+
−"File-based cache backend"
+
−
+
−import os
+
−import time
+
−try:
+
−    import cPickle as pickle
+
−except ImportError:
+
−    import pickle
+
−
+
−from django.core.cache.backends.base import BaseCache
+
−from django.utils.hashcompat import md5_constructor
+
−
+
−class CacheClass(BaseCache):
+
−    def __init__(self, dir, params):
+
−        BaseCache.__init__(self, params)
+
−
+
−        max_entries = params.get('max_entries', 300)
+
−        try:
+
−            self._max_entries = int(max_entries)
+
−        except (ValueError, TypeError):
+
−            self._max_entries = 300
+
−
+
−        cull_frequency = params.get('cull_frequency', 3)
+
−        try:
+
−            self._cull_frequency = int(cull_frequency)
+
−        except (ValueError, TypeError):
+
−            self._cull_frequency = 3
+
−
+
−        self._dir = dir
+
−        if not os.path.exists(self._dir):
+
−            self._createdir()
+
−
+
−    def add(self, key, value, timeout=None):
+
−        if self.has_key(key):
+
−            return False
+
−
+
−        self.set(key, value, timeout)
+
−        return True
+
−
+
−    def get(self, key, default=None):
+
−        fname = self._key_to_file(key)
+
−        try:
+
−            f = open(fname, 'rb')
+
−            exp = pickle.load(f)
+
−            now = time.time()
+
−            if exp < now:
+
−                f.close()
+
−                self._delete(fname)
+
−            else:
+
−                return pickle.load(f)
+
−        except (IOError, OSError, EOFError, pickle.PickleError):
+
−            pass
+
−        return default
+
−
+
−    def set(self, key, value, timeout=None):
+
−        fname = self._key_to_file(key)
+
−        dirname = os.path.dirname(fname)
+
−
+
−        if timeout is None:
+
−            timeout = self.default_timeout
+
−
+
−        self._cull()
+
−
+
−        try:
+
−            if not os.path.exists(dirname):
+
−                os.makedirs(dirname)
+
−
+
−            f = open(fname, 'wb')
+
−            now = time.time()
+
−            pickle.dump(now + timeout, f, pickle.HIGHEST_PROTOCOL)
+
−            pickle.dump(value, f, pickle.HIGHEST_PROTOCOL)
+
−        except (IOError, OSError):
+
−            pass
+
−
+
−    def delete(self, key):
+
−        try:
+
−            self._delete(self._key_to_file(key))
+
−        except (IOError, OSError):
+
−            pass
+
−
+
−    def _delete(self, fname):
+
−        os.remove(fname)
+
−        try:
+
−            # Remove the 2 subdirs if they're empty
+
−            dirname = os.path.dirname(fname)
+
−            os.rmdir(dirname)
+
−            os.rmdir(os.path.dirname(dirname))
+
−        except (IOError, OSError):
+
−            pass
+
−
+
−    def has_key(self, key):
+
−        fname = self._key_to_file(key)
+
−        try:
+
−            f = open(fname, 'rb')
+
−            exp = pickle.load(f)
+
−            now = time.time()
+
−            if exp < now:
+
−                f.close()
+
−                self._delete(fname)
+
−                return False
+
−            else:
+
−                return True
+
−        except (IOError, OSError, EOFError, pickle.PickleError):
+
−            return False
+
−
+
−    def _cull(self):
+
−        if int(self._num_entries) < self._max_entries:
+
−            return
+
−
+
−        try:
+
−            filelist = os.listdir(self._dir)
+
−        except (IOError, OSError):
+
−            return
+
−
+
−        if self._cull_frequency == 0:
+
−            doomed = filelist
+
−        else:
+
−            doomed = [os.path.join(self._dir, k) for (i, k) in enumerate(filelist) if i % self._cull_frequency == 0]
+
−
+
−        for topdir in doomed:
+
−            try:
+
−                for root, _, files in os.walk(topdir):
+
−                    for f in files:
+
−                        self._delete(os.path.join(root, f))
+
−            except (IOError, OSError):
+
−                pass
+
−
+
−    def _createdir(self):
+
−        try:
+
−            os.makedirs(self._dir)
+
−        except OSError:
+
−            raise EnvironmentError, "Cache directory '%s' does not exist and could not be created'" % self._dir
+
−
+
−    def _key_to_file(self, key):
+
−        """
+
−        Convert the filename into an md5 string. We'll turn the first couple
+
−        bits of the path into directory prefixes to be nice to filesystems
+
−        that have problems with large numbers of files in a directory.
+
−
+
−        Thus, a cache key of "foo" gets turnned into a file named
+
−        ``{cache-dir}ac/bd/18db4cc2f85cedef654fccc4a4d8``.
+
−        """
+
−        path = md5_constructor(key.encode('utf-8')).hexdigest()
+
−        path = os.path.join(path[:2], path[2:4], path[4:])
+
−        return os.path.join(self._dir, path)
+
−
+
−    def _get_num_entries(self):
+
−        count = 0
+
−        for _,_,files in os.walk(self._dir):
+
−            count += len(files)
+
−        return count
+
−    _num_entries = property(_get_num_entries)