
model_dir = os.path.join(hub_dir, 'checkpoints')
os.makedirs(model_dir, exist_ok=True)
parts = urlparse(url)
filename = os.path.basename(parts.path)
cached_file = os.path.join(model_dir, filename)
if not os.path.exists(cached_file):
_logger.info('Downloading: "{}" to {}\n'.format(url, cached_file))
hash_prefix = None
if check_hash:
r = HASH_REGEX.search(filename) # r is Optional[Match[str]]
hash_prefix = r.group(1) if r else None
download_url_to_file(url, cached_file, hash_prefix, progress=progress)
if load_fn is not None:
load_fn(model, cached_file)
elif hasattr(model, 'load_pretrained'):
model.load_pretrained(cached_file)
else:
_logger.warning(
"Valid function to load pretrained weights is not available, using random initialization."
)
