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"""Storage providers backends for Memory caching."""
import collections
import datetime
import json
import operator
import os
import os.path
import re
import shutil
import threading
import time
import warnings
from abc import ABCMeta, abstractmethod
from pickle import PicklingError
from . import numpy_pickle
from .backports import concurrency_safe_rename
from .disk import memstr_to_bytes, mkdirp, rm_subdirs
from .logger import format_time
CacheItemInfo = collections.namedtuple("CacheItemInfo", "path size last_access")
class CacheWarning(Warning):
"""Warning to capture dump failures except for PicklingError."""
pass
def concurrency_safe_write(object_to_write, filename, write_func):
"""Writes an object into a unique file in a concurrency-safe way."""
thread_id = id(threading.current_thread())
temporary_filename = "{}.thread-{}-pid-{}".format(filename, thread_id, os.getpid())
write_func(object_to_write, temporary_filename)
return temporary_filename
class StoreBackendBase(metaclass=ABCMeta):
"""Helper Abstract Base Class which defines all methods that
a StorageBackend must implement."""
location = None
@abstractmethod
def _open_item(self, f, mode):
"""Opens an item on the store and return a file-like object.
This method is private and only used by the StoreBackendMixin object.
Parameters
----------
f: a file-like object
The file-like object where an item is stored and retrieved
mode: string, optional
the mode in which the file-like object is opened allowed valued are
'rb', 'wb'
Returns
-------
a file-like object
"""
@abstractmethod
def _item_exists(self, location):
"""Checks if an item location exists in the store.
This method is private and only used by the StoreBackendMixin object.
Parameters
----------
location: string
The location of an item. On a filesystem, this corresponds to the
absolute path, including the filename, of a file.
Returns
-------
True if the item exists, False otherwise
"""
@abstractmethod
def _move_item(self, src, dst):
"""Moves an item from src to dst in the store.
This method is private and only used by the StoreBackendMixin object.
Parameters
----------
src: string
The source location of an item
dst: string
The destination location of an item
"""
@abstractmethod
def create_location(self, location):
"""Creates a location on the store.
Parameters
----------
location: string
The location in the store. On a filesystem, this corresponds to a
directory.
"""
@abstractmethod
def clear_location(self, location):
"""Clears a location on the store.
Parameters
----------
location: string
The location in the store. On a filesystem, this corresponds to a
directory or a filename absolute path
"""
@abstractmethod
def get_items(self):
"""Returns the whole list of items available in the store.
Returns
-------
The list of items identified by their ids (e.g filename in a
filesystem).
"""
@abstractmethod
def configure(self, location, verbose=0, backend_options=dict()):
"""Configures the store.
Parameters
----------
location: string
The base location used by the store. On a filesystem, this
corresponds to a directory.
verbose: int
The level of verbosity of the store
backend_options: dict
Contains a dictionary of named parameters used to configure the
store backend.
"""
class StoreBackendMixin(object):
"""Class providing all logic for managing the store in a generic way.
The StoreBackend subclass has to implement 3 methods: create_location,
clear_location and configure. The StoreBackend also has to provide
a private _open_item, _item_exists and _move_item methods. The _open_item
method has to have the same signature as the builtin open and return a
file-like object.
"""
def load_item(self, call_id, verbose=1, timestamp=None, metadata=None):
"""Load an item from the store given its id as a list of str."""
full_path = os.path.join(self.location, *call_id)
if verbose > 1:
ts_string = (
"{: <16}".format(format_time(time.time() - timestamp))
if timestamp is not None
else ""
)
signature = os.path.basename(call_id[0])
if metadata is not None and "input_args" in metadata:
kwargs = ", ".join(
"{}={}".format(*item) for item in metadata["input_args"].items()
)
signature += "({})".format(kwargs)
msg = "[Memory]{}: Loading {}".format(ts_string, signature)
if verbose < 10:
print("{0}...".format(msg))
else:
print("{0} from {1}".format(msg, full_path))
mmap_mode = None if not hasattr(self, "mmap_mode") else self.mmap_mode
filename = os.path.join(full_path, "output.pkl")
if not self._item_exists(filename):
raise KeyError(
"Non-existing item (may have been "
"cleared).\nFile %s does not exist" % filename
)
# file-like object cannot be used when mmap_mode is set
if mmap_mode is None:
with self._open_item(filename, "rb") as f:
item = numpy_pickle.load(f)
else:
item = numpy_pickle.load(filename, mmap_mode=mmap_mode)
return item
def dump_item(self, call_id, item, verbose=1):
"""Dump an item in the store at the id given as a list of str."""
try:
item_path = os.path.join(self.location, *call_id)
if not self._item_exists(item_path):
self.create_location(item_path)
filename = os.path.join(item_path, "output.pkl")
if verbose > 10:
print("Persisting in %s" % item_path)
def write_func(to_write, dest_filename):
with self._open_item(dest_filename, "wb") as f:
try:
numpy_pickle.dump(to_write, f, compress=self.compress)
except PicklingError as e:
# TODO(1.5) turn into error
warnings.warn(
"Unable to cache to disk: failed to pickle "
"output. In version 1.5 this will raise an "
f"exception. Exception: {e}.",
FutureWarning,
)
self._concurrency_safe_write(item, filename, write_func)
except Exception as e: # noqa: E722
warnings.warn(
"Unable to cache to disk. Possibly a race condition in the "
f"creation of the directory. Exception: {e}.",
CacheWarning,
)
def clear_item(self, call_id):
"""Clear the item at the id, given as a list of str."""
item_path = os.path.join(self.location, *call_id)
if self._item_exists(item_path):
self.clear_location(item_path)
def contains_item(self, call_id):
"""Check if there is an item at the id, given as a list of str."""
item_path = os.path.join(self.location, *call_id)
filename = os.path.join(item_path, "output.pkl")
return self._item_exists(filename)
def get_item_info(self, call_id):
"""Return information about item."""
return {"location": os.path.join(self.location, *call_id)}
def get_metadata(self, call_id):
"""Return actual metadata of an item."""
try:
item_path = os.path.join(self.location, *call_id)
filename = os.path.join(item_path, "metadata.json")
with self._open_item(filename, "rb") as f:
return json.loads(f.read().decode("utf-8"))
except: # noqa: E722
return {}
def store_metadata(self, call_id, metadata):
"""Store metadata of a computation."""
try:
item_path = os.path.join(self.location, *call_id)
self.create_location(item_path)
filename = os.path.join(item_path, "metadata.json")
def write_func(to_write, dest_filename):
with self._open_item(dest_filename, "wb") as f:
f.write(json.dumps(to_write).encode("utf-8"))
self._concurrency_safe_write(metadata, filename, write_func)
except: # noqa: E722
pass
def contains_path(self, call_id):
"""Check cached function is available in store."""
func_path = os.path.join(self.location, *call_id)
return self.object_exists(func_path)
def clear_path(self, call_id):
"""Clear all items with a common path in the store."""
func_path = os.path.join(self.location, *call_id)
if self._item_exists(func_path):
self.clear_location(func_path)
def store_cached_func_code(self, call_id, func_code=None):
"""Store the code of the cached function."""
func_path = os.path.join(self.location, *call_id)
if not self._item_exists(func_path):
self.create_location(func_path)
if func_code is not None:
filename = os.path.join(func_path, "func_code.py")
with self._open_item(filename, "wb") as f:
f.write(func_code.encode("utf-8"))
def get_cached_func_code(self, call_id):
"""Store the code of the cached function."""
filename = os.path.join(self.location, *call_id, "func_code.py")
try:
with self._open_item(filename, "rb") as f:
return f.read().decode("utf-8")
except: # noqa: E722
raise
def get_cached_func_info(self, call_id):
"""Return information related to the cached function if it exists."""
return {"location": os.path.join(self.location, *call_id)}
def clear(self):
"""Clear the whole store content."""
self.clear_location(self.location)
def enforce_store_limits(self, bytes_limit, items_limit=None, age_limit=None):
"""
Remove the store's oldest files to enforce item, byte, and age limits.
"""
items_to_delete = self._get_items_to_delete(bytes_limit, items_limit, age_limit)
for item in items_to_delete:
if self.verbose > 10:
print("Deleting item {0}".format(item))
try:
self.clear_location(item.path)
except OSError:
# Even with ignore_errors=True shutil.rmtree can raise OSError
# with:
# [Errno 116] Stale file handle if another process has deleted
# the folder already.
pass
def _get_items_to_delete(self, bytes_limit, items_limit=None, age_limit=None):
"""
Get items to delete to keep the store under size, file, & age limits.
"""
if isinstance(bytes_limit, str):
bytes_limit = memstr_to_bytes(bytes_limit)
items = self.get_items()
if not items:
return []
size = sum(item.size for item in items)
if bytes_limit is not None:
to_delete_size = size - bytes_limit
else:
to_delete_size = 0
if items_limit is not None:
to_delete_items = len(items) - items_limit
else:
to_delete_items = 0
if age_limit is not None:
older_item = min(item.last_access for item in items)
if age_limit.total_seconds() < 0:
raise ValueError("age_limit has to be a positive timedelta")
deadline = datetime.datetime.now() - age_limit
else:
deadline = None
if (
to_delete_size <= 0
and to_delete_items <= 0
and (deadline is None or older_item > deadline)
):
return []
# We want to delete first the cache items that were accessed a
# long time ago
items.sort(key=operator.attrgetter("last_access"))
items_to_delete = []
size_so_far = 0
items_so_far = 0
for item in items:
if (
(size_so_far >= to_delete_size)
and items_so_far >= to_delete_items
and (deadline is None or deadline < item.last_access)
):
break
items_to_delete.append(item)
size_so_far += item.size
items_so_far += 1
return items_to_delete
def _concurrency_safe_write(self, to_write, filename, write_func):
"""Writes an object into a file in a concurrency-safe way."""
temporary_filename = concurrency_safe_write(to_write, filename, write_func)
self._move_item(temporary_filename, filename)
def __repr__(self):
"""Printable representation of the store location."""
return '{class_name}(location="{location}")'.format(
class_name=self.__class__.__name__, location=self.location
)
class FileSystemStoreBackend(StoreBackendBase, StoreBackendMixin):
"""A StoreBackend used with local or network file systems."""
_open_item = staticmethod(open)
_item_exists = staticmethod(os.path.exists)
_move_item = staticmethod(concurrency_safe_rename)
def clear_location(self, location):
"""Delete location on store."""
if location == self.location:
rm_subdirs(location)
else:
shutil.rmtree(location, ignore_errors=True)
def create_location(self, location):
"""Create object location on store"""
mkdirp(location)
def get_items(self):
"""Returns the whole list of items available in the store."""
items = []
for dirpath, _, filenames in os.walk(self.location):
is_cache_hash_dir = re.match("[a-f0-9]{32}", os.path.basename(dirpath))
if is_cache_hash_dir:
output_filename = os.path.join(dirpath, "output.pkl")
try:
last_access = os.path.getatime(output_filename)
except OSError:
try:
last_access = os.path.getatime(dirpath)
except OSError:
# The directory has already been deleted
continue
last_access = datetime.datetime.fromtimestamp(last_access)
try:
full_filenames = [os.path.join(dirpath, fn) for fn in filenames]
dirsize = sum(os.path.getsize(fn) for fn in full_filenames)
except OSError:
# Either output_filename or one of the files in
# dirpath does not exist any more. We assume this
# directory is being cleaned by another process already
continue
items.append(CacheItemInfo(dirpath, dirsize, last_access))
return items
def configure(self, location, verbose=1, backend_options=None):
"""Configure the store backend.
For this backend, valid store options are 'compress' and 'mmap_mode'
"""
if backend_options is None:
backend_options = {}
# setup location directory
self.location = location
if not os.path.exists(self.location):
mkdirp(self.location)
# Automatically add `.gitignore` file to the cache folder.
# XXX: the condition is necessary because in `Memory.__init__`, the user
# passed `location` param is modified to be either `{location}` or
# `{location}/joblib` depending on input type (`pathlib.Path` vs `str`).
# The proper resolution of this inconsistency is tracked in:
# https://github.com/joblib/joblib/issues/1684
cache_directory = (
os.path.dirname(location)
if os.path.dirname(location) and os.path.basename(location) == "joblib"
else location
)
with open(os.path.join(cache_directory, ".gitignore"), "w") as file:
file.write("# Created by joblib automatically.\n")
file.write("*\n")
# item can be stored compressed for faster I/O
self.compress = backend_options.get("compress", False)
# FileSystemStoreBackend can be used with mmap_mode options under
# certain conditions.
mmap_mode = backend_options.get("mmap_mode")
if self.compress and mmap_mode is not None:
warnings.warn(
"Compressed items cannot be memmapped in a "
"filesystem store. Option will be ignored.",
stacklevel=2,
)
self.mmap_mode = mmap_mode
self.verbose = verbose
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