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MAINT: move cache helper functions to
sympy._cache
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,87 @@ | ||
| """Helper functions for :func:`.perform_cached_doit`.""" | ||
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| from __future__ import annotations | ||
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| import functools | ||
| import hashlib | ||
| import logging | ||
| import os | ||
| import pickle # noqa: S403 | ||
| import sys | ||
| from textwrap import dedent | ||
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| import sympy as sp | ||
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| _LOGGER = logging.getLogger(__name__) | ||
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| def get_system_cache_directory() -> str: | ||
| r"""Return the system cache directory for the current platform. | ||
| >>> import sys, pytest | ||
| >>> if sys.platform.startswith("darwin"): | ||
| ... assert get_system_cache_directory().endswith("/Library/Caches") | ||
| >>> if sys.platform.startswith("linux"): | ||
| ... assert get_system_cache_directory().endswith("/.cache") | ||
| >>> if sys.platform.startswith("win"): | ||
| ... assert get_system_cache_directory().endswith(R"\AppData\Local") | ||
| """ | ||
| if sys.platform.startswith("linux"): | ||
| cache_directory = os.getenv("XDG_CACHE_HOME") | ||
| if cache_directory is not None: | ||
| return cache_directory | ||
| if sys.platform.startswith("darwin"): # macos | ||
| return os.path.expanduser("~/Library/Caches") | ||
| if sys.platform.startswith("win"): | ||
| cache_directory = os.getenv("LocalAppData") # noqa: SIM112 | ||
| if cache_directory is not None: | ||
| return cache_directory | ||
| return os.path.expanduser("~/AppData/Local") | ||
| return os.path.expanduser("~/.cache") | ||
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| def get_readable_hash(obj, ignore_hash_seed: bool = False) -> str: | ||
| """Get a human-readable hash of any hashable Python object. | ||
| The algorithm is fastest if `PYTHONHASHSEED | ||
| <https://docs.python.org/3/using/cmdline.html#envvar-PYTHONHASHSEED>`_ is set. | ||
| Otherwise, it falls back to computing the hash with :func:`hashlib.sha256()`. | ||
| Args: | ||
| obj: Any hashable object, mutable or immutable, to be hashed. | ||
| ignore_hash_seed: Ignore the :code:`PYTHONHASHSEED` environment variable. If | ||
| :code:`True`, the hash seed is ignored and the hash is computed with | ||
| :func:`hashlib.sha256`. | ||
| """ | ||
| python_hash_seed = _get_python_hash_seed() | ||
| if ignore_hash_seed or python_hash_seed is None: | ||
| b = _to_bytes(obj) | ||
| return hashlib.sha256(b).hexdigest() | ||
| return f"pythonhashseed-{python_hash_seed}{hash(obj):+}" | ||
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| def _to_bytes(obj) -> bytes: | ||
| if isinstance(obj, sp.Expr): | ||
| # Using the str printer is slower and not necessarily unique, | ||
| # but pickle.dumps() does not always result in the same bytes stream. | ||
| _warn_about_unsafe_hash() | ||
| return str(obj).encode() | ||
| return pickle.dumps(obj) | ||
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| def _get_python_hash_seed() -> int | None: | ||
| python_hash_seed = os.environ.get("PYTHONHASHSEED", "") | ||
| if python_hash_seed is not None and python_hash_seed.isdigit(): | ||
| return int(python_hash_seed) | ||
| return None | ||
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| @functools.lru_cache(maxsize=None) # warn once | ||
| def _warn_about_unsafe_hash(): | ||
| message = """ | ||
| PYTHONHASHSEED has not been set. For faster and safer hashing of SymPy expressions, | ||
| set the PYTHONHASHSEED environment variable to a fixed value and rerun the program. | ||
| See https://docs.python.org/3/using/cmdline.html#envvar-PYTHONHASHSEED | ||
| """ | ||
| message = dedent(message).replace("\n", " ").strip() | ||
| _LOGGER.warning(message) |
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