Viewing file:  cache.py (2.57 KB) -rw-r--r--
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import hashlib
import logging
import os
import pwd
from contextlib import contextmanager
from dataclasses import dataclass
from typing import ContextManager, Optional
from clwpos import constants, scoped_cache
def _get_cache_directory():
user = pwd.getpwuid(os.geteuid())
cache_dir = os.path.join(user.pw_dir, constants.USER_WPOS_DIR, '.cache')
os.makedirs(cache_dir, exist_ok=True)
return cache_dir
def _get_wp_config_modification_ts(wp_path):
try:
return os.path.getmtime(os.path.join(wp_path, 'wp-config.php'))
except FileNotFoundError:
return os.path.getmtime(os.path.join(wp_path, '../wp-config.php'))
@dataclass
class CacheRecord:
# any data that we would like to save
# important! do not use pickle or any other serializable
# data format that might be loaded in root environment
data: Optional[str]
# marker which becomes true whenever we change our data
is_dirty: bool = False
def __setattr__(self, key, value):
super().__setattr__('is_dirty', True)
super().__setattr__(key, value)
@contextmanager
def wp_config_cache(key, path) -> ContextManager[CacheRecord]:
# there is no need to cache these values
# in not actively requested places
if not scoped_cache.CACHING_ENABLED:
yield CacheRecord(data=None)
return
ts = _get_wp_config_modification_ts(wp_path=path)
record = CacheRecord(
data=get(key, path, valid_after_ts=ts))
try:
yield record
finally:
if record.is_dirty:
set(key, path, record.data)
def get(key: str, path: str, valid_after_ts: float) -> Optional[str]:
cache_file = os.path.join(
_get_cache_directory(), f'{key}.{hashlib.md5(path.encode()).hexdigest()}.cache')
try:
# if file was modified earlier than timestamp,
# we assume that cache is expired
if os.path.getmtime(cache_file) < valid_after_ts:
logging.info('Cache "%s" assumed to be outdated', key)
return None
with open(cache_file, 'r') as f:
cache_info_raw = f.read()
except (IOError, OSError):
# assume that file does not exist
# or we don't have access
logging.info('Cache "%s" is not existing or malformed', key)
return None
return cache_info_raw
def set(key: str, path:str, value: str) -> None:
cache_file = os.path.join(
_get_cache_directory(), f'{key}.{hashlib.md5(path.encode()).hexdigest()}.cache')
try:
with open(cache_file, 'w') as f:
f.write(value)
except (IOError, OSError):
return None
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