mirror of
https://github.com/SickGear/SickGear.git
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456 lines
16 KiB
Python
456 lines
16 KiB
Python
"""Django-compatible disk and file backed cache."""
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from functools import wraps
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from django.core.cache.backends.base import BaseCache
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try:
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from django.core.cache.backends.base import DEFAULT_TIMEOUT
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except ImportError: # pragma: no cover
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# For older versions of Django simply use 300 seconds.
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DEFAULT_TIMEOUT = 300
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from .core import ENOVAL, args_to_key, full_name
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from .fanout import FanoutCache
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class DjangoCache(BaseCache):
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"""Django-compatible disk and file backed cache."""
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def __init__(self, directory, params):
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"""Initialize DjangoCache instance.
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:param str directory: cache directory
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:param dict params: cache parameters
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"""
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super().__init__(params)
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shards = params.get('SHARDS', 8)
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timeout = params.get('DATABASE_TIMEOUT', 0.010)
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options = params.get('OPTIONS', {})
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self._cache = FanoutCache(directory, shards, timeout, **options)
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@property
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def directory(self):
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"""Cache directory."""
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return self._cache.directory
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def cache(self, name):
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"""Return Cache with given `name` in subdirectory.
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:param str name: subdirectory name for Cache
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:return: Cache with given name
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"""
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return self._cache.cache(name)
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def deque(self, name, maxlen=None):
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"""Return Deque with given `name` in subdirectory.
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:param str name: subdirectory name for Deque
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:param maxlen: max length (default None, no max)
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:return: Deque with given name
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"""
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return self._cache.deque(name, maxlen=maxlen)
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def index(self, name):
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"""Return Index with given `name` in subdirectory.
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:param str name: subdirectory name for Index
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:return: Index with given name
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"""
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return self._cache.index(name)
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def add(
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self,
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key,
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value,
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timeout=DEFAULT_TIMEOUT,
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version=None,
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read=False,
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tag=None,
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retry=True,
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):
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"""Set a value in the cache if the key does not already exist. If
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timeout is given, that timeout will be used for the key; otherwise the
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default cache timeout will be used.
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Return True if the value was stored, False otherwise.
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:param key: key for item
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:param value: value for item
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:param float timeout: seconds until the item expires
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(default 300 seconds)
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:param int version: key version number (default None, cache parameter)
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:param bool read: read value as bytes from file (default False)
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:param str tag: text to associate with key (default None)
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:param bool retry: retry if database timeout occurs (default True)
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:return: True if item was added
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"""
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# pylint: disable=arguments-differ
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key = self.make_key(key, version=version)
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timeout = self.get_backend_timeout(timeout=timeout)
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return self._cache.add(key, value, timeout, read, tag, retry)
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def get(
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self,
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key,
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default=None,
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version=None,
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read=False,
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expire_time=False,
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tag=False,
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retry=False,
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):
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"""Fetch a given key from the cache. If the key does not exist, return
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default, which itself defaults to None.
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:param key: key for item
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:param default: return value if key is missing (default None)
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:param int version: key version number (default None, cache parameter)
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:param bool read: if True, return file handle to value
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(default False)
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:param float expire_time: if True, return expire_time in tuple
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(default False)
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:param tag: if True, return tag in tuple (default False)
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:param bool retry: retry if database timeout occurs (default False)
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:return: value for item if key is found else default
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"""
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# pylint: disable=arguments-differ
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key = self.make_key(key, version=version)
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return self._cache.get(key, default, read, expire_time, tag, retry)
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def read(self, key, version=None):
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"""Return file handle corresponding to `key` from Cache.
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:param key: Python key to retrieve
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:param int version: key version number (default None, cache parameter)
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:return: file open for reading in binary mode
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:raises KeyError: if key is not found
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"""
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key = self.make_key(key, version=version)
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return self._cache.read(key)
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def set(
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self,
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key,
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value,
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timeout=DEFAULT_TIMEOUT,
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version=None,
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read=False,
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tag=None,
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retry=True,
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):
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"""Set a value in the cache. If timeout is given, that timeout will be
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used for the key; otherwise the default cache timeout will be used.
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:param key: key for item
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:param value: value for item
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:param float timeout: seconds until the item expires
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(default 300 seconds)
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:param int version: key version number (default None, cache parameter)
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:param bool read: read value as bytes from file (default False)
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:param str tag: text to associate with key (default None)
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:param bool retry: retry if database timeout occurs (default True)
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:return: True if item was set
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"""
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# pylint: disable=arguments-differ
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key = self.make_key(key, version=version)
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timeout = self.get_backend_timeout(timeout=timeout)
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return self._cache.set(key, value, timeout, read, tag, retry)
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def touch(self, key, timeout=DEFAULT_TIMEOUT, version=None, retry=True):
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"""Touch a key in the cache. If timeout is given, that timeout will be
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used for the key; otherwise the default cache timeout will be used.
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:param key: key for item
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:param float timeout: seconds until the item expires
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(default 300 seconds)
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:param int version: key version number (default None, cache parameter)
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:param bool retry: retry if database timeout occurs (default True)
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:return: True if key was touched
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"""
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# pylint: disable=arguments-differ
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key = self.make_key(key, version=version)
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timeout = self.get_backend_timeout(timeout=timeout)
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return self._cache.touch(key, timeout, retry)
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def pop(
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self,
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key,
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default=None,
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version=None,
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expire_time=False,
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tag=False,
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retry=True,
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):
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"""Remove corresponding item for `key` from cache and return value.
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If `key` is missing, return `default`.
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Operation is atomic. Concurrent operations will be serialized.
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:param key: key for item
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:param default: return value if key is missing (default None)
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:param int version: key version number (default None, cache parameter)
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:param float expire_time: if True, return expire_time in tuple
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(default False)
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:param tag: if True, return tag in tuple (default False)
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:param bool retry: retry if database timeout occurs (default True)
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:return: value for item if key is found else default
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"""
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key = self.make_key(key, version=version)
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return self._cache.pop(key, default, expire_time, tag, retry)
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def delete(self, key, version=None, retry=True):
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"""Delete a key from the cache, failing silently.
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:param key: key for item
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:param int version: key version number (default None, cache parameter)
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:param bool retry: retry if database timeout occurs (default True)
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:return: True if item was deleted
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"""
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# pylint: disable=arguments-differ
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key = self.make_key(key, version=version)
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return self._cache.delete(key, retry)
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def incr(self, key, delta=1, version=None, default=None, retry=True):
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"""Increment value by delta for item with key.
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If key is missing and default is None then raise KeyError. Else if key
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is missing and default is not None then use default for value.
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Operation is atomic. All concurrent increment operations will be
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counted individually.
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Assumes value may be stored in a SQLite column. Most builds that target
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machines with 64-bit pointer widths will support 64-bit signed
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integers.
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:param key: key for item
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:param int delta: amount to increment (default 1)
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:param int version: key version number (default None, cache parameter)
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:param int default: value if key is missing (default None)
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:param bool retry: retry if database timeout occurs (default True)
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:return: new value for item on success else None
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:raises ValueError: if key is not found and default is None
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"""
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# pylint: disable=arguments-differ
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key = self.make_key(key, version=version)
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try:
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return self._cache.incr(key, delta, default, retry)
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except KeyError:
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raise ValueError("Key '%s' not found" % key) from None
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def decr(self, key, delta=1, version=None, default=None, retry=True):
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"""Decrement value by delta for item with key.
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If key is missing and default is None then raise KeyError. Else if key
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is missing and default is not None then use default for value.
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Operation is atomic. All concurrent decrement operations will be
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counted individually.
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Unlike Memcached, negative values are supported. Value may be
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decremented below zero.
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Assumes value may be stored in a SQLite column. Most builds that target
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machines with 64-bit pointer widths will support 64-bit signed
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integers.
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:param key: key for item
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:param int delta: amount to decrement (default 1)
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:param int version: key version number (default None, cache parameter)
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:param int default: value if key is missing (default None)
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:param bool retry: retry if database timeout occurs (default True)
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:return: new value for item on success else None
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:raises ValueError: if key is not found and default is None
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"""
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# pylint: disable=arguments-differ
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return self.incr(key, -delta, version, default, retry)
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def has_key(self, key, version=None):
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"""Returns True if the key is in the cache and has not expired.
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:param key: key for item
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:param int version: key version number (default None, cache parameter)
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:return: True if key is found
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"""
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key = self.make_key(key, version=version)
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return key in self._cache
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def expire(self):
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"""Remove expired items from cache.
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:return: count of items removed
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"""
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return self._cache.expire()
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def stats(self, enable=True, reset=False):
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"""Return cache statistics hits and misses.
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:param bool enable: enable collecting statistics (default True)
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:param bool reset: reset hits and misses to 0 (default False)
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:return: (hits, misses)
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"""
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return self._cache.stats(enable=enable, reset=reset)
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def create_tag_index(self):
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"""Create tag index on cache database.
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Better to initialize cache with `tag_index=True` than use this.
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:raises Timeout: if database timeout occurs
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"""
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self._cache.create_tag_index()
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def drop_tag_index(self):
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"""Drop tag index on cache database.
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:raises Timeout: if database timeout occurs
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"""
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self._cache.drop_tag_index()
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def evict(self, tag):
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"""Remove items with matching `tag` from cache.
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:param str tag: tag identifying items
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:return: count of items removed
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"""
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return self._cache.evict(tag)
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def cull(self):
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"""Cull items from cache until volume is less than size limit.
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:return: count of items removed
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"""
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return self._cache.cull()
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def clear(self):
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"""Remove *all* values from the cache at once."""
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return self._cache.clear()
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def close(self, **kwargs):
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"""Close the cache connection."""
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# pylint: disable=unused-argument
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self._cache.close()
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def get_backend_timeout(self, timeout=DEFAULT_TIMEOUT):
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"""Return seconds to expiration.
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:param float timeout: seconds until the item expires
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(default 300 seconds)
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"""
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if timeout == DEFAULT_TIMEOUT:
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timeout = self.default_timeout
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elif timeout == 0:
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# ticket 21147 - avoid time.time() related precision issues
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timeout = -1
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return None if timeout is None else timeout
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def memoize(
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self,
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name=None,
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timeout=DEFAULT_TIMEOUT,
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version=None,
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typed=False,
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tag=None,
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ignore=(),
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):
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"""Memoizing cache decorator.
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Decorator to wrap callable with memoizing function using cache.
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Repeated calls with the same arguments will lookup result in cache and
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avoid function evaluation.
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If name is set to None (default), the callable name will be determined
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automatically.
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When timeout is set to zero, function results will not be set in the
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cache. Cache lookups still occur, however. Read
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:doc:`case-study-landing-page-caching` for example usage.
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If typed is set to True, function arguments of different types will be
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cached separately. For example, f(3) and f(3.0) will be treated as
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distinct calls with distinct results.
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The original underlying function is accessible through the __wrapped__
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attribute. This is useful for introspection, for bypassing the cache,
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or for rewrapping the function with a different cache.
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An additional `__cache_key__` attribute can be used to generate the
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cache key used for the given arguments.
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Remember to call memoize when decorating a callable. If you forget,
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then a TypeError will occur.
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:param str name: name given for callable (default None, automatic)
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:param float timeout: seconds until the item expires
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(default 300 seconds)
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:param int version: key version number (default None, cache parameter)
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:param bool typed: cache different types separately (default False)
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:param str tag: text to associate with arguments (default None)
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:param set ignore: positional or keyword args to ignore (default ())
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:return: callable decorator
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"""
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# Caution: Nearly identical code exists in Cache.memoize
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if callable(name):
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raise TypeError('name cannot be callable')
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def decorator(func):
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"""Decorator created by memoize() for callable `func`."""
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base = (full_name(func),) if name is None else (name,)
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@wraps(func)
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def wrapper(*args, **kwargs):
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"""Wrapper for callable to cache arguments and return values."""
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key = wrapper.__cache_key__(*args, **kwargs)
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result = self.get(key, ENOVAL, version, retry=True)
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if result is ENOVAL:
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result = func(*args, **kwargs)
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valid_timeout = (
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timeout is None
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or timeout == DEFAULT_TIMEOUT
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or timeout > 0
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)
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if valid_timeout:
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self.set(
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key,
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result,
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timeout,
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version,
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tag=tag,
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retry=True,
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)
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return result
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def __cache_key__(*args, **kwargs):
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"""Make key for cache given function arguments."""
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return args_to_key(base, args, kwargs, typed, ignore)
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wrapper.__cache_key__ = __cache_key__
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return wrapper
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return decorator
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