wrw/session.py

   1 import threading, time, pickle, random, os
   2 import cookie, env
   3
   4 __all__ = ["db", "get"]
   5
   6 def hexencode(str):
   7     ret = ""
   8     for byte in str:
   9         ret += "%02X" % (ord(byte),)
  10     return ret
  11
  12 def gennonce(length):
  13     nonce = ""
  14     for i in xrange(length):
  15         nonce += chr(random.randint(0, 255))
  16     return nonce
  17
  18 class session(object):
  19     def __init__(self, lock, expire = 86400 * 7):
  20         self.id = hexencode(gennonce(16))
  21         self.dict = {}
  22         self.lock = lock
  23         self.ctime = self.atime = self.mtime = int(time.time())
  24         self.expire = expire
  25         self.dctl = set()
  26         self.dirtyp = False
  27
  28     def dirty(self):
  29         for d in self.dctl:
  30             if d.sessdirty():
  31                 return True
  32         return self.dirtyp
  33
  34     def frozen(self):
  35         for d in self.dctl:
  36             d.sessfrozen()
  37         self.dirtyp = False
  38
  39     def __getitem__(self, key):
  40         return self.dict[key]
  41
  42     def get(self, key, default = None):
  43         return self.dict.get(key, default)
  44
  45     def __setitem__(self, key, value):
  46         self.dict[key] = value
  47         if hasattr(value, "sessdirty"):
  48             self.dctl.add(value)
  49         else:
  50             self.dirtyp = True
  51
  52     def __delitem__(self, key):
  53         old = self.dict.pop(key)
  54         if old in self.dctl:
  55             self.dctl.remove(old)
  56         self.dirtyp = True
  57
  58     def __contains__(self, key):
  59         return key in self.dict
  60
  61     def __getstate__(self):
  62         ret = []
  63         for k, v in self.__dict__.items():
  64             if k == "lock": continue
  65             ret.append((k, v))
  66         return ret
  67
  68     def __setstate__(self, st):
  69         for k, v in st:
  70             self.__dict__[k] = v
  71         # The proper lock is set by the thawer
  72
  73 class db(object):
  74     def __init__(self, backdb = None, cookiename = "wrwsess", path = "/"):
  75         self.live = {}
  76         self.cookiename = cookiename
  77         self.path = path
  78         self.lock = threading.Lock()
  79         self.cthread = None
  80         self.freezetime = 3600
  81         self.backdb = backdb
  82
  83     def clean(self):
  84         now = int(time.time())
  85         with self.lock:
  86             clist = self.live.keys()
  87         for sessid in clist:
  88             with self.lock:
  89                 try:
  90                     entry = self.live[sessid]
  91                 except KeyError:
  92                     continue
  93             with entry[0]:
  94                 rm = False
  95                 if entry[1] == "retired":
  96                     pass
  97                 elif entry[1] is None:
  98                     pass
  99                 else:
 100                     sess = entry[1]
 101                     if sess.atime + self.freezetime < now:
 102                         try:
 103                             if sess.dirty():
 104                                 self.freeze(sess)
 105                         except:
 106                             if sess.atime + sess.expire < now:
 107                                 rm = True
 108                         else:
 109                             rm = True
 110                 if rm:
 111                     entry[1] = "retired"
 112                     with self.lock:
 113                         del self.live[sessid]
 114
 115     def cleanloop(self):
 116         try:
 117             while True:
 118                 time.sleep(300)
 119                 self.clean()
 120                 if len(self.live) == 0:
 121                     break
 122         finally:
 123             with self.lock:
 124                 self.cthread = None
 125
 126     def _fetch(self, sessid):
 127         while True:
 128             now = int(time.time())
 129             with self.lock:
 130                 if sessid in self.live:
 131                     entry = self.live[sessid]
 132                 else:
 133                     entry = self.live[sessid] = [threading.RLock(), None]
 134             with entry[0]:
 135                 if isinstance(entry[1], session):
 136                     entry[1].atime = now
 137                     return entry[1]
 138                 elif entry[1] == "retired":
 139                     continue
 140                 elif entry[1] is None:
 141                     try:
 142                         thawed = self.thaw(sessid)
 143                         if thawed.atime + thawed.expire < now:
 144                             raise KeyError()
 145                         thawed.lock = entry[0]
 146                         thawed.atime = now
 147                         entry[1] = thawed
 148                         return thawed
 149                     finally:
 150                         if entry[1] is None:
 151                             entry[1] = "retired"
 152                             with self.lock:
 153                                 del self.live[sessid]
 154                 else:
 155                     raise Exception("Illegal session entry: " + repr(entry[1]))
 156
 157     def fetch(self, req):
 158         now = int(time.time())
 159         sessid = cookie.get(req, self.cookiename)
 160         new = False
 161         with self.lock:
 162             if self.cthread is None:
 163                 self.cthread = threading.Thread(target = self.cleanloop)
 164                 self.cthread.setDaemon(True)
 165                 self.cthread.start()
 166         try:
 167             if sessid is None:
 168                 raise KeyError()
 169             sess = self._fetch(sessid)
 170         except KeyError:
 171             sess = session(threading.RLock())
 172             new = True
 173
 174         def ckfreeze(req):
 175             if sess.dirty():
 176                 if new:
 177                     cookie.add(req, self.cookiename, sess.id, self.path)
 178                     with self.lock:
 179                         self.live[sess.id] = [sess.lock, sess]
 180                 try:
 181                     self.freeze(sess)
 182                 except:
 183                     pass
 184         req.oncommit(ckfreeze)
 185         return sess
 186
 187     def thaw(self, sessid):
 188         if self.backdb is None:
 189             raise KeyError()
 190         data = self.backdb[sessid]
 191         try:
 192             return pickle.loads(data)
 193         except Exception, e:
 194             raise KeyError()
 195
 196     def freeze(self, sess):
 197         if self.backdb is None:
 198             raise TypeError()
 199         with sess.lock:
 200             data = pickle.dumps(sess, -1)
 201         self.backdb[sess.id] = data
 202         sess.frozen()
 203
 204     def get(self, req):
 205         return req.item(self.fetch)
 206
 207 class dirback(object):
 208     def __init__(self, path):
 209         self.path = path
 210
 211     def __getitem__(self, key):
 212         try:
 213             with open(os.path.join(self.path, key)) as inf:
 214                 return inf.read()
 215         except IOError:
 216             raise KeyError(key)
 217
 218     def __setitem__(self, key, value):
 219         if not os.path.exists(self.path):
 220             os.makedirs(self.path)
 221         with open(os.path.join(self.path, key), "w") as out:
 222             out.write(value)
 223
 224 default = env.var(db(backdb = dirback(os.path.join("/tmp", "wrwsess-" + str(os.getuid())))))
 225
 226 def get(req):
 227     return default.val.get(req)