276 lines
8.3 KiB
Python
276 lines
8.3 KiB
Python
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import time
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import os
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import sys
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import hashlib
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import gc
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import shutil
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import platform
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import logging
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import warnings
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import pickle
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from pathlib import Path
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from typing import Dict, Any
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LOG = logging.getLogger(__name__)
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_CACHED_FILE_MINIMUM_SURVIVAL = 60 * 10 # 10 minutes
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"""
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Cached files should survive at least a few minutes.
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"""
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_CACHED_FILE_MAXIMUM_SURVIVAL = 60 * 60 * 24 * 30
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"""
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Maximum time for a cached file to survive if it is not
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accessed within.
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"""
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_CACHED_SIZE_TRIGGER = 600
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"""
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This setting limits the amount of cached files. It's basically a way to start
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garbage collection.
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The reasoning for this limit being as big as it is, is the following:
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Numpy, Pandas, Matplotlib and Tensorflow together use about 500 files. This
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makes Jedi use ~500mb of memory. Since we might want a bit more than those few
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libraries, we just increase it a bit.
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"""
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_PICKLE_VERSION = 33
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"""
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Version number (integer) for file system cache.
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Increment this number when there are any incompatible changes in
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the parser tree classes. For example, the following changes
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are regarded as incompatible.
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- A class name is changed.
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- A class is moved to another module.
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- A __slot__ of a class is changed.
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"""
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_VERSION_TAG = '%s-%s%s-%s' % (
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platform.python_implementation(),
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sys.version_info[0],
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sys.version_info[1],
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_PICKLE_VERSION
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)
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"""
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Short name for distinguish Python implementations and versions.
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It's a bit similar to `sys.implementation.cache_tag`.
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See: http://docs.python.org/3/library/sys.html#sys.implementation
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"""
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def _get_default_cache_path():
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if platform.system().lower() == 'windows':
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dir_ = Path(os.getenv('LOCALAPPDATA') or '~', 'Parso', 'Parso')
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elif platform.system().lower() == 'darwin':
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dir_ = Path('~', 'Library', 'Caches', 'Parso')
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else:
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dir_ = Path(os.getenv('XDG_CACHE_HOME') or '~/.cache', 'parso')
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return dir_.expanduser()
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_default_cache_path = _get_default_cache_path()
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"""
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The path where the cache is stored.
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On Linux, this defaults to ``~/.cache/parso/``, on OS X to
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``~/Library/Caches/Parso/`` and on Windows to ``%LOCALAPPDATA%\\Parso\\Parso\\``.
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On Linux, if environment variable ``$XDG_CACHE_HOME`` is set,
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``$XDG_CACHE_HOME/parso`` is used instead of the default one.
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"""
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_CACHE_CLEAR_THRESHOLD = 60 * 60 * 24
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def _get_cache_clear_lock_path(cache_path=None):
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"""
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The path where the cache lock is stored.
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Cache lock will prevent continous cache clearing and only allow garbage
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collection once a day (can be configured in _CACHE_CLEAR_THRESHOLD).
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"""
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cache_path = cache_path or _default_cache_path
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return cache_path.joinpath("PARSO-CACHE-LOCK")
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parser_cache: Dict[str, Any] = {}
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class _NodeCacheItem:
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def __init__(self, node, lines, change_time=None):
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self.node = node
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self.lines = lines
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if change_time is None:
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change_time = time.time()
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self.change_time = change_time
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self.last_used = change_time
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def load_module(hashed_grammar, file_io, cache_path=None):
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"""
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Returns a module or None, if it fails.
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"""
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p_time = file_io.get_last_modified()
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if p_time is None:
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return None
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try:
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module_cache_item = parser_cache[hashed_grammar][file_io.path]
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if p_time <= module_cache_item.change_time:
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module_cache_item.last_used = time.time()
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return module_cache_item.node
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except KeyError:
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return _load_from_file_system(
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hashed_grammar,
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file_io.path,
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p_time,
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cache_path=cache_path
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)
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def _load_from_file_system(hashed_grammar, path, p_time, cache_path=None):
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cache_path = _get_hashed_path(hashed_grammar, path, cache_path=cache_path)
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try:
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if p_time > os.path.getmtime(cache_path):
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# Cache is outdated
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return None
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with open(cache_path, 'rb') as f:
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gc.disable()
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try:
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module_cache_item = pickle.load(f)
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finally:
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gc.enable()
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except FileNotFoundError:
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return None
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else:
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_set_cache_item(hashed_grammar, path, module_cache_item)
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LOG.debug('pickle loaded: %s', path)
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return module_cache_item.node
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def _set_cache_item(hashed_grammar, path, module_cache_item):
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if sum(len(v) for v in parser_cache.values()) >= _CACHED_SIZE_TRIGGER:
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# Garbage collection of old cache files.
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# We are basically throwing everything away that hasn't been accessed
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# in 10 minutes.
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cutoff_time = time.time() - _CACHED_FILE_MINIMUM_SURVIVAL
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for key, path_to_item_map in parser_cache.items():
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parser_cache[key] = {
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path: node_item
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for path, node_item in path_to_item_map.items()
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if node_item.last_used > cutoff_time
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}
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parser_cache.setdefault(hashed_grammar, {})[path] = module_cache_item
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def try_to_save_module(hashed_grammar, file_io, module, lines, pickling=True, cache_path=None):
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path = file_io.path
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try:
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p_time = None if path is None else file_io.get_last_modified()
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except OSError:
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p_time = None
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pickling = False
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item = _NodeCacheItem(module, lines, p_time)
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_set_cache_item(hashed_grammar, path, item)
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if pickling and path is not None:
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try:
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_save_to_file_system(hashed_grammar, path, item, cache_path=cache_path)
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except PermissionError:
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# It's not really a big issue if the cache cannot be saved to the
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# file system. It's still in RAM in that case. However we should
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# still warn the user that this is happening.
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warnings.warn(
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'Tried to save a file to %s, but got permission denied.' % path,
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Warning
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)
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else:
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_remove_cache_and_update_lock(cache_path=cache_path)
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def _save_to_file_system(hashed_grammar, path, item, cache_path=None):
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with open(_get_hashed_path(hashed_grammar, path, cache_path=cache_path), 'wb') as f:
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pickle.dump(item, f, pickle.HIGHEST_PROTOCOL)
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def clear_cache(cache_path=None):
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if cache_path is None:
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cache_path = _default_cache_path
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shutil.rmtree(cache_path)
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parser_cache.clear()
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def clear_inactive_cache(
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cache_path=None,
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inactivity_threshold=_CACHED_FILE_MAXIMUM_SURVIVAL,
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):
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if cache_path is None:
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cache_path = _default_cache_path
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if not cache_path.exists():
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return False
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for dirname in os.listdir(cache_path):
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version_path = cache_path.joinpath(dirname)
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if not version_path.is_dir():
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continue
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for file in os.scandir(version_path):
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if file.stat().st_atime + _CACHED_FILE_MAXIMUM_SURVIVAL <= time.time():
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try:
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os.remove(file.path)
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except OSError: # silently ignore all failures
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continue
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else:
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return True
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def _touch(path):
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try:
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os.utime(path, None)
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except FileNotFoundError:
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try:
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file = open(path, 'a')
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file.close()
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except (OSError, IOError): # TODO Maybe log this?
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return False
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return True
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def _remove_cache_and_update_lock(cache_path=None):
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lock_path = _get_cache_clear_lock_path(cache_path=cache_path)
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try:
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clear_lock_time = os.path.getmtime(lock_path)
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except FileNotFoundError:
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clear_lock_time = None
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if (
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clear_lock_time is None # first time
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or clear_lock_time + _CACHE_CLEAR_THRESHOLD <= time.time()
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):
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if not _touch(lock_path):
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# First make sure that as few as possible other cleanup jobs also
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# get started. There is still a race condition but it's probably
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# not a big problem.
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return False
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clear_inactive_cache(cache_path=cache_path)
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def _get_hashed_path(hashed_grammar, path, cache_path=None):
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directory = _get_cache_directory_path(cache_path=cache_path)
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file_hash = hashlib.sha256(str(path).encode("utf-8")).hexdigest()
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return os.path.join(directory, '%s-%s.pkl' % (hashed_grammar, file_hash))
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def _get_cache_directory_path(cache_path=None):
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if cache_path is None:
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cache_path = _default_cache_path
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directory = cache_path.joinpath(_VERSION_TAG)
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if not directory.exists():
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os.makedirs(directory)
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return directory
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